Relationship between EDM parameters and surface crack formation

This paper presents a study of the relationship between EDM parameters and surface cracks by using a full factorial design, based upon discharge current and pulse-on time parameters. The study analyzes the EDM machining of D2 and H13 tool steels as materials. The formation of surface cracks is explored by considering surface roughness, white layer thickness, and the stress induced by the EDM process. When the pulse voltage is maintained at a constant value of 120V, it is possible to avoid the formation of cracks if machining is carried out with a pulse current in the range of 12-16A together with a pulse-on duration of 6-9μs. Based upon the experimental results, this study establishes a crack prediction map, and indicates whether or not cracks are likely to form for a given pulse-on and pulse current combination. Its use will provide a valuable aid in improving the quality of the EDM process.