Suguru Motonishi

Study on Machining of Titanium Alloys

Summary In this study, an experimental investigation to improve the machining efficiency of titanium alloys has been conducted. In machining titanium alloys, generally, the cutting tools wear off very rapidly because of the high cutting temperature resulted from the low thermal conductivity and density of the work material. In order to increase the tool life, it is necessary to suppress the cutting heat as much as possible. In this experiment, a natural diamond tool characterized by the highest thermal conductivity of all the tool materials available was utilized by applying abundant water-soluble coolant. It was found that the natural diamond tool exhibits an excellent cutting performance in machining titanium alloys, and the cutting speed could be increased up to 3.33 m/s when applying abundant coolant. In addition, the quality of surface machined with the natural diamond tool was found to be better than those with the other tools.

A New Micro-Cutting Device with High Stiffness and Resolution

Abstract A micro cutting device consisting of a pair of parallel springs and a piezo electric actuator has been developed. With the aid of the finite element method, the device was designed to have a good dynamic response up to 2 kHz with a stiffness of 80 N/μm and an infeed resolution of 5 nm. Submicrometer diamond cutting, controlled by a personal computer, was accomplished by means of the piezo electric element capable of detecting the initial contact between the tool and the cutting surface with an accuracy of ± 0.1 μm.

Damage processes and substrate surface design for CVD diamond films

Abstract Experimental results on the development of damage processes for CVD diamond (hereafter referred to as CVDD) films and substrate surface design are presented with the purpose of application to cutting tools. The initial stage of damage was investigated with a mechanically scanned acoustic microscope. It is shown that the damage is formed by development of cracks, which extends to the top surface. Delaminations around the cracks finally result in peeling off from the substrate. These facts suggest that interface structures inhibiting the extension of cracks and delamination around the cracks are advantageous for adhesion enhancement of CVDD films. Accordingly, the phase transformation of cemented carbide was investigated. As a result, it is demonstrated that by a specific surface treatment under H2 plasma atmosphere, a surface structure, which is best suitable for the synthesis of CVDD films, can be obtained.