Content 1) What is Nanofinishing? 2) Need for Nanofinishing 3) ULTRA PRECISION FINISHING PROCESSES - Magnetic Abrasive Finishing (MAF) - Magnetorheological Finishing - Elastic Emission Machining - Magnetic Float Polishing (MFP) - Ion Beam Machining (IBM) 4) References

1. NANOFINISHING
Presented by –
Sandeep
Kashyap(2015PR21)
M.Tech. (Prod. Engg.)
Submitted to –
Dr. Vinod Yadava
Professor
Mechanical Engg.
Department

2. What is Nanofinishing?
 Nanofinishing is ultra precision finishing process which is
developed for obtaining nanometer order surface finish.
 Nanotechnology was first used to provide ultraprecision
machining capabilities in 1 nm order.

3. Need for Nanofinishing
 Traditional finishing processes are
incapable of producing required surface
characteristics to meet demand of
nanotechnology.
 Electronics and computer industries are
demanding higher precision for large
devices and high data packing densities.
 To improve interchangeability of
components, improve quality control and
longer wear/fatigue life.

4.  To name a few, Magnetic Abrasive finishing (MAF),
Magnetorheological finishing (MRF), Elastic Emission Machining
(EEM), Magnetic Float Polishing (MFP) and Ion Beam Machining
(IBM).
ULTRA PRECISION FINISHING PROCESSES

5. Magnetic Abrasive Finishing (MAF)
 Ferromagnetic particles sintered with fine abrasive
particles (Al2O3, SiC, CBN or diamond) are called
ferromagnetic abrasive particles (or magnetic abrasive
particles).
 Homogeneously mixed loose ferromagnetic and abrasive
particles are used in certain applications.
 Magnetic field is applied across gap between workpiece
surface and rotating electromagnet pole.
 Magnetic abrasive grains combined to each other
magnetically form flexible magnetic abrasive brush.
 Force due to magnetic field is responsible for causing
abrasive penetration inside workpiece while rotation of
magnetic abrasive brush results in material removal in form
of chips.

6. Magnetic Abrasive Finishing (MAF)(contd.)

7.  Magnitude of machining force caused by magnetic
field is very low, a mirror like surface finish (Ra
value in the range of nano-meter) can be obtained.
 Controlling exciting current of magnetic coil
precisely controls machining force.
 Good quality finish on internal and external
surfaces of tubes as well as flat surfaces made of
magnetic or non-magnetic materials.
 The surface finishing, deburring and precision
rounding off the workpiece can be done
simultaneously.
Magnetic Abrasive Finishing
(MAF)(contd.)

8. Magnetorheological Finishing
 Uses Magnetorheological (MR) fluid- suspension of
micron sized magnetizable particles (e.g.Carbonyl iron)
dispersed in non-magnetic medium (mineral oil, water).
 On Applying Magnetic field to MR suspension, particles
acquire dipole moments & aggregated into chains of
dipoles.
 Resistance to applied shear strain by chains is responsible
for material removal.

9. Magnetorheological Finishing
(contd..)
 Zone of finishing is restricted to a spot.
 Most efficient & for High precision finishing of optics.
 MRF makes finishing of free form shapes possible for
first time.
 Applications: high precision lenses include medical
equipment such as endoscopes, military's night vision
equipment like infrared binoculars.

10. Elastic Emission Machining
 Uses ultra fine particles to collide with
workpiece surface.
 Finish surface by atomic scale elastic
fracture & directly by removing atoms &
molecules from surface without plastic
deformation.
 Workpiece is submerged in slurry of
abrasive particles (ZrO2 or Al2O3) and
water.
 Polyurethane ball(56 mm dia) mounted on
shaft, driven by motor, is used to apply
working pressure.
 Material removed by erosion of surface
atoms by bombardment of abrasive

11. Elastic Emission Machining
(contd..)

12. Elastic Emission Machining
(contd..)
 It is able to remove material at the
atomic level by mechanical methods.
 Surface roughness as low as 0.5 nm
have been reported on glass.

