Ultra-precision grinding

CIRP Annals - Manufacturing Technology 59 (2010) 652–671

Ultra-precision grinding

E. Brinksmeier (1)a,*, Y. Mutlugunes a, F. Klocke (1)b, J.C. Aurich (1)c, P. Shore (2)d, H. Ohmori (2)e

a University of Bremen, Laboratory for Precision Machining (LFM), Germanyb RWTH Aachen University, Laboratory for Machine Tools and Production Engineering (WZL), Germanyc Technical University of Kaiserslautern, Institute for Manufacturing Engineering and Production Management (FBK), Germanyd Cranfield University, School of Applied Sciences, England, UKe The Institute of Physical and Chemical Research (RIKEN), Japan

A R T I C L E I N F O

Keywords:

Ultra-precision

Grinding

Finishing

A B S T R A C T

Ultra-precision grinding is primarily used to generate high quality and functional parts usually made

from hard and difficult to machine materials. The objective of ultra-precision grinding is to generate parts

with high surface finish, high form accuracy and surface integrity for the electronic and optical industries

as well as for astronomical applications. This keynote paper introduces general aspects of ultra-precision

grinding techniques and point out the essential features of ultra-precision grinding. In particular, the

keynote paper reviews the state-of-the-art regarding applied grinding tools, ultra-precision machine

tools and grinding processes. Finally, selected examples of advanced ultra-precision grinding processes

are presented.

� 2010 CIRP.

Contents lists available at ScienceDirect

CIRP Annals - Manufacturing Technology

journal homepage: http: / /ees.elsevier.com/cirp/default .asp

[(Fig._1)TD$FIG]

1. Introduction

During the last decades the demand for high precision parts hasstrongly increased. Such parts entered a wide range of applicationsin the optical, automotive, and communication industry as well asin medical and life sciences. Ultra-precision machining of non-ferrous metals can reliably be achieved by precision cuttingprocesses which are deterministic. By contrast, hard and brittlematerials like ceramics, carbides, glasses, hardened steel, orsemiconductor materials have to be machined by abrasiveprocesses. The machining of high precision parts by abrasiveprocesses, however, is more difficult due to their complex and non-deterministic nature.

In this sense ultra-precision grinding is primarily used togenerate high quality and functional parts usually made fromdifficult to machine materials. The aim of ultra-precision grindingprocesses is to generate parts with high surface finish, high formaccuracy and high surface integrity. For example, such processesare applied for the manufacturing of moulds for the replication ofoptical elements. In optical mould machining first a fine grindingprocess is applied yielding an acceptable form accuracy, butinsufficient roughness. Also microcracks may occur degradingsurface integrity. Therefore, subsequent polishing processes haveto be applied. The polishing process yields a high surface integritybut is time consuming and expensive. For reducing time and coststhe surface quality achievable by precision grinding processesbecomes more important.

The high relevance of ultra-precision grinding for industrialproduction becomes obvious by the increasing number ofpublications in this field over the last decades (Fig. 1).

* Corresponding author.

E-mail address: [email protected] (E. Brinksmeier).

0007-8506/$ – see front matter � 2010 CIRP.

doi:10.1016/j.cirp.2010.05.001

However, since ultra-precision grinding covers a wide range ofapplications, every piece of research focuses on a specific topic. Thus,a commonly accepted general definition of ultra-precision grindingdoes not exist. Therefore, an attempt is made in this keynote paper tocharacterize ultra-precision grinding and to work out some generalaspects and physical principles before considering specific require-ments on grinding machines, tools and process parameters.Examples of advanced ultra-precision grinding processes indifferent fields of application form a major part of this paper.

Fig. 1. Number of publications (Literature search with online-database FIZ-DOMA/-

WEMA).

http://dx.doi.org/10.1016/j.cirp.2010.05.001

mailto:[email protected]

http://www.sciencedirect.com/science/journal/00078506

http://dx.doi.org/10.1016/j.cirp.2010.05.001

E. Brinksmeier et al. / CIRP Annals - Manufacturing Technology 59 (2010) 652–671 653

Writing this keynote paper and bringing it to its final formatwas only possible through the active support of many CIRPcolleagues and their scientific staff. The authors therefore grate-fully acknowledge the contributions of a number of scientists andCIRP STC G members. Among these are:

� B
. Denkena – Institute of Production Engineering and Machine
Tools, Hannover, Germany,
� R . Hahn – Hahn Engineering, Inc., Tampa, USA, � F . Hashimoto – The Timken Company, Canton, USA, � K . Katahira – The Institute of Physical and Chemical Research
(RIKEN), Saitama, Japan,
� D . Stephenson – Cranfield University, Bedford, UK, � B . Zhang – University of Connecticut, Connecticut, USA.
The authors also wish to express their sincere thanks to furtherco-workers for their effort in compiling this paper, namely

� M
aurice Herben – Fraunhofer Institute for Production Technology
(IPT), Aachen, Germany,
� A ndreas Klink – Laboratory for Machine Tools and Production
Engineering (WZL), Aachen, Germany,
� K athrin Meiners – Laboratory for Precision Machining (LFM),
Bremen, Germany,
� W erner Preuss – Laboratory for Precision Machining (LFM),
Bremen, Germany,
� K ai Rickens – Laboratory for Precision Machining (LFM), Bremen,
Germany,
� O ltmann Riemer – Laboratory for Precision Machining (LFM),
Bremen, Germany,
� S ven Twardy – Laboratory for Precision Machining (LFM), Bremen,
Germany and
� M
[(Fig._2)TD$FIG]

ichael Walk – Institute for Manufacturing Engineering and

Production Management (FBK), Kaiserslautern, Germany.

2. What is ultra-precision grinding?

Although everybody shares an intuitive understanding of whatultra-precision (UP) grinding is or should be, it is by no means easyto establish a set of criteria which would uniquely define a UP-grinding process. The reason is that UP-grinding is a dynamic fieldof research where different methods and technological conceptsare being explored. A general agreement on the surface quality andsub-surface integrity achievable by UP-grinding does not yet exist.Any attempt to characterize UP-grinding in its present state,therefore, has to take into account its innovative nature andunexplored limitations. In this situation the best which canpossibly be done is to formulate an ideal technological goal and askwhether this has been reached or how far we are away from it.Taniguchi described ultra-precision machining as those technol-ogies by which the highest possible dimensional accuracy is, or hasbeen achieved [190].

Starting from our naive understanding of UP-grinding, it couldbe argued that we should hope to achieve by grinding of brittlematerials a similar surface quality and sub-surface integrity as isachievable by UP-turning and -milling of ductile materialscommonly realized by diamond machining. Since there aredifferent approaches to UP-grinding, it is worthwhile recallingwhat the essential features of a grinding process are. Thus, UP-grinding is a material removal process

(1) w
ith fixed abrasives (in order to distinguish it from lapping andpolishing),
(2) w
hich are in interrupted contact with the workpiece surface (inorder to distinguish it from honing), and
(3) w

Fig. 2. Classification of precision and microgrinding with respect to polishing and

conventional grinding based on material removal rate and grain size [116].

here the abrasive surface is characterized by at least onestatistical distributed parameter (in order to exclude millingbut to include grinding with specially designed or ‘‘engineered’’wheels).

An ideal UP-grinding process should yield functionalsurfaces with a surface finish adequate for optical applications(but not exclusively optical applications), i.e.

(4) a
root-mean-squares figure accuracy <l/10 with l < 1 mm, (5) a surface roughness Sq <l/100, and (6) a damage-free sub-surface zone for avoiding light scatter (in the
case of optically transparent materials) and/or crack formation(under load, or even without).

Moreover, which is an implicit but important requirement, aUP-grinding process (like other UP-machining processes)should be deterministic, i.e.

(7) fi
gure, roughness, and damage tolerances should be reached inone single machining step (in order to avoid iterative oradditional machining and testing).
This last requirement turns out to be the biggest challenge forUP-grinding, since it can only be realized with special machinetools with high loop stiffness and special grinding tools which donot wear significantly (or do wear in a predictable way) duringoperation.

It is clear that only very few UP-grinding techniques developedup to date will meet all theses requirements. Thus, UP-grinding inits present state could be defined as a process which is ‘‘reasonablyclose to’’, or ‘‘aiming at’’, the above requirements, where the exactmeaning of this statement must be left open for discussion.

Apart from the academic interest in UP-grinding, an importantpractical concern (which actually is the ultimate technology driverfor the development of UP-grinding) is the reduction of machiningcosts (market driver). UP-grinding is supposed to substitute, oneday not far in the future, many of the traditional but time-consuming machining processes like fine grinding + lapping and/or polishing which, in some cases, make production prohibitivelyexpensive.

In literature many different terms have been used like precisiongrinding, microgrinding [116], ductile-regime grinding [9,11,12],ductile-regime finish machining [124], semi-ductile machining,semi-ductile mode machining [225,226], ductile-regime removal[95,166,167] or ELID grinding [126,127,129].

Miyashita [116], for example, used the proposed specificmaterial removal rate Q 0w and the grain size dg to define the gapbetween polishing and conventional grinding as a precision ormicrogrinding process (Fig. 2).

In general, ‘‘ultra-precision grinding’’ is used in literature as agrinding process for the generation of parts with low surfaceroughness, high form accuracy and high surface integrity. Thisprocess is based on the material removal mechanism which is atthe borderline of brittle-to-ductile transition implying the transi-tion from ductile material removal with no or little sub-surfacedamage to brittle material removal with material cracks andoutbreaks. Fig. 3 shows that soft materials are generally machinedby cutting processes. These processes are quite well understoodand nearly deterministic. Therefore, ultra-precision machiningtechnology can serve as a base for a general characterization ofultra-precision grinding.

However, UP-grinding is not completely characterized byquality criteria. UP-grinding is an abrasive process whose choicedepends on the workpiece material to be machined. Moreover, UP-grinding is a very unique process requiring fine grained wheels,

[(Fig._5)TD$FIG]

Fig. 5. Influence of stress state on shear strength tB, shear yield stress tF and plastic

deformation of hard and brittle materials (according to [120]).

[(Fig._3)TD$FIG]

Fig. 3. Classification of ultra-precision machining depending on material, material

removal mechanism, and process.

E. Brinksmeier et al. / CIRP Annals - Manufacturing Technology 59 (2010) 652–671654

wear resistant abrasives, low run-out spindles and machine toolswith a high loop stiffness.

The ultra-precision grinding process is characterized bymaterial removal with depths of cut in the sub-micrometer rangeoften in ductile mode, low feed and specific removal rates, andcutting speeds up to 30 m/s.

In summary, it can be stated that a simple characterization forultra-precision grinding is neither known nor obvious. But, asdiscussed above, all known processes summarized under the brand‘‘ultra-precision grinding’’ have certain aspects in common. Partquality and the mechanical properties of the workpiece materialserve as a starting point for a characterization and lead to aselection of an abrasive process which should be ultra-precisiongrinding (Fig. 4). Additionally, depending on quality requirementsand material properties, the process itself and the applied toolshave to be specified. Moreover, the demands on the machine tooland on environmental conditions are important features of ultra-precision grinding.

3. Ductile/brittle mode grinding

Usually, grinding of hard and brittle materials causes micro-cracks which deteriorate surface quality. Thus, the transition frombrittle-to-ductile material removal is considered to be of greatimportance for ultra-precision grinding. Much research effort hasbeen spent to identify this transition and to understand theremoval mechanism.

The most important parameter for the transition from brittle-to-ductile behaviour in chip removal is the stress conditions in theworkpiece material around the cutting edge. From plasticity theoryand fracture mechanics it is known that the degree of plasticdeformation depends on temperature, strain rate, as well as on
[(Fig._4)TD$FIG]
Fig. 4. Features entering the characterization of ultra-precision grinding.

multi axial compression and tensile stress in the workpiece. Fig. 5illustrates the Coulomb-Mohr hypothesis which describes multiaxial compression and tensile stress conditions within crystallineand amorphous workpieces which cannot comply with high tensilestresses [120]. From this hypothesis it can be derived thathydrostatic compression stress fields in the shear plane arenecessary for ductile cutting of hard and brittle materials.

Many researchers have investigated the behaviour of hard andbrittle materials under hydrostatic compression[19,20,77,109,158]. It could be shown that hard and brittlematerials can be machined in ductile mode (i.e. visco-plasticmaterial flow) if the hydrostatic compression and shear stressesare sufficiently high. Fig. 6 shows exemplary scratch tracks made insingle-crystalline {1 1 1}-silicon. Whereas the scratch underambient pressure shows only brittle material behaviour, thescratch under 200 MPa was cut in ductile mode with only a fewbrittle material reactions. This comes along with an increase of thecritical depth of cut from less than 50 nm at ambient pressure toapprox. 850 nm under a hydrostatic pressure of 200 MPa [22].

Thus, ductile machining of hard and brittle materials is acomplex interaction between tool geometry, process parametersand material response [14–16].

Schinker et al. showed that hydrostatic compression withoverlaid shear stresses is a prerequisite for ductile machining ofglasses [160–165]. This condition can be met by applying cuttingtools with negative rake angle for cutting processes and bondedabrasives for abrasive processes. Due to the negative rake angle thefrictional heat in the material increases. Thus, the workpiece can bemachined in ductile mode (Fig. 7).

Giovanola, Puttik and Fang et al. investigated the machinabilityof glass workpieces by indentation, plunge cut and turningexperiments [45,46,48,54,150]. They observed ductile materialremoval of glass by applying a diamond cutting tool with a[(Fig._6)TD$FIG]

Fig. 6. Nomarski microscope images of silicon scratch tracks generated under

ambient pressure (top) and 200 MPa hydrostatic pressure (bottom) [22].

[(Fig._7)TD$FIG]

Fig. 7. Cross-sectional cutting area in glass machining with shear zone of glass

lamellae (left) and glass surface with flow lines and tool-paths (right) [164].

[(Fig._9)TD$FIG]

Fig. 9. Critical depths of cut ae,crit of optical glass [88].


negative rake angle of g = �308 and by not exceeding a criticaluncut chip thickness, which depends on the rake angle and theradius of the applied cutting tool. The glass workpiece wasmachined in ductile mode while curled glass chips occurred.

The material removal mechanism of optical glass by grindingstrongly depends on the depth of cut. This dependence has beenconfirmed by many researchers [25,145,149,174]. The contact ofthe abrasives with the machined substrate leads to elastic materialresponse and, with increasing depth of cut, to plastic behaviour, i.e.‘‘micro-grooving’’ and ‘‘micro-ploughing’’ (Fig. 8a and b) [109,228].This type of interaction is defined by the grain tip radius and by itsoverall abrasive geometry. It does not only lead to lateraldeformation, but also to compression of the glass in the cuttingdirection [164]. An increasing depth of cut leads to ‘‘micro-cutting’’(Fig. 8c). Eventually, a further increase in depth of cut leads tomicrocracks below the workpiece surface (Fig. 8d).

A similar description of the material removal mechanisms ofbrittle materials has been given by Bifano, Busch, Koch, Namba andSwain [13,27,88,122,185], who performed plunge cut tests andgrinding experiments. The authors defined three removal mechan-isms: plastic ploughing, development of cracks and chip removal.

