Mechanical model for predicting thrust force with tool wear effects in drilling of unidirectional CFRP

Thrust force is the most influential factor to drill-exit damages in the drilling of carbon fiber reinforced polymer/plastic (CFRP). The accurate prediction of the thrust force is important for drilling process optimization to suppress these damages. However, the thrust force is strongly coupled with rapid tool wear, which brings significant challenges to its accurate prediction. This paper proposed a novel mechanical model for predicting thrust force with the consideration of tool wear effects in the drilling of unidirectional CFRP. Firstly, tool wear geometrical characteristics of a twist drill, including rake face, cutting edge and flank face are identified as a line, elliptical arc and line profiles, respectively. The contact conditions and cutting mechanism between CFRP and drill bit are further analyzed based on the identified wear profiles and contact mechanics. Then the thrust forces of the main cutting edge and the chisel edge are modelled based on these analyses. Integrating these forces along the main cutting edges and the chisel edge, the total thrust force in drilling CFRP is predicted considering the tool wear effects. Drilling experiments are carried out to validate the prediction model. The predicted and experimental results are in good agreement.

Automated summary

This study proposed a novel mechanical model for predicting thrust force in drilling CFRP, considering tool wear effects, which was validated through drilling experiments with good agreement between predicted and experimental results.