Surface Modification by Electric Discharge Machining (2nd Report)

Application of Surface Modification of electric discharge machining for complicated shapes

Abstract

The purpose of this report is to produce, a high-quality surface by electric discharge machining. In the previous paper, we confirmed the formation of a hardened layer upon mixing Ti powder into the working fluid. However surface roughness increased on the treated surface. In this experiment, we tried to apply this treatment to a die with a complicated shape. Some characteristics of the layer modified by electric discharge machining were evaluated by surface roughness measurement, X-ray diffraction analysis and SEM observation. The following results of the experiment were obtained. 1) Although surface roughness was improved by finishing electric discharge machining after surface modification, the hardness decreased only slightly on the surface. 2) A modified layer could be generated on the complicated shape. When applying scanning EDM, it was evident that a modified layer formed on the surface. 3) The gap distance increased when Ti powder was mixed into the working fluid. 4) When these surface modifications were applied to the metal stamping die for a jewel, a uniform modified layer was forming on the whole worked surface.