Several Irons in the Fire€¦ · croinjection molding with part weights in the milligram range, tailored for use on the Battenfeld machine Microsys-tem 50.Thus,the mold for the part

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SPEC I A L TOOL ING

© Carl Hanser Verlag, Munich Kunststoffe international 9/2007

For cost-effective massproduction, the injectionmolds play a key role

even for plastic parts with highgeometrical and functionalcomplexity. While offeringhigh availability and long serv-ice lives, they must reproduceparts with the specified, usual-ly very close, dimensional tol-erances with the largest num-ber of cavities and in the short-est time possible. Unlike injec-tion molding machines andmolding compounds, whichmachine and raw materialsmanufacturers must offer in awide range of standard pro-grams, molds must be individ-ually designed and fabricated

from scratch for each newproduct. However, these one-off products make a clear im-pression at the cost side. Moldcosts can constitute up to 30 %of total production costs.

With the current outsourc-ing trend in Western Europe,which also applies to moldpurchasing, local tool andmold makers must assertthemselves against growingcompetition from low-wagecountries. Organizationalmeasures for continuous im-provement of the cost struc-ture and reduction of leadtimes are indeed necessary, butare not sufficient alone to with-stand the price dumping re-sulting from mold-makingovercapacities in Germany andWestern Europe overall. It isonly by simultaneously spe-cializing in technologicallychallenging precision tools forinnovative plastic productsthat European mold makerswill be able to score in the faceof increasing competitive pres-sure on the world market. Thetrade show focuses that aresummarized here, on the basisof information from the com-panies mentioned, give an in-sight into current mold tech-nology.

Molds with HighAdded Value

Multicomponent molds arestill a strength of Europeanmold-makers. In parallel withthe functional integration by

combining different materi-als, multicomponent technol-ogy allows assembly opera-tions to be integrated into theinjection molding cycle. Thus,Foboha GmbH, Haslach, Ger-many, is presenting a moldconcept for the manufactureof two-component hinges(Fig. 1) from the materialcombination polyethylene(PE-HD) and thermoplasticelastomer (TPE) in one oper-ation. The concept includes a6+6-cavity stack mold withrotary four-station centerblock, also known as a “cubemold.” In the first station,three PE parts connected byfilm hinges are produced, and,in the opposing injection sta-tion, are provided with theTPE component for a ready-to-use hinge. The stack turn-ing technology offers severaladvantages for this applica-tion. For example, the tool canbe operated on an injectionmolding machine with only4,500 kN clamping force. Al-most twice the clamping forcewould be necessary with con-

ventional two-componenttechnology (rotary table).Andsince the rotating center blockhas four stations (indexingthrough 90°), the cycle time issignificantly reduced. The sec-ond station serves as a post-cooling station for the PE pre-forms, and the two-compo-nent parts are demolded in theopposing fourth station, thatis to say parallel to the injec-tion cycle and therefore withno impact on the cycle time.This mold concept is present-ed on the trade show boothfrom Ferromatik MilacronMaschinenbau GmbH, Mal-terdingen, Germany.

A specialty is also present-ed by Battenfeld Kunststoff-maschinen Ges.m.b.H., Kot-tingbrunn, Austria, in cooper-ation with Microsystems UKLtd., Warrington, UK. Thesemolds are for precision mi-croinjection molding withpart weights in the milligramrange, tailored for use on theBattenfeld machine Microsys-tem 50. Thus, the mold for thepart in Fig. 2 – a vascular

Molds, Hot-Runners, and More. Without a new injection mold, there can be no

new molding. But Europe’s mold makers are faced with ever-increasing cost pres-

sure and competition. This requires intelligent solutions, both from the mold mak-

ers themselves and from the component and assembly manufacturers who special-

ize in mold technology. The exhibitors’ program for this year’s K trade show

demonstrates how this can be done.

Several Irons in the Fire

Fig. 1. Two-component hinge for atoilet seat, injection molded withthe rotary stack mold in one opera-tion (photo: Foboha)

Fig. 2. Four-cavity mold in-sert for preci-sion microin-jection mold-ing of tinyvascularclamp (photo:

Battenfeld/

Microsystems)

Translated from Kunststoffe 9/2007,pp. 61–67

� PE104021

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------© 2007 Carl Hanser Verlag, Munich, Germany www.kunststoffe-international.com Not for use in internet or intranet sites. Not for electronic distribution.

