Study on Electric Discharge Machining of Ceramics

本课题包括三项研究，旨在建立一种高精度、高强度的全陶瓷假体矫形器的电火花加工技术。首先研制了齿科用小型电火花加工机床，通过对加工速度、电极损耗、粗糙度和精度的测量，研究了电火花陶瓷的最佳加工条件。其次，研究了两种快速生产电火花加工电极的方法。其中一种是基于铜电铸的方法。研究了铜电铸用银镜溶液和镀液的组成，以获得厚而均匀的铜电铸膜。另一种方法是利用含铜粉的牙石模型进行导电，并镀上铜。由于将其应用于电火花加工，因此可以用作电火花加工的电极。第三，尝试了电火花加工用白色或齿色导电陶瓷的研制。通过这些研究，至少在技术上完成了用电火花加工生产全陶瓷冠。程序如下：首先，将TiBZ-TiC陶瓷块通过电火花加工制成芯，然后将牙瓷熔化到陶瓷芯中。但在加工过程中，存在加工时间和可加工陶瓷的美观性等问题。他们是未来研究的主题。

This project was consisted of three studies for establishment of technique to make a all ceramic prosthetic appliance with high accuracy and strength by electric discharge machining (EDM).In the first study, the compact EDM machine for dental use was produced, and the optimum machining conditions for the ceramics with electric conductivity were researched through the measurement of machining speed, electrode loss, roughness and accuracy.In the second, two methods of rapid production of the electrode for EDM were investigated. One of them was the method on basis of copper electroforming. Silver mirror solution and the composition of the bath for copper electroforming were studied to get a thick and uniform film. And the other was the new and simple method to use the dental stone model containing the copper powder for electric conductivity, and plated with copper. As this was applied to EDM, it is appeared to be able to use for electrode of EDM.In the third, the development of white or tooth color ceramics with electric conductivity for EDM was tried.Through these studies, it was completed at least technically to produce the all ceramic crown by applying the EDM. The procedure are as follows; in first, a core is made by EDM from the TiBZ-TiC ceramic block, and then dental porcelain is fused to the ceramic core.In this procedure, however, there are some problems in regard to machining time and to aesthetic in color of machinable ceramic by EDM. They are the subjects for future studies.