This document discusses abrasive machining processes like grinding. It covers the types of grinding wheels, their specifications and selection criteria. It describes different grinding processes like cylindrical grinding, surface grinding, and centreless grinding. It also discusses broaching machines and broaching processes. The key points are: - Grinding involves removing material with abrasive particles in a grinding wheel. Wheel specifications include abrasive material, grain size, bond type, grade, and structure. - Types of grinding include cylindrical grinding, surface grinding, centreless grinding, and internal grinding. Precision grinders are used for these processes. - Broaching involves removing metal with a row of progressively higher teeth on a broaching tool. It

1. ABRASIVE PROCESSES

2. Content to be covered
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

3. Abrasive machining Process
• Abrasive machining is one of the oldest forms
of metal removal. It is also one of the most
important. Abrasive machining can produce
surface finishes ranging from rough to
extremely fine.
• Abrasive machining is a process where chips
are formed by small cutting edges on abrasive

4. CLASSIFICATION OF MACHINING BY
ABRASION

5. INTRODUCTION
• Grinding is a material removal process in which
abrasive particles arc contained in a bonded
grinding
• The metal is removed with the help of rotating
grinding wheel.
• The grinding wheel is usually disk shaped and is
precisely balanced for high rotational speeds.

6. Grinding Machine

7. Grinding wheel

8. Grinding Wheel Parameters
• Abrasive material
• Grain size
• Bonding material
• Wheel grade
• Wheel structure

9. Abrasive Material Properties
• High hardness
• Wear resistance
• Toughness
• Friability - capacity to fracture when cutting
edge dulls, so a new sharp edge is exposed

10. Abrasives
• Grinding wheel is made up of small abrasive
particles held together by bonding material.
Thus it forms a multi edge cutter.
CLASSIFICATION
1. Natural Abrasives
2. Artificial Abrasives

11. 1. Natural Abrasives
These are obtained from mines
a) Sandstone or solid quartz
b) Emery (50 – 60 % crystalline Al2O3 + iron oxide)
c) Corundum (75-90 % crystalline Al2O3 + iron oxide)
d) Diamond

12. 2. Artificial Abrasives
• To achieve the require property we go for
artificial abrasives than natural.
• These are manufactured under some pressure
and temperature in a furnace
• Aluminium oxide
• Silicon carbide
• Artificial Diamond
• Boron Carbide
• Cubic boron nitride

13. Traditional Abrasive Materials
• Aluminum oxide (Al2O3) - most common abrasive
– Used to grind steel and other ferrous high strength alloys
• Silicon carbide (SiC) - harder than Al2O3 but not as
tough
– Used on aluminum, brass, stainless steel, some cast irons and
certain ceramics

14. Newer Abrasive Materials
• Cubic boron nitride (CBN) – very hard, very expensive
– Suitable for steels
– Used for hard materials such as hardened tool steels and
aerospace alloys
• Diamond – Even harder, very expensive
– Occur naturally and also made synthetically
– Not suitable for grinding steels
– Used on hard, abrasive materials such as ceramics, cemented
carbides, and glass

15. Grain Size
• Coarse grained (small grit number)wheels are
produce rough grinding.
• Fine grained (larger grit number) wheels are
produce finish grinding.
• Soft grade wheels are used for grinding hard
materials.
• Hard grade wheels are used for grinding soft
materials.

16. Bonding Material Properties
• Must withstand centrifugal forces and high temperatures
• Must resist shattering during shock loading of wheel
• Must hold abrasive grains rigidly in place for cutting yet allow
worn grains to be dislodged to expose new sharp grains

17. Wheel Structure
Refers to the relative spacing of abrasive grains
in wheel
• In addition to abrasive grains and bond
material, grinding wheels contain air gaps or
pores
• Volumetric proportions of grains, bond
material, and pores can be expressed as:
0
1.


 p
b
g P
P
P

18. Typical structure of a grinding wheel.
Wheel Structure

19. Wheel Structure
• Measured on a scale that ranges
between "open" and "dense."
– Open structure means Pp is relatively large
and Pg is relatively small - recommended
when clearance for chips must be provided
– Dense structure means Pp is relatively small
and Pg is larger - recommended to obtain
better surface finish and dimensional
control

20. Grinding wheel marking

21. Grinding wheel marking
Wheel grade (Hardness)
Very soft: A,B,C,D, E, F, and G
Soft: H, I, J, K
Medium: L, M, N, O
Hard: P, Q, R, S
Very hard: T, U, V, X, Y, Z
Soft grades are, generally, used for machining hard materials
Hard wheels are used for soft materials
Wheel bond
Vitrified (V)
Resinoid (B)
Silicate (S)
Rubber (R)
Shellac (E)
Oxychloride (O)
Metal