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SPEC I A LTOOL ING

Kunststoffe international 9/2007

clamp made of a special poly-mer that can be resorbed intothe patient’s body – a cavityvolume of only 0.005 cm3

(5 mm3), the shot volume forall four parts, including sprue,is 0.124 cm3. The delicatework of constructing suchmolds can be demonstratednot least by the ejectors: in thecase of the vascular-clampmold, they have a diameter of0.4 mm! Microsystems UKhas specialized for years inconstructing such micropartmolds for medical technologyand optics, and generally forthin-wall parts.At K, the man-

ufacture of an electronic mi-croplug in a two-cavity moldis presented, in which twometal pins – 5 mm long,0.6 mm diameter – are insert-ed per plug, and then over-molded with 16 mg POM per

cavity. The cycle time with fullautomation is 5 s.

Competition in thePrecision Sector

The North Italian mold mak-er Ghilardi Stampi s.r.l.,Cologno Monese, Milan, spe-cializes in molds for medicaltechnology articles, packagingand closures. And the Por-tuguese Molde Matos s.a.,Marinha Grande, is demon-strating its capabilities inmolds up to a weight of 8 met-ric tons for automotive appli-cations, electronic compo-nents, household goods andfittings.

However, Europe’s moldmakers are increasingly receiv-ing competition from Asia,even in the precision segment.For example, Forson Precision(HK) Ltd., which claims to bethe leading moldmaker inHong Kong, will be represent-ed at the K trade show for thefirst time. Since its foundationin 1992, the company has man-ufactured precision molds andtools for customers in Europe,the USA, Asia and the Middle

East, and is now aiming to ex-pand its worldwide customerbase. The company has built a35,000 m2 mold factory inShenzhen on the Chinesemainland, which is equippedwith over 200 European andJapanese injection moldingmachines for individual, group

and multicavity molds. Anannual production capacity ofover 500 molds is currentlyavailable (Fig. 3).

Support by StandardsSuppliers

Suppliers of tools steels, stan-dards, parts and assemblies,through to hot-runner systems

or even complete “hot halves,”support mold makers withcontinuous developments andinnovative new products.Without this strategic partner-ship, mold makers wouldhardly be able to withstand thegrowing time and cost pres-sures.

For example, Hasco Hasen-clever GmbH & Co. KG, Lü-denscheid, Germany, with itsnew Toolox tool steels, offersalternatives to the convention-al 1.2311 and 1.2312 steelsoften used in injection mold-making. Toolox 33 is aparticularly low-stress, pre-hardened and tempered toolsteel with ESU characteristics,high toughness and a tensilestrength of 1,080 N/mm2

(MPa). The steel qualityToolox 44 is a prehardened

tool steel with 45 HRC. Thisbasic hardness, even in the as-supplied condition, meansmoldmakers no longer have toperform the heat treatmentand corresponding post-treat-ment that would otherwise benecessary.

D-M-E Europe C.V.B.A.,Mechelen, Belgium, with itsVectorForm lifter system(Fig. 4), shows how the depthof undercuts in injection moldscan be doubled. Instead of astatic base in the ejector plate,it uses a lifter rod driven by aslide base. This makes muchsteeper lift angles feasible. In-stead of a maximum 15° as rec-ommended for most priorlifter systems, the new systemwith its slide base can receiveangles of 30° and more. An-other new development pre-sented by D-M-E is a centering

Fig. 3. Hot-runner mold from Chinese production (photo: Forson Precision)

Fig. 4. The VectorForm lifter systemallows very deep part undercuts tobe reproduced in the mold (photo: D-M-E)

Fig. 5. New in the program (from left to right): slide units, hydraulic two-stage ejectors and contourable tunnelgate inserts (photo: Meusburger)

Fig. 6. With DMLS moldinserts with conformalcooling channels can bebuilt up layer by layer di-rectly from CAD data (pho-

to: EOS)

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SPEC I A L TOOL ING

system for the stack mold,available as a complete assem-bly. These assemblies now alsoinclude standard housings forhelical-geared shafts and nuts,greatly simplifying the design,construction and maintenanceof stack molds.

