Prediction of critical undeformed chip thickness for ductile mode to brittle transition in the cutting of single-crystal silicon

Abstract

In order to achieve the ductile mode cutting of silicon and avoid the generation of subsurface crack damage, the undeformed chip thickness in the diamond cutting process must be controlled below the critical value. Therefore, the critical undeformed chip thickness (CUCT) for the ductile mode cutting of silicon is studied in this paper for guiding the selection of cutting parameters in the diamond cutting of silicon. Considering the anisotropy of single-crystal silicon, the prediction method of the CUCT in the ductile cutting of silicon is proposed on the basis of calculating the anisotropic fracture strength of silicon and subsurface stress distribution induced by the cutting force. Moreover, the influence of the anisotropy of single-crystal silicon, cutting tool parameters and friction coefficient in the cutting process on the CUCT are discussed, respectively. The results show that the anisotropic CUCT depends on the cutting surfaces and cutting directions. In addition, the diamond cutting tool with a negative rake angle of −40° is generally suitable for ductile cutting on the silicon (001), (110) and (111) surface when the friction coefficient in the cutting process is in the range of 0.05–0.30. Under this cutting condition, the minimum CUCT on the silicon (001), (110) and (111) surface is in the range of 150 ∼ 250 nm, 160 ∼ 290 nm and 150 ∼ 250 nm, respectively. The lower limit of the minimum CUCT on the three surfaces corresponds to the friction coefficient of 0.30 in the cutting process, and the upper limit corresponds to the friction coefficient of 0.05. Furthermore, a sharp-nosed cutting tool is also beneficial to improve the CUCT in the cutting process.