Wear evaluation of CVD diamond coated high-performance drilling tools for machining of carbon fiber reinforced plastics (CFRP)

The application of carbon fiber reinforced plastics (CFRP) as lightweight construction material in aerospace industry is based on the favorable weight-to-strength ratio. But the inherent material properties pose great challenges for the tool- as well as the manufacturing industry. In terms of economic industrial production processes, the quality of machined workpieces exhibits poor reproducibility combined with high tool wear. For this purpose, high-performance drilling tools with different CVD diamond coatings and carbide substrates with varying binder content were tested and analyzed in order to assess coating adhesion and workpiece quality. Due to a reduction of cobalt binder within the tungsten carbide-based tool substrates, an increase of tool performance regarding borehole quantity until coating delamination is demonstrated. While the reduction of tool wear on the rake face of the drilling tools can be correlated with the cutting tool performance, the online monitoring of cutting forces does not explicitly identify damaged cutting tools during machining.