22. GRINDING WHEEL Markings
Wheel structure
Open structure wheels are used for high material
removal rates and consequently produce a rough
surface finish.
Dense structures are used for precision form grinding
operations.
Very compact: 1, 2
Compact: 3, 4
Semi-compact: 5, 6
Porous: 7, 8
Very porous: 9, 10
Extra porous: 11 to 15

23. TYPES OF BOND
• Various types of bonds used in their choice depends on
operating conditions of abrasive tool such as
grinding speed
pressure on the tool
heat formation in the grinding zone
S.NO BOND TYPE BOND
1 Organic Resinoid , rubber , oxy-Chloride
2 Non - Organic Metallic, Vitrified and silicate bond

24. 1. Vitrified Bond
• This is made of the mixture of clay and water.
• This mix is placed in mould to get require shape in
wheel
• Then the dried wheel is fed in to furnace few days at
a temperature of 1260 deg.celcius.
• This fusing gives the uniformity in the bond.
• Then the wheel is trimmed to
required shape & size.

25. 2.Silicate Bond
• The abrasive particles are mixed with silicate of soda.
• Then the mixture is moulded to get a required shape and
dried for few hours
• Then its kept in a furnace at about 260’c for 20 – 80 hours
• This wheel having moderate tensile strength
• Its used more rapidly
than vitrified bond

26. 3. Resinoid Bond
• The abrasive particles are mixed with synthetic resins.
• This mixture is rolled to get a required shape & size
• Then its kept in a furnace at about 210 – 250 ‘c for few
hours
• At this temp. the resins hold the abrasive particles firmly.
• This wheel is strong and elastic
• Operating speeds at 300m/min.
• Used to machine cast iron ,
malleable cast iron.

27. 4. Rubber Bond
• The abrasive particles are mixed with liquid rubber and
sulphur.
• This mixture is rolled in to sheet for require thickness and
then vulcanized.
• These are strong bonds having closed grains in thin sections
also.
• Its mainly used for very close surface finish. And also used in
centreless grinding

28. 5. Shellac Bond
• The abrasive particles are mixed with shellac.
• Then the mixture is rolled and pressed to require shape
and size.
• Then its kept in furnace at about 160’c for few hours
• These are strong and posses some elasticity like rubber
bond
• Used in the finishing of cam shaft and mill rolls

29. 6.Oxy-Chloride Bond
• The abrasives are mixed with oxide and chloride of
magnesium.
• Then its is moulded to required shape and size
• Then its kept in a furnace for few hours
• These wheels are less brittle and less sensitive to side loads
as compared to vitrified bond.
• No coolant required in operation

30. FACTORS IN SELECTION OF GRINDING
WHEEL
COSTANT FACTORS
1. Material to be machined
2. Material removal rate
3. Area of contact
4. Type of grinding machine
VARIABLE FACTORS
1. Work speed
2. Wheel speed
3. Condition of grinding machine
4. Personal factors ---- (labour ability)

31. THANK YOU

32. Truing & Dressing of grinding wheel
• Dressing is the term used
to describe the process of
cleaning the periphery of
grinding wheels. This
cleaning breaks away dull
abrasive grains and
smoothes the surface so
that there are no grooves.
• Truing is the term used to
describe the removal of
material from the cutting
face of the wheel
(Trimming)
• so that the resultant
surface runs absolutely
true to some other surface
such as the grinding wheel
shaft.

33. Types of dressing tools
1. Star wheel dressing tool
2. Round abrasive stick
3. Diamond dressing tool

34. Shapes of grinding wheel

35. Mounting wheels and points
• These are small grinding wheels of different
shapes.
• This is attached to the shank of the portable
grinding machine

36. Types of grinding
machine

37. Types grinding machines
1. Rough grinders
(a) Floor stand grinders (b) Bench grinders (c) Portable grinders
(d) Abrasive belt grinders (e) Swing frame grinders
2. Precision grinders
(a) Cylindrical grinders
(i) Plain centre type grinders (ii) Universal centre type grinders
(iii) Centreless grinders
(b) Internal grinders
(i) Chucking type grinders (ii) Planetary type grinders
(iii) Centreless grinders
(c) Surface grinders
(i) Horizontal spindle – reciprocating table
(ii) Horizontal spindle – rotary table
(iii) Vertical spindle – reciprocating table
(iv) Vertical spindle – reciprocating table
(v) Tool and cutter grinders
(vi) Special grinders