Meusburger Georg GmbH& Co., Wolfurt, Austria, whichspecializes in mold fittings, hasextended its product programwith slide units, hydraulic two-stage ejectors and sprue inserts(Fig. 5).The new slide units ex-tend from small slides for small

lateral recesses and flexibleejector units for small under-cuts (e. g. clips and snap lugs),to angled ejectors for large un-dercuts with positive demold-ing. The hydraulic two-stageejectors can be used particu-larly where high demoldingforces are required. And in theindividually contourable tun-nel-gate inserts for a gate deepwithin the part, an integratedbaffle reduces the pressure lossand melt shearing.

With the DMLS (directmetal laser sintering) process,

EOS GmbH Electro OpticalSystems, Krailling, Germany,shows how mold inserts can bemanufactured individuallyand rapidly directly from CADdata. For example, tool steel in-serts of MS1, a maraging toolsteel, offer a tensile strength of1,950 MPa and a hardness upto 54 HRC in the post-hard-ened state. According to themanufacturer, this special met-al alloy is especially suitable forheavy duty mold inserts. TheDMLS process allows evenparts with complex internal

structures, such as conformalcooling channels, to be manu-factured (Fig. 6).

The continuous measure-ment of cavity pressures oftenserves for monitoring currentproduction. For this purpose,the signals from the sensorsinstalled in the mold oftenhave to be amplified. Cavitypressure measurements andgeneral strain measurementswith piezo sensors can bemade with the DACI 800multi-range charge amplifierfrom Baumer GmbH, Fried-

Fig. 8. “Drop-in” hot-runner system: Hot-runnermanifold, including nozzles, assembled and wiredready for installation (photo: Ewikon)

Fig. 9. Poli-valve hot-runner sys-tem, devel-oped espe-cially formulticavityapplicationsand differentpart sizes(photo: D-M-E)

Fig. 7. Piezo multi-range amplifierfor the high-resolution measure-ment of cavity pressures andstrains (photo: Baumer)


SPEC I A LTOOL ING

berg, Germany (Fig. 7). The14 selectable charge-measure-ment ranges from 100 to1,000,000 pC allow the differ-ent sensitivities of the piezosensors to be amplified andtransmitted as current signalsfrom 4 to 20 mA. Togetherwith the manufacturer’s piezosensors for cavity pressuremeasurements up to 2,000bar, and a DSPN strain sensorfor general strain measure-ments, it provides a high-res-olution measurement chain.

A Wide Variety of Hot-Runners

In the course of continually in-creasing raw materials prices,sprueless injection molding isbecoming more importantthan ever, particularly in thepackaging industry. For exam-ple, Ewikon Heisskanalsys-teme GmbH & Co. KG,Frankenberg, Germany, hasdeveloped a so-called “drop-inhot-runner system,” to makethis compact, preassembled

design principle (Fig. 8),whichwas mainly used for large sys-tems in the past, available forsmaller molds as well. This is aready-to-install unit compris-ing nozzles, manifold andsprue bush, including wiringand connection box. The hot-runner nozzles are firmlyscrewed to the manifold.

With the Polivalve needle-valve hot-runner system(Fig. 9), D-M-E is specificallytargeting applications in mul-ticavity molds, both for small

and large-volume moldingswith geometries that are com-plicated or difficult to fill. Thesystem permits optionally si-multaneous or sequential meltflow for filling the cavities. Thehot-runner system is thereforealso suitable for so-called“family” molds, in which sev-eral parts of different sizes areinjection molded in one cycle.

Mold-Masters Europe GmbH, Baden-Baden, Ger-many, has continued to devel-op its Accu-Valve hot-runner

systems. The CX model de-signed for commodity plasticshas a novel nozzle design(Fig. 10), which permits openmelt flow in the gate region,unhindered by the needlevalve. Dead spaces have alsobeen eliminated, so that, withthe new design, the manufac-turer can, for example, great-ly reduce times for a colorchange. The Accu-Valve EXmodel designed for processingengineering plastics has beenequipped with a needle-valvesystem with precise tempera-ture control directly at thegate.

