Optimization of cutting forces in end milling of CFRP composites using Response Surfaces and desirability function approach

The quality of a machined product relies primarily on the setting of process parameters during the machining operation. To obtain desired outcome, it is vital to identify and control the process parameters which have a significant effect on the response variables. Response Surfaces is one such approach which utilizes statistical and optimization techniques to arrive at an optimal combination of factor settings that can minimize the cutting forces acting on carbon fiber reinforced composite work piece. In this study the effects of process parameters spindle speed, feed rate and fiber orientation on cutting forces generated on the composite material was evaluated. Three level factorial design, Analysis of Variance (ANOVA) and overlay contour plots were utilized to arrive at the combination of factor settings which produced minimum forces. The process parameters were tested at three different levels i.e. Speed at 500, 1000 and 1500 rpm, feed rate at 50.8, 101.6 and 152.4 mm per minute and fiber orientation at 0, 30 and 60 degrees respectively. The minimum forces were achieved at Speed = 905 rpm, feed = 50.8 mm/min and fiber orientation = 0 degrees. The resulting optimal conditions were tested using the Derringer-Suich desirability function approach and similar results were observed. Operating at the above optimal settings of process parameters ensures minimum forces to be acting on the composite material during machining and therefore results in a better surface quality.