A Study Of Material Removal Rate Of Sapphire Lapping By Fixed Abrasive Pad

Because of the stable physical and chemical properties and excellent optical properties, the application areas of sapphire continue to be expanded. As a typical kind of hard brittle material,the high hardness and brittleness of the single crystal sapphire make it very easy to break, and the surface of the workpiece is easy to form cracks and pits which seriously restrict the large-scale application of sapphire. The fixed abrasive technology can consolidation the abrasive particle to the abrasive pad matrix which can make the particle trajectory under control, and than by adjusting the processing parameters, it can not only ensure the good material removal efficiency,but also get more ideal processing surface quality. This paper was focused on the material removal rate based on the lapping of sapphire with fixed abrasive, and than a material removal rate model of the fixed abrasive lapping sapphire was established and verified by experiment. The specific research contents and results are as follows:(1) Based on the characteristic of lapping process, the material removal is considered as the micro cutting of micro abrasive particles. The model of effective abrasive particle number is established by make appropriate assumptions of the distribution and emersion of abrasive particles.In consideration of the contact between the abrasive particles and the workpiece, the average cut depth model under the assumption of rigid-plastic which neglects the elastic recovery of the workpiece and the average cut depth model under the assumption of elastic-plastic which considers the elastic recovery of the workpiece are established. The model of material removal rate of the sapphire is established by combining the model of effective abrasive particle number and average cutting depth.(2) The relationship curves between material removal rate and particle size, particle volume fraction, lapping pressure and lapping speed are drawn with the numerical simulation of MATLAB based on the model of material removal rate. The results show that the influence of particle size on the material removal rate is not significant under the rigid-plastic model, the material removal rate decreases with the increase of the volume fraction of the abrasive particles, increases with the increase of the lapping pressure and the increase of the lapping speed. And the material removal rate under the elastic-plastic model is obviously less than that of the material removal rate under the rigid-plastic model.(3) The lapping experiments of the sapphire are carried out, and the results are compared with the model calculation value under the same parameters. The results show that the material removalrate trends are consistent with theoretical trends. The relative error between the calculated value and experimental value is relatively large under the assumption of rigid-plastic, while it is quite small under the assumption of elastic-plastic.