Parameter Design of EDM Process to Optimize Surface Roughness and Material Removal Rate Using Taguchi Method

Abstract

Electrical discharge machining (EDM) is a non-conventional process that is widely used for high-precision machining, complex product shapes, and high hardness materials. The EDM mechanism is based on the thermoelectric energy between the electrode and the workpiece. The EDM process has many parameters that can be adjusted, such as discharge current, voltage, pulse on time, pulse off time, electrode polarity, workpiece material, electrode material, dielectric fluid type, flushing pressure, flushing direction and flushing method. This study aims to find the parameters of the EDM process to optimize its productivity indicated by material removal rate (MRR) and its quality indicated by surface roughness of SS-316 material. The varied parameters were discharge current, pulse on time, and pulse off time with 3 levels for each parameter. Fractional orthogonal array L9 were applied for three 3-level variables. Performance fluctuation due to noise factors were simply approximated by 3 replicating measurements to estimate mean and standard deviation. Taguchi S/N ratio were adopted as robustness index for the optimum parameter design. The optimization results show that the discharge current 30A, pulse on time 100μs, and pulse off time 8μs are the optimum for MRR. As for surface roughness, the discharge current is 10A, pulse on time is 100μs, and pulse off time is 8μs. The only different of EDM parameter for optimum MRR and optimum Ra is discharge current.