An investigation of burrs, chip formation, hole size, circularity and delamination during drilling operation of GLARE using ANOVA

While there has been a significant amount of research on drilling composite-metal stacks, limited work has been carried out on the machinability of fibre metal laminates (FMLs) used in aerospace structures. Challenges faced in drilling FMLs include those which exist in metals and composites such as delamination, chip and burr formations. The aim of this work is to extend the knowledge of machining fibre metal laminates through the assessment of twist drilling operations in order to improve workpiece quality. The current work presents an experimental study to analyse the effects of drilling parameters (spindle speed and feed rate) on hole quality in two grades of GLARE (2B & 3). The evaluation includes inspecting the hole size, circularity error, entry and exit burrs, chip formations and damage described at the macro level (delamination area) using computerised tomography CT scan, and at the micro level (fibre matrix debonding, chipping, adhesions, cracks) using scanning electron microscopy (SEM). In addition, the results are statistically analysed using analysis of variance (ANOVA) to determine the contribution of cutting parameters on investigated hole quality parameters.