Analysis of large edge breakage of WC-Co cemented carbide tool blades emerging in precision grinding process

Abstract

This paper analyzes the edge damage characteristics of the cutting blade made of WC-Co cemented carbide material after precision grinding. The edge damage characteristics present tiny cracks and serrated continuous edge breakage. The main causes of the edge damage were explored regarding the edge residual stress, microstructure, and the change of element content. The results show that the value of the average residual compressive stress on the rear surface of the caving edge is −1745.7 MPa, which is much larger than that recorded before grinding (−578.6 MPa). The content of element C and element W on the surface increased obviously (from 28.35% to 34.29% and 54.51%–61.06% respectively). The increase of WC grains and the decrease of Co content will lead to the decrease of the bonding strength of the corresponding material, which will easily lead to the crack at the edge and cave. The grinding experiment of WC-Co cemented carbide was carried out with a bowl shape resin-bonded diamond grinding wheel and was optimized with the orthogonal experimental method. The optimized results show that the single grinding amount was the biggest factor affecting the processing time. The angular speed of rotation and the single grinding amount was listed as the factors that had the greatest influence on the blade rejection rate. Considering the processing efficiency and quality comprehensively, adopting the improved combination during the grinding process, the experimental results were as follows the blade rejection rate is 10%, and the processing time of a single blade is 205 s.

Keywords

• Cemented carbide
• Cutting blade
• Grinding process
• Edge breakage
• Process optimization