Skilled workers carry out lathe work operations quickly and smoothly. However, the stopping of tool feed during mode change is often observed in the case of beginners, and sparks are usually generated on the cutting edge when the automatic feed is stopped. In addition, the characteristics of surfaces finished by beginners is influenced greatly by the feeding mode. In this study, we investigated the relationship between the worker's skill and movement of his eyes and hands when the tool feeding mode is changed from automatic to manual operation in lathe work, based on analysis of gaze-point movement and observation with a video camera. The results showed that the stop time of the tool feed for skilled workers was markedly shorter and the operation was smoother than for beginners. Especially, the experimental results showed that there is a remarkable temperature rise on the tool tip, which is considered the main reason for intensive tool wear.

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In turning operation, the thrust force, which is one of the cutting forces, influences the shaft dimension and form accuracy. Adjusting conditions, such as nose radius, approach angle, and depth of cut, can be used to set the thrust force to 0 N. A microshaft with a diameter of 50μm and a length of 1 mm was developed using a precision lathe with conditions obtained experimentally and expected to set the thrust force of 0 N. In addition, theoretical values of thrust forces were calculated with Nakayama's equations. The theoretical and experimental forces were compared and the reasons for the differences were discussed.

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Ultra-precision polishing combined with UV irradiation was applied to the truing of a diamond grit-arranged block to develop a new diamond wheel truing method (UV-truing). By UV-truing experiments, the variation in the top position of diamond abrasive grains could be minimized within 10μm. The formation of a sharpened edge around an abrasive flat area and well-polished abrasive flat areas with 6.8 nmRa were simultaneously achieved. These diamond grit-arranged blocks were applied as a new type of milling tool. The milling of aluminum alloy A5052 indicated an excellent cutting surface with 15 nmRa (estimated by Zygo).

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Hand tools for cutting polyvinyl chloride pipe are very useful. However, these tools require the user to exert enormous amounts of power. To improve the cutting performance of hand tools, we manufactured a special device for measuring the force required for cutting. The relationships between the geometry of the cutting tool and the cutting force were investigated. The cutting force was found not to remain constant and to exhibit large peaks at the initial and final stages of cutting. The cutting force increased with increasing angle of the tool edge or with increasing radius of the tool tip. In addition, the friction force was a major component of the cutting force during the entire cutting process, and the frictional coefficient was markedly affected by the grinding direction of the tool.

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