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In a parts recycling system, reusable parts in the collected waste products are employed to produce new products with new parts. Two assembly methods are considered in the parts recycling system. The primary method is random assembly, in which new parts are selected randomly from the entire population and assembled. The remaining method is selective assembly based on the combinatorial optimization method, in which a combination of reusable parts and new parts is optimized so that high quality assembled units are obtained in a lot unit at the maximum assembly rate while dimensions of each part are referred to appropriately. The assembly methods are applied to the parts recycling system where hole parts are combined with shaft parts. In this paper the effectiveness of parts mix, reusable parts and new parts, is clarified in various situations.

In the previous report, a new material called three-dimensional and functionally gradient material was developed for a precision machine tool. Thermal behaviour and dynamic properties of the material have been experimentally investigated. In this report, a new manufacturing method for making this material quickly has been successfully established. Then, a lathe with a new tool post using this material was made. Evaluation of the composite structure lathe has been investigated by a few cutting tests. It is concluded from the results that: (1) A new method was very easy, low cost and short time. (2) This lathe had high static stiffness, low compliance and chattering less at the same time. (3) The surface roughness of the wrokpiece machined with this composite structure lathe was improved.

In the 1st report, a new material called ceramic resin concrete was developed for precision machine tool structures. In the 2nd report, the thermal and mechanical properties of the material were demonstrated with an eye to designing a machine tool. Then, in the 3rd report, the Young's modulus of the material was improved to be the same as that of cast iron by the prestress method. In this study, a three-dimensional and functionally gradient material has been developed, and bending strength of the boundary area between the materials with two different strengths has been investigated. In addition, thermal behaviour and dynamic properties of the material have been experimentally investigated. It is concluded that: (1) An new manufacturing method for this material has been successfully established. (2) Bending strength of the boundary area is an intermediate value between the two different materials. (3) One structure with some attractive thermal and dynamic properties was found.

In this study, manufacturing of a large-sized structure using the ceramic resin concrete has been attempted. It is a surface plate of 700 mm length, 700 mm width and 450 mm height, which is composed of 94 vol. % of alumina ceramics and 6 vol. % of epoxy resin. Then thermal behaviour of the surface plate was investigated. It was concluded that a large-sized structure can be manufactured with simple method, simple equipment, short working time and low cost. In addition, it was verified that the surface plate has a great advantage from the viewpoint of thermal deformation.

As higher precision machining is required, reducing the themal deformation of a machine tool becomes more important. A few reports have pointed out that heat transfer and thermal radiation are important factors in the thermal deformation of a machine tool. Therefore, more exact information about heat transfer and themal radiation is needed to decrease themal deformation. In this report, the relationship between thermal radiation and surface color has been experimentally investigated using test pieces and a bench lathe model. It is concluded from the results that surface temperatures on the test pieces are influenced considerably by themal radiation dependent on the surface color, and is less influenced by the color and shape of the room in which the experiment is conducted. In addition, the accuracy of the bench lathe model is also affected significantly by its surface color.