Husky Injection MoldingSystems Ltd., Dudelange, Lux-embourg, has further devel-oped and extended its hot-runner nozzle program of theUltra series (Fig. 11). A newaddition is the Ultra 350 sizewith needle valve and ther-mally conducting nozzle tip.This nozzle is designed for athroughput up to 30 g/s anduse in multicavity molds forsmall parts. The compact de-

Fig. 10. Nozzle in-sert of the Accu-

Valve CX hot-run-ner nozzle for

free melt flowand rapid color

change (photo:

Mold-Masters)

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© Carl Hanser Verlag, Munich Kunststoffe international 9/2007

sign permits a nozzle spacingof only 18 mm. Advances, in-cluding the Ultra 500 model,now include nozzles that canwithstand melt pressures up to3,000 bar.

Hasco has extended its nee-dle-valve nozzle program witha Valve Shot Z3145 model(Fig. 12), which has been espe-cially developed for challeng-ing processing tasks in the fieldof closures and packaging. The

new nozzle range is preferablyused for processing polyolefinsand styrenes with a shot-weight range of 5 to 25 g. Notonly can close cavity spacingsin molds with large numbersof cavities be realized, but un-favorable gating positions canbe easily implemented.

New additions to the hot-runner technology program ofthe standard manufacturer

Strack Norma GmbH & Co.KG, Lüdenscheid, Germany,are the Mastip hot-runnernozzles of the X series withnozzles of the MX, BX and SXfamily. The MX nozzles werespecially developed for largenumbers of nozzles and com-plete hot halves, the BX nozzlesfor cost-effective solutionswith low-to-medium numbersof cavities and the SX-nozzlesfor applications requiring on-ly one nozzle. The MX and BXseries are optionally availableas needle-valve nozzles.

Otto Männer Vertriebs GmbH, Bahlingen, Germany,has developed its Sidegateneedle closure nozzle, whichwas until now designed forduplex gating from oppositesides, into a four-gate system(Fig. 13). The four needlevalves arranged perpendicularto the nozzle longitudinal ax-is are opened and closed witha pneumatically operatedcontrol needle in the nozzlebody.

Mold Cooling –Essential

For optimum part quality andcycle time, heat must be effi-ciently removed from the moldcavity filled with melt, with themost uniform possible tem-perature distribution at thecavity surface. Besides the po-sition and geometry of thecooling channels, coolingequipment plays a critical rolein this.

Wittmann Kunststoffge-räte GmbH, Vienna, Austria,has developed the new TemproPlus C cooling equipment se-ries, which can be used as bothan open and closed systemwith one or two circuits. Leak-stop operation, suction clean-ing of the cooling channels onmold exchange and permanentmonitoring of the return tem-perature are standard features.Process control and documen-tation are facilitated by an op-tional interface to the machineand pressure and flow moni-toring.

Remak Maschinenbau GmbH, Reinheim, Germany,has expanded its compactPulseTemp RPT 100 systemwith an “automatic” mode(Fig. 14). Without furtherchoice of the operating mode,only the temperature setpointsfor the individual cooling cir-

cuits need to be entered. Thecontrol decides automaticallywhether intermittent or con-tinuous cooling, cold watermust be mixed with to a hot-water stream,or hot water witha cold-water stream, to ensurethat the setpoint temperatureis maintained.

For its HB-Therm Series 4latest generation of moldcooling units, GrossenbacherApparatebau AG, St. Gallen,Switzerland, has chosen anautomatically air-bled andnevertheless pressurized cool-ing circuit. According to themanufacturer, the higherpressure of the cooling water,and consequent increase inboiling point, reduces the riskof cavitation of the circulationpump.

