Induced thermo-mechanical damage in the drilling of thermoplastic-toughened CFRP composites

This investigation focused on the assessment of the induced thermal and mechanical damage in the drilling of carbon fibre reinforced polymer (CFRP) composites in the 50-200m/min cutting speed range. 3D surface measurement techniques were used to assess the induced mechanical damage by studying the drilled surface and successfully related selected surface parameters to specific types of defects (splintering, fibre pull-out and crater). The workpiece constituents, especially the type of reinforcement, showed significant impact on the extent of the induced mechanical damage. The nanoindentation technique studied the induced thermal damage by measuring the bulk properties of the resin phase from the hole edge up to 1 mm away from the borehole. The type of resin, degree of crosslinking and the ageing temperature exhibited strong influence on different ageing stages studied in this work.