Prediction and optimization of machining time and surface roughness of AISI O1 tool steel in wire-cut EDM using robust design and desirability approach

Wire electrical discharge machining (WEDM) is a non-conventional manufacturing process employed by several industries to machine almost any conductive material with high precision. The success of this process depends on the correct selection of the cutting parameters to achieve key metrics such as high productivity and quality. This paper presents an experimental study to optimize the machining time and the surface roughness in wire-cut EDM of AISI O1 tool steel under roughing conditions. The signal to noise ratio and the analysis of variance (ANOVA) were used to analyze the effects and contributions of four cutting parameters related to the WEDM: pulse-on time, pulse-off time, servo voltage, and wire speed, on the aforementioned response variables when two different thicknesses of the workpiece material were considered in the experimental trials. An L9 orthogonal array was selected to reduce the cost and time needed to perform all the experiments. The desirability method was used to perform a multi-objective optimization that provided the value of the cutting parameters that achieved a reduction of the machining time and the surface roughness at the same time. Servo voltage was the most significant factor for minimizing the machining time, followed by the pulse-on time and wire speed. For surface roughness, the pulse-off time was the most significant factor for reducing this response. The multi-objective optimization provided a reduction of 7.50% for the machining time and 1.16% for the surface roughness when compared with the values of the cutting parameters commonly used in WEDM of AISI O1 tool steel. This study showed that the methodology presented could be of use for any industry that needs to enhance the surface quality and productivity of the wire-cut EDM process by reducing the machining time.