Modeling of solid-liquid coupling and material removal in robotic wet polishing

In this paper, the flow characteristics of the polishing fluid between the polishing pad and the workpiece are studied for the robotic wet polishing process. The distribution of the polishing fluid radial velocity U-r and the liquid film thickness z at different rotating radii r is revealed. The two-dimensional computational domain consisting of the polishing pad surface, the workpiece wall, and the polishing fluid is established. The particle-liquid two-phase flow simulation is carried out in Fluent. The influence of different rotation rates omega of the polishing pad and different robot swing speeds v(2) on the change and distribution of polishing fluid flow rate and temperature is elaborated. For polishing fluids with different average abrasive diameters d(p), the position distribution of the abrasive particles in the wet polishing process is simulated; the velocity distribution of particles in the x and y directions impacting on the workpiece surface is analyzed. The three-dimensional calculation domain for wet polishing is established; the workpiece surface erosion is simulated in Fluent. Considering different combinations of polishing fluid properties C-i and polishing kinematics P-i, the material removal rate MRR and standard deviation of material removal sigma on the workpiece surface are calculated. Under the same process parameters, the material removal rate test value MRRT and the standard deviation of material removal test value sigma(T) are compared with the simulated values, respectively. The results show that under the combination of 64 groups of physical parameters C-1-C-64 of the polishing fluids, the error between the test value (MRRT, sigma(T)) and the simulation value (MRR, sigma) is within 5%. With 64 sets of polishing kinematic parameters P-1-P-64, the average error between the test value MRRT and the simulated value MRR is 4.19%. However, when the polishing pad rotation rate omega is high, there is an inefficient polishing area in the smaller radius from the polishing pad rotation center, which results in a lower MRRT in some tests than that in simulation, with a maximum error of 8.1%. The average error between the test value sigma(T) and the simulation value sigma is 3.77%. When the pressure P of the polishing pad is high, the large particles embedded in the polishing pad surface follow its rotation, causing deep scratches on the workpiece surface, which results in a larger sigma(T) in some tests, with a maximum error of 7.8%. In conclusion, the material removal principle and the influence of different process parameters in the robotic wet polishing process are revealed in this paper through modeling and simulation of the particle-liquid two-phase flow, giving an accurate estimation of the material removal rate of the robotic wet polishing process.

Automated summary

This paper reveals the material removal principle and the influence of different process parameters in the robotic wet polishing process through modeling and simulation of the particle-liquid two-phase flow, providing an accurate estimation of the material removal rate.