Monitoring of orbital drilling process in CFRP based on digital image processing of characteristics of uncut fibres

Abstract

Orbital drilling (helical milling) process with fixed and optimised technological parameters is suitable to produce good-quality holes in carbon fibre reinforced polymer (CFRP) composites, however, after the tool wear increases, the monitoring of drilling process is often required in order to keep the machined holes good-quality. The main objective of the present research was to develop an algorithm for the monitoring and diagnostics of orbital drilling process using digital image processing of characteristics of uncut fibres. Drilling depth and screw pitch of the helical tool path have chosen as independent process parameters. The acceptance criterion was defined as the ratio of drilled hole area to that of a nominal hole. Numerous orbital drilling experiments were carried out in order to validate the goodness and reliability of the developed method. Results show that holes machined by the application of the monitoring algorithm have less uncut fibres than the holes drilled with fixed technological parameters.