This study was performed to manufacture a new desktop type 5-axis NC precision grinder for bioceramics artificial knee joint. A table-on-table type 5-axis grinder with three linear axes on the tool side and two axes on the workpiece side was designed and manufactured. Designing and manufacturing of the grinder based on finite element method analysis and theory of generating motion were carried out. The static compliance, straightness motion error, and the positioning accuracy of the prototype grinder were evaluated. Grinding experiments using carbon steel indicated machining errors < 5 μm. Grinding marks due to plastic deformation were found on the machined surface of zirconia. These results indicated that motion accuracy and grinding characteristics of the prototype desktop type 5-axis NC precision grinder were sufficient for machining of bioceramics artificial knee joints.

A means of hardening TiB₂ base films by controlling oxygen content was developed to improve cutting efficiency of tools against difficult-to-machine materials, such as Ti alloy. By increasing the B/Ti ratio in the films above 2, oxidation of Ti during the film formation process was suppressed and the hardness was increased. The greatest hardness of 35 GPa was obtained in the film with the lowest oxygen content of 3 at% in this study by producing a film with a base pressure of 4 ×10^-4 Pa. The frictional properties of the films were improved by adding C. The coated tools showed excellent cutting performance against Ti alloy. The chip formation process became smooth and the cutting force decreased by using the coated tools.

Powder jet deposition (PJD) is a coating technique that can form films under conditions of room temperature and atmospheric pressure. We have developed a dental treatment with this technique to form hydroxyapatite (HA) films on human teeth. However, the micron-order HA particles show a high degree of cohesiveness, which results in residual particles on the pipe transporting the particles from the particle tank to the handpiece. Therefore, we developed a dental PJD handpiece without a particle-transporting pipe, utilizing a particle feed mechanism of tablet cutting. The experimental results showed that the developed handpiece formed HA film without residual particles on the pipe.