Micromachining selected metals using diamond coated cutting tools

Abstract

Micro and nanotechnology is becoming increasingly important to the needs of society. Therefore, the need to create devices from selected metals becomes more apparent. High-speed milling has been shown to provide a great deal of promise in creating microstructures and in nanotexturing surfaces in engineering materials. Cutting tool rotation is expected to reach 1,000,000 rpm (revolutions per minute) compared with conventional cutting speeds of around 30,000 rpm. Rotating the tool this quickly reduces cutting forces, which produce a high quality of cut so that post-processing is not required. Clearly, strain rates imparted to the workpiece at these speeds are very high and this influences initial chip formation and chip removal mechanisms. High strain rates imparted cause distinct chip formations in certain metals to occur which are similarly observed in other materials. Certain soft metals such as aluminium do not machine very well because the material adheres to the cutting tool. However, high strain rates tend to overcome these limitations. This paper examines high strain rate initial chip formation in metals, compares these results to other materials and shows that an initial chip curl model can be applied to describe high strain rate machining phenomena at the microscale.