The document discusses several advanced nano finishing processes, focusing on abrasive flow machining (AFM). It provides an overview of AFM, explaining the working principles, equipment, process parameters, applications, advantages, and limitations. Specifically, it describes the one-way, two-way, and orbital AFM processes. It discusses the material removal mechanisms in AFM and how surface finish is improved. The document also briefly introduces magnetic abrasive finishing (MAF) and magneto rheological abrasive finishing, defining their basic concepts and differences from AFM.

1. UNCONVENTIONAL
MACHINING PROCESSES
BY
SARAVANAN D
AP / MECH
PERIIT

2. PUZZLES
Name the currency

3. UNIT - IV

4. ADVANCED NANO FINISHING
PROCESSES
Abrasive flow machining, chemo-mechanical
polishing, magnetic abrasive finishing, magneto
rheological finishing, magneto rheological
abrasive flow finishing their working principles,
equipment's, effect of process parameters,
applications, advantages and limitations.

5. • Types of ANF
 ABRASIVE FLOW MACHINING( AFM)
 MAGNETIC ABRASIVE FINISHING (MAF)
 MAGNETO RHEOLOGICAL ABRASIVE
FINISHING

6. Identify the company with
picture

7. ABRASIVE FLOW
MACHINING (AFM)

8. AFM
• Introduction
Abrasive flow machining (AFM) was developed by Extrude Hone
Corporation, USA in 1960.
AFM is used to deburr, radius and polish difficult to reach
surfaces by extruding an abrasive laden polymer medium with
very special rheological properties.
It is widely used finishing process to finish complicated shapes
and profiles.
The polymer abrasive medium which is used in this process,
possesses easy flow ability, better self deformability and fine
abrading capability.
Layer thickness of the material removed is of the order of about 1
to 10 μm. Best surface finish that has been achieved is 50 nm and
tolerances are +/- 0.5 μm.

9. Principle of material removal mechanism in two
way AFM process.
• Principle
AFM

10. Schematic diagram of the action of Single active
abrasive grain.

11. AFM
• Classification
There are three types of AFM machines that have been
reported in the literature:
 One way AFM,
 Two way AFM and
 Orbital AFM.
Commonly used AFM is Two-way AFM in which two
vertically opposed cylinders extrude medium back and forth
through passages formed by the workpiece and tooling.

12. ONEWAYAFM PROCESS
One-way flow AFM
processing pushes abrasive
media through the work piece
in only one direction,
allowing the media to exit
freely from the part. Fig.1.3 Unidirectional
AFM process

13. • Advantages
Easy clean-up
Faster cycle processing
Media temperature control generally not required
Able to process larger parts
Simpler tooling and part change-over
Accurately replicates air or liquids natural flow
Does not encapsulate workpart in media
ONE WAY AFM

14. Two way AFM 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 workpiece 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.
TWO WAY AFM

15. • Advantages
 Excellent process control
 Can finish both ID and OD of component
 Good control of radius generation
 Fully automated system capabilities
 Faster setup & quick-change tooling
Faster change-over of media
TWO WAY AFM

16. Surface and edge finishing are achieved 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
(similar to that used in two way abrasive flow finishing), but
typically higher in viscosity and more in elastic.
ORBITALAFM

17. Orbital AFM before start of
finishing.
Orbital AFM while
finishing

18. • Material removal rate
Two modes of abrasive wear, micro-ploughing and micro-
cutting, have been identified as the mechanisms of removal in
AFM.
In micro-ploughing, surface peaks are smeared and plastically
deformed, resulting in ‘‘leveling out’’ of surface asperities. No
volume loss takes place in this mode of removal. Ridges are
also formed adjacent to the grooves created by abrasive
particles’ sliding path.
On the other hand, in micro-cutting, abrasive particles act as
single-point cutting tools, indenting and removing material in
the form of microchips.
In both forms of abrasive wear, scratches are characterized by
continuous scratches.
AFM

19. AFM

20. • Process parameters
 Extrusion Pressure
 Number of cycles
 Grit composition and Type
 Tooling
 Fixture design
AFM

21. • Operating Range
 Easy flowability
 Better self deformability
 Fine abrading capability
 Layer thickness of material removed is, order of about 1μm
to 10 μm
 Best surface finish that has been achived as 50nm and
tolerances +/- 0,5 μm
AFM

