Abrasive Flow Machining by Tauseef Sir

Abrasive Flow Machining
Tauseef Shaikh
Assistant Professor
Department of Mechanical Engineering
Matoshri Pratishthan’s School Of Engineering
Tauseef Shaikh, Asst. Prof., MPGI SoE Nanded 1

Content
1. What is AFM?
2. Need of AFM
3. Abrasive Material
4. Mechanism of AFM
5. Components of AFM
6. Classification
1. One Way
2. Two Way
3. Orbital
7. Process input parameters
8. Application areas
Tauseef Shaikh, Asst. Prof., MPGI SoE
Nanded
2

Limitations of Conventional Finishing Processes
???
Nanded
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Abrasive Flow Machining
• It is basically used as a deburring process.
• Developed in 1960 by Extrude Hone Cooperation.
• AFM can be used for;
– Polish and deburr parts internally
– Polish through holes
– Polish intersecting holes
– Calibrate fuel injection nozzles to a specific flow rates
– Difficult to accesses areas
– Remove scratching marks (feed marks) of other processes
– radius
• Uses abrasive grains mixed in a putty (a form of
cement) like matrix which abrades the
surface/burrs from the specific area of the
material.
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NEED
• Smooth surfaces – Aerospace and precision
components
• High flow rates – Fluid dynamics and nozzles
• Torque and fuel economy – Fuel nozzles and
engine components
• Eliminate the imperfections – Medical field
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Mechanism Of AFM
1. Initially the material is ploughed by the fine
abrasives which come in contact with the work
material as the rub over the metal surface with high
pressure.
2. The material flow occurs in the direction of the
motion of abrasive particles as well as in lateral
direction, resulting into the formation of the leaps.
3. The further flow of abrasive particles causes
continued work hardening which results in
embattlement and fragmentation of the lips into
micro chips.
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Mechanism of AFM
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Components / Set up of AFM
• Machine
• Abrasive materials/medium
• Tooling
• Workpiece
• Fixture plate
• Fixtures
• Pumping device
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Machine
• It determines extent of abrasion
• It is Essentially provided with
1. Hydraulic controls
2. Fixtures
3. Volume flow rate device
4. Media advance device
• Its accessories are;
1. Automatic flow timer
2. Cycle timer
3. Displacement system
4. Flow control valve
5. Media heat exchanger
• Standard unit operate between 10 bars to 200 bars and with flow rates of
400 lpm.
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Classification of AFM
1. One way
2. Two Way
3. Orbital
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One-way AFM
• 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.
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Advantages of One-way AFM
• Faster cycle processing
• Easy clean-up
• 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 work-part in media
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Two-way AFM
• Most widely used
among the three.
• The typical two-way flow AFM process uses two
vertically opposed cylinders to extrude an
abrasive media back and forth through or around
passages formed by the work piece and tooling.
• Abrasive action occurs wherever the media
enters and passes through the most restrictive
passages
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Two-way AFM cont…
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Two-way AFM(contd.)
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Two-way AFM(contd.)
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Advantages of Two-way AFM
• 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
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Orbital AFM
• 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 (similar to that used in
two way abrasive flow finishing), but typically
higher in viscosity and more in elastic.
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Orbital AFM(contd.)
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Before starting of finishing
After starting of finishing

Abrasive Media
• It is the mixture of
1. Abrasive particles and
2. Elastic Polymer Elastomers
• Abrasive Particles:-
 Generally used Abrasive particles are Aluminum oxide, silicon
carbide.
 Boron carbides are expensive and suitable for hard materials.
 Silicon carbide has high stock removal rate and is both durable
and economical.
 Diamond abrasive is used for most difficult materials like WC. It
is very effective for removing thermal recast layer.
• Elastic Polymer (Elastomers):-
 Abrasive particles are mixed with this visco-elastomers which
shows change in viscosity under pressure.
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Tooling
• Tooling consisting of
• Workpiece
• Fixture plate
• Fixtures
• Pumping device
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Machine Abrasive Workpiece
Extrusion pressure
Flow Volume
Media flow speed
Number of Cycles
Medium viscosity
Abrasive
Concentration
Abrasive
type & size
Restricting
passage flow
and area
Ductile/Brittle
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AFM process parameters
Abrasive Based
– Abrasive grain size used in AFM varies from 500 grit
(tiny hole) to 8 grit (stock removal and stocking)
– Large abrasives- cut faster
– Small abrasives – better surface finish as well as they
can reach narrow and complex surfaces easily.
Machine Based
– Pressure - 0.7 Mpa to 22 Mpa (100 psi to 3200 psi)
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Capabilities of AFM process
• Surface finish in the range of 28 to 280
μm.
• Hole of 0.2 mm can be made.
• Dimensional tolerances achievable upto
± 0.005mm.
• Can reduce surface roughness by 75 to
90% on cast, machined or EDM sufaces.
Nanded
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Application
1. Aerospace industry
– Improved surface quality
– Enhanced cycle fatigue strength
– Optimized combustion and hydraulics
– Increased airflow
– Extended component life
Nanded
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Application
2. Automotive industry
• 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
Nanded
26Grains in same direction will increase the flow rate

Application
3. Dies and mold industry
• Reduced production costs
• Increased production throughput
• Enhanced surface uniformity, finish and cleanliness
• Improved die performance and extend life of dies and molds
Nanded
27

Application
4. Medical industry (Medical implants)
• 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
Nanded
28

THANK YOU
Nanded
29

Abrasive Flow Machining by Tauseef Sir

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