It has been shown in [88,89,93] that generating hydrostaticpressure and maintaining a critical chip thickness are prerequisitesfor crack free, ductile grinding of optical glasses. Ductile anddamage-free grinding of hard and brittle materials requires amaximum chip thickness hcu,max not exceeding the critical andmaterial specific chip thickness hid,crit to avoid crack initiation.Marshall et al. [111] showed by indentation tests that the criticalmaterial specific chip thickness hid,crit depends on Young’s modulusE, Knoop hardness HK and the critical fracture toughness Kc:

hid;crit �E

HK

� �Kc

HK

� �2

(1)

From Eq. (1) the critical chip thickness can be estimated.Bifano et al. [9,11] determined the proportionality factor by

indentation tests and the material specific chip thickness hid,crit

based on grinding processes to determine the ductile-brittletransition. In various grinding experiments of different brittlematerials this factor was found to be approx. 0.15.

Koch determined the critical depth of cut ae,crit for differentoptical glass grades and for the glass ceramic Zerodur [88] (Fig. 9).The critical depth of cut ranges from a few micrometers down to afew nanometers, mainly depending on material properties.

Blake, Blackley and Scattergood [14–16] machined hard andbrittle materials by single-point diamond turning. At the vertex ofa diamond radius tool, ductile machining takes place if a critical[(Fig._8)TD$FIG]

Fig. 8. Material removal mechanism in grinding of glass [174].

chip thickness hcu,crit is not exceeded. However, at other points ofthe engaged cutting edge, microcracks and fracture occured.

These results have been confirmed by single grain cuttingexperiments of glasses [117,164,219], semiconductor materials[39] and technical ceramics [185,195] which showed that thematerial removal mechanism depends on the depth of cut and onthe process forces.

4. Enabling technologies for ultra-precision grinding

As discussed before UP-grinding is strongly based on theavailability of appropriate enabling technologies, i.e. ultra-preci-sion machine tools, grinding tools, tool conditioning and grindingfluids. These will be characterized in the following.

4.1. Machine tools for ultra-precision grinding

Improved accuracy capability of machine tools has beenextensively researched. Taniguchi, who coined the phrase nano-technology, emphasised progressive accuracy capability of man-ufacturing processes which included grinding [189]. The basis forvolumetric geometric accuracy of machine tools was introduced byMcKeown [113]. Significance of the thermal effects in reducingmachining accuracy capability was identified by Bryan [26] andWeck [206], whilst the need for high dynamic loop stiffness wasdescribed by Weck [207]. Vanherck and Peters introduced the basicconcept of machine tool spindle error motions [203]. The work ofthese well recognised CIRP researchers has become embodied intonumerous international standards for describing improvedmachine tool accuracy.

In industry a number of the early ultra-precision grindingmachines were set up by the adaptation of grinding spindles todiamond turning machines. The driving force behind thesedevelopments was the growing demand for rapid manufactureof aspheric glass optics. Ultra-precision grinding was expected tobe a machining process by which optical surface quality could beachieved so that polishing time could be significantly reduced.Diamond turning of aspheric metal optics and of crystallinematerials (e.g. germanium) was already well established by themid 1980s, roughness of 3–5 nm rms and a form accuracy of100 nm p-v on 100 mm diameter parts being reliably achieved bydiamond turning systems [52]. Adding grinding spindles todiamond turning machines was carried out to extend ultra-precision machining to glass type materials that could noteffectively be machined by diamond turning [125,157].

During the same period the microelectronics sector had anumber of manufacturing demands whereby the reduction, orelimination, of polishing was considered a key enabler forimproving manufacturing capabilities and product quality. Pro-ducts including silicon wafer substrates, read/write heads andglass/ceramic memory disks [114] were identified notable


examples. All of these microelectronics applications demanded agrinding process that produced ultra-precise surfaces with lowsub-surface damage. The development of ultra-precision grindingmachines has also been motivated by demands from other sectorsthrough the adoption of advanced ceramic components [94].

In order to perform a high quality ultra-precision grindingprocess there are a number of requirements on the ultra-precisionmachine tool:

� P
recise, smooth, vibration and ‘‘backlash’’ free motions. � L ow levels of synchronous and asynchronous spindle errors. � H igh static/dynamic loop stiffness. � L
[(Fig._11)TD$FIG]

Fig. 11. CUPE OAGM large optic grinder.

[(Fig._10)TD$FIG]

Fig. 10. Tetraform C devised around the NPL Tetraform machine concept.

ong-term thermal dimensional control.

The above requirements are demonstrated through publica-tions of notable ultra-precision machines. The techniques and sub-systems to achieve the above requirements have changed withtime. Selected examples are given here.

4.1.1. Precise, smooth, vibration and ‘‘backlash’’ free motions

In general, the smooth linear and rotary motions demanded byultra-precision grinding machines have been achieved using fluidfilm bearings [175]. For example, the Pneumo Ultra 200 andNanoform 600 aspheric generators were amongst the firstdiamond turning machines to be re-equipped for ultra-precisiongrinding. They employed oil film hydrostatic bearings for its linearaxes and had dedicated grinding facilities using high-speed air-bearing grinding spindles. Laser interferometers were used as thepositional transducers offering 10 nm resolution [220]. Smooth‘‘rumble free’’ motion was achieved by driving the main linearcarriage via a non-influencing coupling that connected to a ball-screw driven primary carriage. Another aspheric generatordiamond grinding machine was the CUPE Nanocentre [28]. Thismachine employed friction drive actuators to achieve smoothbacklash free motion for its linear axes with 1 nm resolution.Modern aspheric generator grinding machines are equipped withdirect drive linear motors that provide smooth drive in conjunctionwith hydrostatic bearing based linear bearings and high resolutionMoire fringe gratings offering 34 pm resolution [67].

4.1.2. Low levels of synchronous and asynchronous spindle errors

The statistical nature of grinding processes results in an‘‘averaging’’ of the cutting action of the grains. However, in orderto grind nanometer quality surfaces, it remains a requirement toachieve extremely low levels of asynchronous errors, which do notrepeat every spindle revolution. This demand is most significantfor surfaces that do not possess self-generation characteristics (e.g.aspherics, free forms, hybrid surfaces). In order to grind nanometersmooth surfaces of this type, complex wheel ‘‘tool-paths’’ arenecessary. Numerous ultra-precision machines have thereforebeen reported employing air-bearing spindles [37,121,123]. Suchspindles achieve asynchronous error motions of 5–10 nm p-p andsynchronous error values of 25–50 nm p-p. Ultra-precisiongrinding machines have been reported that employ hydrostaticoil bearings [170]. These achieve greater load capacity for a givensize with greater robustness than air bearings. Asynchronous andsynchronous error motions of these oil based spindles are reportedto be 15–25 nm and 50–100 nm, respectively.

4.1.3. High static/dynamic loop stiffness

The static loop stiffness demand of ultra-precision grinding is asignificant production issue when ultra-precise shape surfaces are tobe realized. This may appear counter-intuitive since ultra-precisiongrinding is often associated with low levels of materials removal.However, ultra-precision grinding tends to employ grinding wheelshaving fine micrometer scale abrasives. These fine wheels result in ahigh normal to tangential force ratio. Consequently, for producingprecise shape surfaces of nanometer roughness quality themachine’s stiffness must be high. Otherwise features such as ‘‘edge

roll off’’ are generated. To avoid ‘‘edge roll off’’, machines have beendeveloped having significant structure stiffness.

The CUPE 7 axes read/write head grinder made for IBM in theearly 1980s illustrates how important static loop stiffness was toavoid edge roll off on the ground read/write head components. Thestatic loop stiffness of this air-bearing based machine was reportedto be 180 N/mm [8].

The dynamic loop stiffness of ultra-precision grinding machineshas been a significant research topic. The Tetraform machinestructure, developed by Lindsey at NPL, was a notable machinedevelopment aiming to achieve greater levels of dynamic loopstiffness [102]. Subsequently, Corbett developed the Tetraform C[224] (Fig. 10) which demonstrated a correlation between inducedsub-surface damage, dynamic loop stiffness and material removalrate when ultra-precision grinding glasses and ceramics. Theimportance of dynamic stiffness in ultra-precision grinding isassociated with avoidance of harmonic features being generatedon the grinding wheel through non-uniform wear of the grindingwheel around its circumference. In this respect high dynamicstiffness is associated with high loop stiffness at frequenciessignificantly higher than the operating frequency of the grindingspindles [119].

4.1.4. Long-term thermal and dimensional control

Generally, thermal effects in machine tools are often a majorcontributor to workpiece inaccuracy. This finding is especially truein ultra-precision grinding of complex shape, large size surfaces. Inorder to avoid significant thermal errors in ultra-precision grindingmachines two approached have been adopted.

The first approach is illustrated by the OAGM large opticsgrinder (Fig. 11) at Eastman Kodak [97,209]. This machine employsa 3D metrology frame that actively corrects for the majorgeometric and thermally induced errors. The laser based metrologyframe concept, operating at sub-nanometer resolution, alsoactively corrects for ‘‘push off’’ variation that would typically beexperienced through wheel ‘‘dulling’’ and ‘‘edge roll off’’.

[(Fig._13)TD$FIG]

Fig. 13. Fracture surface of CBN grain: CBN-U (left) vs. CBN [70].


An alternative approach has been the utilisation of ultra-precisethermal control systems operating at milli-Kelvin resolutions. Herethermal equilibrium is maintained in the critical heat generatingmachine sub-systems, e.g. the grinding spindle bearings, motors,etc. A modern example of an ultra-precision grinding machine isthe BoX machine [173]. This ultra-precision grinding machineemploys a closed box shape structure, dual drive linear motions, insitu metrology frame, workpiece error compensation, hydrostaticfluid films bearings for all motions and highly sophisticatedthermal management system [172,197].

4.2. Tools for ultra-precision grinding

4.2.1. Abrasive types

Diamond and cubic boron nitride (CBN) are the two mostfrequently applied types of abrasives for ultra-precision grinding[36,70].

There are two types of diamond abrasives – natural andsynthetic diamond – both sharing high wear resistance, heatconductivity, hardness and a low coefficient of friction [3,18,104].

A significant drawback of diamond abrasives is its chemicalaffinity with some metallic materials leading to the transformationof the diamonds into graphite in case of high grinding tempera-tures [187]. This results in high wear when grinding these metallicmaterials that react with carbon to carbides, or grinding at hightemperatures [36]. For this reason diamond abrasives are mainlyapplied for grinding of brittle non-ferrous materials such as silicon,glass, ceramics or tungsten carbide.

Alternatively, diamond grains may be coated with suitablematerials for preventing them from oxidizing or other damagecaused by high temperature during bonding [205]. For example,coated diamonds have been found to improve the grinding ratioand reduce breakout of the diamond grains during the grindingprocess [71]. Furthermore, boron doped diamond grits have anoxidation temperature that is 200 K higher than conventionaldiamond grits [72].

Another approach for extending abrasive tool life is the use oftough and blocky-type, cube-octahedral coarse-grained diamondgrits (Fig. 12) for engineered diamond grinding wheels [23,61,62].These diamond grits possess high strength, thermal stability andabrasion resistance. Furthermore, because of the fine screeningprocedure highly uniform grains are used which ensures constantcutting process interactions. When combined with a titaniumcoating, these grits provide a high mechanical and chemicalbonding strength within the electroplating process which sig-nificantly reduces grain pull-out of the grits and, thus a quasi-wear-less, semi-deterministic grinding processes results.

A special type of abrasive is CVD (Chemical Vapor Deposition)poly-crystalline diamond films with sharp edges of micrometersize diamond crystallites which are used for micro-pencil grindingtools [51]. These types of tools are also referred to as bondlessdiamond grinding wheels [204].

Cubic boron nitride (CBN) has superior thermo-chemicalstability compared to diamond [36,70]. Ultrafine-crystalline CBN

[(Fig._12)TD$FIG]

Fig. 12. Engineered diamond grinding wheels for ultra-precision grinding processes

with blocky-type, cube-octahedral coarse diamond grits after electroplating and

after dressing [154].

(CBN-U) is a special type of CBN, which has a grinding ratio that iseight times higher, and a higher wear resistance than conventionalCBN [36,70] (Fig. 13). For grinding of ferrous components and othermaterials that react with diamond, cubic boron nitride is the bestchoice.

A special type of abrasive is silica EPD (electrophoreticdeposition) pellets, which are bonded to a brass disk and form acup-type grinding wheel. This type of grinding wheel is used inmirror grinding of silicon wafers [106,211]. The pellets consist ofsodium alginate as bonding agent and fine silica powder asabrasive.

4.2.2. Bonding of abrasives tools

Beside the abrasive itself the bonding of abrasive tools is ofmajor importance regarding the achievable quality and the overallgrinding performance [81,178]. The essential function of thebonding system is to hold the abrasive grains on the grinding toolas long as they are sharp, and to release them when they are blunt[81].

The major bond systems are metal-, resin-, and vitrifiedbonding [3,50].

Metal bonding can be separated into two different types:sintered metal bonding and electroplating. In ultra-precisiongrinding the sintered metal bond system is used for thin wheelswhich cut brittle materials, for example silicon wafers (slicing/dicing) [3] or for micro-pencil grinding tools [6,43]. Oftenelectroplated metal bonding is applied to single-layered grindingwheels with stochastically or well-defined positioning of thegrains [61,153]. High heat conductivity and good wear resistanceare the major benefits of metal bonded grinding tools.

Resin bond is made of synthetic resin or synthetic resincombinations. Today, the most common bond components forsynthetic resin bonded grinding wheels are phenol plasters orphenol resins. This bonding type allows high chipping volumes androtational speeds and is insensitive to shock or impact as well aslateral pressure. The main applications for resin bonded grindingwheels are rough grinding and abrasive machining [106]. For ultra-precision grinding, epoxy or polyester resins are used to generatehigh surface qualities by soft, smooth grinding or polishing, forexample in silicon wafer grinding. Polyurethane resin is appliedwhen a high elasticity of the abrasive is needed [106]. Vitrifiedbonds have a glass-like structure and are fabricated at hightemperatures from mineral fluxes such as feldspars, firing clays,ground glass frits and chemical fluxes [73]. Resin and vitrifiedbonds are used for surface grinding, as for example silicon wafergrinding [106]. Vitrified bonds have a higher strength to hold theabrasive grains and are easier to dress. The elastic modulus isnearly four times higher than that of resin bonding [36,187].

Special cases of ultra-precision grinding bonding types arerubber bonded grains and ceramic-forming polymer bonding. Inrubber bonding the abrasive grains are granulated with resin toavoid burying small grains in the rubber bond. These granules withdiameters of approx. 100 mm are dispersed in the rubber [218]. Themajor reason for the application of grinding tools with rubber andother elastic bonded abrasive layers is the excellent damping andtherefore the capability to generate surface roughness in thenanometer range [21]. A ceramic-forming polymer was developedby Sherwood [168] to avoid the oxidation or other damage to the

[(Fig._15)TD$FIG]

Fig. 15. Micro-pencil grinding tools: CVD coated [50], sintered [58] and

electroplated coating [6] (from left to right).


diamond grains during the baking process of vitrified bondingsystems. For preventing graphitization of diamond grains it ispossible to melt ceramic-forming polymers by heating at lowtemperatures [187].

4.2.3. Geometrical classification

Most grinding wheels applied in ultra-precision grinding aremade with diverse design concepts, e.g. with undefined or definedgrain setting, grooved wheels or cup wheels. Typically, the wheeldiameter ranges from 50 to 400 mm and the grain sizes from finegrained (�0.125 mm) to coarse grained (�200 mm). Such grindingwheels are used for machining of materials such as silica, silicon,compound semiconductors and materials for electronics compo-nents.

