Study Of Surface Topography When Machining SKD 11 Tool Steel By EDM

Soh, Pih Lin (2009) Study Of Surface Topography When Machining SKD 11 Tool Steel By EDM. Project Report. UTeM, Melaka, Malaysia. (Submitted)

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Abstract

Electrical discharge machining (EDM) is a thermoelectric process that believed the EDM process will open up an opportunity for the machining of SKD 11 tool steel. This paper represented a comprehensive study which investigated the influence of the machining parameters in EDM to the surface topography, composition of the machined surface and surface roughness of SKD 11 tool steel. The selected EDM parameters were peak current (4, 6, 8 and 16A) and pulse on-time (6, 9, 12 and 15+s). EDM tests on SKD 11 tool steel were conducted on a Sodick 3 axis linear AQ35L EDM die sinking machine, with peak current and pulse on-time varied. The electrode used is copper and produced by lathe machining. The EDMed surface topography and composition of the machined surface was examined with a Scanning Electron Microscope (SEM) Evo 50 and Energy Dispersive X-Ray Spectrometer (EDX). Surface roughness was determined with a Portable Surface Roughness Tester. It is observed from the SEM micrographs that the surfaces generally have a matt appearance formed on the EDMed surface. These various factors increased with the increasing of peak current and pulse on-time. There are no cracks being observed on the EDMed surface since the setting of parameters are considered in a small range and the high carbon and chromium contain of SKD 11 tool steel. There are no significant different in composition of the EDMed surface been observed under different EDM condition compared with non-EDM specimen. It was also found that higher values of peak current and pulse on-time increased the surface roughness. Lower peak current and lower pulse on-time produced a better surface finish. Peak current has a major influence in defining the EDM surface topography and composition of the machined surface. Meanwhile, surface roughness greatly affected by the pulse on-time rather than peak current.

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