MANUFACTURING PROCESS-II UNIT-4 ABRASIVE PROCESS

1. UNIT - IV
ABRASIVE PROCESS AND BROACHING
Abrasive processes: grinding wheel – specifications and selection,
types of grinding process– cylindrical grinding, surface grinding,
centreless grinding and internal grinding- Typical applications –
concepts of surface integrity, broaching machines: broach
construction – push, pull, surface and continuous broaching
machines

2. ABRASIVE PROCESS
Grinding is mainly used for the following purposes:
To remove small amount of metal from the work pieces
and finish them to close tolerances
To obtain a better surface finish
Sharpening of cutting tools

3. GRINDING WHEEL
Grinding wheels are made up of small abrasive particles
held together by bonding materials.
Grinding wheel abrasives
Natural abrasives
Artificial abrasives

4. Natural Abrasives
These are produced by uncontrolled forces of nature. These are
obtained from mines.
 Sandstone or solid quartz
 Emery (50 to 60% crystalline Al2o3 + iron oxide)
 Corundum (75 to 90% crystalline Al2o3 + Iron oxide)
 diamond

5. Artificial Abrasives
 These are manufactured under controlled conditions in
closed electric furnace in order to avoid the introduction of
impurities and to achieve the necessary temperature for the
chemical reaction to take place.
Aluminium oxide
Silicon carbide
Artificial diamond
Boron carbide
Cubic boron nitride

6. TYPES OF BOND
Bond is an adhesive substance which holds the abrasive
grains together to form the grinding wheel.
Bonds are classified into two types.
Organic
Non - organic

7. Organic
Resinoid bond
Rubber bond
Shellac bond
Oxy chloride bond

8. Non - organic
Vitrified bond
Silicate bonds

9. SPECIFICATION OF GRINDING
WHEEL
Grit or Grain size
Grade
Structure of wheels

10. Grit or Grain size

11. Grade

12. Structure of wheels

13. DESIGNATION OF GRINDING
WHEEL
The following elements are represented in a definite order
 type of abrasives
 Grain size or grit number
 Grade of the wheel
 Structure
 Type of bond
 Manufacture’s code

15. SELECTION OF GRINDING
WHEEL
The selection of a proper grinding wheel very important
for getting the best results in grinding work.
The grinding wheel selection will depend the following
factors
Constant factors
Variable factors

16. Constant factors
Physical properties of material to be ground
Amount and rate of stock to be removed
Areas of contact
Type of grinding machine

17. Variable factors
Work speed
Wheel speed
Condition of the grinding machine
Personal factors

18. RECONDITIONING OF
GRINDING WHEEL
Dressing
Star dressing tool
Round abrasive
Diamond dressing tool
Truing

19. Star dressing tool

20. Round abrasive

21. Diamond dressing tool

22. SHAPES OF GRINDING WHEEL

25. MOUNTING WHEELS AND
POINTS

26. TYPE OF GRINDING MACHINES
According to the type of operation
According to the quality of surface finish
According to the type of surface generated

27. Further classification
Rough grinders
 Floor stand grinders
 Bench grinders
 Portable grinders
 Abrasive belt grinders
 Swing frame grinders
Precision grinders
 Cylindrical grinders
 Internal grinders
 Surface grinders
 Tool and cutter grinders
 Special grinders

28. Rough grinders
Rough grinders are mainly used for removing large
amount of metal from the work piece. Therefore the
surface finish and the accuracy in dimension are not
high.

29. Floor stand grinders

30. Bench grinders

31. Portable grinders

32. Abrasive belt grinders

33. Swing frame grinders

34. Precision grinders
Precision grinders are used to manufacture parts of
accurate dimensions and good surface finish. The work
piece and the grinding wheel are rigidly mounted but
they are adjustable according to the requirement of the
machining methods

35. Cylindrical grinders
There are four movements in a cylindrical centre type
grinding.
Rotation of cylindrical work piece about its axis
Rotation of the grinding wheel about its axis
Longitudinal feed movement of the work past the wheel
face
Movement of the wheel into the work perpendicular to
the axis of the work piece to give depth of cut

