Application Of Graphite Electrode In The Mold Processing

　　In recent years, with the high precision mold and die (mould cycle becoming shorter and shorter) launch, people more and more requirement of mold making, copper electrode itself due to various constraints, has become increasingly unable to meet the requirements of the development of mold industry. Graphite as the electrode materials of EDM, with its high cutting, light weight, forming speed, expansion rate, low loss, small dressing is easy, have been widely applied in the mold industry, instead of copper electrode has become an inevitable.

　　A graphite electrode, material properties

　　1.CNC fast processing speed, high, easy machinability of dressing

　　Graphite machining speed, as the copper electrode is 3 ~ 5 times, finishing speed is especially prominent, and its strength is very high, for ultra high (50 ~ 90mm), thin (0.2 ~ 0.5mm) electrode, processing is not easy deformation. But in many cases, the product needs to have ruled surface effect is very good, it is necessary to make the whole electrode in the electrode, while the overall electrode production has many hidden corner, due to the characteristics of the modified graphite, makes the problem easy to be solved, and greatly reduce the electrode the number, and the copper electrode but unable to do so.

　　2 fast EDM forming, thermal expansion of small, low loss

　　Because the graphite conductive than copper, so the speed of discharge it is 3~5 times faster than copper, copper. And the discharge can withstand high current, electric spark machining more favorable. At the same time, same volume, weight is 1/5 times that of copper graphite, greatly reduce the load of EDM. For the production of large electrode, electrode very advantage. Graphite sublimation temperature was 4200 ℃, is 3~4 times that of copper (sublimation temperature of copper is 1100 ℃). At high temperature, minimum deformation (the same electrical conditions for copper 1/3~1/5), do not soften. High efficiency, low consumption can be the discharge energy is transferred to the workpiece. Because the graphite strength at high temperatures but strengthened, can effectively reduce the discharge loss (loss of copper graphite 1/4), ensure the quality of processing.

　　3, light weight, low cost

　　The cost of making a set of mold, electrode CNC machining time, EDM time, electrode loss accounted for most of the total cost, which is determined by the electrode material itself. Graphite compared with copper, graphite machining speed and EDM speed is 3 ~ 5 times of copper. At the same time, making minimal wear characteristics and the overall character of graphite electrode, can reduce the number of electrodes, it reduces the processing time and machine consumable electrode. All these, can greatly reduce the cost of manufacturing mold.

　　B, graphite electrode electrical and mechanical requirements

　　1.Making the electrode

　　Production of graphite electrode is mainly used for professional high speed machine tool machining, machine stability is better, three axis motion to the uniform stability without vibration of spindle rotation accuracy, and the like as much as possible. The machine also can complete electrode the processing, just write path process with different copper electrode.

　　2.EDM electrical discharge machining

　　Graphite electrode is carbon electrode. Because the conductive properties of graphite as well, so in the discharge process can save a lot of time, it is also one of the reasons for graphite electrode.

　　3.The processing characteristics of graphite electrodes

　　Industrial use of graphite of hard and brittle, in the C N C processing on the tool wear is more serious, the tool generally recommend the use of hard alloy or diamond coating. The graphite in the rough machining tool can be directly on the surface of the workpiece under the knife, finishing in order to avoid chipping, fragmentation occurs, often uses the processing of light knife go way. In general, the graphite in the cutting depth is less than 0.2mm case happens rarely break, will get a better surface quality of side wall. The dust produced in graphite electrode CNC processing is relatively large, the possible intrusion to the machine tool guide wire rod and the main shaft, which requires the device of graphite processing machine has the corresponding treatment of graphite dust, machine sealing is better, because the graphite toxic.