Seminar ReportOn

“Magneto Abrasive Flow Machining”

Submitted for the partial fulfillment of requirement for the degree of

BACHELOR OF ENGINEERING(Mechanical Engineering)

Submitted ByMr. Ashish S. Honale

Under the Guidance of

Prof.

Department of Mechanical EngineeringSiddhivinayak Technical Campus, SERT, Khamgaon.

Sant Gadge Baba Amravati University, Amravati2015-2016

CertificateCertificateThis is to certify that the seminar entitled

“Magneto Abrasive Flow Machining”is a bona-fide work and it is submitted to the

Sant Gadge Baba Amravati University, AmravatiBy

Mr. Ashish S. Honalein the partial fulfillment of the degree of Bachelor of Engineering in

Mechanical Engineering during the academic year 2015-2016 under my guidance.

Prof. A. N. RakhondePrincipal

Prof. Guide

Department of Mech Engg

Prof. Pramod S. Wankhade

HOD Department of Mech Engg

Department of Mechanical EngineeringSiddhivinayak Technical Campus, SERT, Khamgaon.

2015-2016

AcknowledgementIt is pleasant endeavor to present seminar report on “Magneto Abrasive Flow

Machining”. I avail this opportunity to express my deep sense of gratitude and whole hearted thanks to my guide Prof. …….. of STC, SERT, Khamgaon for substantial guidance and cooperation in the seminar work. He has provided all the facilities whenever I need and mostly for his gracious encouragement, advice and guidance to make this project a success.

I also express my gratitude to Prof. A. N. Rakhonde Principal, STC SERT, Khamgaon for constant inspiration and valuable advice.

I am equally thankful to Mr. P. S. Wankhade (HOD) Dept of Mech Engg. and All the Faculties of Mechanical engineering Department of STC, SERT, Khamgaon for constant inspiration and valuable suggestions.

Words fall short to express my deep sense of gratitude towards them all, who have directly or indirectly helped in making this project.

Mr. Ashish S. Honale Final year Mech Engg

STC, SERT, KHAMGAON

List of Figure

1. Schematic illustration of the magneto abrasive flow machining process

2. Principle of Material Removal Mechanism

3. Mechanism of Magneto Abrasive Flow Machining

4. Unidirectional MAFM Process

5. Two–way MAFM Process

6. Orbital MAFM Process (a) Before start of finishing (b) While finishing.

7. Surface finish improvement before and after on (a) internal passages within turbine engine

diffuser (b) medical implants (c) complete automotive engine parts.

List of Table

CONTENT

Abstract

Chapter 1

1.1 Introduction …………………………………………………………………

1.2 Aim and specific objectives…………………… ……………………………………

1.3 Method………………………………………………………………………

Chapter 2

2.1 General concept ………………………………………………….…………

Chapter 3

3.1 Experimental set-up …………………………………………………………….

3.2 Types of MAFM machines removal …………………………………………..

3.3 Mechanism of material

Chapter 4

4.1 Advantages ……………………………………………………………………

4.2 Limitations ……………………………………………………………………4.3 Application …………………………………………………………………4.4 Conclusion …………………………..4.5 References …………………………………………………………………………..

1. Abstract

Magneto abrasive flow machining (MAFM) is a new technique in machining. The orbital flow machining process

has been recently claimed to be another improvement over AFM, which performs three-dimensional machining of

complex components. These processes can be classified as hybrid machining processes (HMP)—a recent concept

in the advancement of non-conventional machining. The reasons for developing a hybrid machining process is to

make use of combined or mutually enhanced advantages and to avoid or reduce some of the adverse effects the

constituent processes produce when they are individually applied. In almost all non-conventional machining

processes such as electric discharge machining, electrochemical machining, laser beam machining, etc., low

material removal rate is considered a general problem and attempts are continuing to develop techniques to

overcome it. The present paper reports the preliminary results of an on-going research project being conducted

with the aim of exploring techniques for improving material removal (MR) in AFM. One such technique studied

uses a magnetic field around the work piece. Magnetic fields have been successfully exploited in the past, such as

machining force in magnetic abrasive finishing (MAF), used for micro machining and finishing of components,

particularly circular tubes. The process under investigation is the combination of AFM and MAF, and is given the

name Magneto Abrasive Flow Machining (MAFM).

