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ABSTRACT: This study presents a finite element model (FEM) to model temperature distribution for AISI H13 tool steel workpiece in electrical discharge machining (EDM) at different machining parameters (pulse current, pulse on-time, temperature-sensitive material properties, size of heat source, and material flushing efficiency). Scanning electron microscopy (SEM) with energy dispersive x-ray (EDX) and micro-hardness tests were used to validate accuracy of FEM predictions. Increasing pulse on-time leads to a higher depth of heat affected zone and increasing pulse current results in a slight decrease of depth of heat affected zone. There is a good agreement between experimental and numerical results. Introduction Electrical discharge machining (EDM), a machining process suitable to process hard materials that are difficult to machine with milling or turning, is commonly employed in aerospace, automotive, nuclear, medical and die-making industries 1,2 . 1 AISI H13 tool steel 3 justifies machining with EDM due to its high hardness. During each discharge, a crater is formed on workpiece. Depending on plasma flushing efficiency (%PFE), col-lapse of plasma channel causes very violent suction and sever bulk boiling of some of the molten material and removal from molten puddle 4 . Metal remaining in crater re-solidifies and is called recast layer. An annealed heat affected zone (HAZ) lay directly below recast layer. Both HAZ and recast layer could also contain micro-cracks. HAZ left behind by EDM process is softer than underly-ing material. This annealed zone could weaken prematurely and cause material to develop stress fractures that could lead to anything from a minor malfunction to a catastrophic failure. Therefore, it is imperative to revise specifications on EDM use and develop strategies to manufacture components with minimum depth of HAZ (HD), which involves both recast layer and underlying HAZ 5 . A number of attempts to model EDM process are reported by utilizing analytical or numerical methods 6-8 . Patel et al 6 applied a Gaussian-heat flux for modeling heat distribution at EDM and found model capable of providing precise quality profiles of tool wear ratio. Salah et al 7 presented a numerical model to study temperature distribution at EDM process and reported that temperature dependence of conductivity is of crucial importance to accuracy of numerical results and gives better correlation with experimental observations. Marafona et al 8 employed Finite Element Model (FEM) to estimate surface roughness and removed material from both anode and cathode. This study presents influence of EDM input parameters [pulse current (I) and pulse on-time (Ti)] on the state of thermal distribution in HAZ of AISI H13 tool steel using software ABAQUS/CAE.
Journal of scientific and industrial research 08/2011; 70:493-499. · 0.59 Impact Factor
