EDM FINISHES AND POLISHING FOR MOLDING APPLICATIONS

A series of tests were made combining different EDM rates with polishing operations to determine the optimum combination of the two operations. Lowest total time was with an 160 RMS EDM finish. Using a 40 RMS EDM finish was twice as expensive in total time than the 160 RMS EDM sample. 40 RMS is only justified when fine detail is required. An EDM finish of 40-170 RMS combined with polishing will result in equivalent total times. Shop load plays a part in determining the selected rate.