This study was performed to estimate the fracture rotation speeds of grinding wheels by applying a mathematical model. As the fracture of grinding wheels initially occurs in the internal area of the wheels, comparing the stresses due to the centrifugal force in this area to fracture stresses allows estimation of fracture rotation speed of the wheels. The estimated results of fracture speeds coincided with those observed on fracture tests. The results of this study indicated that fracture rotation speed can be estimated quantitatively using the proposed mathematical model.

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An electromagnetic barrel finishing machine carries out finishing by collision of the workpiece with a magnetic medium, which moves due to the electromagnetic force of the rotating magnetic field. Although this machine is currently used in practical applications, the motion of the medium in the container has not been clarified. Here, the motion of the medium in the magnetic field was investigated to improve the finishing characteristics and to develop new types of magnetic barrel finishing. When the weight of the medium is small, it rotates only around its own axis at the source frequency. When its weight exceeds 10 g, the medium revolves along the circumferential direction of the container in addition to rotating around its own axis. Increasing the current and weight of the medium causes it to revolve at a higher speed. The rotation and revolution of the medium were clarified after examining the experimental results.

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Diamond pellets (DP) are expected to be effective tools for use in fixed abrasive lapping methods. However, there have been few previous reports of use of DP at low lapping speeds, e.g., in 4-way fixed abrasive lapping systems. Therefore, this study was performed to investigate the single DP lapping characteristics at low lapping speed. This paper discusses the correlations of amount of lapping and DP lapping distance with the following parameters: DP diameter, DP wear characteristics, lapping speed, lapping efficiency, and lapping time. The results indicated that there are no strongly correlations between the DP lapping distance and efficiency. However, a weak correlation was observed between DP wear and efficiency.

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