13.  Ceramics are extremely sensitive to surface
defects resulting from grinding and polishing
processes. Fatigue failure of ceramics is driven
by surface imperfections.
 For this gentle and flexible polishing conditions
like low level of controlled forces and use of
abrasives softer than work material are required.
 The schematic diagram of the magnetic float
polishing apparatus used for finishing advanced
ceramic balls is shown in Fig. 5.
Magnetic Float Polishing (MFP)

15.  A magnetic fluid containing fine abrasive grains
and extremely fine ferromagnetic particles in a
carrier fluid such as water or kerosene fills the
aluminium chamber.
 A bank of strong electromagnets is arranged
alternately north and south below the chamber.
 On the application of magnetic field the ferro fluid
is attracted downward towards the area of higher
magnetic field and an upward buoyant force is
exerted on non-magnetic material(abrasive
grains, ceramic balls, and acrylic float) to push
them to the area of lower magnetic field.

16.  Drive shaft is fed down to contact the ball and
presses them down to reach the desired force
level.
 The balls are polished by the relative motion
between the balls and the abrasives under the
influence of buoyant force and resistance.
 Both higher material removal rate and smoother
surface in this polishing method, are attained by
stronger magnetic field and finer abrasives.

17.  Conventional polishing of ceramic balls takes
considerable time(12-15days) to finish a batch of
ceramic balls because of low polishing speeds
and use of expensive diamond abrasive at high
loads can result in scratches, and micro cracks.
 Magnetic Float polishing is used to finish 9.5 mm
diameter Si3N4 balls.
 The surface finish obtained was 4 nm Ra and 40
nm Rmax. Finished surfaces relatively free of
scratches, micro cracks, etc. were obtained.

18. Ion Beam Machining (IBM)
 The system consists of an ion source that
produces sufficient intense beam of ions, for the
removal of atoms from the work surface by
impingement of ions.
 A heated tungsten filament acts as the cathode
from which the electrons are accelerated by
means of a high voltage(1 kV to 100kV) towards
the anode.
 Once the ions strike the machined surface
obliquely, the atom ejection occurs due to the
collision.

19. Main Components of Ion Beam Machine

20.  At higher energies sufficient momentum causes
removal of several atoms from the surface.
 Many microscopic damage centers will result
from the energetic displacements of the atoms.
Clearly it is not desirable from surface quality
point of view. The low energy case is more ideal.

21.  The sputtering yield S is defined as the mean number of
atoms sputtered from the target surface per incident
ion.
 The yield and hence, the machining rate depends on
the binding energy of atoms, in the material being
machined.
 The etch rate V(θ) in atoms per minute is given by :
where,
n = atomic density of the target material in atoms/cm³,
S(θ) = yield, atoms per ion and
θ = ion beam at an angle θ to the normal

22.  Ion beam machining is ideal process for nano-
finishing of high melting point and hard brittle
materials such as ceramics, diamonds etc.
 As there is no load on the workpiece while
finishing, it is suitable for finishing of very thin
objects, optics and soft materials such as CaF2.
 Argon ion beam of an energy E=10keV was used
to sharpened the styli to the tip radius of 10 nm.

23. References :
• Nano-Finishing Techniques
web.iitd.ac.in/~suniljha/nanofinishing.pdf
• Nanofinishing Process using magnetorheological
polishing medium -- Manas Das, V.K.Jain, P.S.
Ghoshdastidar,
Published by Lambert Academic Publishing, Germany, 2012.
• V.K. Jain and Sunil Jha, “Nano-finishing Techniques”,
Micromanufacturing and Nano-Technology, Editor : Prof.
N.P.Mahalik, pp. 171-195, Springer Verlag, 2005.
• Magnetic field-assisted finishing - Wikipedia, the free ...
https://en.wikipedia.org/wiki/Magnetic_field-assisted_finishing
• “Magnetic Float Polishing of Ceramics” ---
M.Raghunandan, N.Umehara, A.Noori-Khajavi and
R.Komanduri, Mechanical and Aerospace Engineering,
Oklahoma State University, Stillwater, OK 74078, November
1997, Vol. 119, pp. 520-528.