LAUSR

Abstract Composites are often one of the foremost difficult-to-machine materials. Out of many defects due to hole making process, the prime concern is delamination. This investigation aims to reveal the best drill geometry and corresponding optimal process parameter levels for making defect tolerance holes in thick pultruded and liquid composite moulded (LCM) composites. The novelty in this work are carrying out drilling operations with special geometry drills in thick composites, considering the entire depth of hole for assessing the damage and studying the influence of self-excited vibration of the work material. Minimization of drilling forces, drilling-induced damage and tri-axial self-excited vibration of the work material have been executed simultaneously to reveal the optimum process parameter levels for drilling the tested composite materials with each of the selected drill tools. It has been found that three flute and four-facet WC twist drills are more suitable for pultruded and LCM composites, respectively.