This document provides information on grinding processes. It discusses the different types of grinding including rough grinding, cylindrical grinding, surface grinding, and form grinding. The key components of grinding wheels such as abrasives, bonds, grit, grade, structure, and wheel shapes are explained. Factors for selecting the appropriate grinding wheel for a given material and operation are outlined. Common grinding machines for rough and precision grinding like pedestal grinders and cylindrical grinders are described. The document also covers grinding wheel conditioning techniques like dressing and truing.

2. Unit 4

5. Grinding is a Metal removal
& Surface Finishing
operation in which the metal
is removed with the help of a
rotating Grinding wheel or
abrasive wheel.
This operation is suitable for
machining very hard metals.

7. Surface
grinding
Form
grinding
Cylindrical
grinding

8.  Rough Grinding - For Removing
Chips, Sharp edges, burr
 Cylindrical Grinding - For
Machining straight or tapered
cylindrical workpiece
 Surface Grinding - For producing
Flat Surface
 Form Grinding – For produce the
shape of grinding wheel in Work
piece

10. •Grinding wheels are
made up of small
abrasive particles
held together by
bonding material.

12. Abrasives

13. •Abrasives are hard
substance which
are used as cutting
edge in the
Grinding Wheel .

14. Types of
Abrasives

15. •Natural Abrasive
•Artificial
Abrasive

16. Natural Abrasive
 Sand Stone (Solid
Quartz)
Emery
Corundum
Diamond

17. Diamond

18. Emery

19. Emery

20. Corundum

21. Sand Stone (Solid Quartz)

22. Artificial Abrasive
Aluminium Oxide
Silicon Carbide
Artificial Diamond
Boron Carbide

23. • Aluminium Oxide:
 Manufactured from Bauxite
 It is Tough & Less Brittle
 For Grinding Steel, Wrought Iron
 Trade Names:
1.Aloxite
2.Alundum
3.Borolon
Represented By A

25. • Silicon Carbide:
 Manufactured from Silica Sand
 It is Hard & Brittle
 For Grinding CI, Brass, Cu, Al
 Trade Names:
1.Carborundum
2.Crystoline Silicon
Represented By S

29. Bonds

30. •Bond is an Adhesive
substance used to
hold abrasive grains
together in the
Grinding Wheel

31. Types of
Bonds

32.  Silicate bond (S)
Elastic bond / Shellac
bond (E)
Rubber bond (R)
Vitrified bond (V)
Oxychloride bond (O)
Resinoid bond (B)

34. Silicate bond (S):
 Mixture of Abrasive Grains
with Sodium Silicate
It is Water Proof
Used for Grinding Cutting
Tools, Cutting Blades

35. Elastic bond (or) Shellac
bond (E):
 Mixture of Abrasive Grains
with Shellac
It have good elasticity
Used for Grinding
Finishing Iron Casting

36. Rubber bond (R):
 Mixture of Abrasive Grains
with Liquid Rubber &
Sulphur
It is more elastic
Used for Grinding Cutting
off metal bars

37. Vitrified bond (V):
 Mixture of Abrasive
Grains with Clay &
Water
 It is Strong & Porous
Not affected by acids

38. Oxychloride bond (O):
 Mixture of Abrasive
Grains with Magnesium
Chloride & Magnesium
Oxide
Used for Making Disc
shaped wheels

39. Resinoid bond (B):
 Mixture of Abrasive
Grains with Synthetic
resin
It runs at high speed
Used for Rough Grinding
of Iron & Steel Casting

40. Grit

41.  Abrasive particles size is
mentioned as Grain or Grit
It is mentioned as Number
For Soft and Elastic materials
Coarse grit wheels
For brittle materials Fine grit
wheels.

43. Coarse 10 12 14 16 20 24
Medium 30 36 46 54 60
Fine 80 100 120 150 180
Very
Fine
220 240 280 320 400 500 600

44. Grade

45. Indicate Bond Strength
(Hardness)
It is mentioned as Alphabets
A is the softest wheel and Z is the
hardest wheel.
For Grinding Hard Material - Soft
Grade Wheel
For Grinding Soft Material - Hard
Grade Wheel

46. Soft A B C D E F G H
Medium I J K L M N O P
Hard Q R S T U V W X Y Z

47. Structure
of the
Wheels

48. Indicate the Space between abrasive
particles
It is denoted by a Number (1 - 15)
Spacing is small - Dense structure
Spacing is more - Open structure
1 is the most dense structure and 15 is
the most wider structure
For Grinding Hard & Brittle Material
- Dense Structure
For Grinding Soft & Ductile Material -
Open Structure

50. Dense 1 2 3 4 5 6 7 8
Open 9 10 11 12 13 14 15

51. Wheel
Shape &
Sizes

52. 1. Peripheral Grinding Wheels
Wheel Periphery is used for
Grinding
Mounted On Horizontal Spindle
Types:
a.Straight Wheels
b.Tapered Face Wheels
c.Recessed Wheels

53. Peripheral Grinding Wheels

54. 2. Face Grinding Wheels
Wheel Face is used for Grinding
Mounted on Vertical Spindle
Types:
a.Ring or Cylindrical wheels
b.Flaring Cup wheels
c.Dish Wheels
d.Cup wheels

55. Face Grinding Wheels

57. 3. Form Grinding Wheels
Some Grinding Operations
Required Special Shaped
Grinding Wheels called as
Form Grinding Wheels
4. Mounted Grinding Wheels
Wheel size is less than 50
mm

58. Form Grinding Wheels

59. Mounted Grinding Wheels

60. Standard
Marking System
For Grinding
Wheels

61. •The grinding wheel is
specified by a standard system
of Marking
•The Indian Standards marking
system for Grinding wheel is
used to specify the various of
characteristic grinding wheel

