Optimization of parameters for drilling composite materials with freeform surfaces

In the drilling process, the angle of surface is one of the parameters that affect hole quality. In study, the effects of feed rate, spindle speed and surface angle on the thrust force, roughness, and delamination, which are the factors affecting the quality of hole, were investigated in the drilling of GFRP (glass fiber reinforced polymer) and CFRP (carbon fiber reinforced polymer) with freeform surfaces. With ANOVA (Analysis of Variance) and regression analysis, the parameter effects were statistically compared, and descriptive mathematical models were derived. The mathematical models were subjected to the Genetic Algorithm approach according to the different surface angles determined and the optimum parameter values were calculated. Guiding data were obtained about the effects of machining on hole quality in drilling composite at different surface angles, which is the main motivation of the study. Optimization results will improve hole quality on curved surfaces, while saving cost and time.