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Analysis of surface layers of hot – forging dies of SKD61 steel fabricated by die – sinking electrical discharge machining using copper and titanium electrodes

This is accepted according to practical experience and the lack of scientific basis because of limited research on the surface layer quality of the products after EDM and the study is focused on the evaluation of the product quality in the final processing. This study is aimed at the investigation of performance and structure of the surface layer in hot-forging die following die-sinking EDM. | Journal of Science and Technology 54 (5A) (2016) 19-26 ANALYSIS OF SURFACE LAYERS OF HOT – FORGING DIES OF SKD61 STEEL FABRICATED BY DIE – SINKING ELECTRICAL DISCHARGE MACHINING USING COPPER AND TITANIUM ELECTRODES Nguyen Huu Phan1, *, Banh Tien Long2, Ngo Cuong1 1 Thai Nguyen Technical-economics College, Thinh Dan ward, Thai Nguyen city 2 Hanoi University of Science and Technology, Hanoi, No. 1, Dai Co Viet, Hanoi * Email: phanktcn@gmail.com Received: 17 July 2016; Accepted for publication: 2 December 2016 ABSTRACT Electrical discharge machining (EDM) is a popular unconventional method for manufacturing tools, molds, and dies. Currently, the surface layer of the hot die after EDM needed to be polished to remove the layer of ≈ 50 μm. This is accepted according to practical experience and the lack of scientific basis because of limited research on the surface layer quality of the products after EDM and the study is focused on the evaluation of the product quality in the final processing. This study is aimed at the investigation of performance and structure of the surface layer in hot-forging die following die-sinking EDM. The machining conditions included the use of copper (Cu) and titanium (Ti) as electrode materials. A crosssectional micrographic and hardness analysis was performed, as well as surface roughness measurements, in order to study the thermally affected zones of the hot-forging die surface layer of the SKD61 steel after EDM using oil as the dielectric fluid. The results showed that the performance of the die was reduced due to changes in the hardness and the chemical composition of the workpiece surface. The surface quality of hot-forging die after EDM with Ti or Cu electrode are similar. In this case, EDM using Ti electrode to improve the quality of hot die surface layer was unreasonable. Keywords: EDM, surface roughness, microscopic hardness, Titanium, Copper. 1. INTRODUCTION EDM is a reproductive shaping process in which the form of the .