Improvement of surface finish on SKD steel using electro-discharge machining with aluminum and surfactant added dielectric

Electrical discharge machining (EDM) process is widely used to process hard materials in the industry. Electrical discharge distribution effects can be achieved by the addition of Al powder in the dielectric. A fine surface roughness value of the workpiece is thus obtained. However, the electrostatic force among fine Al particles is found to agglomerate the Al powders in the dielectric. A surfactant can be adopted to separate the Al powder in the dielectric homogenously. A better surface even the mirror-like quality of the EDMed workpiece is thus desired. In the study, the effect of surfactant and Al powders added in the dielectric on the surface status of the workpiece after EDM is investigated. It is observed the best distribution effect is found when the concentrations of the Al powder and surfactant in the dielectric are 0.1 and 0.25 g/L, respectively. An optimal surface roughness (Ra) value of 0.172 μm is achieved under the following parameter—positive polarity, discharge current 0.3 A, pulse duration time 1.5 μs, open circuit potential 140 V, gap voltage 90 V and surfactant concentration 0.25 g/L. The surface roughness status of the workpiece has been improved up to 60% as compared to that EDMed under pure dielectric with high surface roughness Ra of 0.434 μm.