Analysis and Impacts of Chips Formation on Hole Quality During Fibre-Reinforced Plastic Composites Machining

This work presents the effect of chips formation types on the quality of drilled holes of a natural and conventional hemp and carbon fibre-reinforced plastic (HFRP and CFRP) composites respectively. The results depict that variation in chips morphology depends on drilling parameters, drill geometry and compositions of composites (matrix and fibre properties). HFRP samples produced continuous brown ribbon-like chips, which were short and melted at lower feed rate and cutting speed, implying that higher feed rate and cutting speed produced wider, longer and lighter chips. CFRP samples generated discontinuous black powder-like chips, with small and abrasive chips at the same applied drilling parameters. These formations and morphology affected quality of drilled holes: lower surface roughness in CFRP, but lower delamination and drill wear in HFRP samples. Evidently, an increased feed rate, cutting speed and drill diameter caused an increase in chips formation, validating the material removal rate (MRR) model results.