Composite cogwheels reduce weight and noise

Tom Shelley reports on a new embodiment of an idea from the dawn of mechanical engineering

It is possible to save weight, cost and reduce noise by applying modern materials to the basic idea behind the cogwheels used in old windmills and other early machines. Instead of inserting iron teeth into wooden wheels, researchers at the Franhofer Technology Group in Stuttgart have been attaching metal teeth to a circular template. They then fill the inside of the ring with plastic or foamed aluminium. Another alternative is to weld or bond metal teeth to a flexible rolled steel strip. The strip is then bent round and joined at the ends after which its interior is filled with plastic or foamed metal as before. Matthias Böning, head of the production process department explains, "The great advantage of this type is its tremendous flexibility. The steel strips can be processed while they are straight, and are easy to shape into a ring. This enables us to produce all kinds of cogwheel systems, and even corrugated roller coasters." The new cogwheels contain less metal and are thus lighter than conventional components, making them attractive to the aerospace industry. They are easier to manufacture, and require smaller amounts of materials. It is also possible to reduce stored inventory since it is only necessary to store component parts instead of large numbers of variants of finished products. Böning says, "We keep getting enquiries from industry as to when they can start producing these cogwheels. In four or five months time, we plan to produce a manual, a kind of recipe collection for composite cogwheels. Fraunhofer Technology Development Group TEG Email Matthias Böning