Electrode Wear
Reduced speed for larger holes
Depth of blind holes are difficult to control
EDM drilling works only on electrical CONDUCTIVE material
Only drills in conductive and semi-conductive materials
Can modify the metallurgical quality with recast and heat-affected zone (HAZ) on the surface layer in micron level
A drawback is the formation of a heat affected layer on the machined surface. Since it is impossible to remove all the molten part of the workpiece, a thin layer of molten material remains on the workpiece surface, which re-solidifies during cooling. (White Layer)