Recently, CAI (Computer Aided Instruction) which is a method of education using computer is drawing interest in the fields of business and education. Systems for individual learning are very effective for improving time efficiency and establishing given knowledge. It is therefore expected to become more important in future education. At the Oita National College of Technology, time effective courses are strongly required for reducing the total course hours. This paper discusses the CAI system focused on foundry engineering and the resultant course evaluation. The CAI system composed of foundry engineering including practical training, design engineering and fundamental mechanical engineering, was originally established a few years ago. Since then, it has been applied to the engineering materials course of the college. Two course evaluations performed show that the CAI system plays an important role in establishing the concerned knowledge and arouses students' interests in subjects.

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  Friction welding of spheroidal graphite cast iron (FCD) to mild steel (S20C) were carried out under various bevel angles. The friction surfaces of FCD and S20C were bevel processed with a lathe before friction welding, and the friction welding condition were constant. The friction welding process by the bevel process was examined under various friction times. The dimensions of the test pieces were 15mm in diameter and 70mm in length respectively. Micro and macroscopic observations were employed in order to clarify characteristics at the welding interface.
  The structure of friction welding interface was mainly influenced by the bevel angle. The deformation layer of spheroidal graphite (DLSG) was observed when the bevel angle was small, but not when large. When the bevel angle was small, the DLSG formed at the initial stage of friction welding concentrated at the center of the specimen during friction welding, and remained at the joining interface after friction welding. When the bevel angle was large, the DLSG was discharged out of the specimen during friction welding, and did not remain in the joining interface after friction welding.

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  By varying gate thickness and plunger speed during die casting, multi-cavity metallic mold filling flow was observed and transferred pressure measured to establish their relationship with casting defects.
  Inside the metallic mold, mold filling flow depends on injection speed and pressure. At slow injection speeds, melt injected into the cavity does not rise to the top at first but rather spreads horizontally near the cavity opening (bottom of cavity). Filling therefore starts at the bottom of the cavity and proceeds upwards. In the case of slow injection speed, melt coming into contact with sleeve wall tends to solidify, reducing fluidity and causing the filling ability to deteriorate. During pressurizing after melt fills the cavity, there is a fast increase in melt pressure, decreasing with increasing distance from the pressure source, while transferred pressure time also reduces with increasing distance. Transferred pressure at each location decreases in the case of thin gate. This is due to melt temperature decrease, causing increase in the flow resistance during filling flow. As a result, melt supply to compensate for solidification shrinkage decreases. Simulation carried out for each part shows that; with increasing distance from the pressure source, the solid fraction increases faster in a short time. In the case of ADC 12, the flow limiting solid fraction is calculated to be 0.65 at the position near cavity inlet. Density decreases and casting defects are likely to occur in the case of thin gate. A decrease in melt pressure transfer time causes early solidification near the gate, gradually blocking the supply of melt, hence reducing the density of cast parts.

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  Fracture process of ferritic spheroidal graphite cast iron in Charpy impact test was investigated by means of low energy blow on the specimen followed by fracturing it at 77 K and measuring the crack length propagated by the blow. Bending load-time curves obtained by an instrumented testing machine were converted to load-deflection curves by law of conservation of energy. Crack initiation energy, the energy absorbed up to the maximum bending load, is supposed to be the energy required for the notch root to attain both the fracture strength and fracture strain, but the estimated energy is fairly lower than the experimentally obtained. During crack propagation, the stress intensity factor remained almost unchanged, and the crack extension energy is proportional to the width of the ligament. The observed compliances of spring back after crack propagation are bigger than those expected from the crack opening displacement, a reason of which may be lowered Young’s modulus in distorted ligament section.

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  This work was performed to clarify the sources of phosphorus and its effect on shrinkage characteristics of Al-Si alloy. The results are as follows. 1) The phosphorus content of painted and inked aluminium scrap is 3-8 ppm. 2) The phosphorus content of metallic silicon is 15-95 ppm. 3) The source of phosphorus in Al-Si alloy is its raw material. 4) When phosphorus content increases from 7 ppm to 12 ppm, the exterior shrinkage ratio decreases and interior shrinkage ratio increases.

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  For the purpose of developing oil-impregnated sintered bearing, sintered materials were prepared using cutting powders of growth-treated gray cast iron without crushing them. The offects of particle size distributions and combinations of cutting powders on the sliding properties of sintered materials were investigated. Furthermore, practical use as the oil-impregnated sintered bearing was also investigated.
  It was found that the sintered materials with cutting powders under 420μm in particle size show lower sintered density and hardness. On the other hand, sintered materials with 60 mass% cutting powders of 840μm to 420μm in particle size show lower coefficient of friction and high load carrying capacity as oil-impregnated sintered bearings by the radial thrust rubbing test and radial journal bearing test.

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  Welding of spheroidal graphite cast iron (FCD material) is assumed to be difficult because of its high carbon content. The authors developed a spheroidal graphite cast iron with decarburized layer on the surface (FCD-D material). The spring sheet was inrestigated as a means of putting the FCD-D material developed to practical use. The depth of the decarburized layer obtained by decarburizing treatment in mass production was confirmed and the subsequent processing was examined. Moreover, the depth of the decarburized layer matched the penetration depth, throat, and leg length in each welding condition.

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