Research on the Depth Error in Micro Electrical Discharge Milling

Abstract

Due to the non-contact and thermal-erosion mechanism of material removal, the erosion depth of a certain layer is not always equal to the target depth in micro Electrical Discharge Milling (EDM). In order to reduce the depth error, the main factors influencing the erosion depth and the generation principle of depth error were investigated theoretically and experimentally in this paper. It was found that the actual erosion depth was collectively determined by discharge energy, layer thickness and scanning speed. The erosion depth was larger than the layer thickness when the scanning speed is low, then it decreased with the increase of scanning speed. The optimal scanning speed which made the depth error zero decreased with the increase of layer thickness, but increased with the increase of discharge energy. In this paper, the strategy of Scanning Speed Adjusted with Layer (SSAL) was proposed based on the established mathematical model of erosion depth, and validation experiments were also carried out, the results showed that under studied conditions the accumulative depth error could be effectively lowered to less than 1% with the appropriate match of discharge energy, layer thickness and scanning speed.