MP-2

1. 6. GRINDING MACHINES
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2. Introduction
 Removing of excess material from work piece
 Mechanical action of abrasive particles
 Finishing Process
 Economical for hard material
 High surface finish and dimensional tolerance
 Automobile, camshafts, jet engine rotors
 Bearings, sharpening of knife, drill bit, cutting
tools, cleaning surface
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3. Principle of Grinding
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4. Grinding Wheel
 Abrasive particles
 Bonding materials (Adhesives)
 Filler or additives for producing voids within
the wheel
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5. Types of Abrasives
 Natural Abrasives – mined from the earth
 Sand stone (quartz) – Natural silica
 Diamond- form of carbon, restricted use due
to cost and hardness
 Corundum – pure aluminum oxide(Al2O3)
 Emery – Corundum and iron oxide
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6. Types of Abrasives
 Artificial Abrasives
 Aluminum oxide – refined from bauxite ore,
most widely preferred abrasive, used for HSS
ferrous and wood
 Silicon carbide - non ferrous materials, wood
and leather
 Synthetic diamond – manufactured in high
temp and high pressure process, non ferrous
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7. Types of Abrasives
Not used for steel,
 Cubic Boron Nitride (CBN) – borazon,
manufactured in high temp and high pressure
process,
 CBN and SYNTHETIC DIAMOND are known
as super abrasive
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8. Bonding process
 Binding the abrasive particles with the help of
bonding materials
a) Vitrified bond:
 Also called ceramic bond composed of clay
and other ceramic substance
 Abrasive particles mixed with bonding
material with sufficient water and and
formed in to a wheel
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9. Bonding process
 Dried at temp 1250-1325 c
 Strong, rigid and strong
 Brittle and poor shock resistance
 Denoted by ‘V’
b) Resinoid Bond:
 Synthetic resin or plastic that becomes hard
on heating
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10. Bonding process
 Abrasive particles are mixed with resins in
powder or liquid form along with additives
Pressed in to shape of grinding wheel
 Cured at 180o C cooled at room temp
 good strength and more elastic then vitrified
 Low resistance and chemical reaction and
heat
 Designated by letter ‘B’
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11. Bonding process
c) Rubber bond:
 Composed of pure rubber and sulfur
 Bonding material is mixed with abrasive
particles and pressed between hot rolls
 Wheels are cut from these sheets
 Thin wheels can be used as cutting saw
 Can not be stored for longer period
 Less heat resistance
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12. Bonding process
d) Shellac bond:
 Made of shellac – resin like substance
 Abrasive particles are mixed with shellac in a
steam heated mixer
 Mixture is pressed under rolls and baked for
hour at 1600 C
 Produce good surface finish
 Designated by letter ‘E’
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13. Bonding process
e) Silicate bond:
 Made of sodium silicate
 Abrasive particles are mixed with sodium
silicate and pressed and formed in to wheels
 Baked at 2600 C for a day
 Soft and wear easily
 Designated by ‘S’
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14. Standard designation of
Grinding wheel
 Type of abrasive
 Natural abrasive
 Artificial abrasive
 Type of bond
 Vitrified
 Resinoid
 rubber
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15. Standard designation of
Grinding wheel
 Shellac
 Silicate
 Grain or grit size
S No Type of grain Grain size Charecteristics
1 Course 16-24 grit Remove high volume of material
Less surface finish
2 Medium 36-60 grit Moderate stock removal
Better surface finish
3 Fine 80-120grit Better surface finish
4 Very fine 150 above High surface finish
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16. Standard designation of
Grinding wheel
 Grade
S No Type of grade Grade
1 Very soft A,B,C,D,E,F,G
2 Soft H,I,J,K
3 Medium L,M, N, O
4 Hard P,Q,R,S
5 Very hard T,U,V,W,X,Y,Z
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17. Standard designation of
Grinding wheel
 Structure
S No Type of structure Structure No
1 Dense 1-8
2 Open 9-15 and above
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18. Specification of grinding
wheel
300X30X35W A 36 K 5V 17
300 = wheel diameter in mm
30= wheel thickness in mm
35 = bore diameter in mm
W = Manufacturer symbol for abrasive
A=Type of abrasive
36 = grain size
K = Soft grade
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19. Specification of grinding
wheel
5 = dense structure
V = vitrified bond
17 = manufacturer private marking to identify
wheel
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20. Types of Grinding wheels
S No Type Characteristics
1 Straight Simple flat disc shape without recesses,
cylindrical, centre less, surface , internal grinding
operations
2 Recessed one side cylindrical, centre less, surface , internal grinding
operations
3 Recessed both side cylindrical, centre less, surface , internal grinding
operations
4 Cylinder Used for surface grinding operations, end face
of the wheel is used for grinding
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21. Types of Grinding wheels
S No Type Characteristics
5 Straight cup Surface grinding
6 Flaring cup Sides flare out, sharpening of milling and
reamers
7 Dish For grinding tools and saws
8 Tapered Grinding gear teeth and threads, less wheel
breaking
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22. Classification of Grinding
machines
a) Surface Grinding Machine
 Horizontal spindle type with reciprocating
type table
 Vertical spindle type with reciprocating type
table
 Horizontal spindle with rotary table
 Vertical spindle with rotary table
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23. Classification of Grinding
machines
b) Cylindrical Grinding Machine
 CentreType
 Center lessType
 ChuckingType
c)Internal Grinding Machine
 ChuckType
 Center lessType
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24. Classification of Grinding
machines
d)Special purpose Grinding Machine
 Tool and cutter grinding machine
 Roll grinding machine
 Crankshaft grinding machine
 Thread grinding machine
 Cam grinding machine
 CNC grinding machine
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25. Principle of Grinding
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26. Horizontal spindle type with
reciprocating type table
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27. Vertical spindle type with
reciprocating type table
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28. Horizontal spindle with rotary
table
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29. Vertical spindle with rotary
table
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30. Center type cylindrical
grinding machine
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31. Center less grinding machine
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32. Traverse and plunge grinding
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33. Center less grinding machine
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34. Center less grinding process
with common axis
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35. Types of center less grinding
process
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36. Internal grinding process
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37. Selection of grinding wheel
 Type of work piece material to be ground
 Rate of metal removal from the work piece
 Surface finished required
 Speed of grinding wheel
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38. Dressing and Turning of
Grinding wheels
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39. 7/27/2023 7:10 AM 39
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