Assessment of Secondary Fiber Print-Through Effects on Class-A CFRP Parts Produced with Highly Cost Efficient Processes

Abstract

Cost-optimized materials and processes are the key to high-performance components at attractive production costs. This study shows that non crimp fabrics (NCF) used as inner layers of high performance Class-A cfrp parts can lead to unwanted print-through effects on Class-A composite surfaces, even though they are not the surface layer. This surface distortion that is expressed in scattered lines in the direction of inner NCF layers can lead to high reject rates and is normally first noticed in the painted state. The presented methodology is able to quantify this secondaryprint-through effect for cured composites as well as for the dry textile intermediates. The surface can be measured with conventional measuring techniques, such as laser triangulation or interferometers, and characterized with the standardized values Sz and Sz25. The results show that the visible and measurable more uneven surface of a 50k biaxial NCF leads to significantly higher Sz and Sz25 values in the dry textile and the cured component. Also the regularity of the measured textiles can be detected by determining the variation of different areas of a 800 by 800mm sized sample. The presented methodology has the potential to optimize the incoming goods inspection of high volume Class-A composite manufacturers, as well as the requirement-orientated and cost-efficient development of textile intermediates by suppliers.