62. 1. Manufacturer's symbol indicating
the type of Abrasive (Optional)
2.Abrasive Type
3.Grit or Grain Size
4.Grade
5.Structure
6.Bond Type
7. Manufacturer's Code about wheel

63. Ex:
51 A 16 Y 6 V 15

64. 51 Manufacturer's Symbol
A Aluminium Oxide (Abrasive Type)
16 Coarse (Grain Size )
Y Hard Grade (Grade)
6 Dense Structure (Structure)
V Vitrified Bond (Bond Type)
15 Manufacturer's Code

69. Selection of
Grinding
Wheels

70.  Material to be ground
Amount of material to be removed
Type of grinding operations
Wheel speed
Work speed
Area of contact
Type of grinding machine
Material physical property
Machine condition
Personal factor

71. Mounting of
Grinding
Wheels

73. •Before mounting, all
grinding wheels should be
inspected by Ringing test
•A good wheel gives a
ringing sound
• A cracked wheel will give
a dull sound

77. I. LOADING IN WHEELS
 The removed fine particles enter
into the spaces between the
abrasive particles in a grinding
wheel. This is called loading.
 After the loading, the cutting
ability of the wheel will be reduced.
 Loading of fine particles is
removed by dressing.

78. II. GLAZING
 When a grinding wheel is used for a
long time, the cutting surface of the
grinding wheel becomes smooth and
gets a glass like appearance. It is
known as glazing.
 If the grinding wheel gets a glazed
surface, then it will not grind the
surface effectively.
 Glazing of Wheel Surface is removed
by dressing.

79. RECONDITIONING OF GRINDING
WHEEL
• Due to the long-time usage of grinding
wheel, it is affected by Glazing and
Loading.
• To make the wheel surface in good
condition, it must be reconditioned.
• The grinding wheels are reconditioned
by Dressing and Truing operations.

80. Dressing

81. It is an operation of
removing glazing and
loading from a grinding
wheel.
This is done by using a
tool called Dresser

82. Types of Dresser:
•Star wheel dresser
•Round abrasive stick
•Diamond dressing tool

83. Star wheel dresser
•A star dresser made of steel is
used for dressing coarse
grained wheel the dresser tool
has hardened teeth on its
periphery and it is kept in a
tool rest.

84. Star wheel dresser

87. Round abrasive stick
• Bonded abrasives are filled in a
tube and it is called round
abrasive stick.
• Dressing is done on the grinding
wheel by moving the tube on
the rotating grinding wheel face.

91. Diamond dressing tool
• A diamond tipped dresser is used
for dressing the grinding wheel
which are used for precision
grinding.
• The diamond tip is held in a holder
and kept at an angle to the wheel.

94. Truing

95. • After long use, Grinding wheel
face may become irregular.
Truing is used to bring back the
original shape of the grinding
wheel by using diamond tool tip
• Cutting ability of wheel is
improved by truing
• Truing is done periodically

96. Balancing of
Grinding
Wheel

99. •If there is any imbalance in the
wheel, the wheel will come to
rest with a particular portion at
the bottom
•This means portions which
comes to the bottom is heavier
than the other portions

100. Rough
Grinding

101. Rough Grinders:
Large amount of metal
remove from work piece
Surface finish is not
important

102. Pedestal Grinder (Floor stand
grinder )
• Floor grinder is used for
sharpening the tools, boring
tools and drills.
• The machine has a grinding wheel
with coarse grains on one end
and a grinding wheel with fine
grains on the other end.

105. Portable grinder
• The machine can be carried from
place to place.
• A small electric motor is provided in
this grinder.
• A small grinding wheel is attached to
the end of the motor.
• This grinder is suitable for grinding
castings, and welded joint

110. Abrasive belt grinder
•In this grinder, abrasive
belt is used instead of the
grinding wheel.
•Small & irregular shaped
work piece can be grind

115. Precision
Grinding

116. Precision Grinding
Small amount of metal
remove from work piece
Surface finish is
important & finishing
parts to very accurate
dimensions

117. Cylindrical Grinders
Main Parts:
Base or Bed
Upper Table & lower
table
Head stock & tail stock
Wheel head

123. CENTRELESS GRINDER
Workpiece is placed in a
floating condition between
the GW & RW .So this is
called centreless grinding

124. The grinder has Grinding
wheel & Regulating wheel
Both rotate in same direction
GW is larger than RW
RW rotates at slow speed
RW not remove metal

125. METHODS OF CENTRELESS
GRINDING
•1. Through feed
•2. In feed
•3. End feed

131. SURFACE GRINDERS:
• This machine is suitable for grinding
flat and plane surface.
• Irregular, curved and tapered surfaces
also can be ground using this
machine.
• Die, Valve, Piston rings, surface plates
are finished by this grinding machine.

132. HORIZONTAL SPINDLE – RECIPROCATING TABLE
SURFACE GRINDER

135. HORIZONTAL SPINDLE – ROTARY TABLE
SURFACE GRINDER

138. VERTICAL SPINDLE – RECIPROCATING TABLE
SURFACE GRINDER

140. VERTICAL SPINDLE-ROTARY TABLE
SURFACE GRINDER

142. Planetary type grinders
• The work piece is held in the reciprocating
table and the work piece is clamped rigidly.
• The work piece will not be moved.
• But for grinding the work piece, the
rotating grinding wheel is moved inside
the work piece and reciprocates for
grinding the surface.
• Planetary grinder is useful for grinding the
large size holes.

145. Tool and cutter grinders
 Its used for sharpening the single point
cutting tool & multi point cutting tool (
Reamers, drills, milling cutter )
Main parts
 Base
 Saddle
 Column
 Wheel head