2. INTRODUCTION

Magneto Abrasive flow machining (MAFM) is one of the latest non-conventional machining processes,

which possesses excellent capabilities for finish-machining of inaccessible regions of a component. It has been

successfully employed for deburring , radiusing and removing recast layers of precision components. High levels

of surface finish and sufficiently close tolerances have been achieved for a wide range of components . In MAFM,

a semi-solid medium consisting of a polymer-based carrier and abrasives in a typical proportion is extruded under

pressure through or across the surfaces to be machined. The medium acts as a deformable grinding tool whenever

it is subjected to any restriction. A special fixture is generally required to create restrictive passage or to direct the

medium to the desired locations in the work piece

3.3. Aim and Specific Objectives

This report discusses the possible improvement in surface roughness and material removal rate by applying a

magnetic field around the work piece in AFM. A set-up has been developed for a composite process termed

magneto abrasive flow machining (MAFM), and the effect of key parameters on the performance of the process

has been studied. Relationships are developed between the material removal rate and the percentage

improvement in surface roughness of brass components when finish-machined by this process.

3.4. Method

In almost all non-conventional machining processes such as electric discharge machining, electrochemical

machining, laser beam machining, etc., low material removal rate is considered a general problem and attempts

are continuing to develop techniques to overcome it. This report presents the preliminary results of an ongoing

research project being conducted with the aim of exploring techniques for improving material removal (MR) in

AFM. One such technique studied uses a magnetic field around the work piece. Magnetic fields have been

successfully exploited in the past, such as machining force in magnetic abrasive finishing (MAF), used for micro

machining and finishing of components, particularly circular tubes. Shinmura and Yamaguchi and more recently

Kim et al., Kremen et al. and Khairy have reported studies on this process. The process under investigation is the

combination of AFM and MAF, and is given the name magneto abrasive flow machining (MAFM).

4. OVERVIEW

AFM was developed in 1960s as a method to deburr, machining. This provides improvement in surface

roughness and material removal rate, polish intricate geometries. The process has found applications in a wide

range of fields such as aerospace, defence, and surgical and tool manufacturing industries. Extrusion pressure,

flow volume, grit size, number of cycles, media, and work piece configuration are the principal machining

parameters that control the surface finish characteristics. Recently there has been a trend to create hybrid

processes by merging the AFF process with other non-conventional processes. This has opened up new vistas for

finishing difficult to machine materials with

complicated shapes which would have been otherwise impossible. These processes are emerging as major

technological infrastructure for precision, meso, micro, and nano scale engineering. This review provides an

insight into the fundamental and applied research in the area and creates a better understanding of this finishing

process, with the objective of helping in the selection of optimum machining parameters for the finishing of

varied work pieces in practice.MAFM is a new non-conventional machining technique .It produces surface

finishes ranging from rough to extremely fine. Here chips are formed by small cutting edges on abrasive

particles.The use of magnetic field around the work piece. It deflects the path of abrasive flow. Here

‘Microchipping’ of the surface is done.

The various limitations of Abrasive Flow Machining are overcome like:

1. Low finishing rate.

2. Low MRR.

3. Bad surface texture.

4. Uneconomical.

6. EXPERIMENTAL SET-UP

6.1 MAFM set - up.

An experimental set-up is designed and fabricated, it is shown in fig:6.1. It consisted of two cylinders (1)

containing the medium along with oval flanges (2). The flanges facilitate clamping of the fixture (3) that contains

the work piece (4) and index the set-up through 180° when required. Two eye bolts (5) also support this purpose.

