Fabrication of wedge-shape tool via electrochemical micromachining with diamond-like carbon coating

A wedge-shaped micro cutting tool with an edge radius of 0.6 μm is fabricated from stainless steel using pulse electrochemical machining method (PECM). This tool is then coated with Ti-containing diamond-like hydrocarbon (Ti-DLC) to enhance its surface roughness and hardness. Surface roughness and edge sharpness of the ECMed tool face are shown to improve with decreasing pulse width of the ECM supply voltage. The Ti-DLC coatings on the electrochemical fabricated stainless steel tools have been synthesized by unbalanced magnetron sputtering process. The microstructures and mechanical properties of Ti-DLC coating are characterized by Raman spectroscopy and nano-indentation techniques. The results show that the sp2 bonding increases with decreasing Ti composition. Therefore, as Ti composition decreases, the hardness of Ti-DLC coatings increases. On the other hand, the elastic modulus of the coating is found to decrease with decreasing Ti composition. For improved wear resistance, the high ratio of hardness to elastic modulus is achieved at 7.2% of Ti composition. The fabricated tool is tested successfully in a scribing experiment and compared with a single crystal diamond cutter. Due to its higher surface roughness and the consequent higher rubbing resistance, the specific cutting energy of the fabricated tool is found to be greater than that of the single crystal diamond cutter.