Optimization of process parameters in Nano-particle mixed EDM of hardened die steel AISI H13 using RSM and GA

Abstract

EDM is an unconventional manufacturing technique that utilizes electrical discharges to create complex or robust components from various materials. AISI H13 hot work tool steel is well-suited for applications involving forming and hot working tooling, owing to its exceptional strength, hardness, hardenability, and resistance to thermal softening. The great mix of characteristics makes it challenging to manufacture. This study evaluates the latest EDM techniques applied to machining AISI H13. This study investigates the influence of peak current (10A–30A), pulse ON-time (100μs–250μs), pulse OFF-time (7μs–18μs), and powder concentration (2gm/L-5gm/L) on surface roughness (SR), tool wear rate (TWR), and material removal rate (MRR) for machining AISI H13 material by nano particle mixed EDM. The experimental runs were developed using concepts from Response Surface Methodology within the Design of Experiments (DOE) framework to minimize the number of tests conducted. Central Composite Design (CCD) was employed to develop regression models, resulting in quadratic model for SR, TWR and MRR. ANOVA was used to assess the influence of input factors on outcomes. Optimization was conducted utilizing Response Surface Methodology (RSM) and Genetic Algorithm (GA). The execution of a test run facilitated a comparison between the actual outcomes and the optimized results. In both instances, RSM and GA yielded satisfactory results. A scanning electron microscope was employed to investigate the morphology of machined surfaces. The impact of EDM bombardment on the machined surface and its layers was assessed by examining a cross-section under SEM. This allowed for a comparison of the composition of the recast layer, heat-affected zone, and base metal through visual inspection and EDX analysis. The micro-hardness of the machine surface integrity was evaluated by analysing the heat-affected zone, recast layer, and parent material. The operation of nano particle mixed EDM modifies the composition and micro-hardness of the recast layer and heat-affected zones in comparison to the base metal.