This Document Covers Grinding Operatio

1. Prepared By:- Prajapati Urvesh
Mirza Hamza
Patel mo.Kamil
Department:- Mechanical-C
Semester:- 3rd Sem

3. 1. Introduction
2. Principle of Grinding Machine
3. Types of grinding
4. Various elements of grinding wheel
5. Shapes and Coding of a Grinding Wheel
6. Wheel surface finishing
7. Classification of Grinding Machines

4. 1. Introduction
 Grinding is a metal cutting operation performed by
means of abrasive particles rigidly mounted on a rotating
wheel.
Each of the abrasive particles act as a single point cutting
tool and grinding wheel acts as a multipoint cutting tool.
 The grinding operation is used to finish the workpieces
with extremely high quality of surface finish and accuracy
of shape and dimension.
Grinding is one of the widely accepted finishing
operations because it removes material in very small size of
chips 0.25 to 0.50 mm.
 It provides accuracy of the order of 0.000025 mm.

5. 2. Principle of Grinding Machines
 Work piece is fed against the rotating abrasive wheel.
 Due to action of rubbing or friction between the
abrasive particles and work piece material is
removed.

6. 3. Types of Grinding
On the basis of quality of grinding, it is classified
as rough grinding and precision grinding.
 Rough Grinding
 Precision Grinding
 Rough Grinding:-
It involves removal of stock without
any reference to the accuracy of results.
 Precision Grinding:-
Precision grinding removes
negligible amount of metal. It is used to produce finished
parts and accurate dimensions.

7. 4. Various elements of a Grinding Wheel
The various main elements of a grinding wheel are
abrasive; bonds and structure which are described below.
Abrasive:- Generally abrasive properties like hardness,
toughness and resistance to fracture uniformly abrasives are
classified into two principal groups:-
 Natural abrasives
 Artificial abrasive
 Natural abrasive:- There are a few examples of natural
abrasives which include sand stone (solid quartz), emery, &
diamond.

8.  Artificial abrasive:- Main artificial abrasive are silicon
carbide and aluminium oxide. Artificial abrasive are
preferred in manufacturing of grinding wheels because of
their uniformity and purity.
NATURAL ABRASIVE ARTIFICIAL ABRASIVE

9. Bond:- A bond is an adhesive material used to held
abrasive particles together relatively stable that constitute a
grinding wheel.
Different types of bonds are:-
(a) Vitrified bond
(b) Silicate bond
(c) Shellac bond
(d) Resinoid bond
(e) Rubber bond
(f) Oxychloride bond

10. (a) Vitrified bond:-
 This bond consists of mixture of clay and water. Clay
and abrasives are thoroughly mixed with water to make a
uniform mixture.
 This bond is denoted by symbol ‘V’ in specification.
(b) Silicate bond:-
 Silicate bonds are made by mixing abrasive particles
with silicate and soda or water glass.
These wheels are denoted by ‘S’ in specification.

11. (c) Shellac bond:-
 These are prepared by mixing abrasive with shellac than
moulded by rolling and pressing and then by heating up to
150` C for several hours.
 This bond is denoted by ‘E’ in specifications.
(d) Resinoid bond:-
 These bonds are prepared by mixing abrasives
with synthetic resins like backelite and redmanol
and other compounds & baked up to 200` C.
 A Resinoid bond is denoted by the letter ‘B’.

12. (e) Rubber bond:-
 Rubber bonded wheels are made by mixing abrasives
with pure rubber and sulphur.
A rubber wheel bonded wheel is denoted by the letter ‘R’.
(f) Oxychloride bond:-
 These bonds are processed by mixing abrasives with
oxides and chlorides of magnesium.
 An oxychloride bonded wheel is specified the letter ‘O’.

13.  STRUCTURE OF GRINDING WHEEL

14. 5. Shapes and Coding of a Grinding Wheel
Shapes:-
There are different shapes of grinding wheel
which mention below.
 Straight Wheel:- These are generally used for cylindrical,
internal, centreless and surface grinding operations. These
wheels vary in size, diameter and width of the face.
 Tapered Face Straight Wheels:- It is also a straight wheel
but its free is slightly tapered to facilitate the grinding of
threads an gear teeth.

16.  Cylindrical Wheel Ring:- It is used for surface grinding,
i.e. production of flat surfaces. Grinding takes place with
the help of face of the wheel.
 Cup Wheel:- It is used for grinding flat surfaces with the
help of face of grinding wheel.
Flaring Cup Wheel:- It is used in grinding of tools in tool
room.
 Saucer Wheel:- It is used for sharpening of circular or
band saw.

17.  Segmented Wheel:- These are normally on vertical
spindle, rotary type and reciprocating type surface grinders.
 Dish Wheel:- It is used for grinding of tools in tool room.
It is capable to grind very narrow places due to its thinners.

