Application characteristics of electrode materials, EDM electrode materials should have the following basic performance requirements:
1: High melting point, the higher the melting point of the tool electrode material, the smaller the electrode loss.
2: Good thermal conductivity, can quickly diffuse the heat generated by the discharge, quickly restore the insulation performance of the processing medium, and inhibit the occurrence of arc burn.
3: Good conductivity, easy to produce ionization, and meet the basic conditions of discharge.
4: Low thermal expansion coefficient, during the EDM process, the electrode size can remain stable to ensure machining accuracy.
5: Good mechanical properties, easy processing and good deformation resistance.
The electrode can be use by below material.
Red copper
The red copper has a wide range of sources and good conductivity. It can be processed stably under difficult conditions, is not easy to generate arcs, and has low processing loss; high precision can be obtained, and the surface roughness better than Ra1.25μm can be achieved by fine processing. Spend. The machining process can maintain sharp edges and corners and fine shapes. Disadvantages: Machining performance is not as good as graphite, and grinding is difficult; low mechanical strength, which is not conducive to clamping, correction and stable processing for a long time during processing; high specificity, which increases the burden on the processing feed system and improves In addition to the requirements of the system, it is also not conducive to the installation and calibration of electrodes.
graphite
Compared with the copper electrode, the advantages are: the electrode loss is small, which is 1/5~1/3 of the copper during rough machining; the processing speed is about 1.5~3 times that of the copper; the machining performance is good, and the cutting resistance is that of the copper. 1/4; The processing efficiency is twice that of copper; the specific gravity is light, which is 1/5 of that of copper, which can be used for large electrodes; it is resistant to high temperature and has a low thermal expansion coefficient, which is about 1/4 of that of copper. Disadvantages: brittleness (soaking in the working fluid can reduce brittleness), easy to damage; easy to produce arc burn phenomenon; large finishing loss, the surface roughness can only reach Ra2.5μm; it is not easy to be made into flakes and sharp edges.
Copper tungsten and silver tungsten alloy
Because of its high thermal conductivity, low loss rate, low thermal expansion and high melting point of tungsten, copper tungsten electrodes are widely used in mold steel and tungsten carbide workpieces and precision machining. Copper-tungsten and silver-tungsten alloys have similar machinability, good processing stability and low electrode loss, but they are expensive, about 40 times and 100 times that of copper, respectively.
brass
Brass electrode wears a lot, and the processing speed is slower than that of copper, but there are fewer short circuits during discharge, and the processing is stable. At present, brass electrodes are generally not used in EDM forming processing, but they are still used in low-speed wire cutting.
steel
As an electrode material, steel has good machinability, but poor processing stability. In the processing of steel punching dies, the processing speed is 1/3~1/2 of that of copper, and the electrode loss ratio is 15%~20%, which cannot be achieved. loss.