38. Floor stand grinder

39. Bench grinder

40. Portable Grinder

41. Abrasive belt Grinder

42. Swing Frame Grinder

43. Precision Grinder
- Cylinderical Grinder

44. TYPES OF OPERATIONS IN
CYLINDRICAL GRINDING
(i). Traverse grinding.
(ii). Plunge grinding.

45. Traverse Grinder

46. Plunge cut Grinder

47. CYLINDERICAL GRINDING

48. PLAIN CENTRE TYPE
CYLINDERICAL GRINDING MACHINE

49. USES
• Used for machining cylindrical parts and also for
tapers , fillets, contoured cylinders etc.
• It has base
head stock
tail stock
wheel head

50. UNIVERSAL GRINDING MACHINE

51. Universal grinding Machine
• These grinders are used in tool room for grinding tools.
• It has same operation as like of plain type grinding M/C
• The wheel head can be swiveled into any shape
• The head stock can be swiveled in to any angle in
horizontal plane.

52. Surface grinder
• To machine flat plane surface
• The various machine parts such as machine guide ways,
piston rings, dies, surface plates, valves are finished by
surface grinding.
• Small work pieces are held by magnetic chuck and heavy
work pieces are clamped on the table by means of pads,
strap clamps and other devices or fixtures.
Types
1. Horizontal spindle reciprocating table surface grinder
2. Horizontal spindle Rotary table surface grinder
3. Vertical Spindle reciprocating table surface grinder
4. Vertical Spindle Rotary table surface grinder

53. Horizontal spindle reciprocating table
surface grinder

54. Horizontal spindle Rotary table surface
grinder

55. Vertical Spindle reciprocating table
surface grinder

56. Vertical Spindle Rotary table surface
grinder

57. CENTRELESS GRINDING MACHINE

58. CENTRELESS GRINDING
• Its performed on the work pieces which do not
having centers such as pistons, valves, rings, tubes,
balls, wrist pins, drills , bushings, shafts etc
• It can be done on both external and internal
cylindrical surfaces.
• It has two wheels – larger grinding wheel
small regulating wheel

59. CENTRELESS GRINDING
The regulating wheel make the work piece to rotate.
So the work piece is pressed between the wheel
Grinding wheel only remove the material

60. METHODS OF CENTRELESS GRINDING
• Through feed -
This is used for machining lengthy work piece. Regulating wheel
tilted to some angle.
• In Feed –
Its similar to plunge grinding. The end stop limit the axial
movement of the work piece
• End Feed –
Here both grinding and regulating wheels are tapered. So it can
machine tapered surfaces

61. INTERNAL GRINDERS
• They are used to finish straight , tapered or formed
holes to the correct size, shape and finish.
1. Chucking type
2. Planetary Type
3. Center less Type

62. Chucking type Internal Grinder
• The work is held in the
chuck and rotated.
• The rotating grinding
wheel is moved from
left to right for making
hole

63. Planetary Type Internal Grinder
• Here the work is
stationary and the
rotation of the wheel
spindle gives an eccentric
motion according to the
diameter of the hole to
be ground

64. Center less Type Internal Grinder
• It has the same working
like external centre less
grinding. The work is
supported by three
rollers.
• It has one regulating
wheel and supporting
wheel and one pressure
roll to hold the work
piece on the other two
wheels
The grinding wheel directly contact the inside diameter of the
work piece and reciprocates about its axis for the given feed.

65. SPECIAL PURPOSE GRINDING
MACHINE

66. USES
• Its designed to do specific works
• like forming , gear teeth grinding, thread grinding,
cam grinding , tool and cutter grinding etc.

67. FORM GRINDING
• To produce complex
shapes.
• EXAMPLE.
DOVE TAIL WAY

68. Gear Teeth Grinding
• Two methods
Gear generating Process – using 2 saucer type wheel
Gear Forming Process – Using Form tool with fixtures

69. Thread Grinding
• Its same like forming process.
• The grinding wheel itself having the contours
of the thread to be machined on the work
piece

70. Cam Grinder
• From the rotation of cam
shaft , the grinding wheel
having the up and down
movement in radial
direction.
• A hardened steel roller in
conjunction with the
template actuates the
movement of whole unit to
produce the desired shape

71. Tool post grinder
• This grinder is mounted on the tool post of
the lathe for doing small operations.

72. Disc Grinder
• This is for removing material rapidly.
• Used for small polishing work
• Operated by hand wheel.

73. Tool and Cutter Grinder

74. Tool and Cutter Grinder
• To reconditioning various tools like milling, drilling,
tapping, hobs and single point tools
• By using special attachment this machine perform
various operations
• Single purpose and cutter grinder – to grind drills , tool bits
• Universal tool and cutter grinder – to sharpening milling tool ,
reamer, special driller etc.

