Parametric study on thrust force of core drill

Drilling-induced delamination is among the major concerns of applying the fiber-reinforced composite materials in various industries. Core drill possesses the advantage for reducing the delamination by distributing the drilling thrust force toward the drill periphery. The thrust force of core drill varying with the conditions in drilling carbon fiber reinforced plastic (CFRP) is experimentally investigated in this study. The experimental results show that reduced thickness of core drill, large grit size of diamond, low feed rate and medium spindle speed are effective in reducing the thrust force. The grit size of diamond is the most significant factor among the four control factors, while the drill thickness shows limited influence. The correlation between thrust force and cutting parameters is obtained by multi-variable linear regression and compared with the experimental results. A feasible method for the evaluation of thrust force in drilling CFRP laminate with errors within 16% is derived.