The setup is integrated to a hydraulic press (6). The flow rate and pressure acting on piston of the press were

made adjustable. The flow rate of the medium was varied by changing the speed of the press drive whereas the

pressure acting on the medium is controlled by an auxiliary hydraulic cylinder (7), which provides additional

resistance to the medium flowing through the work piece. The resistance provided by this cylinder is adjustable

and can be set to any desired value with the help of a modular relief valve (8). The piston (9) of the hydraulic

press then imparts pressure to the medium according to the passage size and resistance provided by opening of

the valve. As the pressure provided by the piston of the press exceeds the resistance offered by the valve, the

medium starts flowing at constant pressure through the passage in the work piece. The upward movement of the

piston (i.e. stroke length) is controlled with the help of a limit switch. At the end of the stroke the lower cylinder

completely transfers the medium through the work piece to the upper cylinder. The position of the two cylinders

is interchanged by giving rotation to the assembly through 180° and the next stroke is started. Two strokes make

up one cycle. A digital counter is used to count the number of cycles. Temperature indicators for medium and

hydraulic oil are also attached.

6.2 The Fixture.

The work fixture was made of nylon, a non-magnetic material. It was specially designed to accommodate

electromagnet poles such that the maximum magnetic pull occurs near the inner surface of the work piece.

6.3 The Electromagnet.

The electromagnet was designed and fabricated for its location around the cylindrical work piece. It consists of

two poles that are surrounded by coils arranged in such a manner as to provide the maximum magnetic field near

the entire internal surface of the work piece.

6.4 The Abrasive Medium.

The medium used for this study consists of a silicon based polymer, hydrocarbon gel and the abrasive grains. The

abrasive required for this experimentation has essentially to be magnetic in nature. In this study, an abrasive

called Brown Super Emery (trade name), supplied by an Indian company, was used. It contains 40%

ferromagnetic constituents, 45% Al2O3 and 15% Si2O3.

Figure 6.1: The Workpiece

Figure 6.2: Schematic illustration of the magneto abrasive flow machining process

(1.Cylinder containing medium, 2. Flange, 3.Nylon fixture, 4.Workpiece, 5.Eye bolt, 6.Hydraulic press, 7.Auxiliary

cylinder, 8.Modular relief valve, 9.Piston of Hydraulic press, 10.Directional control valve, 11.Manifold blocks,

13.Electromagnet).

Figure 6.3: Typical Machining Centre.

8. PRINCIPLE

The volume of abrasive particles is carried by the abrasive fluid through the work piece. Abrasives are impinged

on the work piece with a specified pressure which is provided by the piston and cylinder arrangement or with the

help of an intensifier pump. The pressure energy of the fluid is converted into kinetic energy of the fluid in order

to get high velocity.

When a strong magnetic field is applied around the work piece, the flowing abrasive particles (which must

essentially be magnetic in nature) experience a sideways pull that causes a deflection in their path of movement

to get them to impinge on to the work surface with a small angle, thereby resulting in microchipping of the

surface. The magnetic field is also expected to affect the abrasive distribution pattern at the machining surface of

the work piece. The particles that otherwise would have passed without striking the surface now change their

path and take an active part in the abrasion process, thus causing an enhancement in material removal. It is to be

mentioned here that although the mechanical pull generated by the magnetic field is small, it is sufficient to

deflect the abrasive particles, which are already moving at considerable speed. Therefore it appears that, by

virtue of the application of the magnetic field, more abrasive particles strike the surface. Simultaneously, some of

them impinge on the surface at small angles, resulting in an increased amount of cutting wear and thereby giving

rise to an overall enhancement of material removal rate.

(a) (b)

Figure 8.1: (a) Off-state MR fluid particles (b) Aligning in an applied magnetic field.

Figure 8.2: Principle of Material Removal Mechanism

9. ABRASIVE MEDIUM

The mainly used abrasive media is a Silicon based polymer, hydrocarbon gel and the abrasive grains.The abrasive

required is essentially magnetic in nature for the proper machining process to take place. An abrasive called

Brown Super Emery (trade name), supplied by an Indian company is normally used. It contains 40%

ferromagnetic constituents, 45% Al2O3 and 15% Si2O3. SiC with silicon gel is also used as an abrasive media.Also

diamond coated magnetic abrasives can be used to finish ceramic bars.

