2. ➢ Abrasive process
➢ Metal is removed with the help of rotating
grinding wheel.
➢ Wheels are made of fine grains of abrasive
materials held together by a bonding material
called a bond.
➢ Grinding is one of the widely accepted finishing
operations because it removes material in very
small size of (micro-chips) chips 0.25 to 0.50
mm.
➢ It provides accuracy of the order of 0.000025
mm. Grinding of very hard material is also
possible.
2
3. ➢ Investment is less and design is simple
➢ Surface finishing will be approximate 10 times better as
compared to milling and turning process of machining.
➢ Dimensional accuracy will be quite good
➢ Grinding process could be performed on hardened and
unhardened work piece like metals, alloys, carbides,
ceramics, composites materials.
3
Advantages of grinding
4. ➢ Surface finishing
➢ Grinding of tools and cutters and re-
sharpening
➢ Internal hole finishing
➢ Form finishing
4
5. According to the accuracy of the work to be done on a grinding
machine, they are classified as
➢Rough grinding machines
➢Floor stand and bench grinders
➢Portable and flexible shaft grinders
➢Swing frame grinders
➢Abrasive belt grinders
➢Precision grinding machines
5
7. ➢Surface grinding machine
➢Cylindrical grinding machine
➢Centre less grinding machine
➢Internal grinding machine
7
Conventional grinding machines can
be broadly classified
8. 8
According to type of surface
➢Cylindrical grinders
➢Centre type(plain, universal).
➢Centre less.
➢Internal grinders
➢Chucking (plain, universal)
➢Planetary.
➢Centre less.
➢Surface grinders
➢Reciprocating table.
➢Rotating table.
8
➢Tool and cutter grinders
➢Universal
➢Special
9. 9
Surface grinding machines are employed to finish plain or flat
surfaces horizontally, vertically or at any angle.
There are four different types of surface grinders
➢Horizontal spindle and reciprocating table type
➢Horizontal spindle and rotary table type
➢Vertical spindle and reciprocating table type
➢Vertical spindle and rotary table type
Surface grinding machines
11. This machine is used to produce external cylindrical surface.
Cylindrical grinders are generally used to grind external surfaces
like cylinders, taper cylinders, faces and shoulders of work.
11
(i)Plain center type cylindrical grinder
➢The work piece is held between head
stock and tailstock centers.
➢ A disc type grinding wheel performs
the grinding action with its peripheral
➢For heavy repetitive simple work
(ii)Universal cylindrical grinding
machine
➢These grinders are provided with a
swiveling headstock and a swiveling
wheel head.
➢ This permits the grinding of taper of
any angle, much greater than is
possible in plain grinder
Cylindrical grinding machine
13. Centre-less grinding is a method of grinding external cylindrical,
tapered and formed surfaces on work pieces that are not held and
rotated between centre's or in chucks.
There are two types of centre-less grinding
and they are
➢ External centre-less grinding
➢ Internal centre-less grinding
13
Centre-less grinders
14. ➢ Two wheels - a grinding and a regulating wheel are used in external centre-
less grinding.
➢ Both these wheels are rotated in the same direction.
➢ The work is placed upon the work rest and rotated between the wheels.
➢ The feed movement of the work along its axis past the grinding wheel is
obtained by tilting the regulating wheel at a slight angle from the horizontal.
➢ An angular adjustment of 0 to 10 degrees is provided in the machine for this
purpose
14
External centre-less grinding
15. ➢ The principle of external centre-less grinding is applied to internal
centre- less grinding also.
➢ Grinding is done on the inner surfaces of the holes.
➢ In internal centre-less grinding, the work is supported by three rolls
➢ regulating roll, a supporting roll and a pressure roll.
➢ Pressure roll- To hold work-piece firmly against support and
regulating roll.
➢ The grinding wheel contacts the inside surface of the work-piece
directly opposite the regulating roll.
➢ Grinding wheel and work rotates in same direction
15
17. 17
➢ Work piece is supported the entire length, grinding is done very
accurately.
➢ Small, slender and fragile work pieces can be ground easily.
➢ No chucking or other holding devices are required.
➢ As the process is continuous, it is best adapted for production work.
➢ The size of the work can easily be controlled.
➢ Low order of skill is needed in the operation of the machine.
Advantages of centre-less grinding
18. In hollow work, there is no certainty that the outer
diameter will be concentric with the inside diameter.
Works having multiple diameters are not handled easily
18
.
19. It is an abrading process used to :
➢ Produce geometrically true surfaces
➢ Correct minor surface imperfections
➢ Improve dimensional accuracy
➢ Provide very close fit between two contact
surfaces
➢ Refining geometrical accuracy of flat,
cylindrical and spherical surfaces
Very thin layers of metal – 0.005 to 0.01mm
are removed
Lapping can be done with loose grains abrasive or
with bonded abrasive disc or wheel
19
20. ➢ Hand Lapping
Hand lapping of flat surface is carried out by rubbing the component over
accurately finished flat surface of master lap usually made of cast iron
block.
➢ Machine Lapping
These machines are fairly simple pieces of equipment consisting of a
rotating table, called a lapping plate, pressure plate and
conditioning ring.
20
22. ➢ Grinding or abrading process mostly for finishing round holes
by means of bonded abrasive stones
➢ Typical applications are the finishing of cylinders for internal
combustion engines, bearing spindles and gears.
➢ Honing can be done on materials like plastic, silver, brass,
aluminium, cast iron and steel
➢ Remove less than 0.25 micrometer
➢ Used to correct out of roundness, taper, tool marks and axial
distortion
22
