AM of WC-Co Additive manufacturing of solid carbide cutting tools

 

The laser-based additive manufacturing (AM) of tools made of WC-Co carbide has been little studied so far. Up to now, WC-Co additive has only been produced with a high proportion of the cobalt binder phase (> 10 %). In most industrial applications, tools with a lower binder content are used because of their higher wear resistance. For an industrial application of carbide tools manufactured with AM the quality is yet not satisfactory in terms of density, cracks and bonding. This leads to uneconomical machining processes due to low applicable process parameters. However, the process offers attractive advantages in terms of near-net-shape production and geometrical freedom. In particular, the possible realization of internal, contour-adapted cooling channels leads to improved cooling and lubrication, whereby the cutting speed and productivity of the cutting process can be significantly increased.

In the project the near-net-shape laser-based AM of cutting tools made of WC-Co with internal contour-adapted cooling channels is carried out. The aim is to achieve a performance at least equal to that of sintered cutting tools. The primary material-technical approach is to improve the homogeneity and density of the microstructure in comparison to the previous WC-Co carbides produced via AM and to minimize the formation of brittle phases. The competences of the three participating research institutes complement each other to achieve these goals.

The task of the Fraunhofer ILT is to develop the process technology for the laser-based AM of cutting tools. New preheating concepts with direct heating of the powder bed are investigated. The task of the IWM of the RWTH Aachen University is to characterize the microstructure and mechanical properties of the additive-manufactured carbides and to correlate them with the process parameters of the AM in order to draw conclusions for the adaptation of the AM. The task of the WZL of the RWTH Aachen University is to develop a post-processing concept for the additive manufactured cutting tools and to determine and interpret the cutting properties in cutting investigations. On this basis conclusions are to be drawn about the manufacturing parameters. Tests with conventionally manufactured cutting tools serve as a reference. Through the participation of the three institutes with their specific project-relevant competences (process - material - machining), the project illustrates the laser-based additive manufacturing of cutting tools made of WC-Co from powder material to function test.