Surface flatness and roughness of diamond wire electrical discharge sawing mono-crystalline silicon with improved bath cooling

The cooling method of silicon material sawing in solar energy industry is jet cooling and flood cooling. In this paper, a machining method of diamond wire electrical discharge sawing (DWEDS) under environmentally improved bath cooling was proposed. Its advantages were compared to jet cooling by carrying a series of sawing tests. It was found that DWEDS under bath cooling obtained better machining accuracy and better surface quality than that under jet cooling. Also, the machining accuracy and cutting efficiency in DWEDS were better than those in diamond wire sawing (DWS). The same conclusions were proved by scanning electron microscope observation of the wafer surface. In addition, the wire tension in DWEDS sawing was found more stable than that in DWS. Finally, the wire wear was as another indicator to evaluate the cooling effect. No significant difference in wire wear between bath cooling and jet cooling was found. However, the wire wear of DWEDS under the same cooling method is higher than that of DWS, which means the discharge effect is helpful to the wire self-sharpening from another point of view.