A new approach for analyzing machining-induced damage in correlation with tool wear during dry drilling of CFRP/Ti stacks

The machining process of Carbon Fiber Reinforced Polymer/Titanium (CFRP/Ti) stacks presents significant challenges owing to the inherent inhomogeneity of CFRP and the low thermal conductivity of Ti. The drilled hole surface can experience machining-induced damage, such as delamination, fiber pull-out, and burr formation. The present study aimed to examine the influence of cutting parameters and coatings, as well as tool wear mechanisms, on the occurrence of machining-induced damage in CFRP/Ti stacks during dry drilling. Moreover, a new method called MATLAB-Assisted Image Processing (MAIP) is introduced to assess machining-induced damage, specifically delamination and burr formation, in the context of CFRP/Ti stack drilling. The use of advanced MATLAB-assisted image processing improves the precision of MAIP. The coefficient of repeatability is 0.001394. TiAlN-coated drills offer notable advantages, resulting in a 13% decrease in the maximum thrust force for CFRP and a 10% reduction for Ti. Furthermore, there is an 11% decrease in delamination compared to a tool that lacks a coating. The experimental findings revealed a significant correlation between machining-induced damage and the mechanisms of tool wear.