Figure 9.1: Mechanism of Magneto Abrasive Flow Machining

10. MAFM MACHINES

MAFM Machines are classified into 3, namely:-

1. One-Way Machines

2. Two-Way Machines

3. Orbital Machines

10.1 One-way machines.

One way MAFM process apparatus is provided with a hydraulically actuated reciprocating piston and an extrusion

medium chamber adapted to receive and extrude medium unidirectionally across the internal surfaces of a work

piece having internal passages formed therein. Fixture directs the flow of the medium from the extrusion

medium chamber into the internal passages of the work piece, while a medium collector collects the medium as

it extrudes out from the internal passages. The extrusion medium chamber is provided with an access port to

periodically receive medium from the collector into extrusion chamber.

The hydraulically actuated piston intermittently withdraws from its extruding position to open the extrusion

medium chamber access port to collect the medium in the extrusion medium chamber. When the extrusion

medium chamber is charged with the working medium, the operation is resumed.

Figure 10.1: Unidirectional MAFM Process

10.2 Two-way machines.

Two-way machine has two hydraulic cylinders and two medium cylinders. The medium is extruded, hydraulically

or mechanically, from the filled chamber to the empty chamber via the restricted passageway through or past the

work piece surface to be abraded. Typically, the medium is extruded back and forth between the chambers for

the desired fixed number of cycles. Counter bores, recessed areas and even blind cavities can be finished by using

restrictors or mandrels to direct the medium flow along the surfaces to be finished.

Figure 10.2: Two–way MAFM Process

10.3 Orbital machines.

In orbital MAFM, the work piece is precisely oscillated in two or three dimensions within a slow flowing ‘pad’ of

compliant elastic/plastic MAFM medium.

In orbital MAFM, surface and edge finishing are achieved by rapid, low-amplitude, oscillations of the work piece

relative to a self-forming elastic plastic abrasive polishing tool. The tool is a pad or layer of abrasive-laden elastic

plastic medium, but typically higher in viscosity and more in elastic.

Orbital MAFM concept is to provide transitional motion to the work piece. When work piece with complex

geometry translates, it compressively displaces and tangentially slides across the compressed elastic plastic self-

formed pad which is positioned on the surface of a displacer which is roughly a mirror image of the work piece,

plus or minus a gap accommodating the layer of medium and a clearance.

A small orbital oscillation (0.5-5 mm) circular eccentric planar oscillation is applied to the work piece so that, at

any point in its oscillation, a portion of its surface bumps into the medium pad, elastically compresses (5 to 20%)

and slides across the medium as the work piece moves along its orbital oscillation path. As the circular eccentric

oscillation continues, different portions of the work piece slide across the medium. Ultimately, the full circular

oscillation engages each portion of the surface.

To assure uniformity, the highly elastic abrasive medium must be somewhat plastic in order to be self-forming

and to be continually presenting fresh medium to the polishing gap.

Figure 10.3: Orbital MAFM Process (a) Before start of finishing (b) While finishing.

12. MECHANISM OF MATERIAL REMOVAL.

Solid particle erosion proposed by Finnie is considered as the basic mechanism of material removal in MAFM

with some modifications. In abrasive jet machining the energy of the striking abrasive particle is imparted by the

high speed of the medium stream, but in MAFM the required energy to the abrasive particles is provided by high

pressure acting on the viscoelastic carrier medium. The medium dilates and the abrasive particles come under a

high level of strain due to the pressure acting in the restriction. The momentum that abrasive particles acquire

due to these conditions can be considered to be responsible for microploughing and microchipping of the surface

in contact with the abrasive. Microploughing causes plastic deformation on the surface of the metal. Initially no

material removal takes place. However, the surface atoms become more vulnerable to removal by subsequent

abrasive grains. More abrasive particles attack the surface repeatedly, which causes the detachment of material

often referred to as ‘cutting wear’. When a strong magnetic field is applied around the work piece, the flowing

abrasive particles (which must essentially be magnetic in nature) experience a sideways pull that causes a

deflection in their path of movement to get them to impinge on to the work surface with a small angle, thereby

resulting in microchipping of the surface. The magnetic field is also expected to affect the abrasive distribution

pattern at the machining surface of the work piece. The particles that otherwise would have passed without

striking the surface now change their path and take an active part in the abrasion process, thus causing an

enhancement in material removal. It is to be mentioned here that although the mechanical pull generated by the

magnetic field is small, it is sufficient to deflect the abrasive particles, which are already moving at considerable

speed. Therefore it appears that, by virtue of the application of the magnetic field, more abrasive particles strike

the surface. Simultaneously, some of them impinge on the surface at small angles, resulting in an increased

amount of cutting wear and thereby giving rise to an overall enhancement of material removal rate.

