Machining parameter optimization in shear thickening polishing of gear surfaces

The non-Newtonian fluid polishing is an advanced method that is applied to machining the complex surfaces. This method significantly improves the surface quality and mechanical properties of the material. In addition, it also reduces the concentrated stress at the root of the gear, so the fatigue resistance of the material is increased. The characteristics of shear thickening fluid are applied to machining the alloy steel SCM435 gears in this study. Firstly, the relationships between main machining parameters (distance D, velocity V, and inclination angle I) and responses (pressure and surface roughness of gear) is investigated in the polishing process. The effect of three machining parameters to the polishing process is carried out by conducting the simulation and experiment. The simulations results found that the pressure area is distributed throughout all the gear surfaces and maximum pressure value is achieved about 16.3kPa with inclination angle of 26 degrees. In addition, experimental results indicated that the surface roughness of the gear surfaces can be reach 12nm after 25min polishing. Finally, the multi-responses optimization is utilized to optimize the pressures on the gear surfaces in machining process. The experimental results illustrated that the surface roughness is achieved the smallest at maximum pressure area. The best surface roughness of the gear surfaces can be reach 13nm under optimal machining parameters such as the distance of 15mm, velocity of 1.5m/s and inclination angle of 32 degrees.