A Comprehensive Understanding of Knife Cutting: Effects of Hardness, Blade Angle and the Micro-Geometry of Blade Edge on the Cutting Performance

The cutting performance of steel blades is an eternal, attractive topic in the knife industry. It is a complicated process to cut up materials because it usually involves the contact mechanics of the material been cut, the geometry and roughness of the blade edge and the hardness and wear resistance of the blade steel. Therefore, a comprehensive analysis is required to evaluate the cutting performance of knife blades. In this study, such an analysis was conducted based on a quantitative model to describe the cutting depth of paper cards containing SiO2 particles by steel blades, and major contributing factors were summarized. The effect of the micro-geometries of blade edges was thoroughly discussed, and a geometry factor ξ for the micro-geometry of a blade edge was introduced into the model. The experimental results indicated that mechanical processing could produce a rough blade edge and a higher ξ value, accordingly. A similar effect was caused by the carbides in the martensitic steels for blades, and the ξ value was found to increase linearly with the volumetric fraction of the carbides. The extraordinary cutting behavior of the 3V blade implied that fine coherent carbides may result in an efficient improvement (40–50%) in the total cutting depth.