Gear materials Gear

wooden gears of historic windmill

numerous nonferrous alloys, cast irons, powder-metallurgy , plastics used in manufacture of gears. however, steels commonly used because of high strength-to-weight ratio , low cost. plastic commonly used cost or weight concern. designed plastic gear can replace steel in many cases because has many desirable properties, including dirt tolerance, low speed meshing, ability skip quite , ability made materials don t need additional lubrication. manufacturers have used plastic gears reduce costs in consumer items including copy machines, optical storage devices, cheap dynamos, consumer audio equipment, servo motors, , printers.

another advantage of use of plastics, formerly (such in 1980s), reduction of repair costs expensive machines. in cases of severe jamming (as of paper in printer), plastic gear teeth torn free of substrate, allowing drive mechanism spin freely (instead of damaging straining against jam). use of sacrificial gear teeth avoided destroying more expensive motor , related parts. method has been superseded, in more recent designs, use of clutches , torque- or current-limited motors.