One of the great mysteries of the world is why just sandbags cost so much. They never seem to last long after having a few scrubs there, so stupid that they basically run out the hair instead of cutting it. MIT has conducted a new study to find out why, despite human hair being 50 times softer than steel, razor blades dull quickly.
Razors, scalps, and knives are typically made of stainless steel that is made into a razor-sharp edge encoded with harder materials such as carbon. Knives require regular shearing, and razor heads need to be much softer than they are despite cutting materials. Engineers at MIT have studied the act of near shaving and observed how the razor blade can be damaged if it cuts human hair.
The team found that shaving deforms the blade in a way that is more complex than just bearing the edge over time. The study found that a single hair of the blade can cause the edge of the blade chip under certain circumstances. Once the first crack occurs, the blade is then vulnerable to further chipping, leading to deepening of the edge of the blade.
The researchers say that the microscopic structure of the blade plays an important role, and that the blade is more prone to chipping if the microstructure of the steel is not uniform. The angle at which the blade approaches a hair strand and the presence of defects in the microscopic structure of the steel play a role in initiating cracks. The team believes that research can provide clues as to how to maintain the sharpness of a blade.
The main aim of the study was to determine why knives become useless when they interact with a much softer material. In the study, the team used dispositive razors to shave facial hair, and after each shave, they took images of the edge of the razor blade with a scanned electron microscope to see how the blade dried. The team used blades from various commercial razors at different angles for shaving.
The blades chipped in certain places, and when the hair was free to bend, chips were less likely to occur. Chips in the blade were most common in places where the blade edge struts on the sides of the hair. The result of the study is a patent filed for a process to manipulate steel into a more homogeneous form to make it more durable.
