Seminar Report
On
"Magneto Abrasive Flow Machining"
Submitted for the partial fulfillment of requirement for the degree of
BACHELOR OF ENGINEERING
(Mechanical Engineering)
Submitted By
Mr. Ashish S. Honale
Under the Guidance of
Prof.
Department of Mechanical Engineering
Siddhivinayak Technical Campus, SERT, Khamgaon.
Sant Gadge Baba Amravati University, Amravati
2015-2016
Certificate
This 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, Amravati
By
Mr. Ashish S. Honale
in the partial fulfillment of the degree of Bachelor of Engineering in
Mechanical Engineering during the academic year 2015-2016 under my
guidance.
"Prof. "Prof. Pramod S. Wankhade "
"Guide "HOD "
"Department of Mech Engg "Department of Mech Engg "
Prof. A. N. Rakhonde
Principal
Department of Mechanical Engineering
Siddhivinayak Technical Campus, SERT, Khamgaon.
2015-2016
Acknowledgement
It 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.
16 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.
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