Abstract: Owing to the extremely high hardness and brittleness, the hard and brittle crystalline materials, such as SiC, Ge and Si, are very difficult to improve cutting efficiency and obtain better surface quality in conventional wiresaw cutting process.The transverse ultrasonic vibration was applied to the diamond wiresaw cutting single crystal SiC in this research.Based on analysing the characteristics of ultrasonic vibration cutting process, the necessary conditions for flexible vibrating wiresaw cutting SiC workpiece was studied and obtained.Furthermore, dynamic cutting process model for flexible diamond wiresaw excited by transverse ultrasonic cutting SiC workpiece was established, the influence of transverse vibrating wiresaw on intermittently cutting arc length and cutting speed was researched, and the mathematical expressions of increment of cutting speed in transverse vibrating wiresaw cutting process was derived.Based on the model of indentation cracking, the effect of conventional wiresaw cutting and ultrasonic vibrating wiresaw cutting on cutting speed, cutting force and surface roughness was analyzed.Comparative experiment of cutting SiC crystals by ultrasonic vibration wiresaw and by conventional wiresaw was conducted.The experimental result indicates that the surface roughness of wafers cut by transverse ultrasonic vibrating wiresaw is improved obviously, and the cutting speed in vibrating wiresaw cutting increases 45; than that in conventional wiresaw cutting, the cutting force reduces 28;-53; under the same machining conditions.Experimental result is more consistency with it in theoretical analysis.

Key words: Owing to the extremely high hardness and brittleness, the hard and brittle crystalline materials, such as SiC, Ge and Si, are very difficult to improve cutting efficiency and obtain better surface quality in conventional wiresaw cutting process.The transverse ultrasonic vibration was applied to the diamond wiresaw cutting single crystal SiC in this research.Based on analysing the characteristics of ultrasonic vibration cutting process, the necessary conditions for flexible vibrating wiresaw cutting SiC workpiece was studied and obtained.Furthermore, dynamic cutting process model for flexible diamond wiresaw excited by transverse ultrasonic cutting SiC workpiece was established, the influence of transverse vibrating wiresaw on intermittently cutting arc length and cutting speed was researched, and the mathematical expressions of increment of cutting speed in transverse vibrating wiresaw cutting process was derived.Based on the model of indentation cracking, the effect of conventional wiresaw cutting and ultrasonic vibrating wiresaw cutting on cutting speed, cutting force and surface roughness was analyzed.Comparative experiment of cutting SiC crystals by ultrasonic vibration wiresaw and by conventional wiresaw was conducted.The experimental result indicates that the surface roughness of wafers cut by transverse ultrasonic vibrating wiresaw is improved obviously, and the cutting speed in vibrating wiresaw cutting increases 45; than that in conventional wiresaw cutting, the cutting force reduces 28;-53; under the same machining conditions.Experimental result is more consistency with it in theoretical analysis.