One of the world’s great mysteries is why exactly razor blades are so expensive. They never seem to last long because after a few shaves there they get too dull, they basically rip the hair apart instead of cutting it. MIT conducted a new study to find out why even though human hair is 50 times softer than steel, the blades quickly dull.
The razors, scalpels and knives are typically made from stainless steel that is honed into a razor-sharp edge encoded with harder materials like carbon. The knife requires regular sharpening, and the razor tip must be replaced even though the cutting material is much softer. Engineers at MIT studied the act of a close shave and observed how a razor blade can be damaged when cutting human hair.
The team found that shaving deformes the blade in a way that is more complex than just eroding the blade part over time. Research has found that a single strand of hair can cause the edge of the blade under certain conditions. When the crack first forms, the blade is then more susceptible to chipping resulting in the blade̵7;s edge quickly tarnishing.
The blade’s microstructure plays an important role, the researchers said, and the blade is more susceptible to chipping if the steel’s microstructure is not uniform. The angle at which the blade approaches the filament and the presence of defects in the steel’s microstructure play a role in creating cracks. The team believes the study can give clues about how to preserve a blade’s sharpness.
The main goal of the study is to determine why blades become useless when they interact with a much softer material. In the study, the team used disposable razors to shave their face, and after each shave, they photographed the edge of the razor blade with a scanning electron microscope to see how the razor blade looks. . The team used different commercial razors at different angles to shave.
The tongues get chipped at certain points and when hair freely curls, splinting is less likely. Cracks in the blade most often occur where the edge of the blade comes into contact with the sides of the hair. The result of the study is a patent filed for the process that drives the steel into a more homogeneous form to make it last longer.