In the industrial use of stereolithography, precision is always a problem. The basic phenomenon of solidification shrinkage has not been sufficiently investigated. This study aims at clarifying the initial linear shrinkage of cured resin in a minute volume. Experimental equipment has been developed which measures the time history of the single strand in situ in a stereolithography machine. An analysis model of the time history of a minute volume linear shrinkage was shown using the measured shrinkage of a cured line segment. The relation between the time history of the linear shrinkage and temperature was measured and the shrinkage in the minute volume after irradiation was found to result due to temperature variation. Deformation and linear shrinkage were measured with two scanning orders to control the thermal distribution in layer forming. The effects of thermal distribution were also observed in one layer forming.

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The characteristics of the cutting phenomena in linear high polymers, such as polytetrafluoroethylene, polystyrene, and poly(methyl methacrylate) are described in order to make clear the cutting mechanism which is available to produce high quality and accurate parts. Thus, the types of chips, the deformation of the work material, and the critical rake angle defined by the authors are described. Several discussions on the thermal, the time (or cutting speed), and the frictional dependencies are also described. The chips are divided into two main categories the continuous (curl, flow, and shear type) and discontinuous (crack and tear type). These are influenced by the kinds and temperature of the work materials, the rake angle of a tool, and the depth of the cut and cutting speed. It was clarified by the discussions that the viscoelastic behavior of the work material was important during cutting of high polymers. Therefore, the Voight and Maxwell Model were introduced to explain the time dependencies. We could say that the types of cutting mechanism of high polymers are classified as, slip on the shear plane, crack at the tip of a tool, tear at the cutting edge accompanied by heavy strain, and some combinations of these. Cutting with the critical rake angle (that is a rake angle which makes the thrust force during cutting equal to zero), the work material was neither deformed upwards nor downwards, thus the highest accuracy was obtained. Furthermore, the work material must be equal to the frictional angle of the rake surface of the tool, and was decided upon by the frictional behavior of the chip on the rake surface.

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