Magnetic abrasive finishing is a process that uses a magnetic field to apply or remove abrasive particles from a workpiece surface. It originated in the 1930s and was patented. By the 1980s, it was commonly used. The process involves mixing magnetic particles with abrasive particles and using a magnetic field, typically from an electromagnet or permanent magnet, to force the particles against the workpiece surface. Relative motion between the particles and workpiece causes material removal or coating. Careful selection of particles allows for precise surface finishing, even in hard to reach areas. Common applications include prosthetics, cutting tools, turbine blades, and medical devices.

1. Magnetic Abrasive Finishing
Process
Hiran Gabriel D J

2. History of Magnetic Abrasive Finishing
• Magnetic abrasive finishing has origins dating back to the 1930s, during
which it was used by manufacturing companies in the United States.
• The first patent for magnetic abrasive finishing was filed with the United
States Postal and Trademark Office (USPTO).
• By the 1980s, magnetic abrasive finishing was a well-known and frequently
used finishing process in the manufacturing industry.

3. Magnetic Abrasive Finishing (MAF) Process
• Also known as magnetic field-assisted finishing, magnetic abrasive finishing is a finishing process
that involves the use of a magnetic field to apply or remove particulate matter onto the surface of a
workpiece or object.
• The magnetic field is used to force abrasive particles against the target surface
• The purpose of magnetic abrasive finishing is to remove or coat materials in order to provide
superior finish.
• The magnetic field forcefully pushes the particular matter of the powder onto the workpiece or
object thus able to provide a superfinished surface.

4. Working of MAF
• Magnetic Assisted Finishing or "MAF" is essentially the manipulation of a homogeneous
mixture of magnetic particles and abrasive particles with a magnetic field to impart a
machining force on a workpiece.
• Relative motion between the particle mixture and the workpiece surface result in material
removal.
• Since MAF does not require direct contact with the tool, the particles can be introduced into
areas which are hard to reach by conventional techniques.
• Careful selection of magnetic particles and abrasive particles give rise to surface texture and
roughness control that was previously impossible especially for hard to access areas

5. Sources of magnetic field
• The magnetic field source in MAF is typically an electromagnet or a rare earth permanent
magnet.
• A permanent magnet offers high energy density, lack of overheating resulting in a constant flux
density, low cost, ease of integration into existing CNC equipment, and simplicity.
• Some applications require adjustment of the flux density during finishing, or require a
switching magnetic field, which is only attainable with an electromagnet since the magnetic
field in a permanent magnet cannot simply be switched off.

6. Working of MAF
• Relative motion between the magnetic/abrasive particle mixture and the workpiece is essential
for material removal.
• There are several options for achieving the necessary motion. A common setup is the rotation of
the magnetic pole tip.
• This is done by either rotating the entire permanent magnet setup or by rotating only the steel
pole.
• Another method which is commonly utilized in internal finishing is the rotation of the workpiece,
this is unfortunately limited to axial symmetric workpieces. In addition to rotational motion there
is oscillatory and vibrational configurations that are applicable.

7. Equipment for MAF
Fig 1: Equipment for MAF (a) Side view (b) Top view

8. Equipment for MAF
Fig 2: Equipment for MAF (a) Polishing (b) Burnishing

9. Common magnetic and abrasive materials
• White Alumina + Iron
• Diamond + Iron
• Tungsten Carbide + cobalt
• Iron and its oxides
• Cobalt
• Nickel
• Steel and Stainless steel
• Synthetic diamond
• Cubic boron nitride CBN
• Aluminum oxide
• Silicon carbide
Magnetic materials Abrasive materials
Commonly used mixture

10. Applications of MAF
• Prosthetics
• Cutting Tools
• Turbine Blades
• Airfoils
• Optics
• Sanitary Pipes
• Food Industry
• Capillary Tubes in Medical Field
• Stents, Catheter shafts, Needles, Biopsy Needles, etc
• Curved Pipes