Grinding wheels with undefined grain distribution are the mostcommon type, where the abrasive is bonded to the perimeter of thewheel. Therefore, these grinding wheels are applied with radialfeed for surface grinding of optical products like lenses or mirrors.

Grinding tools with single electroplated abrasive layers oractively brazed grains with defined grain settings are rarelyapplied in ultra-precision grinding. However, Heinzel et al. [61]ground optical glass BK7 with an actively brazed diamond grindingwheel with well-defined grain positions and have demonstratedtheir advantage.

Cup wheels are a special type of grinding wheel. The abrasivelayer or the abrasive segments (grooved abrasive layers) are notarranged in radial direction on the rim of the wheel but are bondedin the axial direction. Cup wheels are used to machine very thinplane surfaces, for example in wafer grinding, mirror grinding andthinning (Fig. 14).

Grooved grinding wheels have deep grooves in their abrasivelayers or, alternatively, the abrasive consists of abrasive segmentsbonded to the wheel. These grooves are used to minimize the heattransfer into the workpiece by improving the cooling conditions[202]. In ultra-precision grinding the application of groovedgrinding wheels is mainly surface finishing, wafer grinding,thinning and mirror grinding with cup wheels.

4.2.4. Dicing blades

Dicing blades with thickness of 10 mm–1 mm are used forprecision cut-off grinding. Dicing blades consist of abrasive grainsof sizes from 1 to 46 mm, a metal bond (sintered or electroplated),and have a wheel diameter of 50–60 mm [98]. Furthermore, thevery thin dicing blades require highly breaking-resistant bondingtypes. Dicing blades are used for grooving, cutting and dicingsilicon, compound semiconductors, glass, ceramics, crystals, andmany other materials [112].

4.2.5. Micro-pencil grinding tools

Micro-pencil grinding tools are applied for generating micro-structures (Fig. 15). These tools are manufactured in differentways, e.g. tungsten carbide blanks electroplated with CBN ordiamond grains. Diameters down to 5 mm can be realized [6].

Another type of micro-pencil grinding tool is a sintered toolwhere the grains are bonded in a sintered bronze layer on atungsten carbide blank. Typically, sintered tools have diameters ofabout 200 mm [58].

[(Fig._14)TD$FIG]

Fig. 14. Cup wheel and 300 mm wafer (thickness 5 mm) [41].

A third type of micro-pencil grinding tool is CVD coated. Here ablank is coated with poly-crystalline diamond grinding layers. Aminimum tool diameter of 50 mm has been achieved [51]. Pencilgrinding tools are often used to manufacture complex three-dimensional microstructures. Common applications are formgrinding and jig grinding. This approach allows the structuringof hard and brittle materials which are particularly wear resistantand durable against chemicals for moulding applications or forfluid reactors or medical devices [43].

4.3. Tool conditioning and ELID grinding

During ultra-precision grinding of hard and brittle materials thecondition of the grinding tool before and during the process isinfluencing the process performance. Thus, successful ultra-precision grinding is only possible with a stable condition of thegrinding wheel over the whole grinding cycle. Generally, there aretwo tasks for the trueing and dressing operation:

(1) T
he desired macro-geometry has to be created by a profilingoperation before the process.
(2) A
suitable micro-geometry with an adequate grit protrusionmust be established by a sharpening operation.
Both geometries have to be maintained during the grindingoperation. If needed, additional trueing and dressing cycles have tobe added.

Fine grained diamond grinding wheels are often utilized for theprecision machining of functional surfaces in ‘‘optical quality’’(regarding form accuracy and surface roughness). In particular, fora combination with metal bonded systems, high profile reliabilityand high wear resistance together with high material removalrates can be achieved. Conventional trueing and dressing of thesegrinding wheels is difficult. Due to the small depth of cut in ultra-precision grinding and the small chip thickness, the grinding wheeldoes not sharpen itself. Therefore, the development of suitable pre-process and in-process trueing and dressing technologies is a focusof research. By utilizing thermal and electrochemical materialremoval there is no mechanical contact between tool andworkpiece as in conventional trueing and dressing with profileor form rollers. Therefore, a high wear of the tool and a mechanicaldamage of the grinding wheel can be avoided [80].

Before grinding, an EDM process can be efficiently used in orderto produce the desired profile of the grinding wheel [80,85].Different process variants have been investigated (Fig. 16).

By using a wire-EDM process, a high flexibility is given in orderto achieve nearly any macro- or even micro-geometry without theneed for an additional wear compensation. The use of block or diskelectrodes offers the advantage of higher system stiffness andhence an opportunity for higher material removal rates. On theother hand additional wear compensation could be required. Dueto the thermal material removal principle, very small dischargeenergies have to be used during the process in order to avoidthermal damage of the fine diamond grits. By applying suitableprocess conditions it is generally possible to create a desired gritprotrusion.

EDM trueing and dressing of the grinding wheel can be done onconventional EDM machines or in situ on the grinding machine

[(Fig._17)TD$FIG]

Fig. 17. Principle of on-machine electro discharge trueing and dressing [184].

[(Fig._16)TD$FIG]

Fig. 16. Process variants of electro discharge trueing and dressing methods for

circumferential grinding wheels [80].

[(Fig._19)TD$FIG]

Fig. 19. Further developments of ELID-technology [132,151].

[(Fig._20)TD$FIG]

Fig. 20. Further developments of ELID-technology (continuation) [128,130].


(Fig. 17). In the latter case clamping distortions and the alignmentof different machine systems can be avoided.

The electrochemical material removal (ECM) can be efficientlyused especially for continuous in-process dressing of grindingwheels. The metal bond is continuously removed during thegrinding process by electrolysis. Thus, the constant usage of sharpgrits can be guaranteed. In addition, the electrochemical materialremoval will not damage the diamond grits. The coolant used in thegrinding process also serves as an electrolyte for the ECM process.Rapid wear of the bond material can be avoided by a definedelectrochemical process in the passive area of the electrolysissystem [80]. This so-called ‘‘ELID grinding’’ technique was firstproposed by Nakagawa and Ohmori [131]. An oxide layerformation at the surface of the anode prevents excessive grindingwheel wear. Only due to the mechanical removal of the oxide layerduring grinding the electrolysis will continue. With suitableprocess parameters a dynamic equilibrium of oxide layer growthand removal will be formed. This will result in stable dressingconditions, and therefore in a stable finish grinding process. Theprinciple of ELID grinding is shown in Fig. 18.

For adaptation of the ELID process to different grindingkinematics several developments have been made (Figs. 19 and20). The ELID CG-Grinding set up allows the continuous dressingduring cup wheel grinding of flat and spherical workpieces. ELIDinterval dressing (ELID-II) is especially suited for internal grinding
[(Fig._18)TD$FIG]
Fig. 18. Principle of ELID grinding [131].

operations without space for a counter-electrode. ELID withoutadditional electrode (ELID-III) is used in microgrinding whereaccess to the electrode is also very difficult.

Nozzle-based ELID allows a very limited bond oxidation onlyinduced by the provision of hydroxide ions to the grinding wheelsurface. ELID grinding with an additional electrical potentialapplied to the workpiece enables a controlled oxidation of theworkpiece during grinding. This can efficiently be used for theformation of protecting oxide layers for example on titaniumalloys.

Especially for the trueing and dressing of micro-tools, processcombinations of EDM (for efficient rough machining) with ELIDtrueing and dressing (for softening of the bond material) andfinally conventional conditioning (for achieving sharpest edges)turned out to be very efficient [132,215].

Besides the trueing and dressing of metal bonded grindingwheels by EDM and ECM processes, several other tool conditioningtechniques have to be taken into account for fine grit sizes:

� C
onventional trueing by profile roller. � C onventional dressing by block sharpening. � C onventional trueing and dressing by dressing diamond and
multiple grain dresser.
� C rushing. � L aser trueing and dressing.
4.4. Grinding fluids

Grinding fluids are used to reduce the friction betweenworkpiece and grinding wheel and to conduct heat out of thegrinding zone in order to avoid thermal damages of the workpiecesurface. Generally, in ultra-precision grinding small depths of cutand hence small grain contact lengths occur. Small depths of cutresult in low grinding forces and heat flow into the workpiececompared to conventional grinding. Applying grinding fluids with

[(Fig._22)TD$FIG]

Fig. 22. Free-form and aspherical glass lenses [courtesy of: Docter1 Optics].

[(Fig._23)TD$FIG]

Fig. 23. Diamond cup wheel [courtesy of: Satisloh GmbH].


a high lubricant effect may prevent ductile material removal, sincethe normal forces increase due to high pressure in the contact zone[103]. Klocke et al. [82] showed that the pressure in the contactzone is proportional to the grinding wheel peripheral speed andthe viscosity of the grinding fluid. This leads to a degrading ofsurface roughness and contour accuracy achieved in the grindingprocess. Therefore, only water based grinding fluids should be usedin ultra-precision grinding.

In peripheral face grinding experiments the influence ofmineral oil and water based grinding fluids on the surfaceroughness was investigated [55]. The grinding experiments weredone with a fine grained resin bonded diamond wheel (D3), a depthof cut of 3 mm and a feed rate of 3 mm/min. The workpiecematerial was a titanium-nickel-nitride coated steel. Fig. 21 showsthat by using oil as coolant a surface roughness of about Sa = 30 nmwas achieved. While using water based coolant a surfacesroughness of about Sa = 10 nm is achievable.

5. Fields of application

Although ultra-precision grinding is a dynamic field of researchwhose potential has not yet been fully explored, a number ofimportant applications have evolved mainly in the optical,semiconductor, and communication industries. Ultra-precisiongrinding is employed as a pre-finish machining step in theproduction of glass lenses and other optical elements, and for themanufacturing of optical mould inserts for large volume produc-tion of aspherical lenses, e.g. for optical pick-up systems, sensorsand fibre coupling elements. Moreover, ultra-precision grinding,often with electrolytic in-process dressing (ELID), is used for smallbatch production of physical and astronomical instrumentation. Inthe wafer industry, ultra-precision grinding is of increasingimportance for the fabrication of large (300 mm diameter) siliconwafers. It is hoped that the future development of ultra-precisiongrinding will also stimulate the fabrication of microstructuredoptical mould inserts for the mass production of next generationillumination devices.

5.1. Grinding of glass optics

Optical glass lenses are used in digital cameras, scanners andprojectors but also for sensors and microscopes, telescopes andother optical equipment. Such optical elements are often flat,spherical and aspherical glasses lenses.

The choice of an ultra-precision grinding process is determinedby its specific field of application. Depending on contact conditions,three principle classes of process kinematics can be distinguished:area, line and point contact. Area and line contact kinematics areused for high and medium volume production in optics manu-facturing, where cup and pellet wheels are applied for thegeneration of flat and spherical geometries. For a smaller numberof workpieces as well as for prototype production, point contactkinematics is favourably used. Since workpiece and tool arecontacting just in one single point, this kinematic is highly flexible,

[(Fig._21)TD$FIG]

Fig. 21. Finish of titanium-nickel-nitride coated steel [55].

e.g. for the generation of aspherical and freeform surfaces, butlimited in productivity (Fig. 22).

For grinding of spherical optical lenses diamond grinding cupwheels and pellet grinding tools are used. Usually, three processsteps are required for generating optical lenses [79,89,91,176]:

(1) A

Fig.Sati

semi-finished lens will be ground with a diamond cup wheel(Fig. 23). In this process sub-surface damages cannot beavoided.

(2) T
his is followed by a fine grinding process with a pellet grindingtool to remove or reduce sub-surface damage and to generatethe final shape of the optical lens.
(3) T
he final process step is polishing for improving surfaceroughness and removing sub-surface damage.
Workpieces with aspherical and freeform surfaces are usuallyground by contour grinding (Fig. 24). Due to the point contactkinematics between the workpiece and the grinding wheel[(Fig._24)TD$FIG]

24. Contour grinding process for grinding asperical glass lenses [courtesy of:

sloh GmbH].


freeform and aspherical surfaces can be generated. For themanufacturing of aspherical surfaces peripheral grinding wheelswith grain sizes down to 10 mm are used [60,217].

The first systematical grinding experiments of optical glasseswere done by Kern [78] by face grinding with diamond cup wheelsand constant depth of cut. Based on the experiments of Kern,Pahlitzsch et al. [17,138,139,140] machined optical glasses by facegrinding and external cylindrical grinding. The focus of theseexperiments was to find out the influence of machiningparameters, tool specifications and grinding fluids on the grindingprocess. These experiments were fundamental for machining ofoptical glasses.

In the early 1980s Konig et al. [91,92] and Pahl [137] optimizedthe pre-grinding process for the generation of spherical glasssurfaces with diamond cup wheels. The results showed that highcutting speeds and fine grained wheels with grain sizes of 25–54 mm lead to superior surface roughness. Using diamond grindingcup wheels better surface roughness and shorter machining timescould be achieved. Also other publications showed that using cupwheels with grain sizes in the micron range can yield very highsurface quality [22,91,107].

Publications in the field of glass grinding with diamond palletswere done by [79,89,90,91]. In particular, Kleinevoß [79] showedin his research that the machining parameters and the toolspecifications are dominating the achievable surface quality. Onthis basis strategies for grinding different types of glasses weredeveloped.

Stephenson et al. [177] ground BK7 with ELID grinding and useda cast iron-bonded cup with a grain size of 2 mm at a wheel speedof 39 m/s, 5 mm depth of cut and feed rate of 5 mm/min. Thediameter of the cup wheel was 124 mm with a width of 4 mm. ELIDgrinding is influenced by the duty ratio and peak voltage. Theseparameters produce the corrosive layer on the cup wheel surface.Experimental results showed that different combinations of theduty ratio and peak voltage influence the ground surface of BK7glass. Fig. 25a shows a ground surface at 10% duty ratio and 60 Vpeak voltage. Several cracks were generated on the glass surfacewhich were caused by some blunt grains on the wheel surface.Increasing the duty ratio up to 70% and 60 V peak voltage results ina better surface (Fig. 25b). Only a few cracks can be found on theground surface. Fig. 25c shows the combination of 70% duty ratioand 90 V peak voltage. A surface nearly free of cracks and rubbingmarks was obtained.

Ball et al. [8] ground optical glasses BK7 and SF10 with an ELIDsystem developed by the authors. The grinding experiments werecarried out on an ultra-precision machine tool which had a loopstiffness of about 135 N/mm. Using their ELID system and metalbonded grinding wheels, glass samples with a surface roughness ofRa = 1–2 nm were ground. Moreover, very little sub-surface andsurface damages were found.
[(Fig._25)TD$FIG]
Fig. 25. Ground surfaces of BK7 glass with different ELID parameters measured with

optical microsopy (a) 10% duty ratio and 60 V peak voltage, (b) 70% duty ratio and

60 V peak voltage and (c) 70% duty ratio and 90 V peak voltage [177].

Mairlot [108] demonstrated in his work that the materialremoval was dominated by fracture. It could be shown thatgrinding of glasses with diamond abrasives was significantlydifferent from grinding with conventional abrasives. Grinding withdiamond abrasives lead to lower temperatures in the grinding zoneso that brittle material removal could be reduced substantially anda surfaces roughness of about Ra = 0.4 mm could be achieved.

Yoshioka [219] achieved a surface quality of Rmax = 2 nm bygrinding a flat glass surface with a cup wheel grinding machinebuilt by himself. This machine employed hydrostatic oil bearingsand an extremely high overall lop stiffness. The investigation of thesub-surface and surface of the glass samples showed very littledamage.

