To protect machine tool operators and/or instruments from abrasive fragments generated by grinding wheel distraction, a safe wheel cover design is required. The authors designed and assembled a collision experimental apparatus, which used an abrasive product for fragment and cold steel plate used as the target. The fracture mechanism of the abrasive product and cold steel plate were investigated experimentally. The damage could be classified in three patterns: "plastic defamation," "crack generation," and "penetration." Crack generation was defined as the border between safe and unsafe regions of the guard. The results indicated that the safe thickness of the wheel guard is proportional to the square of fragment speed. Furthermore, the fine element method was used to simulate a wide range of collision conditions.

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Carbon fiber-reinforced plastic (CFRP) is widely used in the aircraft and automotive industries because of its high strength and low weight. Conventionally, milling has been used to produce grooves in CFRP. However, problems such as delamination, burr formation, and severe tool wear arise during the milling process. In this study, ultrasonic vibration-assisted grinding was employed to machine CFRP, and the results were compared with those of conventional grinding. By applying ultrasonic vibration to the grinding tool, removability of debris was improved and tool clogging was suppressed, as confirmed by scanning electron microscopy. Furthermore, ultrasonic vibration resulted in decreases in both grinding force and grinding temperature. As a result of these improvements, delamination at groove edges was greatly reduced compared to conventional grinding.

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