Effect of tungsten particle size and copper content on working behaviour of W-Cu alloy electrodes during electrodischarge machining

The effect of the average particle size (APS) of tungsten powders and copper content on the working behaviour of W-Cu alloy electrodischarge machining electrodes fabricated by pressing, sintering, and infiltration was investigated. Five batches of tungsten powder with an APS of 1.0-3.0 mu m were used. The green density of tungsten compacts increased with increasing compacting pressure and APS of tungsten powder, but the volume change which occurred during sintering and infiltration decreased with increasing compacting pressure and APS. When machining a die steel, a low erosion ratio and high erosion rate resulted. Only slight erosion of the electrode occurred and the experimental data showed no obvious difference between specimens from the five batches of tungsten powder. In heavy erosion tests machining WC-Co annular workpieces, the W-Cu alloy made from the tungsten powder with an APS of 2.0 mu m exhibited the lowest erosion ratio and highest erosion rate. Increasing the tungsten content of the W-Cu alloy reduced the erosion ratio markedly, but the erosion rate of the die steel workpieces slightly decreased.