22. • Properties
Deburring , radiusing, and polishing are performed
simultaneously in a single operation
 AFM can produce true round radii even on complex edges
 Reduces surface roughness by 75 to 90 % on cast and
machined surfaces
AFM can process dozens of holes or multiple passages
parts simultaneously with uniform results
AFM

23. • Monitoring process
For online monitoring of material removal and surface
roughness in AFM process, Williams and Rajurkar applied
acoustic emission technique.
They developed a stochastic model of AFM generated surfaces
by using Data Dependent Systems (DDS) methodology.
It was established in their research that AFM finished surface
profiles possess two distinct wavelengths, a large wavelength
that corresponds to the main path of abrasive while the small
wavelength is associated with the cutting edges.
AFM

24. • AFM machining and
monitoring system
 AFM machining and
monitoring setup.
 schematic of the process
monitoring system.
AFM

25. AFM
 Surface finish improvement before and after
(a) internal passages within turbine engine diffuser
(b)Medical implants
(c) complex automotive engine parts

26. • Aerospace Applications
Improved surface quality
Enhanced high cycle fatigue strength
Optimized combustion and hydraulics
Increased airflow
Extended component life
AFM

27. • Automotive Industry Application
Enhanced uniformity and surface
quality of finished components
Increased engine performance
Increased flow velocity and volume
Improved fuel economy and reduced
emissions
Extended work piece life by reducing
wear and stress surfaces
Polishing and blending
the internal surfaces
Grains in the same
direction to increase
flow rates.
AFM

28. • Dies & Mold Industry Applications
Reduced production costs
Increased production throughput
Enhanced surface uniformity, finish and cleanliness
Improved die performance and extend life of dies and molds
AFM

29. • Medical Industry Applications
Eliminate the surface imperfections where dangerous
contaminates can reside
Improved functionality, durability and reliability of
medical components
Enhanced uniformity and cleanliness of surfaces
Extended component life
AFM

30. • Limitations
Geometries such as blind holes remain difficult to be
finished effectively by AFM.
AFM’s media are also governed by the fluid flow properties,
leading to difficulty in exerting uniform finishing forces on
complex internal surfaces.
Preferential flow over more restricted areas results in non-
uniform finishes.
Furthermore, abrasive particle embedment onto the
workpiece surface had been reported by various researchers,
thereby raising contamination issues. This could be
undesirable in parts where high material purity of the
component is required.
AFM

31. Identify the logo

32. MAGNETIC
ABRASIVE
FINISHING
(MAF)

33. Identify the logo

34. • Introduction
 Various industrial applications require very high surface finish
up to the range of nanometers or even above.
 Presently, it is required that the parts, used in manufacturing
semiconductors, atomic energy parts, medical instruments and
aerospace applications, have a very fine surface roughness.
 Amongst them, vacuum tubes, wave-guides and sanitary tubes
are difficult to be polished by conventional finishing methods
such as lapping, because of their shapes.
 The technology for super finishing needs ultra clean
machining of advanced engineering materials such as silicon
nitride, silicon carbide, and aluminum oxide which are used
in high- technology industries and are difficult to finish by
conventional grinding and polishing techniques with high
accuracy, and minimal surface defects, such as micro cracks.
MAF

35.  Therefore, magnetic abrasive finishing (MAF) process has been
recently developed for efficient and precision finishing of
internal and flat surfaces.
 This process can produce surface finish of the order of few
nanometers.
 In addition,MAF possesses many attractive
advantages, such as self-sharpening, adaptability,
controllability, and the finishing tool requires neither
compensation nor dressing.
 Magnetic abrasive finishing (MAF) is a high-precision
nontraditional finishing process in which the finishing forces
are controlled by a magnetic field. Magnetic abrasive particles
supplied to a work piece are influenced by magnetic poles,
thus forming a flexible magnetic abrasive brush.