75. ABRASIVE JET MACHINING
• 10 % MATERIAL REMOVAL BY ABRASIVE JET
• 90% MATERIAL REMOVAL BY WHEEL

76. Broaching

77. Introduction
• Broaching is the process of removing metal with a
tool which has “teeth” arranged in a row. Each
tooth is successively higher than the previous
tooth and removes more material. In broaching,
one stroke or cycle of the machine produces a
finished part.
• Broaching is used to produce both internal and
external features. Production rates are high and
tolerances of +/- .0005” are possible.

78. SPECIFICATION
• Max. length of stroke in mm.
• Type of drive: Electro-Mechanical or Hydraulic drive.
• Power range.
• Speed and Feed.
• Weight of the machine.
• Floor space.

79. Broaching machine

80. Broach

81. TYPES OF BROACHES
1. According to types of tool movement
(a) Horizontal type (b) Vertical type (c) Continuous type
2.According to the types of operation
(a) Push type (b) Pull type
3. According to the types of surface to be broached
(a) Internal type (b) External type
4. According to the construction of broach
(a) Solid type (b) Progressive cut type
5. According to the operation to be performed on the work piece
(a) Surface broach (b) Round hole broach (c) Keyway broach
(d) Spline broach (e)Burnishing broach

82. Broaching methods
Pull Broaching
Workpiece is clamped to the broaching machine in stationary position and the broach is
pulled through the work. Broaches are usually long and are held in a special head. Pull
broaching is mostly used for internal broaching.
Push Broaching
Workpiece is held in the broaching machine in stationary position and broach is pushed
through the portion of workpiece to the machined. Normally push broaching is done by
hand and arbor presses (hydraulic press). This method is also recommended for internal
broaching like for sizing and finishing the holes, cavities, and key ways.
Surface Broaching
Any one of two, either workpiece or the broach (tool) is kept moving and other is kept
stationary. The method is widely used as surface finishing operation. In case of surface
broaching, the broaching tool is specifically designed for the shape to be finished.
Continuous Broaching
In continuous broaching the broach is held stationary in the broaching machine and
workpiece is moved continuously. The teeth of movement of the workpiece may be either
straight, horizontal or circular. This is generally used for broaching a large number of
similar workpieces at a time.

83. Operation

84. Horizontal type internal broaching
machine

85. Horizontal type surface
broaching machine

86. Vertical broaching machine
- push down type

87. Vertical broaching machine
- pull down type

88. Continuous type
Broaching Machine

89. Rotary table continuous
Broaching Machine

90. Broach tool nomenclature

91. Nomenclature
Pull End ---- Pull end is made to attach the broach to the broaching machine through the puller head.
Front Pilot -- This centres the broach in the hole to be finished just before start of processing.
Roughing Teeth --These are the cutting edges which remove larger amount of stocks during cutting. Larger amount
removal generates poor quality of surface finish but makes the operation faster.
Finishing Teeth --- These are cutting edges removing smaller stocks of material. These are used for final finishing of the
surfaces and their accurate sizing.
Rear Pilot and Follower Rest --This is a supporting device to the broach when it is likely to complete its operation of
broaching.
Land --It is the width of flank face of the broach normally it is kept slightly inclined to give relief angle to the flank face of
broach.
Pitch -- It is the distance between two corresponding points on two successive teeth of a broach. Normally pitch of
finishing teeth of a broach is kept comparatively smaller than the rough cutting teeth.
Height of the Teeth ---Height of the roughing and finishing teeth gradually increases from the shank to the finishing
teeth. This increment is called the cut per tooth, it depends on the material being machined. Normally the cut per
tooth is taken from 0.01 or 0.2 mm for the finishing teeth and it may go up 0.2 mm for the cutting teeth.

92. Parts produced in broaching

93. Advantages
(a) Used in mass production.
(b) Production run time is less
(c) cheaper.
(d) Both rough cutting as well as finished cutting can be completed in a single pairs of tool.
(e) Semi skilled labors enough
(f) Broaching provides accurate and excellent quality of surface finish. It is capable to maintain
tolerance of the order of 0.007 mm and surface finish CLA value upto 0.8 .
(g) It is also capable to process internal and external surface including intricate shaped cavities.
(h) Broaching makes the effective use of cutting fluids as it facilitates the flow of cutting fluid
into the cuts.

94. Disadvantages
(a) Its initial cost is quite high.
(b) Very large sized work pieces can not be subjected to broaching operation.
(c) Broaching is not possible for the surfaces having obstructions.
(d) Removal of larger stocks is not possible in broaching operation.
(e) Clamping devices require frequent maintenance and cost.