With its TFC chiller self-draining (TFC: total free cool-ing), Eurochiller s.r.l., Castel-

Fig. 13. Sidegate four-point needlevalves, which can inject simulta-neously at four lateral gates (photo: Männer)

Fig. 14. PulseTemp RPT 100 cooling unit with six mold circuits, equippedwith automatic operating mode (photo: Remak)

Fig. 11. 192-cavity hot-runner system with Ultra 500 hot-runner nozzles,now also available for injection pressures up to 3,000 bar (photo: Husky)

Fig. 12. Valve Shot needle-valve nozzle specially developed for injectionmolding closures and packaging (photo: Hasco)


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SPEC I A LTOOL ING

lo d’Agogna, Italy, presents adesign of this cooling unit,which is intended for mount-ing outdoors and for the firsttime manages without glycolantifreeze in the cooling circuit(Fig. 15). The so-called free-cooling model is energy saving,since before the cooling waterpasses into the cooling unit,most of the heat has alreadybeen removed by the exteriorair and fan assistance. In thenew environmentally friendlymodel of the cooling unit, Eu-rochiller only uses purified wa-ter. If there is a risk of freezingat low outdoor temperatures inwinter, e. g. because of a pro-duction stoppage, the contin-uous temperature monitoringon the cooler automaticallyopens an emergency drainvalve.

Minimizing ToolingTimes

Tooling times are unproduc-tive times in the injectionmolding shop. Every measurethat minimizes this time im-proves the economy. EAS Eu-rope B.V., Renswoude, TheNetherlands, with its moldclamping devices, modulesfor automatic mold changingand devices for facilitatingmold maintenance, special-izes in reducing non-value-adding phases. The latestmagnetic clamping systemmodels (Fig. 16) for all sizes

and designs of injectionmolding machines are nowequipped throughout with aso-called “4 = 1 sensor.” In-stead of, as previously, twoproximity switches for the

presence testing, a tempera-ture sensor and a magneticflux sensor, the new combi-nation sensor performs all themonitoring functions andthereby simplifies, e. g., signalexchange with the machinecontrols. For the mold ex-change, EAS, as another in-novation, offers a completelymodular program of moldchanging stations. These sta-tions are available in threesizes with a load-bearing ca-pacity of 10, 20 and 40 t permold position, with either

one or two roller conveyorstations, in rigid table designor as a railcar with longitudi-nal feed.

For rapid mold changing,D-M-E employs a self-locking,

mechanical bayonet, quick-change system (Fig. 17). Theadapter plates mounted on theinjection molding machineclose with special centeringrings mounted on the mold.For this purpose, the mold isplaced as usual, the centeringring is introduced into theadapter plate and locked witha wrench. The new system canbe used for all horizontal andvertical injection molding ma-chines to 1,800 kN clampingforce, both with and withouttie bars.

Cost Transparency inMold Calculation

Mold making always dealswith complicated and expen-sive products; precise costcalculation in advance istherefore increasingly be-coming the rule. To deter-mine these costs, TranscatKunststofftechnik GmbH,Karlsruhe, Germany, has de-veloped the CalCard soft-ware, which is currently avail-able in version 5.0.24. Thismakes use of the technologyinformation integrated in thesystem, which is kept currentby regular updates. Users canalso update the data them-selves, for example if theybring a new machine onstream. Another data sourceis the 3-D model of the partto be produced. The softwareanalyzes the geometry andmakes proposals for mold de-sign. The necessary calcula-tions largely run fully auto-matically in the background.For example, it determinesthe milling volume of moldhalves, and – after the choiceof milling tools – calculatesthe machining time, amongother data. There is alwaysthe possibility of revising theproposed results. The devel-opment of the costs duringthe course of a project can al-so be tracked. ■

Georg Krassowski

Kunststoffe international 9/2007

Fig. 16. Magnetic clamping system, in which all the monitoring functionsare combined in only one sensor (photo: EAS)

Fig. 17. Bakra quick-clamping system – rapid mold exchange with self-locking bayonet closure (photo: D-M-E)

Fig. 15. The TFC chiller self-draining operates without glycol antifreeze(photo: Eurochiller)


Documents

Several Irons in the Fire€¦ · croinjection molding with part weights in the milligram range, tailored for use on the Battenfeld machine Microsys-tem 50.Thus,the mold for the part