On the cutting performance of steel razor blades

Razor blades are ubiquitous cutting tools for daily use all over the world. Daily consumption reaches millions of units, and many men and women can check their cutting performance face-to-face. It has been calculated that the average man can spend more than 3000 hours shaving. The number of users is high, as well as the number of applications in practice. Wherever the separation of soft materials is needed, the use of razors is a simple and effective solution. Five types of shaving blades from respected world producers were tested, specifically examining the quality of material, cutting microgeometry, and surface roughness (the Alicona IF G5). The cutting performance is expressed by cutting forces (Kistler dynamometer 9575B), as well as wear and life (TESCAN Mira 3 and TESCAN CLARA Electron Microscopy). A special jig was designed and produced to keep the same cutting conditions for manual cutting of the GUNKI fishing line (hard mono, diameter 0.5 mm, tensile strength 687.5 MPa). The best results (542–611 cuts of the fishing line) were found for the double-wedge design with top angles 19.8 ± 0.8° and 10.9 ± 0.8°, edge radius 0.62 ± 0.15 μm, and average roughness 0.071 ± 0.008 μm. The best material contained 14.10–14.33 wt.% of chromium and was hardened to a hardness of HV0.5 654–658. The wear mechanism began with the yielding (a plastic deformation) of the cutting-edge asperities, then continued with the production of the bent hooked cutting edges, causing loss of stability (due to buckling), and finally ended with the total collapse and destruction of the cutting blade. The deflected area ~0.04 mm2 at the place where contact was made with the fishing line (diameter 0.5 mm, tensile strength of 687.5 MPa) was found to limit wear when the razors lost the ability to cut. The experimental results in this work confirmed a good correlation between the price and the quality of the razors.