Optimization of Machining Parameters in Multi-stage Planetary EDM

The planetary machining technique in NC EDM, is effective technique to improve machining efficiency and accuracy. The multi-stage planetary machining technique, which machines a workpiece by changing machining condition step by step from roughing to finishing, is an important one in the planetary techniques. This paper describes optimal condition for minimizing the machining time in multi-stage planetary machining analyzed by COMPLEX method of non-linear programming. The optimal number of machining stage and optimal parameters as the combination of the surface roughnesses are calculated for three types of machining models having different safety margins. The following results are obtained: (1) When safety margin is zero, number of optimal machining stage is infinite. When safety margin is greater than zero, the machining models have an applicable number. (2) When an applicable optimal number of machining stages exists, it varies relevant of form factor and safety margin factor. (3) Optimal machining condition greatly depends on safety margin. As of optimal machining condition at the optimal number of machining stages, the ratio of surface roughness at one stage and the next stage is nearly constant.