| 1) Abrasives |
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| Diamond and Cubic Boron Nitride (CBN) are resistant to wear and are the hardest abrasives available for materials that cannot be ground with conventional abrasive wheels. Both Diamond and CBN abrasives have similar structures. Diamond consists of pure carbon; CBN is composed of boron and nitrogen. Despite their physical relationship, their behaviour differs in application. |
What type of materials can be machined by Diamond and CBN wheels? |
| Diamond Wheels |
CBN Wheels |
| 1) Tungsten Carbide |
1) High Speed Steel (HSS) |
| 2) Glass |
2) Tool Steels |
| 3) Precious and Semi - Precious Gems |
3) Alloyed Steels |
| 4) Glass Reinforced Plastics (GRP) |
4) Stellite |
| 5) Ferrite |
5) Case Hardened Steels |
| 6) Graphite, Electrocarbon |
6) Heat Treated Steels |
| 7) Granite, Marble, Concrete |
|
| 8) Ceramics & Refractories |
|
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| 2) GRIT SIZE |
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| The grit size determines the stock removal rate and the surface finish of the workpiece. Coarse grit gives high stock removal rates, fine grit improves finish with reduced stock removal rates. The standard grit size for Diamond and CBN are show in this table, together with FEPA standard and other grit size designations. The FEPA standard is for both Diamond and CBN wheels. The code letter " D " represents Diamond and CBN is repressented by the prefix " B ". |
| |
| 3) STANDARD GRIT FOR DIAMOND AND CBN |
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FEPA Grit Designation |
Norminal grit size (mesh) |
U.S. Standard ASTM-E-11-70 |
D1181 |
16 |
16 / 18 |
D1011 |
18 |
18 / 20 |
D 851 |
20 |
20 / 25 |
D 711 |
25 |
25 / 30 |
D 601 |
30 |
30 / 35 |
D 501 |
35 |
35 / 40 |
D 426 |
40 |
40 / 45 |
D 356 |
45 |
45 / 50 |
D 301 |
50 |
50 / 60 |
D 251 |
60 |
60 / 70 |
D 213 |
70 |
70 / 80 |
D 181 |
80 |
80 / 100 |
D 151 |
100 |
100 / 120 |
D 126 |
120 |
120 / 140 |
D 107 |
140 |
140 / 170 |
D 91 |
170 |
170 / 200 |
D 76 |
200 |
200 / 230 |
D 64 |
230 |
230 / 270 |
D 54 |
270 |
270 / 325 |
D 46 |
325 |
325 / 400 |
D 35 |
400 |
|
D 30 |
600 |
|
D 25 |
800 |
|
D 20 |
1000 |
|
D 16 |
1500 |
|
D 15 |
2000 |
|
D 10 |
3000 |
|
D 7 |
|
|
D 3 |
|
|
D 1 |
|
|
|
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| 4) CONCENTRATION |
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| Concentration means how much diamond is contained in a unit volume of grinding wheel. |
| When its content is 25 volume %, it is said that the concentration is 100, this being equivalent to 4.4 ct/cm3 of diamond in the grinding wheel. Hence, the relationship between the grit content, condentration and diamond content in ct/cm3 is as follows: |
|
| |
Gril |
Concentration |
Diamond content in cl. |
25 vol% |
100 |
4.4 ct / cm3 |
18.8 |
75 |
3.3 |
12.5 |
50 |
2.2 |
6.3 |
25 |
1.1 |
|
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