The effect of material selection and manufacturing process on the surface finish of carbon fibre composites

Using a design of experiment (DOE) approach, this work investigated the surface finish of as-moulded and painted carbon fibre composite laminates manufactured by two alternative methods, autoclave and a rapid curing process—Quickstep™. The effect of two fibre architectures on the surface finish of unidirectional and 2 × 2 twill laminates combined with a surfacing film was studied using surface profilometry and wave-scan distinctness of image (DOI) techniques. Investigation of the as-moulded surface finish showed that the autoclave cured laminates had lower surface roughness than the Quickstep laminates in terms of arithmetic mean (Ra), maximum peak to valley height (Rt), skewness (Rsk) and kurtosis (Rku). Interaction effects showed that the surfacing film reduced the Rsk and Rku when combined with the unidirectional fibre architecture but increased with the twill material. The autoclave manufactured panels combined with the unidirectional material improved the painted surface finish as identified by the DOI and long-term waviness main effect plots. Surface roughness results could not detect the influence of manufacturing and material variables on the painted surface finish. The painting process caused the microsurface defects to be concealed, resulting in defects of larger structure sizes to remain as observed using the wave-scan DOI technique.