Razors, scalpels, and knives are typically made from stainless steel for a razor-sharp edge surrounded by hard materials such as carbon. The knife needs to be sharpened regularly, and the razor head has to be replaced even though it is much softer than the material. MIT engineers studied the act of shaving closely and saw how razor blades can be damaged as it cuts human hair.
The team found that shaving deteriorates the blade in a way that is more complicated than wearing it down the edge over time. The study found that a single strand of hair can cause the edge of the blade chip under certain conditions. Once the initial crack is formed, the blade is pushed forward, causing the blade edge to quickly slacken.
Researchers say the microstructure of the blade plays an important role, and the risk of peeling of the blade is greater if the steel microstructure is not uniform. The angle at which the blade approaches a strand of hair and the presence of defects in the microstructure of the steel play a role in initiating cracks. The team believes that research can provide clues on how to preserve the sharpness of a blade.
The main goal of the study was to determine why the blades become useless when the blades interact with too much material. In the study, the team used disposable razors to shave facial hair, and after every shave they viewed images of the razor blade’s edge with a scanning electron microscope to see how the blade wore. The team used blades from various commercial razors at different angles for shaving.
The blades were glued in some places, and when the hair was free to bend, it was less likely to have chips. Chips in the blade usually occur in places where the blade edge meets the hair edges. The result of the study is a patent filed on the process of manipulating steel in a more homogeneous form to make it long lasting.