Investigation and optimization of the electro-discharge machining parameters of 2024 aluminum alloy and Al/7.5% Al2O3 particulate-reinforced metal matrix composite

Being newly advanced materials, metal matrix composites enjoy the properties of high service temperature, light weight, high specific strength, good wear resistance, high stiffness, and a low thermal expansion coefficient. However, machining these materials by conventional methods is difficult. A key machining process for difficult-to-machine materials like composites is electro-discharge machining, which is widely used in non-conventional material removal processes. The current work aims to identify different parameters, such as voltage, current, pulse on-time, and pulse off-time, which influence the material removal rate (MRR), tool wear rate (TWR), and surface roughness (SR). By applying regression equations, a mathematical model is adopted to estimate MRR, TWR, and SR. The optimum machining parameters are investigated using the Taguchi method with L9 orthogonal array. The optimum values are also analyzed by multi-objective Taguchi method with calculation of total normalized quality loss (TNQL) and multi-signal to noise ratio (MSNR) included. Analysis of the Taguchi method introduced voltage and pulse off-time as the two main significant factors that influence the value of the material removal rate. The discharge current and pulse off-time also have a statistically significant impact on both tool wear rate and surface roughness