Improving the Micro-Hardness of OHNS Die Steel by EDM Process Using Taguchi Approach
10 Pages Posted: 6 Aug 2013
Date Written: August 6, 2001
Electrical Discharge Machining (EDM) process is extensively used in tool and die making industry for accurate machining of internal profiles in hardened materials. Surface alloying by EDM process has emerged as a major research area in the field of non-traditional machining processes. As the dissolution of the tool electrode takes place during the process, the constituents of the electrode material may be deposited on the machined surface. Some additive powders in the dielectric medium may also form part of the plasma channel in the molten state and alloy with the recast layer under appropriate machining conditions. In this experimental work, Oil-Hardening Non-Shrinkable (OHNS type ‘O2’) die steel was machined with tungsten powder suspended in the dielectric medium. L9 orthogonal array of Taguchi approach to design of experiments was used for setting input process parameters. The machined surfaces were subjected to micro-hardness testing, SEM (Scanning Electron Microscopy) and XRD (X-ray Diffraction) analysis. The results show the presence of additional elements in the surface in the form of tungsten and tungsten carbide (WC) and improvement in micro-hardness by more than 100 %. Chemical composition of the machined surface was further checked on an optical emission spectrometer to verify the results.
Keywords: Taguchi Experimental Design, EDM, Tungsten Powder, OHNS die steel, Powder-mixed dielectric
Suggested Citation: Suggested Citation