Workpiece surface integrity and productivity when cutting CFRP and GFRP composites using a CO₂laser

Following a brief literature review, results from tests involving laser cutting of carbon and glass fibre reinforced plastic (CFRP and GFRP) composites are presented. The influence of cutting speed, laser beam power and gas pressure on material removal rate (MRR), kerf width and workpiece surface integrity were investigated. Productivity was up to ~100% higher when cutting GFRP compared to CFRP, with a maximum MRR of ~8 cm3/min achieved when operating at a cutting speed of 1750 mm/min, 2500 W beam power and gas pressure of 5 bar. Charring and melting of the matrix phase was observed in both materials and similarly surface voids/cavities were evident on the CFRP and GFRP samples. Three-dimensional topographic maps also revealed the presence of grooves on the latter, which would explain the significantly higher surface roughness levels obtained (up to ~13ìm Ra). Heat affected zones were visible in the majority of CFRP specimens assessed which extended to a depth of ~1.5mm (depending on the fibre orientation) while only minor damage in terms of fibre protrusion was apparent in corresponding GFRP workpieces. Kerf widths decreased with increasing cutting speed and were typically over 2 times larger in the GFRP material.