Bifano [10] built a special plunge mode grinding apparatus inwhich a cup wheel was mounted on a high precision air-bearingspindle. With different feedrates and types of grinding wheels abroad of glasses was ground. It was shown that glasses can bemachined in the ductile mode when the infeed rate was between1.5–75 nm per revolution. Also the influence of the grinding wheelbonding was investigated. The experiments showed that ductilematerial removal could be realized with resin bonded grindingwheels. The grain size should be about 4 mm (4000 mesh) forgrinding in the ductile mode.

Zhao et al. [224] studied the surface and sub-surface integrity ofdiamond-ground optical glasses after ELID grinding. With selectedmachining parameters and a 6–12 mm grain-size diamondgrinding wheel, nanometric quality surfaces (Ra < 5 nm) withminimal sub-surface damage depth (<0.5 mm) can be generated infused quartz (Fig. 26).

Namba [122] discovered that the maximum depth of cut bywhich ductile mode grinding is possible is not limited to thecalculated ‘‘critical depth’’ as described by Bifano (cf. chapter 2). On avery stiff grinding machine Namba demonstrated that glass can beground in ductile mode at depth of cuts larger than 10 mm. Nambapoints out the importance of the chip thickness in determining thematerial removal mode. According to Namba, it is the chip thicknessand not only the depth of cut which must be considered.

Shore [170] identified the grain size as the most importantparameter for achieving a surface roughness of Ra = 1–3 nm.Wheels with a grain size smaller than 6 mm provided smoothoptical surfaces. But after etching and polishing of the groundsamples sub-surfaces damages could be seen. The depth of the sub-surface damages was in the range of 1–10 mm and the majority ofthe micro-fracture extended to a depth of 1–2 mm.[(Fig._26)TD$FIG]

Fig. 26. Surface analysis of ground fused quartz surface (Ra < 5 nm) [224].

[(Fig._27)TD$FIG]

Fig. 27. Surface roughness analysis of ground BK7 glass substrates versus specific

material removal rate [154].

[(Fig._29)TD$FIG]

Fig. 29. Hot isostatic pressing [courtesy of: Fraunhofer IWM] and tungsten carbide

moulds with moulded lenses [courtesy of: Moore Nanotechnology Systems].


In contrast, Brinksmeier et al. [22,23] and Heinzel et al. [61,62]showed that also coarse-grained diamond grinding wheels withgrain sizes of 91 mm, 151 mm and 181 mm are capable to generatesurface roughness within the nanometer range on optical glasssubstrates. Here, single-layered, electroplated diamond grindingwheels were initially applied to a special developed dressingprocess, generating blunt diamond grains and a uniform abrasivetopography. Subsequent grinding experiments showed that thesedressed coarse-grained diamond wheels, in combination with lowspecific material removal rates, generated surface roughness downto approx. 20 nm and below (Fig. 27).

Sun et al. [180] ground BK7 glass in parallel and cross grindingmodes and investigated the grinding process, maximum chipthickness, ductile/brittle regime, surface roughness and the sub-surface damage. Special attention has been given to generatingcrack free surfaces by ductile mode grinding. With the polishing-etching method the depth of sub-surface damage has beenobtained. The sub-surface damage zone (microcracks) increaseswith an increase of the feed rate. In the centre of the workpiece nosub-surface damages was observed in both parallel and crossgrinding. The sub-surface damage morphology of each grindingmode varies because of the different relative movement betweenworkpiece and grinding wheel.

5.2. Optical mould manufacturing

In the last decade optical consumer devices have becomeconsiderably smaller and more complex, e.g. digital cameras(Fig. 28, left) and camera-equipped mobile phones, DVD recorders,blue-ray players as well as optical elements for fibre coupling andhigh power diodes (Fig. 28, right). Besides low surface roughnessand high form accuracy in the nanometer range, optical lenses
[(Fig._28)TD$FIG]
Fig. 28. Digital camera with moulded glass lens [courtesy of: Canon] and a v-step-

optic for power diode laser [courtesy of: Ingeneric GmbH].

require a high transparency (no sub-surface damage), high index ofrefraction without birefringence and high thermal and mechanicalstability [29,133,159,188,196]. These requirements can only bemet by glass lenses.

For the high volume manufacturing of glass lenses hotembossing and hot isostatic pressing are the most commonprecision mass replication techniques [74,101,182,183,188,196,213] (Fig. 29, left). These processes are characterized by hightemperatures near the transition temperature of the applied glass(400–800 8C or even above) [196,214] and high moulding forces(up to 25 kN). Therefore, suitable mould materials must possesshigh material hardness, high thermal stability and corrosionresistance [75,76,188,196]. Usually, binderless tungsten carbide(WC), silicon carbide (SiC) and silicon nitride (Si3N4) [76,212] arechosen as mould material (Fig. 29, right).

Unfortunately, grinding of these ceramic materials turns out tobe a non-deterministic and time-consuming process [29], if tighttolerances regarding surface roughness and form accuracy have tobe achieved [196].

In recent years, several grinding kinematics for the manufac-turing of moulds for glass moulding have been developed.According to Tohme [196] cross axis grinding is the most commongrinding technique which is useful for grinding of large convexaspherical moulds as well as shallow concave moulds for precisionglass moulding. In this technique the wheel rotational direction isopposite to the rotational direction of the workpiece, either with avertical or a horizontal grinding spindle. Grinding is carried out bya 2-axis movement, following a well-defined tool path [212]. Ingeneral, fine grained, resin bonded diamond grinding wheels, smalldepths of cut less than 0.5 mm and feed rates less than 0.5 mm/minare advisable [69] for achieving a high surface roughness qualityand minimized wheel wear.

The disadvantage of cross axis grinding is the clearancebetween the grinding shaft and the mould surface necessary forgrinding the vertex of concave moulds. This disadvantage can beovercome by tilting the grinding wheel axis by an angle a withrespect to the normal of the workpiece spindle axis, providing amore comfortable access to the workpiece surface. It also allows amore compact tool design with a smaller shaft length, increasingthe stiffness of the set up and hence improving the achievable formaccuracy. A parallel grinding process employing a ball shapedgrinding wheel, where the grinding spindle is tilted by 458 withrespect to the workpiece axis, was developed by Saeki et al. [159],which has been further investigated by several scientists andengineers [34,35,68,69,96,101,159,186,196,212],.

Tohme [196] also reported a wheel normal grinding processwith two linear axes and a rotary axis. In this case, the grindingwheel is kept normal to the workpiece surface by maintainingperpendicularity between the rotary B-axis and the point ofcontact. Therefore, the included angle a between grinding spindleaxis and surface tangent needs to be kept constant over the entiregrinding process, which ensures that the tool geometry errors donot transfer into the part. This requires the grinding wheel to beadjusted with respect to the B-axis center line (Fig. 30).

The process allows a variety of different tool geometries likespherical microgrinding wheels for aspheric, concave mouldcavities, or sharp-edged cylindrical wheels for the generation of

[(Fig._32)TD$FIG]

[(Fig._30)TD$FIG]

Fig. 30. Wheel normal grinding of precision moulds [courtesy of: Moore

Nanotechnology Systems].


small blend radii between convex and flat functional surfaces ormicrostructured surfaces.

Wheel normal grinding was also developed by Yamamoto et al.[213], using three simultaneously moving linear axes (X, Y, Z) and a458-tilted grinding spindle in the Y–Z-plain. By moving thegrinding wheel along a certain curve in space it is possible tomaintain tool normal conditions, i.e. the circular grinding zone ofthe wheel surface does not change. This wheel normal grindingtechnique ensures highly accurate surfaces due to minimized toolwear with the grinding wheel following a 3-dimensional, curvedtool path along the convex or concave shaped workpiece surface.Both, the X–Z–B and the X–Y–Z wheel normal grinding techniquesare highly accurate and deterministic regarding surface roughnessand form accuracy of rotational symmetric contours.

Another grinding method has been developed for precisionmachining of freeform shapes, i.e. freeform wheel normal grinding,[(Fig._31)TD$FIG]

Fig. 31. Flow chart for grinding of optical glass moulds (according to

[68,159,182,196]).

sometimes called slow-tool grinding. In this method the workpiecespindle is equipped with a rotary encoder (C-axis), so that theposition of the grinding wheel can be moved back and forth as afunction of the angular position of the workpiece (tool servo).Using this grinding technique a huge number of different lensesand moulds with cylindrical or torical shapes as well as lens arrayscan be ground [196].

However, these grinding techniques rely on the ability todetermine and compensate workpiece form errors caused by wheelwear and machine tool repeatable errors [196]. The flow chart inFig. 31 describes a step-by-step procedure for achieving the requiredfigure tolerance of the mould by ultra-precision grinding.

Prior to machining, the grinding wheel and the workpiece mustbe adjusted in the machine tool coordinate frame. After adjustmentthe grinding tool has to be dressed and its geometry has bedetermined for creating an NC tool path [182,183]. If the figuretolerance is not met, the NC tool path has to be modified forcompensating the residual errors [35,68]. Huang et al. [68] havepointed out that error sources affecting the profile accuracy ofground surfaces include tool setting errors, tool dimensionalerrors, tool path error as well as tool wear. Frequent redressing ofthe grinding wheel and reprogramming the tool path is required.

Typically, form errors <0.5 mm rms and surface roughnessSa < 5 nm (Fig. 32) can be achieved.

5.3. Astronomy

Optics traditionally play a key role in astronomy. Astronomicaldevices are in the first place telescopes but also other instrumentslike spectrometers requiring optical components such as glasslenses for refractive optics and mirror substrates for reflectingoptics of extremely high quality and large geometrical dimensionsup to the 10 m scale. As an historical example Fig. 33 shows

Fig. 32. Surface roughness of a precision ground tungsten carbide mould measured

with a white-light interferometer.[(Fig._33)TD$FIG]

Fig. 33. Prince Adolph Friedrich, Duke of Cambridge visits Bailiff Hieronymus

Schroter and his big 27 feet telescope with a primary concave 500 mm parabolic

mirror, 20th September 1800 in Lilienthal/Bremen.

[(Fig._34)TD$FIG]

Fig. 34. Concave 500 mm parabolic mirror from Schroter’s 27 feet optical telescope.

[(Fig._36)TD$FIG]


Schroters powerful 27 feet telescope with a primary concave500 mm parabolic mirror (Fig. 34) which was built in 1784.

Telescopes have been used as optical instruments for theobservation of stars for centuries either as ground based systems ornowadays also in space. As lenses have specific restrictions mainlyinstruments with monolithic primary mirrors have been appliedfor scientific purposes. The effectiveness of a telescope isdetermined by the amount of light collected by the subsequentinstruments. This quantity of light is on the on hand influenced bythe size of the telescope itself and on the other hand by thedetectors used in the instruments. As modern electronic detectorshave nearly reached the limit in sensitivity the size of thetelescope, i.e. predominantly the size of the main optical surface,has to be enlarged. In the last decades the development of a newgeneration of telescopes took decades and each one doubled in sizeto their preceding one – comparable to a Moore’s law forastronomy [53]. Over the last 100 years the telescopes developedfrom meter size to the 8–10 m class installed today also involvingthe development of challenging machining tasks (Fig. 35).

Major prerequisites for these developments were e.g. the activecontrol of the telescopes by advanced computer controls, andappropriate substrate materials including casting and machiningtechnologies. In the past monolithic mirror substrates have beenmade from borosilicate glass with minimum coefficient of thermalexpansion (CTE) until materials with nearly zero thermal expan-sion like ULE1 from Corning and Zerodur1 from Schott weredeveloped. The structure of these monolithic mirrors has changed

[(Fig._35)TD$FIG]

Fig. 35. Final acceptance tests of 8.2-meter astronomical mirror for the ESO Very

Large Telescope (VLT) in 1995 at the REOSC factory in Saint Pierre du Perray, France

(photo: by courtesy of ESO).

from first solid to light weight and now flexible substratesapplicable as adaptive optics. Examples are the VLT (Very LargeTelescope) meniscus type primary mirrors with a diameter of8.2 m at a thickness of 175 mm made from Zerodur1 or theprimary mirror of the Hubble telescope, a ULE1 based light weightsubstrate of 820 kg at a diameter of 2.4 m. Still depending on theirspecific application and the spectrum of interest typical require-ments for telescope mirrors are some 10 nm of form accuracy andsurface roughness in the Angstrom range over the full aperture ofseveral meters.

The involved machining technology for these large mirrorsincludes precision grinding and polishing like sub-aperture robotpolishing or ion beam figuring and also in situ metrology systems.Precision engineering technologies for astronomical mirrors arediscussed in detail by Shore et al. [171]. The levels of accuracyachieved for the 8.2 m mirrors by different labs and companiesresult for instance in 18–43 nm rms wave front error and 0.8–2 nmaverage roughness for the primary mirrors of the VLT; 14 nm RMSfigure error was achieved for 8.2 m mirror of the Japanese Subarutelescope.

The pure size – up to 10 m – and weight – several 10 tons – ofgiant telescope mirrors has reached the practical and technicallimits for production, machining, metrology, handling andtransportation. Therefore, over the last several years technologiesfor the machining of segmented mirrors have been developedpaving the way for even larger earth bound telescopes and as spacebased telescopes. Examples are already installed instruments, e.g.the Keck telescopes (36 hexagonal, 1.8 m off axis aspheric shapemirror segments; 10.2 m primary mirror) or coming instrumentslike the European Extremely Large Telescope E-ELT (42 m primarymirror of 906 segments) (Fig. 36) and the James Webb SpaceTelescope (JWST).

The advantages of segmented mirror substrates will be used forthe next generation of Extremly Large Telescopes – ELTs – withprimary mirror diameters of several ten meters. Besides the abilityof this technology to arrange the segments to mirrors of anywanted size (scalability) it is also flexible to generate segments ofeven more complex shape, e.g. aspherical off-axis segments, andtherefore allowing for steep mirror contours like deep aspheres.Nevertheless, if the actually existing machining technologies areapplied, several decades would be needed for the production of allmirror segments for one single ELT. As this is not acceptable thechallenge is to set up appropriate sequences of machiningprocesses to reduce the production time at least by a factor of

Fig. 36. 3-dimensional model of the European Extremely Large Telescope with 42-m

primary mirror composed of 906 segments (photo: by courtesy of ESO).

[(Fig._37)TD$FIG]

Fig. 37. Process chain for the serial production of 1–2 m segments (Cranfield

University).

[(Fig._39)TD$FIG]

Fig. 39. Process chain for 200–300 mm silicon wafers.


ten. Shore et al. are proposing a process chain of three subsequentmachining steps starting with precision grinding (Fig. 37).

The fixed abrasive grinding process will have to ensure a highmaterial removal rate for improving the mirror blanks from 1 mmdown to 1 mm form accuracy. At the same time the abrasivemachining has to guarantee a minimum roughness and a low levelof sub-surface damage to reduce machining time of the followingfinishing steps. Further crucial constraints taken into account arethe critical depth of cut (approx. 50 nm for Zerodur1) and theminimization of edge roll-off of the segments to prevent stray lightand therefore a reduction in efficiency of the telescope.

