Magnetic abrasive finishing (MAF),

Abrasive Flow Finishing(AFF),

Electro Stream Drilling (ESD),
Shaped Tube Electrolytic Machining
(STEM)
Magnetic Abrasive Finishing (MAF)
(magnetic field assisted finishing process)
 Magnetic Abrasive Finishing (MAF)

Magnetic abrasive finishing (MAF) can be

defined as a process by which surface is
finish by removing the material in the
form of debris particles by magnetic
abrasive particles in the presence of
magnetic field in the finishing zone.
Magnetic Polishing
Magnetic Abrasive Finishing Principle
It is an advanced Finishing process, in this the working gap between the work
piece and the magnet is filled with magnetic Abrasive particles (MAPs),
composed of ferromagnetic particles and abrasive powder (Al2O3, SiC,
diamond and boron nitride). MAPS can be used as bonded or unbounded.
Bonded MAPS are prepared by sintering of ferromagnetic particles and
abrasive particles whereas unbounded MAPs are mechanical mixture of
ferromagnetic particles and abrasive particles with a small amount of
lubricant to provide some holding strength between the constituents of
MAPs.
After the application of magnetic field, the magnetic and abrasive particles
join each other along the lines of magnetic force and form a flexible
magnetic abrasive brush (FMAB) between the work piece and the magnetic
pole, like a multi-point cutting apparatus for finishing operation.
Advantages of MAF
1. Minimizes the micro-cracks and surface damage of work piece.
2. MAF is able to produce surface roughness of nanometre range (produce
efficiently mirror like good surface)
4. This process can be used on flat surfaces as well as internal and external
surfaces of tube type work pieces.
5. Due to the flexible magnetic abrasive brush, it can finish any symmetric
work piece shape, if electromagnet designed accordingly.
6. It possesses self-adaptability and controllability.
7. The method can finish ferromagnetic materials as well as non-
ferromagnetic materials.
8. The finishing tool requires neither compensation nor dressing.
Disadvantages of MAF
1. It is difficult to implement Magnetic abrasive finishing in mass
production operation.
2. Not applicable for some ordinary finishing task where conventional
finishing technique can be easily implemented.
3. Time consuming process.
4. The cost of process is high.
Applications of MAF
1. Ferromagnetic materials like steels and Non -ferromagnetic materials
like stainless steel, brass and aluminium can also be machined.
3. Finishing of bearing.
4. Aerospace components.
5. Electronics components with micro meter or sub micrometre ranges.
6. MAF is used for Cutting tools, Turbine blades, Air foils, Optics,
Sanitary pipes, Food industry, Capillary tubes, needles, biopsy needles
in ,medical field, Curved pipes.
Abrasive Flow Finishing (AFF)
Abrasive Flow Finishing
It is basically used as a deburring process. It 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.
AFM can
Polish and deburr parts internally.
Polish through holes.
Polish intersecting holes.
Calibrate fuel injection nozzles to a specific flow rates.
Generally Al2O3, SiC, Boron carbide and Diamond are used as a abrasive
particles. Which are Mixed in Polymeric medium like Viscoelastic polymer-
shows change in viscosity when under pressure.
Abrasive Flow Finishing
Abrasive Flow Finishing
Abrasive Flow Finishing
Advantages and Disadvantages of AFF
Advantages are
Better performance is achieved.
Improve surface quality.
Reduction in Friction.
Eliminate imperfection.
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.

Disadvantage of this process is low finishing rate.

Applications
Method is used to radius difficult to reach surfaces like intricate
geometries.
It can produce surface finish (Ra) as good as 0.05 m, deburr holes as
small as 0.2 mm, radius edges from 0.025 mm to 1.5 mm.
Widely used for finishing process to finish complicated shapes and
profiles.
It can applicable to
Aerospace and precision components (Smooth surfaces to reduce friction)
Fluid dynamics and nozzles (High flow rates)
Fuel nozzles and engine components (Torque and fuel economy )
Medical field (Eliminate the imperfections )
Electro Stream Drilling

Capillary Drilling is also referred to as Electro Streaming and is a form of

ECM. Capillary drilling is an acid electrolytic drilling technique for drilling
small holes in hard, corrosion resistant metals.
Electro Stream Drilling
Acid electrolyte(Hydrochloric acid/ sulphuric acid) is placed in a tank
and pumped to the glass tube through the filter.
Intake manifold is placed on the upper side of the glass tube where
ve terminal dc supply is connected and workpiece is connected to
the +ve terminal of dc supply.
The diameter of the glass tube gets reduced at the workpiece to the
0.025 to 0.05 mm.
Acid electrolyte passes to the work piece through the intake
manifold because of the chemical reaction there the material is
removed (anodic dissolution) and carried away by the electrolyte
solution.
Shaped Tube Electrolytic Machining (STEM)

STEM is, therefore, a modified variation of

the ECM that uses acidic electrolytes. The
process is capable of producing small holes
with diameters of 0.76 to 1.62 mm and a
depth-to-diameter ratio of 180:1 in
electrically conductive materials. It is difficult
to machine such small holes using normal
ECM as the insoluble precipitates produced
obstructs the flow path of the electrolyte.
Shaped Tube Electrolytic Machining
Shaped tube electrolytic machining (STEM) is based on the dissolution
process when an electric potential difference is imposed between the
anodic work piece and a cathodic tool. Because of the presence of this
electric field the electrolyte, often a sulphuric acid, causes the anode
surface to be removed. After the metal ions are dissolved in the
solution, they are removed by the electrolyte flow the tool is a
conducting cylinder with an insulating coating on the outside and is
moved toward the work piece at a certain feed rate while a voltage is
applied across the machining gap. In this way a cylindrically shaped
hole is obtained.
Applications
Because the process uses acid electrolytes, its use is limited to drilling
holes in stainless steel or other corrosion-resistant materials in jet
engines and gas turbine parts such as:
Turbine blade cooling holes.
Fuel nozzles.
Any holes where EDM recast is not desirable.
Starting holes for wire EDM.
Drilling holes for corrosion-resistant metals of low conventional
machinability.
Drilling oil passages in bearings where EDM causes cracks.
Advantages
The depth-to-diameter ratio can be as high as 300.
A large number of holes (up to 200) can be drilled in the same run.
Nonparallel holes can be machined.
Blind holes can be drilled.
No recast layer or metallurgical defects are produced.
Shaped and curved holes as well as slots can be produced.
Disadvantages
The process is used for corrosion-resistant metals.
STEM is slow if single holes are to be drilled.
A special workplace and environment are required when handling acid.
Hazardous waste is generated.
Complex machining and tooling systems are required.