Performance of Lasered PCD- and CVD-Diamond Cutting Inserts for Machining Carbon Fiber Reinforced Plastics (CFRP)

Carbon fiber reinforced plastics (CFRP) combine superior mechanical properties with a low weight. Consequently, this material is highly interesting for the aircraft as well as the automotive industry, leading to a massively increased application over the last years. However machining CFRP still faces different difficulties: The material is highly abrasive, most tool substrates and coatings face massive abrasive wear. Machining CFRP often results in many material defects like delamination, fiber pull-out, high surface roughness and burnt matrix material. Several technologies have been developed to combine ultra-hard tool surfaces and most adaptable cutting edge geometries. One of the most interesting approaches is laser machining of diamond cutting edges. The technology combines the wear resistance of thick layer diamonds with a geometrical flexibility so far known only for carbide tools. In the presented study, the wear resistance of different Polycrystalline Diamond (PCD) and Chemical Vapor Deposition (CVD)-Diamond grades machined with two different laser systems has been tested for machining CFRP. In comparison state-of-the-art grinded PCD cutting inserts are being tested. The comparison of machining characteristics is done by machining CFRP in a continuous turning process with a single fiber orientation. Machining forces are measured to evaluate tool wear. The resulting work piece quality is analyzed by measuring the surface roughness. The machined CFRP is a M21 resin system with an IMA-12K fiber from Hexcel©. Laser machined cutting inserts show equal or superior wear resistance compared to the grinded cutting inserts. In result today lasered cutting inserts are the machining tools available with the highest tool life time. In combination with the freely adaptable tool geometry, lasered cutting inserts are the superior tool system for upcoming machining tasks.