To fulfil these demands a dedicated ultra-precision grindingmachine tool was designed and built by Morantz et al. [118]. ThisBig OptiX Machine follows the philosophy of a high dynamic loopstiffness as a primary design criterion. Moreover, the movingmasses of the sub-systems have been minimized and machinemotions are limited to three fundamental axes which have specificimplications to control kinematics, wear compensation and feedrate control. For instance, as the local slope of the mirror segmentschanges across the freeform surface the contact region of the toricgrinding wheel has to be compensated in the control [119].Machining experiments have demonstrated the capability of thegrinding process and the machine tool on Zerodur1 and ULE1

substrates with material removal rates of 187.5 mm3/s with resinbonded diamond wheels. Applying a fine grit diamond wheel (D25)surface roughness of 124 nm for ULE1 and 137 nm respectively forZerodur1 were achieved with sub-surface damage levels of 6.6 mmand 9.5 mm respectively [198].

5.4. Wafer grinding

For integrated circuit (IC) manufacturing, silicon in the form ofthin round disks called ‘‘wafers’’, with a current maximum diameterof 300 mm, remains the fundamental substrate material (Fig. 38). In2008, global integrated circuit fabs required approx. 190 millionwafers of 200 mm equivalent, worth 12 billion US$ [199].

Silicon wafers exhibit a monocrystalline structure with lowdefect density and defined crystal orientation depending on theapplication. The wafers have a typical thickness of 600–900 mm,and their surface properties meet highest requirements regardingflatness and surface roughness. Fig. 39 shows an example of acurrent silicon wafer process. The process chain can be divided intofour main stages: pre-shaping, mechanical wafering, finishing, andinspection and epitaxy.
[(Fig._38)TD$FIG]
Fig. 38. State of the art application of silicon wafers.

The quality characteristics commonly used to assess waferquality after ultra-precision grinding can be divided into fourcategories:

� G

Fi(r

eometrical quality (diameter, thickness, dimensional accuracy).
� M acroscopic surface quality (edge chipping, cracks). � M icroscopic surface quality (scratches, handling marks,
roughness).
� M icroscopic sub-surface quality (sub-surface damage depth,
contaminations).

Whereas the properties affiliated to the first three categoriescan be measured with state-of-the-art measurement systems, in-line measurement of sub-surface damage depth is currently notavailable.

The damage layer model for lapped wafers established by Mohrin the 1960s [57] divides the sub-surface into four zones: a poly-crystalline zone, a fracture zone, a transition zone and, an elasticdeformation zone (Fig. 40, left). The boundary zone in waferssubjected to ductile machining processes like ultra-precisiongrinding can also be divided into four sections on the same basis asdescribed above (Fig. 40, right). The top zone I consists ofamorphous material, regardless of whether the wafer has beensubjected to ductile turning or grinding [16,30,31,32,33,47,56,87,126,136,169,221,222]. The layer can be up to 200 nm thick[32,33], depending on the specific process, the tool and the processparameters used.

For the production of 300 mm wafers one-sided[83,84,86,99,194] and double-sided rotational grinding [1,147]has been established. The rotational grinding process offerssuperior geometrical parameters with TTV < 0.5 mm [142], excel-lent surface qualities [153] and small sub-surface damage depthsbelow 3 mm [136]. Diamond grinding wheels with small grit sizesenable a ductile cutting mechanism without chipping of thesurface [9]. This process can be automated easily. Moreover, water-cooling can be used.

In single-side grinding/rotational grinding (Fig. 41) a finegrained cup wheel with a grinding layer that is only a fewmillimeters wide is used to improve the flatness of the silicon[(Fig._40)TD$FIG]

g. 40. Sub-surface structures of wafers machined in brittle (left) and ductile mode

ight).

[(Fig._41)TD$FIG]

Fig. 41. Rotational grinding technique.

[(Fig._42)TD$FIG]

Fig. 42. Sub-surface damage distribution on fine ground wafers [135].

[(Fig._43)TD$FIG]

Fig. 43. Cup grinding wheel with integrated force sensor [135].


wafers and to reduce or eliminate polishing [105,106,141,143,144].

There are also cup wheels with two concentric grinding layerswhere the inside layer is coarse grained and the outside layer is finegrained. The coarse-grained layer is used to achieve higher removalrates, while the fine layer the required surface finish will beachieved [191]. The cup wheel and the wafer are positioned in sucha manner, that the outer edge of the grinding layer intersects thewafer’s rotational axis. In single-side grinding, the wafer is vacuumchucked to a porous ceramic chuck. Both, the wheel and the wafer,usually rotate anti-clockwise which results in a superimposedcutting speed vc depending on the radial position on the wafer.

Another method for ultra-precision grinding of silicon wafers isdouble-side grinding or double disk grinding. In this process bothsides of the wafer are ground in one single process step. The waferis ground between a pair of parallel grinding cup wheels which aresynchronously fed towards the wafer surface. The grinding cupwheels are mounted on collinear axes and rotate counter clockwise [59,63,100,146,148].

The material removal mechanism in double-side grinding is thesame as in single-side grinding. Typically, the cup wheels are in fullperipheral contact with the wafer. Each wheel exhibits a ‘‘leadingedge’’ with a high material removal rate and a ‘‘trailing edge’’ witha low removal rate. The peripheral removal is characterized bycross-cutting. Compared to single-side grinding, double-sidegrinding is more effective for reducing waviness, because chucksare not needed [100,146,148].

Another ultra-precision grinding process with high potential forgrinding flat and disc-type parts of hard and brittle materials is sidegrinding with planetary kinematics, which was derived fromlapping processes [4,5,156,200,201]. By double-side grinding withplanetary kinematics high flatness, excellent parallelism and tightthickness tolerance can be achieved [49,192,210].

Due to its crucial role within modern wafer manufacturing lines,the rotational grinding process has been intensively examined,focusing on the effects of differently specified grinding wheels andprocess parameters on surface roughness and sub-surface damage[99,193,194]. According to Pei [142], the polishing removal amountrequired to eliminate grinding induced sub-surface damage andgrinding marks should be less than 5 mm in order to achieve asignificant cost reduction for the wafer manufacturers.

Three major wafer geometry errors are surveyed in rotationalgrinding related studies: fan-like radial grinding marks, centraldimples and wafer waviness. Fan-like grinding marks are causedby an axial run-out of the grinding wheel due to improper dressing[142,179]. The mechanisms generating the central dimple havestill not been identified. Two different hypotheses are presented byZhou and Zhang [223,227]. Wafer waviness is caused by the multiwire slicing process. Special components for flexibly holding thewafer during rotational grinding are proposed to minimize orremove waviness.

Investigating the sub-surface damage distribution on the wafer,Pahler determines a four lobed pattern of neighbouring areas withsevere and less severe damage. He finds that sub-surface damagedepth depends on the radial distance from the wafer center and,above all, on the relative position between the cutting directionand the main axes of the crystal (Fig. 42). Pahler derives acorrelation between the observed damage pattern and the Schmid-factor of activated slip systems [135].

Mechanical and thermal loads within the contact zone willinfluence the process in terms of crystal damage, tool wear orwafer geometry, which makes their determination a desirableobjective. However, the determination of local process forces andtemperatures is intricate [115]. Measurement of process forcesacting onto the wafer during rotational grinding is considered to bechallenging. Due to wafer rotation, the mechanical engineeringtasks, signal transmission and the evaluation procedures arereported to be demanding [99].

Pei und Strasbaugh [143] measured the total normal forceacting onto the wafer during single-side grinding with load cellsimplemented into the machine frame. Couey and Marsh [38,110]inserted capacitive probes into an aerostatic spindle to measurethe total normal force on the rotating wafer. This approach is non-intrusive to the process, but unable to determine local contact zoneforces.

Ahearne and Byrne [2] integrated a piezo sensor into a roughgrinding wheel to measure locally varying contact zone forces.First results for brittle grinding of glass are available, indicatingthat the forces hardly show any dependence on the distance fromthe center.

Pahler [135] realized the assessment of the process forces inductile rotational grinding of silicon by integrating a three-component piezo sensor under a segment of a resin-bond D3grinding wheel (Fig. 43). By means of process parameter variations,he discovered a direction dependence of the process forces, whichcorrelates well with his findings on the sub-surface damage depthdistribution.

[(Fig._46)TD$FIG]

Fig. 46. Microstructured surface: Ground micro-pillars in silica glass (SQ1) [65,66].

[(Fig._45)TD$FIG]

Fig. 45. Manufactured microstructures in tungsten carbide (DK460) [7].


Knowledge about contact zone temperatures is generallyconsidered beneficial for the interpretation of rotational grindingprocesses. Nevertheless, the lack of access to the contact zone andthe use of cooling water are supposed to make it very difficult tomeasure contact zone temperatures [99].

Following his process force analyses, Pahler developed aconcept for a measuring system which for the first time allowsthe determination of the temperatures in the contact zone duringrotational grinding of silicon. The concept utilizes the opticalproperties of Si monocrystals: being opaque to the human eye, Si ishighly transparent for infrared light of wavelengths below 6 mm,which makes the contact zone accessible for IR-cameras. A testbench enabling rotational grinding processes was used to verifythe measuring concept. Temperature gradients along the length aswell as the width of the contact zone can be determined [135].

5.5. Grinding of microstructures

The demand for macro-parts with features and structures at themicro- and nano-scale level is growing continuously [42],presenting new challenges to production technology, since processknowledge and machine tool design cannot be scaled down tosmall dimensions [24].

Micro-cutting operations are distinguished from other pro-cesses like lithography by their high flexibility [66], for this reasonthey are appropriate for small batch production and especially formould making.

Structuring of most non-ferrous metals can be performed bysingle point diamond machining in a very deterministic way[44,155]. However, machining of silicon, glass and advancedceramics like tungsten carbide can only be achieved by grinding.For this reason a number of microgrinding processes have beendeveloped during the last years, especially for decreasing thecutting tool dimensions and increasing the achievable aspect ratio.For the manufacturing of microstructures two notch grindingmethods with different tool shapes have been developed, i.e.peripheral grinding wheels for machining of continuous structures(e.g. pyramid arrays) and pin-type grinding wheels for discontin-uous structures (Fig. 44).

Aurich [6,7] developed a method for manufacturing micro-pin-type grinding wheels. The tool bodies were made of ultrafinegrained carbide (grain size 0.2 mm) and ground down to a diameterof 13 mm. These pins were electroplated with diamond grains of 1–3 mm in diameter. Grinding of tool bodies and machining with theelectroplated pins was performed with the same air-bearingspindle mount for achieving a minimum run-out. Tests haveshown that micro-slots (30 mm wide and 3 mm deep) with aroughness Ra of 10 nm can be ground with these micro-pins intotungsten carbide (Fig. 45).

Onikura [134] also investigated the manufacturing of micro-pin-type grinding wheels with a diameter of 100 mm byelectroplating of diamond grits on ultrafine grain cementedcarbide. It was shown that ultrasonic assisted grinding leads toan increase of tool wear when machining stainless steel.

[(Fig._44)TD$FIG]

Fig. 44. Micro-structuring processes and cutting tools [208].

Hoffmeister [64] showed that the application of CBN-tools isalso suitable for machining hardened steel in the micro-regime. Anaspect ratio of 40:1 could be achieved with pin-type grindingwheels with a diameter of 100 mm. With decreasing grain size theroughness was improved down to 47 nm Sa using a superfine CBNgrain size of 1 mm.

For the grinding of riblets a novel dressing strategy usingdiamond profile rollers was introduced for the generation ofmicroprofiles of vitrified grinding wheels by Denkena [40]. Thistechnology allows the generation of riblets, i.e. microgrooves witha width of 40 mm and depth of 20 mm on the surface of jet turbinecompressor blades with the purpose of drag reduction in turbolentflow.

Notch grinding of hard and brittle materials like tungstencarbide and aluminium oxide with CVD-diamond microgrindingwheels was investigated by Hoffmeister [66]. It was shown thatincreasing cutting speed and feed rate reduces the cutting forcesand edge breakout. Edge breakout was found to be higher in theup-grinding than in the down-grinding mode.

Hoffmeister and Wenda [65] have machined microstructuresdown to minimal dimensions of approx. 20 � 20 � 100 mm3 intosilicon and silica glass substrates with microgrinding wheelsnormally used for semiconductor wafer dicing (Fig. 46).

Ramesh [152] has generated deep microgrooves with aspectratios up to 15:1 in tungsten carbide and alumina applying hightable reversal speed (feedrate up to 55 m/min).

Suzuki [181] proposed a new 4-axes grinding system forgrinding micro-Fresnel moulds (tungsten carbide, 4 mm indiameter with approx. 5 mm structure height) for glass moulding.A form accuracy of about 100 nm p-v could be achieved.

Yin and Ohmori [216] introduced a V-groove fabricationprocess to achieve large array microstructures (908 V-grooves,217.5 � 559.2 mm2 on a surface of 355 cm2) of constant quality ingermanium. An ultra-precision grinding technique applying ELIDand different truing operations (ED, ELID, mechanical) wasinvestigated. A minimum wheel tip radius of 8.2 mm was achievedby truing the #4000 grinding wheel with a diameter of 305 mm.Finally, a corner radius of 15 mm could be realized.

6. Conclusions

Ultra-precision grinding is primarily used for the generation ofhigh quality surfaces and functional parts made from difficult tomachine materials for both optical and non-optical applications.


Important applications of ultra-precision grinding are to be foundin the semiconductor industry (manufacturing of 300 mmdiameter silicon wafers) and in the optical industry (e.g. machiningof hardened steel and ceramic moulds for the replication of glasslenses for pick-up systems, sensors and camera objectives). In thiskeynote paper the authors have tried to characterize ultra-precision grinding and to point out the essential features basedon part quality, material properties, process characteristics andspecial demands on tools and machine tools.

In most applications ultra-precision grinding is used as anintermediate, or pre-finish, machining step, since finish tolerancesregarding form accuracy, surface roughness and sub-surfacedamage can often not be reached by one single ultra-precisiongrinding operation. Therefore, research in the field of ultra-precision grinding is focusing on two central problems:

(1) H
ow can an optical surface finish be obtained without sub-surface damage (e.g. microcracks)?
(2) H
ow can ultra-precision grinding be made more predictableand reliable (i.e. more deterministic)?
The answer to the first question is believed to be ductile modegrinding. Much research efforts have been spent on improving ourunderstanding of the transition form brittle-to-ductile modemachining and on investigating the conditions and requirementsfor ductile mode grinding. It has been discovered that a criticaldepth of cut (or more precisely: a critical uncut chip thickness)exists depending on material properties and machining para-meters, which must not be exceeded in ductile mode machining ofbrittle materials.

Ananswertothesecondquestionhasnotyetbeenfound,althoughasubstantialprogresswasmadebytheintroductionofelectrolytic in-process dressing (ELID) yielding superb surface finishes (Sa < 2 nm)and very little sub-surface damage. However, controlling figureaccuracy remains a problem, especially with large surfaces. Anotherapproach for reducing tool wear in ultra-precision ductile modegrinding is the use of ‘‘engineered’’ grinding wheels with large(average grain size >100 mm), ‘‘truncated’’ grains whose tips form aclose tolerance envelope surface. It has been demonstrated thatductile mode grinding with engineered wheels is possible yieldingexcellent surfaces comparable, or even superior, to those obtained byELID grinding, while no appreciable tool wear occurs even aftergrindinglargevolumesofopticalglasses[61].Furtherdevelopmentinthisfielddependsontheimprovementoftheartofwheelpreparation,especially with circular profiles for contour grinding. Besideschallenges in process control and grinding wheel preparation, thereis a growing demand for machine tools with high loop stiffness andgrinding spindles dedicated to ultra-precision grinding.

In summary, it may be predicted, that in the future ultra-precision grinding will become even more reliable, faster andversatile and will conquer new areas of application.

