From the viewpoints of reduction of tooling cost and saving resources, the demand for re-sharpening of ball end mills in manufacturing floors is high. In this study, the practical feasibility of re-sharpened ball end mills was examined. First, an inexpensive re-sharpening machine driven by stepping motors was developed and the re-sharpening of the secondary flank of ball end mills was carried out with data generated using a CAD/CAM system. The cost effectiveness of tool re-sharpening is discussed. Second, cutting test of inclined workpiece surfaces of die steel was compared between new and re-sharpened tools. Then, the cutting properties of both tools were examined by comparing tool life, cutting force, and surface roughness. The results confirmed that the differences in cutting performance between re-sharpened and new tools are small. Especially, the cutting performance was equivalent up to 100 μm flank wear. These observations indicated that it is both practical and cost-efficient to re-sharpen ball end mills using the prototype machine developed here.

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Rapid Rotation Mirror-like surface Grinding (RRMG), which combines Rapid Rotation Grinding (RRG) and Truncate Truing with Micro Dressing (TTMD), has the potential to achieve highly efficient mirror-like surface grinding and to obtain high-quality surfaces, such as a very small heat-affected layer, because the contact time between each abrasive grain and the workpiece can be reduced. In this study, RRMG of induction-hardened steel was conducted under conditions in which the peripheral speed of the grinding wheel and workpiece were 200 m/s and ten times as fast as the conventional workpiece speed, respectively. The results indicated that surface roughness was less than 0.1 μm (Ra) and the surface quality could be improved under RRMG conditions.

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We proposed a new grinding processing method with a dual-axis-driven grinding wheel. In this method, although many types of grindstone could be used, we used the SiC-grinding wheel, which is both inexpensive and generally available, and we examined the durability of SiC-grinding stone wheels. The results indicated that the durability of SiC-grinding stone wheels improves with large grindstone particle size and high peripheral wheel speed.

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Electrolytic in-process dressing (ELID) grinding technology is a processing technology that provides high-quality industrial products with low production costs. However, along with machining performance, environmentally friendly machining is also required. To meet such social demands, basic experiment applying electrolyzed reduced water during ELID grinding using a cast iron-bonded grinding wheel has been carried out. We found that there is a passive film formation region on the cast iron-bonded grinding wheel due to the pH of the electrolyzed reduced water and the ELID current density. In addition, the results of processing experiments confirmed that a stable machining process similar to standard ELID grinding can be achieved.

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