Abstract:

：Applying the transverse ultrasonic vibration to the diamond wire-saw cutting hard-brittle materials processing, the normal cutting force applied to workpiece by diamond abrasive particle at different locations on wire-saw’s cross-section is analysed based on the principle of impulse. Applying indentation fracture mechanics theory, the propagating length and depth of median/lateral crack beneath the abrasive particle induced by normal and tangential load are analysed quantitatively. The shielding effect inhibiting median crack expansion and promoting lateral crack propagation preferentially as vibrating abrasive particle loading and unloading on workpiece surface intermittently is studied. The material removal model by abrasive on different locations of vibrating wire-saw cross-section is discussed, and the formula predicting wafer’s surface roughness is obtained. The comparative experiments of cutting SiC monocrystalline with conventional wire-saw and transverse ultrasonic vibration wire-saw are carried out respectively, in which the cutting force of wire-saw, surface roughness and surface morphology of wafer are measured and observed. The result indicates that the material removal mode of SiC cut by transverse ultrasonic vibration wire-saw is mixing mode which brittle fracturing mode is dominant while the plastic removal mode is minor, the wafer surface roughness decreasing by 25.7% under the same experimental conditions. The result of measuring surface roughness is more consistent with it in theoretical analysis prediction.

Key words: madian/radial cracks, SiC monocrystalline, surface roughness prediction, transverse ultrasound excitation, vibration cutting, diamond wire-saw