In 2000 Hashimoto stated that grinding is fun. As a generalconclusion we would like to state that: Ultra-precision grinding is

even more fun.

References

[1] Abe K, Ishikawa T, Koma Y, Arai K, Kitano M (1999) Development of an Ultra-precision Grinding Machine with Trigonal Prism Type Pentahedral Structurefor 400 mm Silicon Wafer. Proceedings of the 1st euspen International Con-ference, vol. 1, Bremen, Germany, 16–19.

[2] Ahearne E, Byrne G (2008) Simulation of the Local Kinematics in RotationalGrinding. Annals of the CIRP 57(1):333–337.

[3] Anderson J, Hollman P, Jakobson S (2001) Abrasive Capacity of Thin FilmDiamond Structures. Key Engineering Materials 196:141–148.

[4] Ardelt T (2001) Einfluss der Relativgeschwindigkeit auf den Prozess und dasArbeitsergebnis beim Planschleifen mit Planetenkinematik. German Ph.D.Thesis, Technische Universitat Berlin.

[5] Ardelt T (2001) Belastung der Schleifscheiben beim Planschleifen mit Plan-tenkinematik. Industrial Diamond Review 35:116–124.

[6] Aurich JC, Engmann J, Schueler G, Haberland R (2009) Micro Grinding Tool forManufacture of Complex Structures in Brittle Materials. Annals of the CIRP58(1):311–314.

[7] Aurich JC, Schuler GM, Engmann J (2009) Komplexe Mikrostrukturierung vonHartmetall mit 20 mm Mikroschleifstiften. Diamond Business 22–27.

[8] Ball MJ, Murphy N, Shore P (1991) Electrolytically Assisted ‘‘Ductile’’ ModeDiamond Grinding of BK7 and SF10 Optical Glasses. Proceedings of the SPIE1573:30–38.

[9] Bifano TG (1988) Ductile-Regime Grinding of Brittle Materials. Ph.D. Thesis,North Carolina State University.

[10] Bifano TG (1988) Ductile-Regime Grinding of Brittle Materials: ExperimentalResults and the Development of a Model. Proceedings of the SPIE 966:108–115.

[11] Bifano TG, Dow TA, Scattergood V (1991) Ductile-Regime Grinding – A newTechnology for Machining Brittle Materials. Transactions of the ASME113:184–189.

[12] Bifano TG, Bierden PA (1997) Fixed-Abrasive Grinding of Brittle Hard-DiskSubstrates. International Journal of Machine Tools and Manufacture 37(7):935–946.

[13] Bifano TG, Yi Y (1992) Acoustic Emission as an Indicator of Material-RemovalRegime in Glass Micro-Machining. Precision Engineering 14(4):219–228.

[14] Blackley WS, Scattergood RO (1991) Ductile-Regime Machining Model forDiamond Turning of Brittle Materials. Journal of the International Society forPrecision Engineering and Nanotechnology 13(2):95–103.

[15] Blake PN (1989) Ductile Regime Diamond Turning of Germanium and Silicon.Ph.D. Thesis, North Carolina State University.

[16] Blake PN, Scattergood RO (1990) Ductile-Regime Machining of Germaniumand Silicon. Journal of the American Ceramic Society 73(4):949–957.

[17] Bockem J (1973) Technologisches Verhalten von Diamant-Topfschleifschei-ben beim Flachschleifen optischer Glaser. German Ph.D. Thesis, TechnischeUniversitat Braunschweig.

[18] Braun O, Warnecke G, Aurich JC (2005) Simulation-Based Development ofSuperabrasive Grinding Wheels with Defined Grain Structure. Transactions ofNorth American Manufacturing Research Institution 33:351–358.

[19] Bridgman PW (1947) The Effect of Hydrostatic Pressure on the Fracture ofBrittle Substances. Journal of Applied Science 18:246–258.

[20] Bridgman PW, Simon I (1953) Effects of very High Pressures on Glass. Journalof Applied Science 24(4):405–413.

[21] Brinksmeier E, Heinzel C, Bleil N (2009) Superfinishing and Grind-strength-ening with Elastic Bonding System. Journal of Materials Processing Technology209:6117–6123.

[22] Brinksmeier E, Rickens K, Grimme D (2001) Duktiler Materialabtrag beimSchleifen sprodharter Werkstoffe. Jahrbuch Schleifen Honen Lappen und Polie-ren 60:50–67.

[23] Brinksmeier E, Rickens K, Riemer O, Grimme D (2006) Engineered DiamondWheels for Precision Ductile Grinding. Production Engineering 13(2):275–280.

[24] Brinksmeier E, Riemer O (2005) Metal Cutting of Microstructures. Proceedingsof the 1st International Conference on Multi-Material Micro Manufacture (4M),Karlsruhe, Germany, 19–25.

[25] Bruche E (1965) Die mechanisch beanspruchte Oberflache nach Beobachtun-gen im Elektronenmikroskop. VDI-Berichte 90:95–100.

[26] Bryan J (1990) International Status of Thermal Error Research. Annals of theCIRP 39(2):645–656.

[27] Busch M (1968) Ritz- und Verschleißuntersuchungen an sproden Werkstof-fen mit einzelkornbestuckten Hartstoffwerkzeugen. German Ph.D. Thesis,Technische Hochschule Hannover.

[28] Carlisle K, Fitzpatrick J, McKeown P, Shore P (1994) Review of the UltraPrecision Machining Research Facility – the ‘NION’ Machine. Proceedings ofthe 3rd International Conference on Ultra Precision Manufacturing Engineering,Aachen, Germany, 89–95.

[29] Cha DH, Kim HJ, Lee JK, Kim HU, Kim SS, Kim JH (2008) A Study of MoldGrinding and Pressing Conditions in the Molding of Aspheric Glass Lenses forCamera Phone Module. Materials and Manufacturing Processes 23:683–689.

[30] Chao CL, et al, (2001) A Study on the Surface Integrity of Single Crystal SiliconGround by CIFB Diamond Wheels (ELID) and Resin-bonded Diamond Wheels.Proceedings of the 10th International Conference on Precision Engineering,Yokohama, Japan, 376–380.

[31] Chao CL, et al, (2002) Ductile Behaviour in Single-point Diamond Turning ofSingle-crystal Silicon. Journal of Material Processing Technology 127:187–190.

[32] Chao CL, Ma KJ, Chien HH, Lin HJ (2003) Surface and Sub-surface Character-istics of Metal-bond/ELID and resin-bond diamond ground single crystalsilicon. Proceedings of the International Workshop on Extreme Optics andSensors, Tokyo, Japan, 155–162.

[33] Chen J, De Wolf I (2003) Study of Damage and Stress Induced by Backgrindingin Si Wafers. Semiconductor Science and Technology 18:261–268.

[34] Chen WK, Kuriyagawa T, Huang H, Yosihara N (2005) Machining of MicroAspherical Mould Inserts. Precision Engineering 29:315–323.

[35] Chen WK, Kuriyagawa T, Huang H, Ono H, Saeki M, Syoji K (2004) A NovelForm Error Compensation Technique for Tungsten Carbide Mould InsertsMachining Utilizing Parallel Grinding Technology. Key Engineering Materials257–258:41–46.

[36] Chen X, Rowe WB, Cai R (2001) Precision Grinding Using cBN Wheels.International Journal of Machine Tools and Manufacture 42:585–593.

[37] Corbett J, Morantz P, Stephenson DJ, Read R (2002) An Advanced UltraPrecision Face Grinding Machine. Journal of Advanced Manufacturing Technol-ogy 20:639–648.

[38] Couey JA, Marsh ER, Knapp BR, Vallance RR (2005) In Process Force Monitor-ing for Precision Grinding Semiconductor Si Wafers. International Journal ofManufacturing Technology and Management 7(5–6):430–440.

[39] Danyluk K (1986) Smoother Scribing of Silicon Wafers. . NASA Technical Briefs09/10.

[40] Denkena B, de Leon L, Wang B (2009) Grinding of Microstructured FunctionalSurfaces, A Novel Strategy for Dressing of Microprofiles. Production Engineer-ing 3:41–48.

[41] Disco Corp. (2009) http://www.disco.co.jp/eg/index.html.

http://www.disco.co.jp/eg/index.html


[42] Dornfeld D, Min S, Takeuchi Y (2006) Recent Advances in Mechanical Micro-machining. Annals of the CIRP 55(2):745–768.

[43] Engmann J, Schuler GM, Haberland R, Walk M, Aurich JC (2009) EfficientTechnique for 3rd Micro Structuring of Carbide and Brittle Materials withDiamond Micro-shaft Grinding Tools. Proceedings of the 9th euspen Interna-tional Conference, vol. 2, San Sebastian, Spain, 97–100.

[44] Evans CJ, Bryan JB (1999) Structured’’, ‘‘Textured’’ or ‘‘Engineered’’ Surfaces.Annals of the CIRP 48(2):541–556.

[45] Fang FZ, Chen LJ (2000) Ultra-Precision Cutting for ZKN7 Glass. Annals of theCIRP 49(1):17–20.

[46] Fang FZ, Liu XD, Lee LC (2003) Micro-Machining of Optical Glasses – A Reviewof Diamond-Cutting Glasses. Sadhana – Proceeding in Engineering Sciences ofthe Indian Academy of Sciences 28(5):945–955.

[47] Fang FZ, Wub H, Zhouc W, Hu XT (2007) A Study on Mechanism of Nano-cutting Single Crystal Silicon. Journal of Materials Processing Technology184(1–3):407–410.

[48] Fang FZ, Zhang GX (2004) An Experimental Study of Optical Glass Machining.International Journal of Advanced Manufacturing Technology 23:155–160.

[49] Funck A (1994) Planschleifen mit Lappkinematik. German Ph.D. Thesis,Technische Universitat Berlin.

[50] Gabler J (2004) CompeDIA Micro Abrasive Pencils. Jahresbericht FrauenhoferIST 36–37.

[51] Gabler J, Schafer L, Menze B, Hoffmeister HW (2003) Micro Abrasive Pencilswith CVD Diamond Coating. Diamond and Related Materials 12:707–710.

[52] Gerchman MC (1986) Specifications and Manufacturing Considerations ofDiamond Machined Optical Components. Proceedings of the Society of PhotoOptical Instrumentation Engineer’s Conference, vol. 607, Los Angeles, 36–45.

[53] Gilmozzi R (2006) Riesenteleskope der Zukunft. Spektrum der Wissenschaft8:28–36.

[54] Giovanola JH, Finnie I (1980) On the Machining of Glass. Journal of MaterialsScience 15:2508–2514.

[55] Grimme D (2010) Ultraprazisionsschleifen von Stahl und neu synthetisiertenPVD-Hartstoffschichten. German Ph.D. Thesis, Universitat Bremen.

[56] Haapalinna A (2004) Characterization Methods for Silicon Photodiode andSilicon Sub-surface Properties. Ph.D. Thesis, Helsinki University of Technol-ogy.

[57] Hadamovsky HF (1990) Werkstoffe der Halbleitertechnik. Deutscher Verlag furGrundstofftechnik, Leipzig. 2. Auflage.

[58] Haefeli R (1997) Anwendungsmoglichkeiten von Schleifstiften. IndustrialDiamond Review 2(97):164–168.

[59] Hahn PO (2001) The 300 m Silicon Wafer – A Cost and Technology Challenge.Microelectronic Engineering 56:3–13.

[60] Hashimoto H, Takeda J, Imai K, Blaedel K (1993) Shear-Mode Grinding ofBrittle Materials and Surface Characteristics. International Journal of the JapanSociety for Precision Engineering 27(2):95–99.

[61] Heinzel C, Rickens K (2009) Engineered Wheels for Grinding of Optical Glass.Annals of the CIRP 58(1):315–318.

[62] Heinzel C, Rickens K, Grimme D, Zhao Q (2006) Dressing of Coarse-GrainedDiamond Wheels for Ductile Machining of Brittle Materials, Towards Synthesis ofMicro-/Nano-Systems. JSPE Publication Series No. 5. Springer, London. pp. 305–307.

[63] Heisel U, Avroutine J (2001) Process Analysis for the Evaluation of theSurface Formation and Removal Rate in Lapping. Annals of the CIRP50(1):229–232.

[64] Hoffmeister HW, Hlavac M (2002) Grinding of Microstructures in HardenedSteel with CBN Tools. Proceedings of the 17th Annual Meeting of the ASPE, vol.27, St. Louis, USA, 490–494.

[65] Hoffmeister HW, Wenda A (1998) Investigations into the MicrogrindingTechnique for the Production of microstructures in Silicon and Glass MicroSystem Technologies 98. 6th International Conference on Micro Electro, Opto,Mechanical Systems and Components, 433–438.

[66] Hoffmeister HW, Wittmer R (2009) Grinding Hard and Brittle Materials withCVD-Diamond Microgrinding Wheels. Proceedings of the 24th Annual Meetingof the ASPE, Monterey, USA, .

[67] http://www.nanotechsys.com.[68] Huang H, Chen WK, Kuriyagawa T (2007) Profile Error Compensation

Approach for Parallel Nanogrinding of Aspherical Mould Inserts. InternationalJournal of Machine Tools and Manufacture 47:2237–2245.

[69] Hwang Y, Kuriyagawa T, Lee SK (2006) Wheel Curve Generation ErrorAspheric Microgrinding in Parallel Grinding Method. International Journalof Machine Tools and Manufacture 46:1929–1933.

[70] Ichida Y (2008) Mechanical Properties and Grinding Performance of Ultra-fine-crystalline cBN Abrasive Grains. Diamond and Related Materials 17:1791–1795.

[71] Ihara E (2005) Metal-coated Abrasives, Grinding Wheel Using Metal-coatedAbrasives and Method of Producing Metal-coated Abrasives. US Patent20050129975.

[72] Iwai M, Nakagawa K, Sano S, Tanaka K, Uematsu T, Mei W, Suzuki K (2005) ANew Diamond Wheel Containing Boron Doped Diamond Abrasives EnablingElectrically Conductive Cutting Edge and High Thermal Stability. Key Engi-neering Materials 291(292):57–62.

[73] Jackson MJ, Mills B (2009) Vitrification Heat Treatment and Dissolution ofQuartz in Grinding Wheel Bonding Systems. British Ceramic Transactions100(1):1–9.

[74] Kamada T (2002) Molding Examples (V Grooves, Complicated Surface Parts)and Quartz Glass Molding by Precise Glass Molding Method. Journal of theJapan Society for Grinding Engineering 46(4).

[75] Katahira K, Ohmori H, Saito T, Komotori J, Mizutani M (2007) ELID GrindingCharacteristics and Surface Modifying Effects on Precise Lens Mold Materials.Proceedings of the 7th Euspen International Conference, vol. 2, Bremen, Ger-many, 441–444.

[76] Katahira K, Schmidt C, Dambon O, Schneider U, Klocke F, Ohmori H (2003)ELID Grinding Characteristics for the Machining of Optical Surface Quality forCeramic Spherical Lens Molds. Proceedings of the 5th Euspen InternationalConference, vol. 1, Aachen, Germany, 317–320.

[77] Karman Thv (1911) Festigkeitslehre unter allseitigem Druck. Zeitschrift desVereins deutscher Ingenieure 55(42):1749–1757.

[78] Kern D (1969) Flachschleifen von optischem Glas mit Diamanttopfs-chleifscheiben. German Ph.D. Thesis, Technische Universitat Braunschweig.

