Abstract
In the present work, attempts have been made to optimize the EDM process with an aspect of surface modification of AISI P20+Ni die steel using powder metallurgy (P/M) electrode. Experiments have been performed according to central composite rotatable (CCD) design using response surface methodology (RSM). Effects of compaction pressure (Cp), peak current (Ip), pulse-on time (Ton), and duty cycle (τ) were correlated with surface roughness (SR) and microhardness (MH). Adequacy of mathematical model has been checked by performing ANOVA. Composite desirability approach was used to obtain optimal set of parameters for minimum SR and maximum MH. The errors between the predicted and experimental value of responses at the optimal set of parameters for SR and MH maintain within 5.26% and -3.64% respectively. Scanning electron microscope and energy dispersive spectroscopy analysis confirmed the transfer of P/M electrode material on the work surface. The result indicates three times improvement in microhardness of EDMed surface.
Highlights
Electrical Discharge Machine (EDM) [1] has become the most popular and extensively recognised non-traditional machining processes [2] in the die making industries [3]
The surface roughness and microhardness of AISI P20+Ni die steel samples machined on electrical discharge machine through powder metallurgy electrode were modelled and analysed using response surface methodology
The good agreement was observed between predicted values and experimental values of responses such as surface roughness (SR) with R2 of 0.9986 and MH with R2 of 0.9805
Summary
Electrical Discharge Machine (EDM) [1] has become the most popular and extensively recognised non-traditional machining processes [2] in the die making industries [3]. The surface treatment processes such as CVD, PVD, plasma coating and Electro Plating are used to enhance the life of die and mould [8, 13,14,15] These secondary surface treatments are very expensive and time-consuming; further, there is addition of cost and time due to removal of the recast layer of EDMed surface prior to performing secondary surface treatments [16]. The EDM electrode manufactured using powder metallurgy has been observed as feasible alternative than conventional electrode because it helps to improves die life due to the modification of recast layer, reduction of cost and time due to the elimination of secondary surface treatments [17,18,19].
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