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Rodent Teeth - Saw Blades
Beavers, rats, rabbits and similar rodents depend on their
teeth for survival. They are experts at gnawing, and their teeth are designed with a self-sharpening ability. Unlike our own,
rodent teeth are covered with enamel on only the front side. Softer dentine is exposed on the back of the front teeth. As
the rodent chews and wears down its teeth, it alternates grinding its lower incisors against either the front or the back
of the upper incisors. As a result, the hard enamel slowly wears down the softer dentine and the teeth remain sharp. The teeth
also continue to grow from the root, maintaining their length. The animals must continue to gnaw or their teeth will outgrow
their mouth.
German engineers
have applied the tooth sharpening ability of rodents to cutting tools. Cutting is part of most industrial processes including
paper, cloth, wood, and metal. Dull cutting blades are inefficient and expensive to replace. To increase efficiency, blades
can be made similar to rodent teeth with distinct front and back sides. In one prototype blade, the harder, resistant side
consists of titanium nitride ceramic. The back side, similar to the tooth dentine, is coated with a weaker tungsten-carbon-cobalt
alloy. This latter material rubs against the materials to be cut, slowly wearing down and keeping the outer ceramic edge exposed
and sharp. Unlike the growing rodent teeth, the entire industrial blade eventually wears down. Engineers learn much from the
abilities of God’s created creatures, but cannot quite duplicate them.
Reference:
Meyers, M., A. Lin, Y. Lin., E. Olevsky, and S. Geogalis.
2008. The cutting edge: sharp biological materials. Journal of Minerals, Metals and Materials 60(3):19-24.