[79] Kleinevoß R (1991) Feinschleifen optischer Glaser. German Ph.D. Thesis,Rheinisch-Westfalische Technische Hochschule Aachen.

[80] Klink A (2009) Funkenerosives und elektrochemisches Abrichten feinkorni-ger Schleifwerkzeuge. German Ph.D. Thesis, Rheinisch-Westfalische Tech-nische Hochschule Aachen.

[81] Klocke F (2009) Manufacturing Processes 2. Springer-Verlag, Berlin Heidelberg.[82] Klocke F, Baus A, Beck T (2000) Coolant Induced Forces in CBN Grinding with

Shoe Nozzels. Annals of the CIRP 49(1):241–244.[83] Klocke F, Gerent O, Pahler D, Jakob A (2000) Flat Rates on Future

Silicon Wafers: Precision Grinding. Industrial Diamond Review 2:149–156.[84] Klocke F, Gerent O, Pahler D (2000) Effiziente Prozesskette zur Waferferti-

gung. Zeitschrift fur Wirtschaftlichen Fabrikbetrieb 95(3):79–82.[85] Klocke F, Konig W (2007) Fertigungsverfahren Band 3: Abtragen Generieren und

Lasermaterialbearbeitung. Springer, Berlin.[86] Klocke F, Pahler D (2000) Rotational Grinding of Future Silicon Wafers.

Proceedings of the 7th Scientific and Business Conference on Silicon Technology,Roznov, Czech Republic, .

[87] Klocke F, Pahler D, Haapalinna A (2003) Rotational Grinding is Solution toSurface Damages – Silicon Wafer Production Altered. Semicon West 2003,SEMI Technical Symposium: Innovations in Semiconductor Manufacturing, SanFrancisco, USA, 473–474.

[88] Koch N (1992) Duktile Bearbeitung optischer Glaser zur Herstellung asphar-ischer optischer Linsen. Industrial Diamond Review 2:118–126.

[89] Koch N (1991) Technologie zum Schleifen aspharischer optischer Linsen.German Ph.D. Thesis, Rheinisch-Westfalische Technische HochschuleAachen.

[90] Konig W, Kleinevoß R (1988) Feinschleifen optischer Glaser. Industrie-Anzei-ger 99:26–28.

[91] Konig W, Koch N, Kleinevoß R (1990) Schleif- und Werkzeugtechnologie beider Feinbearbeitung optischer Glaser. Jahrbuch Schleifen Honen Lappen undPolieren 169–182.

[92] Konig W, Meis FU, Pahl F (1984) Auswahl von Diamantwerkzeugen fur dieKugelbearbeitung optischer Glaser. Industrial Diamond Review 18(3):136–143.

[93] Konig W, Meyer HP (1993) Uberwachung des Abricht- und Schleifprozesses –ein wichtiger Schritt fur die automatisierte Schleifbearbeitung. JahrbuchSchleifen Honen Lappen und Polieren 57:217–233.

[94] Koichi K, Yukiyasu N (2006) Newly Products Ultra-Precision Surface GrindingMachine and Grinding Techniques. Journal of the Japan Society for AbrasiveTechnology 50:377–380.

[95] Komanduri R, Lucca DA, Tani Y (1997) Technological Advances in FineAbrasive Processes. Annals of the CIRP 46(2):545–596.

[96] Kuriyagawa T, Zahmaty MSS, Syoji K (1996) A New Grinding Method forAspheric Ceramic Mirrors. Journal of Materials Processing Technology62(4):387–392.

[97] Leadbeater PB, Clarke M, Wills-Moren WJ (1989) A Unique Machine forGrinding Large, Off-axis Optical Components: the OAGM 2500. PrecisionEngineering 11(4):191–196.

[98] Lee SB, Tani Y, Enomoto T, Sato H (2005) Development of a Dicing Blade withPhotopolymerizable Resins for Improving Machinability. Annals of the CIRP54(1):293–296.

[99] Lehnicke S (2000) Rotationsschleifen von Silizium-Wafern. Ph.D. Thesis,Universitat Hannover.

[100] Li ZC, Pei ZJ, Fisher GR (2006) Simultaneous Double Side Grinding of SiliconWafers: A Literature Review. International Journal of Machine Tools andManufacture 46:1449–1458.

[101] Li LJ, Zhang FH, Dong S (2009) Research on the 3-axis CNC Ultra-precisionGrinding of Aspherical Mould. Advanced Materials Research 69–70:39–43.

[102] Lindsey K (1991) Tetraform Grinding. Proceedings of the SPIE 1573:129–135.[103] Linke B, Maier B, Klocke F, Zeppenfeld Ch (2007) Tribologisches Einsatzver-

halten von CBN beim Schleifen mit unterschiedlichen Kuhlschmierstoffen.Diamond Business 03:72–76.

[104] Liu YK, Tso PL (2003) The Optimal Diamond Wheels for Grinding DiamondTools. International Journal of Advanced Manufacturing Technology 22(5–6):396–400.

[105] Liu WJ, Pei ZJ, Xin XJ (2002) Finite Element Analysis for Grinding and Lappingof Wire-sawn Silicon Wafers. Journal of Materials Processing Technology129(1–3):2–9.

[106] Liu JH, Pei ZJ, Fisher GR (2007) Grinding Wheels for Manufacturing of SiliconWafers: A Literature Review. International Journal of Machine Tools andManufacture 47:1–13.

[107] Ludwig Ch, Thieme V (1985) Feinschleifen in der Kleinserienfertigung sphar-ischer optischer Bauteile. Feingeratetechnik 34(2).

[108] Mairlot H (1972) The Texture of Ground Glass Surface. Industrial DiamondReview 2:61–68.

[109] Marsh DM (1964) Plastic Flow in Glass. Proceedings of the Royal Society ofLondon, Series A, vol. 279, Burlington House, London, 420–435.

[110] Marsh ER, Couey JA, Vallance RR, Yi AY (2007) The Role of CrystallographicOrientation on the Forces Generated in Ultraprecision Grinding of Aniso-tropic Materials such as Monocrystalline Silicon. International Journal ofManufacturing Technology and Management 12:270–283.

[111] Marshall DB, Lawn BR, Cook RF (1987) Microstructural Effects on Grinding ofAlumina and Glass-ceramics. Communications of the American Ceramic Society70(6):139–140.

http://www.nanotechsys.com/


[112] Matsumaru K, Takata A, Ishizaki K (2005) Advanced Thin Dicing Blade forSapphire Substrate. Science and Technology of Advanced Materials 6:120–122.

[113] McKeown PA, Loxham J (1973) Some Aspects of the Design of High PrecisionMeasuring Machines. Annals of the CIRP 22(1):139–141.

[114] McKeown PA (1986) Ultra-Precision Diamond Machining of Advanced Tech-nology Components. Journal of Materials and Manufacturing Processes1(1):107–132.

[115] Meyer LW (2006) Einsatz von Temperatur- und Kraftsensoren in Schleif-werkzeugen. German Ph.D. Thesis, Universitat Bremen.

[116] Miyashita M (1985) 1st Annual Precision Engineering Conference, North Car-olina State University, Raleigh, USA, .

[117] Molly P, Schinker MG, Doell W (1987) Brittle Fracture Mechanisms in SinglePoint Glass Abrasion. Proceedings of the SPIE 802:81–88.

[118] Morantz P, Shore P, Stephenson D, May-Miller R, Read R (2005) FromTetrahedral to Box: Design Philosophy Behind the Cranfield Big OptiXSystem. Proceedings of the 5th Euspen International Conference, Montpellier,France, .

[119] Morantz P, Shore P, Luo X, Baird I (2006) Control Strategy of the Big OptixGrinding Machine. Proceedings of the 6th euspen International Conference, vol.1, Baden bei Wien, Austria, 257–260.

[120] Mohr O (1900) Welche Umstande bedingen die Elastizitatsgrenze und denBruch eines Materials. Zeitschrift des Vereins deutscher Ingenieure 24:1524–1530. and 1572–1577.

[121] Nakao M, Hatamura Y (1996) Development of an Intelligent Face GrindingMachine to Fabricate Ultraflat Surfaces on Thin Brittle Substrates. Annals ofthe CIRP 45(1):397–400.

[122] Namba Y, Abe M, Kobayashi A (1993) Ultraprecision Grinding of OpticalGlasses to Produce Super-Smooth Surfaces. Annals of the CIRP 42(1):417–420.

[123] Namba Y, Wada R, Tsuboi A, Okamura K (1989) Ultra Precision GrinderHaving a Glass-Ceramic Spindle of Zero Thermal Expansion. Annals of the CIRP38(1):331–334.

[124] Ngoi BKA, Sreejith PS (2000) Ductile Regime Finish Machining – A Review.International Journal of Manufacturing Technology 16:547–550.

[125] Nicholas DJ, Boon JE (1981) The Generation of High Precision AsphericalSurfaces in Glass by CNC Machining. Journal of Physics D Applied Physics14:593–600.

[126] Ohmori H (2002) State of the Art in ELID Assisted Grinding – Suitability forDifferent Material. Presentation of H. Ohmori, ELID workshop at the FraunhoferIPT Aachen, May 31, .

[127] Ohmori H, Ebizuka N, Morita S, Yamagata Y (2001) Ultraprecision Micro-Grinding of Germanium Immersion Grating Element for Mid-infrared SuperDispersion Spectrograph. Annals of the CIRP 50(1):221–224.

[128] Ohmori H, Katahira K, Mitzutani M, Komotori J (2004) Investigation on Color-Finishing Process Conditions for Titanium Alloy Applying a New ElectricalGrinding Process. Annals of the CIRP 53(1):455–458.

[129] Ohmori H, Katahira K, Uehara Y, Lin W (2002) ELID-Grinding of Microtool andApplications to Fabrication of Microcomponents. International Journal ofNanotechnology 41(2):193–204.

[130] Ohmori H, Lin W, Katahira K, Mizutani M, Naruse T, Uehara Y, Watanabe Y,Kameyama Y, Hachisu Y, Maekawa K, Sasaki C, Itoh N, Yoshida K, Hiraj S,Kasuga H, Mishima T, Asami M, Mitsuishi N, Matsuzawa T (2008) Develop-mental History and Variation of Precision and Efficient Machining Assistedwith Electrolytic Process Principle and Applications. Proceedings of the 1stInternational ELID Grinding Conference, Changsha, China, 1–5.

[131] Ohmori H, Nakagawa T (1995) Analysis of Mirror Surface Generation of Hardand Brittle Materials by ELID (Electrolytic In-Process Dressing) Grinding withSuperfine Grain Metallic Bond Wheels. Annals of the CIRP 44(1):287–290.

[132] Ohmori H, Yin S, Lin W, Uehara Y, Morita S, Asami M, Ohmori M (2005)Development on Micro Precision Truing Method of ELID-Grinding Wheel (1stReport: Principle and Fundamental Experiments). Key Engineering Materials291–292:207–212.

[133] Ong NS, Oen SK (1999) Partial-Ductile Grinding and Reduces Polishing forOphthalmic Glass Molds. Materials and Manufacturing Processes 14(5):725–739.

[134] Onikura H, Inoue R, Okuno K, Ohnishi O (2003) Fabrication of ElectroplatedMicro Grinding Wheels and Manufacturing of Microstructures with Ultra-sonic Vibration. Key Engineering Materials 238–239:9–14.

[135] Pahler D (2009) Rotational Grinding of Silicon Wafers. German Ph.D. Thesis,Rheinisch-Westfalische Technische Hochschule Aachen.

[136] Pahler D, Schneider D, Herben M (2007) Nondestructive Characterization ofSub-surface Damage in Rotational Ground Silicon Wafers by Laser Acoustics.Microelectronic Engineering 84:340–354.

[137] Pahl F (1985) Kugelschleifen optischer Glaser. German Ph.D. Thesis, Rhei-nisch-Westfalische Technische Hochschule Aachen.

[138] Pahlitzsch G, Bockem J (1972) Einfluß der Einstellgroßen beim Flachschleifenvon optischem Glas mit Diamanttopfschleifscheiben. Industrial DiamondReview 7:138–142.

[139] Pahlitzsch G, Bockem J (1973) Schleifbarkeit optischer Glaser beim Flachs-chleifen mit Diamant-Topfschleifscheiben. Industrial Diamond Review 7:157–167.

[140] Pahlitzsch G, Bockem J (1973) Flachschleifen von optischem Glas mit Dia-mant-Topfschleifscheiben unterschiedlicher Bindung. Industrial DiamondReview 7:200–207.

[141] Pei ZJ, Billingsley SR, Miura S (1999) Grinding Induced Subsurface Cracks inSilicon Wafers. International Journal of Machine Tools and Manufacture39:1103–1116.

[142] Pei ZJ, Fisher GR, Bhagavat M, Kassir S (2005) A Grinding Based Manufactur-ing Method for Silicon Wafers: An Experimental Investigation. InternationalJournal of Machine Tools and Manufacture 45:1140–1151.

[143] Pei ZJ, Strasbaugh A (2001) Fine Grinding of Silicon Wafers. InternationalJournal of Machine Tools and Manufacture 41:659–672.

[144] Pei ZJ, Xin XJ, Liu W (2003) Finite Element Analysis for Grinding of Wire-sawnSilicon Wafers: A Designed Experiment. International Journal of Machine Toolsand Manufacture 43:7–16.

[145] Peter K (1964) Sprodbruch und Mikroplastizitat von Glas in Eindruckversu-chen. Glastechnische Berichte 15:303–345.

[146] Pietsch GJ, Kerstan M (2001) Simultaneous Double-disk Grinding MachiningProcess for Flat Low-damage and Material Saving Silicon Wafer SubstrateManufacturing. Proceedings of the 2nd euspen International Conference, vol. 2,Turin, Italy, 644–648.

[147] Pietsch GJ, Kerstan M (2003) Kinematics and Application of SimultaneousDouble-disk Grinding. Proceedings of the 5th International Euspen Conference,vol. 1, Aachen, Germany, 113–116.

[148] Pietsch GJ, Kerstan M (2005) Understanding Simultaneous Double-diskGrinding: Operation Principle and Material Removal Kinematics in SiliconWafer Planarization. Precision Engineering 29:189–196.

[149] Preston FW (1921–1922) The Structure of Abraded Glass Surfaces. Transac-tions of the Optical Society 23:141–164.

[150] Puttick KE, Rudman MR, Smith KJ, Franks A, Lindsey L (1989) Single-PointDiamond Turning of Glasses. Proceedings of the Royal Society of London, SeriesA, 19–30.

[151] Rahman M, Sentil Kumar A, Biswas I (2009) A Review of Electrolytic In-Process Dressing (ELID) Grinding. Key Engineering Materials 404:45–59.

[152] Ramesh K, Huang H, Yin L, Zhao J (2004) Microgrinding of Deep MicroGrooves with High Table Reversral Speed. International Journal of MachineTools and Manufacture 44:39–49.

[153] Rickens K, Grimme D, Brinksmeier E (2006) Deterministic Machining ofBrittle Materials Applying Engineered Diamond Wheels. Proceedings of the6th euspen International Conference, vol. 2, Baden bei Wien, Austria, 216–219.

[154] Rickens K (2010) Deterministisches Schleifen optischer Glaser mit grobkor-nigen Diamantschleifscheiben. German Ph.D. Thesis, Universitat Bremen.

[155] Riemer O (2008) Diamond Machining of Micro-Structures. Proceedings of the1st International Conference on Nanomanufacturing, Singapore, 329–330.

