In the finishing method using lapping tape, new tape is continuously supplied to the processing area and rubbed by a pressure roller. In recent years, relatively expensive lapping tapes are used for working of high-hardened materials, in which super-abrasive grains are formed into a texture structure by a binder. Used tapes have been discarded, increasing the processing costs. Here, we propose a method to remove clogging on lapping tape after processing by ultrasonic cavitation, and reproduce processing ability. First, it was confirmed that clogging could be eliminated by cavitation using an ultrasonic cleaning machine. Next, the tape was passed through the slit of the ultrasonic vibrating horn at the same feed rate as the polishing process to eliminate clogging. The vibrating horn is so small that it can be installed in the tape polishing machine. The clog removal ability was evaluated by examining the clog area and the polishing characteristics were evaluated from the surface roughness and load curve of polished workpieces. The results confirmed that this method can regenerate the polishing ability of the used tape during the polishing process. By reducing the tape feed speed or repeating the removal process, the clogging area decreased and the clogging area could be reduced by half in two removal steps.

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The application of sapphire wafers has been expanding for LED boards and/or power devices. Due to the excellent mechanical properties, sapphire wafer is difficult to grind. On the other hand, ultrasonic-assisted grinding can be applied to machining of difficult-to-grind materials, and shows high-efficiency machining. However, as the cup grinding wheel is heavy, it cannot be applied to ultrasonic grinding. We have developed a grinding wheel vibration system, which was applied to infeed surface grinding of sapphire and silicon wafers. Although, high-efficiency grinding could be achieved for sapphire wafer, it could not be realized for silicon wafer.

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