raw material for graphite electrodes

Requirements of raw material for graphite electrodes on discharge conditions

Raw material for graphite electrodes requirements for discharge conditions 1. Surface roughness adjustment: The surface roughness is determined by the pulse width, peak current, raw material for graphite electrodes and the workpiece material. The surface of EDM and machining The surface is different. It is composed of countless small pits and hard convex edges without directionality. The surface roughness of EDM is usually expressed by the average arithmetic deviation Ra of the micro-profile flatness.

The surface roughness is affected by the diameter of the graphite particles. The larger the particle size, the coarser the surface roughness. Generally, fine-grained graphite is used to improve the surface finish; the larger the pulse width, the longer the discharge time per unit time, and the discharge The deeper the etch, the thicker the processing surface. The raw material for graphite electrodes completes the discharge process with a smaller pulse width, and forms a shallower etch that is conducive to polishing. Copper raw material for graphite electrodes is used for less loss. Longer pulse width to complete the discharge, the formation of deeper etch marks and higher surface hardness, which makes polishing difficult; the greater the peak current, the roughness of the processed surface, which does not have a large impact on the pulse width, so the raw material for graphite electrodes The principle of “high current, small pulse width” is also the characteristic of reducing the surface roughness of the machined. Spindle shaking processing method is also an effective means to reduce the surface roughness and obtain uniform texture. 2. Adjustment of loss of raw material for graphite electrodes: During electrical discharge processing, the amount of erosion of raw material for graphite electrodes per unit time is called the loss rate.

In actual production, relative loss is usually used as a measure of the resistance of raw material for graphite electrodes. There are four types of loss in EDM: overall loss, angular loss, end loss and side loss. Since the corner loss determines the accuracy of the final processing, its loss rate is the most important, especially when the raw material for graphite electrodes are refined, the viewing angle loss should be emphasized. During electrical discharge processing of raw material for graphite electrodes, the larger the current, the smaller the loss of raw material for graphite electrodes. Under normal circumstances, the larger the pulse width, the lower the loss of raw material for graphite electrodes. But in the electrical discharge processing of raw material for graphite electrodes Excessive pulse width will cause the negative loss of burrs in raw material for graphite electrodes, so the maximum pulse width of raw material for graphite electrodes generally does not exceed 420μs, and as the discharge area is smaller, its pulse width value is also smaller ; Reasonable matching with the pulse width can also reduce the loss of raw material for graphite electrodes. When IP=10A～120A, ON=100μs～300μs, it is a lossless condition for raw material for graphite electrodes.