The influence of additive powder on machinability and surface integrity of SKD61 steel by EDM process

Abstract

The powder mixed electrical discharge machining, also called PMEDM, is gaining much attention, because it is demonstrated as a good solution for enhancing productivity and surface integrity. In this research, the influence of main process parameters, including peak current, pulse on time, and powder concentration in the PMEDM with tungsten carbide powder on the machinability of SKD61 steel – i.e., material removal rate (MRR) and tool wear rate (TWR), was firstly investigated. Subsequently, the surface integrity of the recast layer, including the chemical composition, the recast layer thickness (RLT), and the percentage of the surface micro-crack density acreage (PSCDA) was analyzed and discussed. The results show that peak current, pulse on time, and powder concentration have influence on the machinability and surface integrity. MRR and TWR have changed in an uptrend when peak current, pulse on time, and powder concentration increase. At Ip = 3A; Ton = 200 µs; Cp = 60 g/l, the largest change in MRR and TWR are 165.714% and 163.830% respectively as compared with the EDM method. The chemical composition of machined surfaces was also transformed. In comparison to the EDM method, PSCDA and RLT generated by the PMEDM method were significantly reduced, up to 52.558% and 63.366%, respectively.