37. Type of grinding operations are carried out
Transverse grinding
Plunge grinding

39. Type of cylindrical grinding
Plain centre type cylindrical grinding machine
Centre type universal grinder

41. Surface grinders
Surface grinding machines are used to produce and
finish flat and plane surfaces. By using special fixtures and
form dressing devices, angular and formed surfaces can
also be ground.
Horizontal spindle reciprocating table surface grinder
Horizontal spindle rotary table surface grinder
Vertical spindle reciprocating table surface grinder
Vertical spindle rotary table surface grinder

42. Horizontal spindle reciprocating table
surface grinder

43. Horizontal spindle rotary table
surface grinder

44. Vertical spindle reciprocating table
surface grinder

45. Vertical spindle rotary table surface
grinder

46. CENTRELESS GRINDERS
– Centreless grinding is performed on work pieces which
do not have centres, such as pistons, valves, rings, shafts
etc. centreless grinding can be done on both external
and internal cylindrical surfaces.

49. METHODS OF EXTERNAL
CENTRELESS GRINDING
There are three different methods
Through feed
In feed
End feed

51. Internal grinders
There are three types of internal grinders
Chucking type
Planetary type
Centreless type

52. Chucking type

53. Planetary type

54. Centreless type

55. TYPICAL APPLICATIONS OF
GRINDING MACHINES
Form grinders
Thread grinding
Cam grinding
Tool and cutter grinding

56. Form grinders

57. Thread grinding

58. Cam grinding

59. Tool and cutter grinders

60. CUTTING FLUIDS IN GRINDING
It cools the workpiece
It acts as a lubricant and reduces friction between chips,
workpiece and grinding wheel.
It removes chips from the contact area

61. CONCEPTS OF SURFACE
INTEGRITY
Surface integrity is the surface condition of a workpiece
after completing by a particular manufacturing process. In
grinding process, the surface integrity of ground specimen is
analysed.
Classification of surface integrity
Traditional process
Non traditional process
Finishing treatment

62. BROACHING
 Broaching is a process of machining a surface with a special
multipoint cutting tool called broach which has successively higher
cutting edges in a fixed path.
 It is a faster and cheaper method of machining but the depth of
removed material is limited to 6mm or less.
 Broaching the inside surface is called “internal or hole broaching”
and the outside surface is known as “surface broaching”.

64. SPECIFICATION OF A
BROACHING MACHINE
 Maximum length of stroke in mm.
 Maximum force developed by the slide in tonnes.
 Power rating of electric motor in H.P
 Speed and feed ranges
 Weight of the machine
 Floor space required

65. ADVANTAGES OF BROACHING
 Roughing , semi-finishing and finishing cuts are completed in one
pass of the broach.
 Broaching can be used for either external or internal surface
finishing processes.
 Semi skilled worker can perform a broaching operation
 Broaching is mostly adopted for mass production.

66. LIMITATIONS
 Initial cost of the broach tool is high when compared to other
tools
 Broaching is not suitable for the removal of large amount of stock.
 Almost all the work pieces will need the fixture for rigid support.

67. TYPES OF BROACHING
MACHINE
 Horizontal broaching machine
 Vertical broaching machine
 Continuous broaching machine

68. Horizontal broaching machine
 Horizontal type internal broaching machine
 Horizontal type surface broaching machine

69. Horizontal type internal
broaching machine

70. Horizontal type surface broaching
machine

71. VERTICAL BROACHING
MACHINES
– Pull up type
– Pull down type
– Push down type

72. Pull up type

73. Pull down type

74. Push down type

75. CONTINUOUS BROACHING
MACHINE
– Horizontal type
– Vertical type
– Rotary type

76. Horizontal type

77. Rotary type

78. BROACH NOMENCLATURE

79. TYPE OF BROACHING TOOLS
 Push broach
 Pull broach
 Progressive broach

80. Push broach

81. Pull broach

82. Progressive broach

83. BROACHING OPERATIONS
– Broaching splines
– Broaching a keyway

84. Broaching splines

85. Broaching a keyway