Modelling and investigating the effect of input parameters on surface roughness in electrical discharge machining of CK45

Original scientific paper Electrical discharge machining is an unconventional machining process in which successive sparks are applied to machine the electrically conductive materials. Any changes in electrical discharge machining parameters lead to the pieces with distinct surface roughness. The electrical discharge machining process is well applied for high hardness materials or when it is difficult to use traditional techniques to do material removing. Furthermore, this method is widely applied in industries such as aerospace, automobile, moulding, and tool making. CK45 is one of important steels in industry and electrical discharge machining can be considered as a proper way for its machining because of high hardness of CK45 after thermal operation of the electrical discharge machining process. Optimization of surface roughness as an output parameter as well as electrical discharge machining parameters including current, voltage and frequency for electrical discharge machining of CK45 have been studied using copper tools and kerosene as the dielectric. For such a purpose and to achieve the precise statistical analysis of the experiment results design of experiment was applied while non-linear regression method was chosen to assess the response of surface roughness. Then, the results were analysed by means of ANOVA method and the machining parameters with more effects on the desired outputs were determined. Finally, mathematical model was obtained for surface roughness.