Burr Height as Quality Indicator in Single Shot Drilling of Stacked CFRP/Aluminium Composite

In drilling metallic parts, burr height is one of the quality indicators that is used for hole quality assessment, and burr height need to be minimized for best hole quality. This is important because the induced exit burr height usually causes serious problem for further assembly of the stack up during the riveting and fasteners installation. This paper aims to establish an appropriate choice of drill geometry and drilling parameters to achieve a minimum or eliminate the burr height formation when drilling stacked Carbon Fibre Reinforced Plastic (CFRP)/aluminium 7075 T-6 composite in a single shot drilling process. The two levels of fractional factorials method was used to determine the optimum setting that give minimum burr height and the percentage of significance for each parameter in drilling a stack up materials was further analysed. The results revealed that burr height formation for stack up materials can be minimized at 15° of helix angle, 8° of primary clearance angle, 130°of point angle, 30° of chisel edge angle at spindle speed 2600 RPM and 0.05 mm/rev. A minimum burr height of 133.62 µm was found at these optimized combinations of parameters.