Before we get into anything else, it's important to understand exactly what a worm gear is. There has been some misunderstanding in the past, due to imprecise wording. A worm gear is the round gear itself, shaped much like a spur gear, while the worm is the gear in the shape of a screw. Plastic worm gears have been used in many applications around the world.
Plastic worm gears are used throughout the world, predominantly in small electric motors. These applications require that an output less than what the motor delivers be used and frequently sees use in high-speed applications like R/C cars and other electronic items.
Plastic worm gears are also used in some beginner's musical instruments for tightening the strings. Metal worm gears have been used for a long time in full scale professional musical instruments, as they are very effective at holding tension. Plastic worm gears have seen use in many different applications around the world and are not limited to the toys and other children related industries. They are especially useful in any application requiring precision gearing without the weight of metal gears. Plastic worm gears offer the precision engineered performance, coupled with the forgiving element of manmade materials. Unlike metal worm gears, plastic worm gears can absorb higher speed impacts without concern for damage; they also allow for the inconsistencies of manufacture without sacrificing performance.
Plastic worm gears are most often used in small applications, from toys to lawn sprinklers, though larger applications have been developed. They are very beneficial for any application where elements persist that would be corrosive to metal gears, in high moisture environments, outdoor environments and other such applications. These gears have revolutionized many industries, by drastically reducing the manufacturing costs of a wide array items. Without plastic worm gears, metal would have to substituted, resulting in greater weight, higher production cost and frequent repairs and higher cost of maintenance.
Due to their low cost of manufacture, durability and strength, plastic worm gears have found a home in the automotive industry as well. Many people would be surprised to learn that plastic gears can be found operating within their transmissions, but their unique properties make them ideal for many uses within an automatic transmission. Plastic worm gears offer superior performance to metal worm gears in many cases. They withstand relatively high temperatures very well and their nature means that little lubrication is required. The very low wear rate means that they do not have to be replaced as frequently as metal worm gears and they withstand impact well. When they do eventually wear to the point of replacement, the cost of the gears themselves is lower than that of metal worm gears, allowing manufacturers and reconditioning companies to save money.
With their low cost, longevity and performance, it's no wonder that these little beauties have made inroads even into the automotive industry. Their superior qualities have proven that a lightweight, durable alternative to metal worm gears is available at low manufacturing and installation costs.