Study on UV laser machining quality of carbon fibre reinforced composites

The large differences in material properties of the carbon fibre and the epoxy resin in carbon fibre reinforced plastic (CFRP) composite make laser processing very challenging. The heat affected zone (HAZ) has been the major obstacle for wide industry applications of laser machining of CFRP composites. This paper investigates the quality of CFRP machined by a diode pumped solid state (DPSS) UV laser. The results show that minimum HAZ (about 50 μm) is achievable in machining of CFRP composite by using short pulsed UV laser. The study found that heat is easily accumulated in the material during laser processing, especially when the carbon fibres are sliced into small pieces. The paper discusses how to make use of the heat accumulation and how to avoid potential damage by the heat accumulation. Bearing strengths test and fracturing mechanisms study were conducted. Method of characterization of thermal damage in polymer matrix is developed.