Fabricating micro-structured surface by using single-crystalline diamond endmill

A ball endmill made of single-crystalline diamond was used for cutting micro-structures on two kinds of mold materials, oxygen-free copper, and reaction-bonded silicon carbide (RB-SiC). The cutting performance of the ball endmill was investigated by examining surface roughness and form accuracy of the machined workpiece as well as tool wear characteristics. Micro-dimple arrays, micro-grooves, and micro-pyramid arrays with extremely smooth surface and high-accuracy profile could be obtained on oxygen-free copper without remarkable tool wear. When machining RB-SiC, however, tool flank wear takes place, leading to a rough surface finish. After the tool has worn off, the cutting performance of the endmill significantly depended on the tool feed direction. The optimum tool feed direction for micro-grooving was experimentally investigated.