36. • Principals
 When current is supplied to the coils around the
magnetic yoke, magnetic abrasive particles
conglomerate according to magnetic field
distribution at the finishing zone, acting as a
flexible brush.
 the work piece is also vibrated axially at amplitude
of 10–50mm and frequency between 5 and 20 Hz
 With repeated revolutions, a smooth inner surface
would be generated. To prevent excessive frictional
force, lubricating fluid such as oil could also be fed
into the passage during finishing.
 The material is removed in the form of fine
abrasion with increasing machining time.
MAF

37. • Process Parameters
MAF

38. • Magnetic Abrasive Mix
 The modern mixed-type magnetic abrasive was invented to obtain a
balance between magnetic susceptibility and abrasion properties of
magnetic abrasive conglomerates.
 Large ferromagnetic particles (100–500mm) are responsible to produce
magnetic force and
 finishing pressure; while hard abrasive particles (5–20mm) are responsible for
abrading Work piece surface and removing material.
 In general, as ferromagnetic particle size increases, finishing force per particle
increases, thus resulting in increasing MRR. However, beyond particle size of
330mm, excessive material removal occurs, which negatively impacts
minimum Ra achievable. On the other hand, smaller abrasive particle size
leads to more particles being sintered on each ferromagnetic particle.
MAF

39. SINTERING: ADHESIVE BONDING:
 It’s a method for making
objects from powder.
 By heating the material in a
sintering furnace below its
melting point (solid state
sintering).
 Traditionally used for
manufacturing ceramic objects
& in the field of powder
metallurgy.
 A special type of adhesive is
required for providing a strong
bond between magnetic and
abrasive component.
 The amount of adhesive in
mixture of abrasive and Ferro
magnetic components was
decided in such a way that
adhesive completely wets the
mixture and at the same time
the mixture should not behave
like a fluid.
• MATERIAL PREPARATION METHODS
MAF

40.  MAF with permanent magnet
 MAF with Direct Current
 MAF with Alternating Current
• Types Of MAF
MAF

41.  The work piece is kept between the two
poles of a magnet.
 The working gap between the work piece
and the magnet is filled with magnetic
abrasive particles.
 A magnetic abrasive flexible brush
(MAFB) isformed, acting as a multipoint
cutting tool, due to the effect of the
magnetic field in the working gap.
• Permanent Magnet
MAF

42.  Direct Current
 In MAF operation, work piece is kept
between the two magnets.
 The magnetic poles N & S were placed face
to face with their axes crossing at right angle
with a brass pipe in the configuration as
shown in figure.
 The experimental setup has major
components like electromagnet (10 k
Gauss),control unit, D.C. motor, variable
D.C. supply.
MAF

43. • Alternative Current
The rotating magnetic field obtained by
electrifying three coils arranged in the directions at
intervals of 120 degrees with three phase AC
current for internal finish cylindrical work pieces.
MAF

44. MAF offers mirror-like surface finishing
capabilities as roughness could be reduced down to
10nm Ra. It is a high-precision process whereby
form accuracy is not adversely affected. The
concept of internal MAF was first demonstrated on
difficult-to- access area of the internal surface of a
clean gas bomb.
• Processcapability
MAF

45.  Fig. shows a schematic of the plane magnetic
abrasive finishing process using alternating
magnetic field.
 The tray contains the compound magnetic
grinding fluid (oily grinding fluid, iron
powder and abrasive), the lower is the
magnetic pole and the upper is the work
piece. After electromagnetic coil entering
alternating current, alternating magnetic field
will be produced.
• Study on Magnetic Abrasive Finishing Process using Low -
Frequency Alternating Magnetic Field
MAF

46. • Experimentation(Setup)
MAF

47. Work piece SUS304 stainless steel plate with
the size of 80mm×90mm×1mm
Finishing time 60 min
Abrasive Al₂O₃, 0-1[μm] in mean dia: 0.3[g]
Cutting fluid Neat cutting oil (Honilo 988): 0.8[ml]
Feed speed of mobile stage 260 [mm/min]
Rotational speed of magnetic pole 350 [r/min]
Magnetic field Type 1:Direct magnetic field:
1.9[A]. Type 2:Alternating
magnetic field: 1.9[A] Current
frequency :3[Hz]
• Experimentation(Conditions)
MAF

48. • Experimental results and discussion.
MAF

50. • 3D photographs of polished surfaces before and after finishing
By DC
MAF

51. MAF
• 3D photographs of polished surfaces before and after finishing
By AC

52.  In the case of using this experimental setup MAF process using low
frequency alternating magnetic field may obtain a smoother and more
uniform finished surface than that of direct magnetic field.
 Based on analysis of the mechanism of increasing material removal on
MAF process using alternating magnetic field, we can calculate that
material removal in alternating magnetic field is approximately 2.05 times
than that of direct magnetic field in this experimental setup, and the
results of prediction and calculation are verified by finishing experiments
• ExperimentalConclusion
MAF

