Excessive tool wear and moisture content in ceramic plaster machining

In the ceramics industry the creation of moulds for new product design, through the use of rapid machining has become an alternative to traditional techniques. During an investigation into the potential of mould creation through this technique it was noted that the rate of tool wear while machining the plaster material was greater when a ceramic plaster, Molda 3, was completely dry, than when moisture was present. The present paper reports on the causes of excessive tool wear which occurs in the machining of plaster and how the moisture content of the plaster can have a considerable effect on the rate of wear. A series of experiments has been conducted to determine the optimum level of moisture retained in the plaster to achieve the best machining results. In addition, the method of machining was also investigated, to determine if this had any relationship with tool wear. BCT/303