Graph 12.1: Effect of magnetic flux density and medium flow rate on MRR

Graph 12.2: Effect of number of cycles and magnetic flux density on MRR

Graph 12.3: Effect of medium flow rate and number of cycles on MRR

14. ADVANTAGES

1. A very high volume of internal deburring is possible.

2. MAFM deburrs precision gears.

3. MAFM polishes internal and external features of various components.

4. MAFM removes recast layer from components.

5. Effective on all metallic materials.

6. Controllability, repeatability and cost effectiveness.

7. Less Time Consumption.

15. LIMITATIONS

1. Abrasive materials tend to get embedded, if the work material is ductile.

2. Require closed environment.

3. Require start up hole.

4. Mostly Magnetic materials.

16. APPLICATIONS

1. Automotives.

The demand for this process is increasing among car and two wheeler manufacturers as it is capable to make the

surfaces smoother for improved air flow and better performance of high-speed automotive engines. MAFM

process is capable to finish automotive and medical parts, and turbine engine components. Internal passages

within a turbine engine diffuser are polished to increase air flow to the combustion chamber of the engine. The

rough, power robbing cast surfaces are improved from 80-90% regardless of surface complexities.

2. Dies and Moulds.

Since in the MAFM process, abrading medium conforms to the passage geometry, complex shapes can be

finished with ease. Dies are ideal workpieces for the MAFM process as they provide the restriction for medium

flow, typically eliminating fixturing requirements. The uniformity of stock removal by MAFM permits accurate

‘sizing’ of undersized precision die passages.

The original 2 micron ∑Rs (EDM Finish) is improved to 0.2 micron with a stock removal of (EDM recast layer)

0.025 mm per surface.

3. Laser Shops with materials as titanium, and steel

(Thicker metal or composites).

4. Prototype, R&D, Maintenance and Repair Shops.

5. Controls Just-in-Time inventory requirements.

6. Metal Fabricators: Offer "clean edge" plate work.

7. Aerospace engine and control system components.

Figure 16.1: Surface finish improvement before and after on (a) internal passages within turbine engine diffuser

(b) medical implants (c) complete automotive engine parts.

Figure 16.2: Photomicrograph showing complete removal of EDM recast layer.

17. CONCLUSION

A magnetic field has been applied around a component being processed by abrasive flow machining and an

enhanced rate of material removal has been achieved. Empirical modelling with the help of response surface has

led to the following conclusions about the variation of response parameters in terms of independent parameters

within the specified range.

1. Magnetic field significantly affects both MRR and surface roughness. The slope of the curve indicates that MRR

increases with magnetic field more than does surface roughness. Therefore, more improvement in MRR is

expected at still higher values of magnetic field.

2. For a given number of cycles, there is a discernible improvement in MRR and surface roughness. Fewer cycles

are required for removing the same amount of material from the component, if processed in the magnetic field.

3. Magnetic field and medium flow rate interact with each other .The combination of low flow rates and high

magnetic flux density yields more MRR and smaller surface roughness.

4. Medium flow rates do not have a significant effect on MRR and surface roughness in the presence of a

magnetic field.

5. MRR and surface roughness both level off after a certain number of cycles.

MAFM is a well-established advanced finishing process capable of meeting the diverse finishing requirements

from various sectors of applications like aerospace, medical and automobile. It is commonly applied to finish

complex shapes for better surface roughness values and tight tolerances. But the major disadvantage of this

process is low finishing rate. The better performance is achieved if the process is monitored online. So, acoustic

emission technique is tried to monitor the surface finish and material removal .Various modelling techniques are

also used to model the process and to correlate with experimental results. But experts believe that there is still

room for a lot of improvements in the present MAFM status.

18. REFERENCES

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8. http://www.tnmsc.cn