Binderless nano-polycrystalline diamond (NPCD) as cutting material for precision machining cemented carbide

• Applicant: Professor Dr.-Ing. Eckart Uhlmann
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 446389511

Due to the hardness and strength properties as well as the good wear behaviour is tungsten carbide industrially used for punching moulds, injection moulds and cutting tools. Tungsten carbide belongs to the group of hard-brittle materials and is mainly manufactured with undefined cutting edges by grinding processes. The machining with turning- and milling processes is difficult but enables an effective manufacturing and increased geometry complexity. A limiting factor during the manufacturing with geometrical defined cutting edges is increased tool wear.In this investigation a new cutting material nano polycrystalline diamond (NPCD) is used for the cutting of cemented carbide (WC-Co). Due to the material structure NPCD achieves a hardness H comparable to single-crystalline diamond (SCD) without sharing their disadvantages such as anisotropy. In consequence of the diamond particles with particle diameter in a range of 10 nm ≤ dk ≤ 50 nm as well as the absent binder NPCD has an improved wear behaviour and promises a more efficient machining of hard to cut materials.In order to be able to use this cutting material for specific machining of cemented carbide basic knowledge about the cutting behaviour of cemented carbide, the process behaviour of NPCD during the ultra-precision turning and ultra-precision milling process, as well as their interactions needs to be acquired. Therefore, profound knowledge about the wear mechanisms and process variables, such as the surface roughness values resulting from the process and the process forces Fpr, will be acquired. Furthermore, finite element simulations for description of the mechanical interactions between the tool and the workpiece will be developed. In a first funding period about 24 month the basic knowledge with the turning process and the process simulation will be achieved. In the second funding period, which is also calculated about 24 month, the knowledge is transferred on the milling process and at the end fundamental applications for the ultra-precision turning and ultra-precision milling process with NPCD will be defined.

• DFG Programme: Research Grants