The effect of grits interference on materials removal mechanism during scratching process of silicon carbide

Silicon carbide (SiC) as a difficult-to-process material is hard to achieve ductile grinding completely, and is likely to occur brittle breakage with low processing efficiency, leading to its low performance, therefore, it is necessary to study its removal mechanism to improve the processing quality. The removal mechanism of single grit cutting is well understood. In the real processing of SiC, there are multiple grits at different positions to remove the materials simultaneously, but the phenomenon of materials removal by multiple grits cannot be observed separately. In order to clarify the interference behavior of neighbored grits, current study conducted a neighbored scratch experiment under varied force in sequence. The experiment evidently revealed the deformation, pits, fracture morphology and removal modes under different interference conditions. Since in-situ monitor of materials removal is unable to be realized, a numerical model with different scratch intervals by coupling the smoothed particle hydrodynamics (SPH) and finite element method (FEM) was used to understand the material damage and stress distribution. Based on the observation from experimental and SPH-FEM results, a theoretical model of neighbored scratch stress field is established to explain the mechanism from plastic and fracture mechanics. From the model, the size of the plastic zone and the interval between the neighbored plastic zone are critical to control the interference mode. The interference mode affects the distribution of stress field and realizes the enhancement effect of material removal. Therefore, the materials removal model could be adopted to control the grinding efficiency and quality in industry.