INVESTIGATION OF CUTTING PARAMETERS INFLUENCE ON THERMAL EXPANSION OF DRILL AND HOLE ACCURACY WHEN DRILLING CFRP/ TI ALLOY STACKS

Abstract

This paper presents the results of an experimental study which investigates the influence of technological parameters (cutting parameters) on the accuracy of holes and thermal expansion of the drill during drilling. The experiment was planned at three levels by varying the cutting speed, feed, and time delay according to the Taguchi method. During the experiment the controlled parameters were the holes' accuracy, which was measured by the coordinate method on a CNC coordinate measuring machine. In addition, during machining the drilling temperature was controlled via WICUTEM wireless device that combined an artificial thermocouple method with Bluetooth technology. The finite element method tested the hypothesis about the influence of thermal expansion of the drill and the accuracy of the holes depending on the technological parameters. According to the results of the study, it was determined that the value of thermal expansion of the drill does not significantly affect the accuracy of holes when drilling CFRP layer, which was mostly affected by sliding titanium chips on the hole walls. However, thermal expansion is an essential factor in determining the accuracy of the holes in the titanium alloy layer.