Study of Material Transfer Mechanism in Die Steels Using Powder Mixed Electric Discharge Machining

Abstract

The present article investigates the effect of process parameters and mechanism of material deposition in powder mixed electric discharge machining (PMEDM) on surface properties of EN31, H11, and High Carbon High Chromium (HCHCr) die steel materials. Current, powder, and interaction between workpiece and electrode affected the microhardness significantly. Copper electrode was found best for EN31 and H11 die steel, whereas tungsten-copper electrode was better suited for HCHCr steel to achieve higher microhardness. Graphite powder was found to be more suitable compared to aluminum in improving the microhardness of all three materials. Selected samples were analyzed for X-ray diffraction (XRD) followed by microstructure analysis using a scanning electron microscope (SEM). The results showed significant material transfer from the electrode as well as powder, either in free form and/or in compound form. For maximizing the microhardness of the machined surface, optimum parametric settings were identified for the three materials.

Keywords:

• Die
• Electric-discharge
• Material transfer
• Microhardness
• Microstructure
• Modification
• Powder
• Steels
• Surface

ACKNOWLEDGMENT

Authors sincerely acknowledge the financial support from DST, New Delhi, India, regarding the completion of the project.

Notes

** = Dummy treated.

** = Dummy treated; R-I, R-II are the results of two repetitions.