DAMAGE DEVELOPMENT IN DRILLING GLASS-FIBER-REINFORCED PLASTICS

In the drilling of reinforced plastics the quality of the cut surfaces is strongly dependent on the appropriate choice of drilling parameter s. The aim of this work is to clarify the interaction mechanisms betwe en the drilling tool and material. Drilling tests were carried out on glass-polyester composites using standard HSS tools; drilling was inte rrupted at preset depths to study damage development during drilling. The specimens, polished by a metallographic technique, were examined b y optical microscopy to identify any damage. The results obtained are useful in describing the damage history and to help design drill geome tries specifically conceived for composite machining. The qualitative agreement of the observed behaviour with the predictions of the model presented in the literature and some of their intrinsic limitations ar e assessed.