Influence of Crystal Anisotropy on Ultra-precision Cutting of Single Crystal Copper (111) Surface

抄録

In ultra-precision cutting of polycrystalline material with single crystal diamond tool, grain boundary steps become obvious on the machined surface due to crystal anisotropy between adjacent grains. Therefore, to establish ultra-precision cutting technology, it is necessary to clarify the micro cutting mechanism of single-crystal material. In our past work, we have focused on elastic recovery of single crystal copper in micro groove cutting. However, affected layer were formed at the stage of planar cutting, which was a prior process of groove cutting. It was difficult to observe the influence of crystal anisotropy once the affected layer was formed. Thus, appropriate cutting conditions of prior process are necessary to minimize the affected layer. In this study, single crystal copper (111) plane, one of slip planes, was used as a cutting surface.We defined [112] direction as 0° and conducted prior cutting process at 13 directions ranging from -60° ([211]) to 60° ([121]). Cutting forces were measured and hardness of the finished surfaces were examined. Chips, tools and cutting surface were observed with an electron microscope. The Schmidt factor of each slip system was calculated from the measured three-component forces. Then, we investigated the influence of crystal orientation on cutting mechanism and machined surface in prior cutting. As a result, cutting parallel to [121] direction (60°) generated the best cutting surface. In contrast, cutting parallel to [112] direction (0°) generated the most defective cutting surface. In addition, the finished surface had periodicity of 120° with good surface and defective surface, respectively. Results suggest that the slip systems and its Schmidt factors may explain the periodicity.