Experimental study on the brush tool–assisted shear-thickening polishing of cemented carbide insert

To obtain uniform surface roughness of the complex cutting edge of the cemented carbide insert in the polishing process, a novel method, brush tool–assisted shear-thickening polishing (B-STP), was proposed in this study. This method introduces the flexible brush tool into the shear thickening polishing process to improve the surface roughness consistency of the complex cutting edge. The influence of the fiber-density of the brush tool and its contact length with insert on the B-STP performance was firstly investigated, and then the effects of four main processing parameters including polishing speed, diamond abrasive concentration, abrasive size, and inclination angle on the surface roughness and its consistency of the cutting edge were analyzed by Taguchi method. The ANOVA method was employed to evaluate the effective weight of the four factors and optimize the polishing conditions. The polishing experiment under optimum processing parameters combination with polishing speed 70 rpm, abrasive concentration 6 wt%, abrasive size no. 5000, and inclination angle 2°. The average surface roughness R_a of the seven measuring points on the cutting edge decreases from 118.01 to 8.13 nm in 10 min polishing, while the standard deviation decreases from 7.40 to only 0.3 nm. The comprehensive performance of surface quality obtained by the B-STP method is improved by 9.47 times and 3.67 times, respectively, compared with the STP method and the non-optimized B-STP method. The results show that the B-STP is an effective method for high consistency polishing of the cemented carbide insert cutting edge with complex shape.