53. • Advantages
 Minimizes the micro-cracks and surface damage
of work piece.
 MAF is able to produce surface roughness of
nanometer range with hardly any surface defects
 The flexible magnetic abrasive brush (tool)
requires neither compensation nor dressing.
MAF

54. MAF
 Applications
 Non -ferromagnetic materials like stainless steel, brass
and aluminum.
 Ferromagnetic materials like steels.
 Finishing of bearing.
 Aerospace components.
 Electronics components with micro meter or sub
micrometer ranges.

55.  Despite the promise of producing mirror-like surface, MAF’s biggest
limitation lies in the restriction on the materials that are suitable to be
processed. Surface finishing is negligible on ferromagnetic materials such as
nickel and cobalt alloy. This is due to the work piece being magnetized in the
presence of magnetic field, thus attracting magnetic abrasive particles to it
strongly. So no any relative motion between magnetic abrasive particles and
work piece surface.
 Complicated internal features such as fins and protuberances would render
MAF inefficient as magnetic abrasive particles are unable to navigate around
these features. However, these limitations could be stretched by further
research effort. More experimental studies are needed to extend understanding
and fully realize the potential of this finishing process.
• Limitations
MAF

56. Identify the logo

57. MAGNETIC
RHEOLOGICAL
ABRASIVE FLOW
(MRAF)

58. Identify the tagline
“The ultimate driving machine”

59. In magneto-rheological abrasive finishing abrasive mixed with magneto-
rheological (MR) fluid is used. Kordonski and Jacobs (1996) developed a setup
in which magnetically stiffened magneto- rheological fluid mixed with abrasives
is made to flow over a moving flat rigid wall and the polishing happens at a
converging gap formed by the surface to be finished and a moving wall. Now it
finds an interesting industrial application in polishing of optical lenses.
Introducing the abrasive mixed MR fluid, the relative motions between the work
piece and abrasive medium are imparted in different ways; using reciprocation,
rotation or combination of both.
• Introduction
MRAF

60. • Machine setup
MRAF

61. Magnetorheological (MR) fluids, invented by Rabinow in late 1940s, belong to a
class of smart controllable materials whose rheological behavior can be
manipulated externally by the application of some energy fields . These
applications include shock absorbers, damping devices, clutches, brakes,
actuators, and artificial joints.
MR fluid works as polishing tool.
MRF uses MR fluid which is invented by Rabinow in late 1940s consist of
 CIP (Magnetic)
 Abrasive Particle (Non-magnetic)
 carrier liquid (Oil or water)
 additives (glycerol,grease)
• MR Fluid
MRAF

62. MRAF
APPLICATION LIMITATION
 MRF has been used for
finishing a large
 variety of brittle material
ranging from optical glasses to
hard crystals.
 Internal and specially complex
surfaces can’t
 be finished.

63. Guess the tagline with picture

64. MAGNETIC
RHEOLOGICAL
ABRASIVE FLOW
FINISHING
(MRAFF)

65. Which company operates in India
under this name?

66. (MRAFF)

67.  In order to maintain the versatility of Abrasive Flow Machining process and at
the same time introducing determinism and controllability of rheological
properties of abrasive laden medium, a new hybrid process termed as
“Magnetorheological Abrasive Flow Finishing (MRAFF)” is used.
 It is deterministic process.
 Any complex geometries can be finished by this process.
 MRAFF process has the capability of finishing complex internal geometries up to
nanometer level. It imparts better control on the process performance as
compared to AFM process.
 In MRAFF process, a magnetically stiffened slug of magnetorheological
polishing fluid is extruded back and forth through or across the passage formed
by work piece and fixture. Abrasion occurs selectively only where the magnetic
field is applied across the work piece surface, keeping the other areas unaffected.
The mechanism is shown in Fig.
MRAFF

68. MRAFF

69. MRAFF
• Machine setup

70. MRAFF
INITIAL SURFACE BEFORE
MRAFF
FINAL SURFACE AFTER
MRAFF
• Comparison of surface before and after MRAFF(for 200
cycles at B = 0.574 T)

71. Identify the logo