A study on the laser-assisted cutting of single crystal Si for optimal machining

Single crystal silicon (sc-Si) is a typical infrared optical material with good heat resistance and high infrared transmittance which is widely used in infrared optical systems , aerospace and other fields. However, due to the higher hardness and lower fracture toughness of this material, brittle fracture is very prone to occur during single-point diamond machining, resulting in poor surface finish and roughness. Hence, like ceramics, and composites, the machining of this alloy is considered as difficult-to-machining materials. Micro-laser-assisted machining (mu-LAM) method has become a promising solution in recent years to lessen cutting stress when materials that are considered difficult-to-machining, such as sc-Si and ZnSe are employed. This paper investigated the influence of input variables of mu-LAM on the machinability aspect of the sc-Si. The influence of cutting parameters on surface roughness in LAM is studied by orthogonal experiment, and optimal processing conditions are obtained. The second-order regression model of process parameters and surface roughness was established by response surface method. The results show that the change of cutting depth had little effect on surface roughness, the spindle speed and feed speed were main factors affecting the surface roughness. According to the 3D response surface, the interaction between different factors had a significant effect on surface roughness. The optimal combination of process conditions were a spindle speed of 4000rpm, a feed speed of 2mm/min and a cutting depth of 51 mu m.