凹模电火花加工（EDM）广泛应用于制作极硬导电材料的模具。在凹模电火花加工中，当伺服将刀具送入工件时，电极和工件之间相对较小的间隙会阻碍碎屑的清除，导致冲洗条件较差。冲洗不良会导致间隙不稳定和有害电弧，导致工件和刀具不准确和损坏。许多典型形状（如圆柱、圆锥、平面、渐开线、摆线和复杂曲面）可以通过刀具和工件电极之间的共轭运动进行加工。

Die sinking electrical discharge machining (EDM) is widely used in making dies and molds of very hard, electrically conductive materials. In die-sinking EDM, as the servo feeds the tool into the workpiece, a relatively small gap between the electrode and workpiece hampers debris removal resulting in poor flushing conditions. The poor flushing leads to gap instability and harmful arcing resulting in inaccuracy and damage to both the workpiece and the tool. Many typical shapes (such as cylinder, cone, plane, involute, cycloid, and complex curved surfaces) can be machined using conjugate motion between the tool and the workpiece electrodes.