Ultra-precision machining with polycrystalline binderless-cBN

• Applicant: Professor Dr.-Ing. Eckart Uhlmann
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering
• Term: from 2012 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 222309489

Optical surface quality can be achieved by ultra-precision turning with diamond tools. Ultra precision machining requires cutting edge radii of fewer than rB = 50 nm which can be realized with diamond as cutting material. Mold and die makers prefer steel materials because of their high resistance to wear in replication compared to non-ferrous metals. Machining steel with diamond tools is mostly inefficient due to intensive wear. Cubic boron nitride with binder phase is widely used for cutting operations and is after diamond the second hardest cutting material. Due to a weak binder phase which causes outbreaks, cubic boron nitride with binder phase cannot be used for high precision surfaces. But polycrystalline cubic boron nitride without binder phase has the potential to be used in ultra-precision machining. Goal of the project is to have fundamental knowledge about the application of tools made of polycrystalline cubic boron nitride without binder phase for the ultra-precision machining of steel materials. Optical surface qualities with roughness values below Ra = 10 nm shall be obtained. For this, research regarding the cutting process, tools and tool preparation is necessary. Three cutting edge preparation technologies will be examined in respect to the effects on the obtainable surface quality. Tool geometry and cutting technology will be investigated, optimized and verified by means of cutting trails, modeling, and simulation.

• DFG Programme: Research Grants