Electrical discharge slicing of single crystal SiC by utilizing ultra-thin foil tool electrode

用厚度为0.03 mm的薄箔工具电极(铜或黄铜)成功地对碳化硅钢锭进行了电火花切割。在箔片EDS加工方法中，当箔片走刀速度足够高时，箔片刀具的磨损很小，可以忽略不计，切割过程类似于普通的电火花线切割加工。另一方面，在较低的箔片运行速度下，由于停留时间较长，箔片刀具磨损严重。稳态时，箔片刀具在工作区的磨损形态为一条斜直线。刀具磨损长度与刀具面积磨损率、被加工件厚度成正比，与箔片运行速度成反比，刀具电极的负极性和较短的脉冲宽度更适合于箔片电火花切割碳化硅，从而获得较高的加工速度和较低的刀具磨损率。箔电极越薄，切割速度越快，但刀具磨损率也越大。当钢锭工件相对于工具电极向上固定并向下进给工具时，可以获得更高的加工速度。此外，实验还证实，通过改善放电间隙条件，增强清洗效果和提高加工速度都能提高加工效率。与电火花加工相比，碳化硅在去离子水中的电火花加工具有更高的切割速度、更高的刀具磨损率和更大的切缝宽度。另一方面，电火花加工油的表面完整性更好。

Electrical discharge slicing (EDS) of SiC ingot using thin foil tool electrodes (copper or brass) with thickness of 0.03mm was conducted successfully. Kerf width less than 0.1mm was achieved.In foil EDS method, when the foil running speed is sufficiently high, the foil tool wear is little and can be neglected and the slicing process is similar to common wire electrical discharge machining (EDM). On the other hand, at a low foil running speed, the foil tool wear is significant owing to a long dwelling time. At steady state, the foil tool wear shape is an inclined straight line at the working area. The tool wear length is proportional to the tool area wear ratio, workpiece thickness and inversely proportional to the foil running speed.Negative polarity of tool electrode and short pulse duration are confirmed more suitable for foil EDM slicing of SiC which can result in a higher machining speed and a lower tool wear ratio. Thinner foil electrode can result in a higher area cutting speed, however the tool wear ratio also increases. When the ingot workpiece is fixed upside relative to the tool electrode and fed downwards to the tool, higher machining rate can be obtained. In addition, it was confirmed that both enchantment of flushing and higher foil running speed can improve the machining rate by improving the discharge gap conditions.Foil EDM of SiC in deionized water featured higher cutting speed, higher tool wear ratio and larger kerf width compared to those in EDM oil. On the other hand, the surface integrity is better by EDM oil.