There are several problems associated with the milling process using end mills with an ultra-small diameter, such as low cutting accuracy, short tool life, and tool breakage. In this study, the relationships between these problems and imbalance of the machine tool main spindle were investigated. The results of this study indicated that machine tool main spindle imbalance caused expansion of the width of the cut groove and increased burr formation. In conclusion, it was suggested that a precision groove corresponding to the diameter of the end mill could be obtained by reducing the rotational imbalance to less than 2 nm.

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The fundamental friction properties between monocrystalline diamond and tungsten carbide were investigated experimentally. Friction experiments regarding two types of tungsten carbide were performed in atmospheres of air, dry air, argon and nitrogen. Cobalt-free tungsten carbide and 7% cobalt tungsten carbide were used, and the following conclusions are reached. 1) Physical abrasive wear was predominant in these experiments, as the temperature of the friction point was less than 130°C. 2) The presence of oxygen in air atmospheres reduced friction between diamond and tungsten carbide. 3) As cobalt behaves as a solid film lubricant, the friction coefficient was smaller and diamond wear was reduced using 7% cobalt tungsten carbide. 4) In nitrogen atmospheres, wear of 7% cobalt tungsten carbide was limited, but wear of diamond was pronounced.

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In this study, an approach using feed rate control was applied for improvement of form accuracy in the micro-end milling process. In this approach, called adaptive control constraint, the feed rate is controlled such that the cutting load is kept constant and deflection of the tool does not occur. However, this method is not always effective in the micro-cutting process, and the influence of the size effect cannot be ignored. Therefore, the relationships between cutting conditions and form error in micro-end milling were experimentally investigated. The experiments on the machining of metal mold steel with the micro-end mill were carried out and the formulation as a function of the cutting conditions and the form error was identified by regression analysis. The performance of the feed rate control was validated based on experimental results. The results confirmed improvement of the form accuracy.

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Our goal is to develop a design system for mechanochemical superabrasive stone containing both cBN and CeO₂ abrasives. As the first step of development, this paper describes the morphological structure model for the stone using fractal-modeling techniques. We have proposed two models to represent the conventional stone structure: the "agglomerate model of a plastic mixture" on the basis of the diffusion-limited aggregation algorithm and the "morphological model of a burnt stone" on the basis of the sandpile algorithm. In consideration of the characteristics of the mechanochemical stone, we have improved these models by adding the following procedures: the "cluster formation" algorithm and the "judgment of a bonded grain" algorithm. Both models bear resemblance to real wheels in the spatial distributions of both grains and the fractal dimensions in each grain of the real stone are approximately equivalent to those of the models.

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Three-dimensional micro hemispheres with two different curvature radiuses along two orthogonal directions are realized at optical fiber ends by utilizing the precision bending of the optical fiber. In the machining process we developed, an optical fiber held perpendicularly to the machining plane at the middle part of fiber is bent as it approaches the machining plane and revolves in a planetary manner over the machining plane. In this process, a two-curvature-radius micro hemispherical fiber end can be obtained by anisotropic machining, which is achieved by adopting aan oval trajectory for planetary revolution, and by changing the contact point and contact angle by raising the holding point little-by-little. This machining is achieved using the high precision shape and the high uniformity material of the optical fiber. This process is also suitable for mass-production because it can simultaneously machine many-fibers.

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