METALLOGRAPHIC EXAMINATION OF SURFACE LAYER AFTER ELECTRICAL DISCHARGE MACHINING

Abstract

This paper presents analysis of the influence of selected electrical parameters of hollowing on the state of the surface layer after electrical discharge machining (EDM). Namely, paper focuses on the analysis of the EDM cutting process, in terms of the influence of individual parameters on the number of occurrences and sizes of erosion craters on the machined surface. The basic parameters include electrical pulse discharge time, electrical discharge pause time, voltage, current amplitude and servo voltage. The initial values of the mentioned parameters were selected based on technology tables provided by the machine manufacturer and on the basis of own empirical tests. The tests were carried out according to static determined poliselective experimental plan (Hartley plan). Analysis of the machined surface was carried out using a scanning microscope (SEM) and an optical microscope. Quantitative metallographic analysis was used to determine the stereological features of erosion craters occurring on the surface of the machined material. The results were illustrated by means of three-dimensional graphs. The presented studies show a significant effect of electrical parameters of EDM on the quality of the machined surface, i.e. the number of occurrences and diameter of erosion craters. The research presents an approach based on mathematical modelling of electrical discharge machining. This approach can form the basis for developing methods of modeling technological processes and optimizing their parameters.