A study of cutting forces when drilling CFRP/Ti stacks

Abstract

sTwist drilling is a widely used machining technology for composite materials. Delamination is a serious drilling problem. The main purpose of the study is to improve the quality and productivity of the process of drilling holes in CERP/Ti stacks by minimizing delamination defects without undue changes in the cutting modes. The stack consists of a CFRP layer and titanium alloy layers. The holes are drilled with the Atlas Copco PFD-1500 automatic feed drilling machine. The HAM carbide drill was used for cutting. The range of variations in the cutting modes was selected and an experiment plan was drawn up in Statistica 6. Three factors (cutting speed, feed and accumulated cutting length) were taken into account. Using the experiment results, multivariate regression analysis models were built. They describe the effects of cutting modes and cutting length on the axial cutting force in the CFRP layer. The cutting length is the most significant factor. An increase in this factor increases the axial cutting force. An increase in feed also increases the cutting force, but its effect is less pronounced. The squared cutting speed has the least effect on the axial cutting force.