Orthogonal experimental study on the influence of machining parameters on flat lapping of sapphire substrate

Sapphire is extensively utilized in the optical, aerospace, and civil electronic industries due to its favorable optical, physical, and chemical characteristics. To enhance the efficiency and quality of sapphire lapping, an orthogonal experiment was conducted on a single-side sapphire substrate using a ceramic lapping plate. The study examined the impact of lapping plate material, lapping pressure, lapping speed, and abrasive particle size on the surface roughness, profile, and removal rate. By analyzing the signal-to-noise ratio and variance of machining parameters, the influence rule and influence of the weight of machining parameters on machining results were obtained. The results of the experiment demonstrate that the material removal rate of sapphire was positively affected by an increase in lapping pressure, speed, and abrasive particle size. Moreover, the removal rate of the SiC lapping plate was the highest among the experimental materials. The roughness of the sapphire surface decreased with increasing lapping pressure, speed, and abrasive particle size, while the SiC plate had the lowest surface roughness. The profile tolerance of sapphire diminished as the lapping pressure, lapping speed, and the abrasive particle size increased. Additionally, the ZrO2 lapping plate exhibited the most minor profile tolerance. The size of the abrasive particle significantly impacted the material removal rate, with a specific gravity exceeding 70%. Similarly, the lapping pressure had a significant effect on both the surface roughness and the profile tolerance. The ideal machining parameter combination comprised an abrasive particle size of 10 µm, a lapping pressure of 22 785.0 Pa, a lapping speed of 60 rpm, and a lapping plate of SiC. Under optimal machining conditions, sapphire exhibited a material removal rate of 0.65 µm/h, a surface roughness of 0.0920 µm, and a profile tolerance of 2.0915 µm after 20 min of lapping. This demonstrated that the lapping process enables highly efficient and high-quality machining of sapphire substrates.