18. Coding:-
The Indian Standard Coding system of
grinding wheel is IS : 551-1954. It gives a general
indication of the hardness and abrasive size of any wheel as
compared with another.
 Coding of a grinding wheel consists of six symbols as
described below.
W : Symbol for Manufacturer’s Abrasive Type (Prefix)
C : Name of Abrasive
30 : Grain Size
L : Grade
5 : Structure Type
R : Bond Type
17 : Manufacturer Symbol for Record (Suffix)

19.  The sequence of codes of a grinding should be followed
in the same sequence as described above Their brief
description is given below.
 Prefix:- Manufacturer’s Symbol.
 Abrasive:- Types of abrasive used in Grinding Wheel.
i.e. A= Aluminium Oxide
C= Silicon Carbide
 Grain Size:- It affects the metal removal rate & finishing
of surface. Coarse Medium Fine Very fine
10 30 80 220
12 36 100 240
14 46 120 280
16 54 150 320

20.  Grade:- Ability of bonding material to sustain abrasive.
 Structure:- Structure between bonding material &
abrasive grain inside the grinding wheel.
Dense Open
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Very soft A,B,C,D,E,F,G
Soft H,I,J,K
Medium L,M,N,O
Hard P,Q,R,S
Very hard T,U,V,W,X,Y,Z
`

21.  Types of Bond:- It shows which type of bonding material
is used.
V= Vitrified Bond
B= Resinoid Bond
R= Rubber Bond
E= Shellac Bond
S= Silicate Bond
 Suffix:- Manufacturer’s own identification

22.  Example of Coding
51A 36L5V23
• 51 = Manufacture’s symbol
• A = Abrasive ( Aluminum Oxide)
• 36 = Grain size (Medium)
• L = Grade (Medium)
• 5 = Structure ( Dense)
• V = Bond type (Vitrified Bond)
• 23 = Manufacture’s identification.

23. 6. Wheel Surface Finishing
Glazing:-
 This is the effect when the abrasive have become dull &
ground to the ground.
 It is a condition in which cutting edge take glass-like
appearance.
 This occurs due to high speed or the tool is very hard.
 To avoid glazing use softer wheel or decrease speed of
wheel.

24. Loading:-
 When the material of the work piece is filled the gap
between the abrasive grain then it is called as loading.
 This material prevent the wheel from cutting freely.
 It may caused be grinding a soft material or by using a
heel of too hard and running it too slowly.
Truing:-
 It is a process of changing the shape of grinding wheel.
 It can be done on the new wheel or on the used tool.
 This is done to make tool true and equal distance from
the center.

25. 1. LOADING 2. GLAZING

26. Dressing:-
 This is done on loaded and glazed tool to gain there
sharp abrasive particles.
 This is done using different types of dresser,
o Metal crusher
o Diamond dresser
o Abrasive sticks/wheels.

27. 7. Classification Of Grinding Machine
Grinding Machines are classified as,
a. Bench grinding machine
b. Surface grinding machine
c. Cylindrical grinding machine
d. Center less grinding machine
e. Internal grinding machine
f. Special purpose grinding machine

28. a. Bench grinding machine
 These types of grinding machine is used to hand grind
cutting tools and perform rough grinding.
 It may be used for sharpening cutting tool such as lathe
tools or drill bits.

29. b. Surface grinding machine
 It is machine basically used to grind flat surface.
 Job is mounted to a table which moves longitudinally
as well as in transverse direction.
 Manual feed or power feed.
 Work piece can clamped in two ways
– Manual clamps.
– Magnetic chuck.
 Internal pump and piping arrangement for coolant.
 Protective guard for safety.

30.  Surface Grinding Machine

31. c. Cylindrical grinding machine
 It is a process of grinding curved surfaces.
 Surface may be straight or tapered.
 Work piece is mounted on two centers, one is
tailstock centre and the other is headstock centre.
 Head stock center may or may not revolve.

32.  WORKING PRINCIPLE

33.  CYLINDRICAL GRINDING MACHINE

34. d. Centre less grinding machine
 It is used to grind curved surface work piece which
are long and slender.
 Work piece rests on a work-rest blade and is backed
by a second wheel called as regulating wheel.
 Grinding wheel pushes the work piece down the
work-rest blade against the regulating wheel.

35.  WORKING PRINCIPLE

36.  CENTERLESS GRINDING MACHINE

37. e. Internal grinding machine
 In this type the grinding is done in the internal side of
work piece.
 In this operation the work piece may rotate or may
not be rotate.
 It can be done on different internal surface like
straight, tapered, grooved, or profile.

38.  WORKING PRINCIPLE

39. f. Some special grinding
 It uses the principle of cylindrical grinding.
 Mainly it used for threaded profile.
 Specially formed wheel is use
 A single ribbed or multy ribbed wheel can be
used as shown in fig.

40.  SOME SPECIAL GRINDING