General carbon graphite material’s production process：
Graphite can be machined wet or dry with ordinary machine tools but is normally machined dry in order to maintain its purity. It is best to avoid the dry and wet machining conversion operations on the same machine.
Dust extraction
When machining carbon and graphite it is important to prevent ingress of dust into electrical motors and control panels.Individual extraction arrangements are essential on all machines when dry machining is carried out. Centralised extraction equipment is not worth installing except in large graphite machine workshops.
Cutting
Carbon can be cut with bronze based diamond wheels. The roughness of the wheels is 200 – 300mm and the line speed is 50-60 M / s. Cutting of graphite does not necessarily require specialist tools. However optimum results may be achieved using diamond cutting wheels.
Turning
The workpiece is preferably placed in a spring jacket or with an expansion ring. In view of the characteristics of graphite ceramics, the clamping pressure should be dispersed in the area as large as possible. In principle, K01, K05 and K10 carbide inserts can be used. If the requirement is less than 1T7, diamond tools are recommended. By using the fillet or chamfering of the tool edge, the collapse angle can be reduced.
| Processing instructions (hard alloy tools) | rough machining | finishing |
| Cutting speed (m/min) | 100-300 | 200-600 |
| Inlet velocity (mm/u) | 0.2 – 0.6 | 0.05 – 0.20 |
| Incision depth (mm) | 10-20 | 0.2 – 0.5 |
Note: the lower data are mainly used for higher processing data of carbon materials for graphite material processing, while higher data for graphite material processing.
Milling
Milling is usually made of cemented carbide and diamond tools. The rear angle should not be less than 10 degrees.
Using diamond tools, the cutting speed can be increased by 50%.
| Processing instructions (hard alloy knives) | rough machining | finishing |
| Cutting speed (m/mm) | 100-300 | 150-600 |
| Feed speed (mm/u) | 300-800 | 200-300 |
| Notch depth (mm) | 5-10 | 0.5－2.0 |
Note: lower data are used for carbon material processing, while higher data for graphite processing.
Grinding
Carbon graphite materials can be grinded. The density of the grinding wheel should be between 6-9. When high precision surface treatment is needed, honing, grinding and polishing processes must be adopted.
Graphite can be bonded, and the bonding material can be made of polyester, dioxygen resin, alumina or alumina or zirconium oxide as the matrix.