[156] Rohn J (2003) Weiterentwicklung der Planparallelbearbeitung mit Planeten-kinematik. Jahrbuch Schleifen Honen Lappen und Polieren 61:119–127.

[157] Ruckman J, Fess E, Li Y (1991) Contour Mode Deterministic Micro-Grinding.Proceedings of the 14th Annual Meeting of the ASPE, vol. 20, Monterey, USA,542–546.

[158] Sakka S, Mackenzie JD (1969) High Pressure Effects on Glass. Journal of Non-crystalline Solids 1:107–142.

[159] Saeki M, Kuriyagawa T, Lee J-S, Syoji K (2001) Machining of Aspherical Opto-Device Parallel Grinding Method. Proceedings of the 16th Annual Meeting of theASPE, vol. 25, Crystal City, USA, 433–436.

[160] Schinker MG, Doll W (1982) Plasticity and Fracture of Inorganic Glasses atHigh Speed Grinding. Journal de physique 603–606.

[161] Schinker MG, Doll W (1982) Untersuchung zur Optimierung des Materialab-trages und der Oberflachenqualitat durch schnellstschneidende Diamanten inGlas. . Abschlussbericht zum Forschungsvorhaben AiF Nr. 4613, Freiburg.

[162] Schinker MG, Doll W (1983) Basic Investigation into the High Speed Proces-sing of Optical Glasses with Diamond Tools. Proceedings of the SPIE 381:32–38.

[163] Schinker MG, Doll W (1985) in Kurkjian CR, (Ed.) Plasticity and FractureInduced by Scratching Optical Glasses at High Speed Strength of Inorganic Glass.Plenum Publishing Corporation, pp. 115–133.

[164] Schinker MG, Doll W (1987) Turning of Optical Glasses at Room Temperature.Proceedings of the SPIE 802:70–80.

[165] Schinker MG (1991) Sub-Surface Damage Mechanisms at High-Speed DuctileMachining of Optical Glasses. Journal of the International Society for PrecisionEngineering and Nanotechnology 13(3):208–218.

[166] Shaw MC (1995) Precision Finishing. Annals of the CIRP 44(1):343–348.[167] Shaw MC (1996) Principles of Abrasive Processing. Calendon Press, Oxford.[168] Sherwood Jr. WJ (2003) Ceramic Bonded Abrasive. US Patent 20030041525.[169] Shibata T, Shigeru F, Eiji M, Masayuki I (1996) Ductile-Regime Turning

Mechanism of Single-crystal Silicon. Precision Engineering 18/(2–3):129–137.[170] Shore P (1995) Machining of Optical Surface in Brittle Materials Using an

Ultra-precision Machine Tool. Ph.D. Thesis, Cranfield University.[171] Shore P, Cunningham C, DeBra D, Evans C, Hough J, Gilmozzi R, Hocken R,

Kunzman H, Morantz P, Tonnellier X (2010) Precision Engineering of Astron-omy and Gravity Science. Annals of the CIRP .

[172] Shore P, Luo X, Jin T, Tonnellier X, Morantz P, Stephenson D, Collins R, May-Miller R, Read R (2006) Grinding Mode of the ‘‘BOX’’ Ultra Precision Free-formGrinder. Proceedings of the 20th Annual Meeting of the ASPE, Norfolk, USA, .

[173] Shore P, Morantz P, Lou X, Tonnellier X, Collins R, Roberts A, May-Miller R,Read R (2005) Big OptiX Ultra Precision Grinding/Measuring System. Pro-ceedings of the SPIE 5965. 59650Q.1–59650Q.8.

[174] Sinhoff VR (1997) Feinbearbeitung optischer Glaser in der Kleinserie. GermanPh.D. Thesis, Rheinisch-Westfalische Technische Hochschule Aachen.

[175] Slocum A, Basaran M, Cortesi R, Hart AJ (2003) Linear Motion Carriage withAerostatic Bearings Preloaded by Inclined Iron Core Linear Electric Motor.Precision Engineering 27:382–394.

[176] Steffens K, Kleinevoß R, Koch N (1989) Schleifen polierfahiger Glaslinsen mitDiamant-Topfwerkzeugen. Jahrbuch fur Optik und Feinmechanik 144.

[177] Stephenson DJ, Sun X, Zervos C (2006) A Study on ELID Ultra PrecisionGrinding of Optical Glass with Acoustic Emission. International Journal ofMachine Tools and Manufacturing 46:1053–1063.

[178] Stoica GF, Capitanescu C, Biolan AI (2003) Wear Behavior of Thin CoatingsBased on Diamond. National Tribology Conference, 133–135.

[179] Sun WP, Pei ZJ, Fisher GR (2005) Fine Grinding of Silicon Wafers: Effects ofChuck Shape on Grinding Marks. International Journal of Machine Tools andManufacture 45:673–686.

[180] Sun X, Stephenson DJ, Ohnishi O, Baldwin A (2005) An Investigation intoParallel and Cross Grinding of BK7 Glass. Precision Engineering 30:145–153.


[181] Suzuki H, Higuchi T, Nishioka M, Kitajima T, Yui A, Okuyama S, Shibutani H,Horiuchi O (2001) Precision Grinding of Micro Fresnel Shape and PrecisionGlass Molding of Micro Fresnel Lens. Proceedings of the 16th Annual Meeting ofthe ASPE, vol. 25, Crystal City, USA, 437–440.

[182] Suzuki H, Kitajima T, Okuyama S, Syoji K, Kuriyagawa T, Yan J (1998)Precision Grinding of Micro Aspherical Surface – Feasibility Study of250 mm Aspherical Grinding. Proceedings of the 13th Annual Meeting of theASPE, vol. 18, Scottsdale, USA, 149–152.

[183] Suzuki H, Kodera S, Hara S (1995) Grinding of Micro Aspherical Surface.Proceedings of the 10th Annual Meeting of the ASPE, vol. 12, Austin, USA, 183–186.

[184] Suzuki K, Uematsu T, Nakagawa T (1987) On-Machine Trueing/Dressing ofMetal Bond Grinding Wheels by Electro-Discharge Machining. Annals of theCIRP 36(1):115–118.

[185] Swain MV (1979) Microfracture about Scratches in Brittle Solids. Proceedingsof the Royal Society A366:575–597.

[186] Syoji K (2001) Some Problems of Grinding in the 21st Century. Journal of theJapan Society for Precision Engineering 45(1):88–93.

[187] Tanaka T, Esaki S, Nishida K, Nakajima T, Ueno K (2004) Development andApplication of Porous Vitrified Bonded Wheel with Ultrafine Diamond Abra-sives. Key Engineering Materials 257(258):251–256.

[188] Tanaka K, Fukuta M, Suzuki K, Iwai M, Uematsu T, Mishiro S (2006) Improve-ment of Grinding Performance in Ultra-precision Grinding of Lens Moulds bythe Help of Megasonic Coolant. International Journal of Manufacturing Tech-nology and Management 9(1–2):79–93.

[189] Taniguchi N (1974) On the Basic Concept of Nano-Technology, Proceedings ofthe International Conference of Production Engineering, Tokyo, Part II. JapanSociety of Precision Engineering 18–23.

[190] Taniguchi N (1983) Current Status in, and Future Trends of UltraprecisionMachining and Ultrafine Materials Processing. Annals of the CIRP 32(2):573–582.

[191] Tonshoff HK, Egger R, Lehnicke S (1997) Einsatz feinstkorniger Diamanttopfs-chleifscheiben zum Planschleifen von Halbleitersubstratscheiben. JahrbuchSchleifen Honen Lappen und Polieren 3:310–320.

[192] Tonshoff HK, Egger R, Longerich W, Preising D (1998) Superfinshing Cera-mics. Fine Grinding can Replace Lapping for a Superior Finish. ManufacturingEngineering 2:52–59.

[193] Tonshoff HK, Lehnicke S (1997) Grinding of Monocrystalline Silicon Wafersby Ultra-fine Grained Diamond Wheels. Proceedings of the UME4/IPES9, vol. 2,570–573.

[194] Tonshoff HK, Lehnicke S (1999) Sub-surface Damage Reduction of GroundSilicon Wafers. Proceedings of the 1st euspen International Conference, vol. 2,Bremen, Germany, 511–515.

[195] Toh SB, McPherson R (1986) Fine Scale Abrasive Wear of Ceramics by a PlasticCutting Process, Science of Hard Materials. Institute Physics Conference Series75(9):856–871.

[196] Tohme YE (2007) Grinding Aspheric and Freeform Micro-Optical Molds,Micro-machining Technology for Micro-Optics and Nano-Optics V andMicrofabrication Process Technology XII. in Maher M-AStewart HD, ChiaoJ-CSuleski TJ, Johnson EG, Nordin GP, (Eds.) Proceedings of the SPIE 6462.64620K.1–64620K.8.

[197] Tonnellier X (2009) Precision Grinding for Rapid Manufacturing of LargeOptics. Ph.D. Thesis, Cranfield University.

[198] Tonnellier X, Shore P, Morantz P, Baldwin A, Evans R, Walker DD (2007)Comparison of the Subsurface Damage Induced when Precision GrindingULE1 and Zerodur1 Surfaces. Laser Metrology and Machine Performance VIII,8th International Conference and Exhibition on Laser Metrology, Machine Tool,CMM & Robotic Performance, Lamdamap, .

[199] Tracy D (2008) Market Statistics Semiconductor. Silicon Manufacturers GroupSMG Executive Meeting, SEMICON Japan, Chiba.

[200] Uhlmann E, Ardelt T (1999) Influence of Kinematics on the Face GrindingProcess on Lapping Machines. Annals of the CIRP 48(1):281–284.

[201] Uhlmann E, Ardelt T, Stingl P, Rußner C, Magg T, Reiser A (1999) Planschleifenmit Lappkinematik. Industrial Diamond Review 33:79–83.

[202] Uhlmann E, Kirchgatter M (2009) Technologischer Nutzen von Schleifbelags-nutungen Vorteile teuer erkauft? wt Werkstatttechnik online 99(6):390–395.

[203] Vanherck P, Peters J (1973) Digital Axis of Rotation Measurements. Annals ofthe CIRP 22(1):135–136.

[204] Venkatesh VC, Izman S, Vichare PS, Mon TT, Murugan S (2005) The NovelBondless Wheel, Sperical Glass Chips and a New Method of Aspheric Gen-eration. Journal of Materials Processing Technology 167:184–190.

[205] Wang YH, Zhao MZ, Zang JB (2003) Structure and Properties of Diamond GritsCoated with Corundum Micron Powder. Key Engineering Materials 250:94–98.

[206] Weck M, McKeown PA, Bonse R, Herbst U (1995) Reduction and Com-pensation of Thermal Errors in Machine Tools. Annals of the CIRP44(2):589–598.

[207] Weck M, Schiefer KH (1979) Interaction of the Dynamic Behaviour betweenMachine Tool and Cutting Process for Grinding. Annals of the CIRP 28(1):281–286.

[208] Wenda A (2000) Jahrbuch Schleifen Honen Lappen und Polieren 59:273–284.[209] Wills-Moren WJ, Wilson T (1989) The Design and Manufacture of a Large CNC

Grinding Machine for Off-axis Mirror Segments. Annals of the CIRP 38(1):529–533.

[210] Wolters P, Mackensen Vv, Longerich P, Dennis P, Preising D (1998) Feins-chleifen ebener Flachen auf Maschinen mit Lappkinematik. Jahrbuch SchleifenHonen Lappen und Polieren 58:215–226.

[211] Yamamoto Y, Maeda H, Shibutani H, Suzuki H, Horiuchi O (2004) A Study onConstant-pressure Grinding with EPD Pellets. Key Engineering Materials 257–258:135–138.

[212] Yamamoto Y, Suzuki H, Moriwaki T, Okino T, Hijikata Y, Roblee J, Miyashita T(2006) Development of Cross and Parallel Mode Grinding Machine for HighNa Aspherical Mold and Die. Proceedings of the 21st Annual Meeting of theASPE, vol. 39, Monterey, USA, 499–502.

[213] Yamamoto Y, Suzuki H, Okino T, Hijikata Y, Moriwaki T, Fukuta M, NishiokaM, Kojima Y (2004) Ultra Precision Grinding of Micro Aspherical Surface –Development of a Three-Axes Controlled Single Point Inclined GrindingMethod. Proceedings of the 13th Annual Meeting of the ASPE, vol. 34, St. Louis,USA, 558–561.

[214] Yi AY (2003) Optical Fabrication. in Mallick PK, (Ed.) Encyclopedia of AppliedPhysics. Marcel Dekker Publishers.

[215] Yin S, Lin W, Uehara Y, Morita S, Ohmori H, Asami M, Ohmori M (2005)Development on Micro Precision Truing Method of ELID-Grinding Wheel(2nd Report: Application to Edge Sharpening of Large Wheel). Key EngineeringMaterials 291–292:213–220.

[216] Yin S, Ohmori H, Uehara Y, Shimizu T, Lin W (2003) Micro V-grooves GrindingTechnique of Large Germanium Immersion Grating Element for Mid-infraredSpectograph. International Conference on Leading Edge Manufacturing in 21stCentury, 223–228.

[217] Yoshida S, Ito H (1990) The Present and Future of Ductile-Regime Grinding ofOptical Parts. Bulletin of Japan Society of Precision Engineering 24:239–243.

[218] Yoshihara N, Yan J, Kuriyagawa T (2007) Development of Rubber-BondedGrinding Wheel – Studies on Asperical Grinding. Key Engeneering Materials329:465–470.

[219] Yoshioka J, Koizumi K, Shimuzu M, Yoshikawa H, Miyasahita M, Kanai A(1982) Surface Grinding with Newly Developed Ultra Precision GrindingMachine. . SME Technical Paper, MR82-930.

[220] Youden D (1986) Recent Developments in Diamond Turning. Proceedings ofthe 3rd International Machine Tool Technical Conference, Illinois, USA, .

[221] Zarudi I, Zhang LC (1997) Sub-surface Structure Change of Silicon after Ultra-precision Grinding. International Symposium on Advances in Abrasive Technol-ogy (ISAAT97), 33–37.

[222] Zhang L, Zarudi I (1999) Understanding of the Chemical Effect on the Nano-wear Deformation in Monocrystalline Silicon. Wear 225–229:669–677.

[223] Zhang XH, Pei ZJ, Fisher GR (2006) A Grinding-based ManufacturingMethod for Silicon Wafers: Generation Mechanisms of Central Dimpleson Ground Wafers. International Journal of Machine Tools and Manufacture46:397–403.

[224] Zhao QL, Liang YC, Stephen D, Corbett J (2007) Surface and SubsurfaceIntegrity in Diamond Grinding of Optical Glasses on Tetraform ‘C’. Interna-tional Journal of Machine Tools and Manufacture 47:2091–2097.

[225] Zhong Z, Venkatesh VC (1995) Semi-Ductile Grinding and Polishingof Ophthalmic Aspherics and Spherics. Annals of the CIRP 44(1):339–342.

[226] Zhong Z (2002) Surface Finish of Precision Machined Advanced Materials.Journal of Materials Processing Technology 122:173–178.

[227] Zhou LB, Eda H, Shimizu J (2002) State of the Art Technologies and Kine-matical Analysis for One-stop Finishing of 300 mm Si Wafer. Journal ofMaterials Processing Technology 129:34–40.

[228] Zum Gahr KH (1987) Microstructures and Wear of Materials Tribology Series,vol. 10. Elsevier, Amsterdam/Oxford.

Documents

Ultra-precision grinding