A plastic gear is a gear manufactured from plastic. Plastic gears are used in many machines, from copiers to printers. The plastic gears are much more economical to produce and allow the manufacturer to provide a product at a lower cost to the customer. Plastic gears are quieter and require less lubrication than their steel counterparts.
When deciding to use a plastic gear in a machine, the manufacturer must examine a number of variables. The load being placed on the plastic gear is at the top of that list. Other factors are the noise level the machine will operate at. Most machines used in an office setting use a series of plastic gears to allow the machine to operate at a substantial noise reduction.
Cost is always a factor in deciding to use a plastic gear. The cost of machining a metal gear is substantially higher than the cost of casting a plastic gear. Also, often the use of a metal gear would be detrimental to the life of an office product. The use of plastic and polymers in light machines mandate a plastic gear be used. Metal gears would tend to grind away the plastic tracks that they operate on.
Machines such as video cassette players that are subjected to dust and dirt use plastic gears not only for the light weight properties but for the ability to function in dirty environments. A plastic gear will tolerate dirt and debris much better than a metal gear. Metal gears tent to grind and pulverize a dirt particle while a plastic gear tends to absorb the dirt particle. This prevents frequent maintenance issues.
Many plastics are self-lubricating. This tendency for the plastic to lubricate itself is a much relied upon trait when designing household products. By using the plastic gears, the product is able to provide continuous service without the need for as much routine maintenance. This is especially useful in food preparation machinery. This type of machine is typically not able to use petroleum-based lubricants in certain areas, particularly those that actually come in contact with the food product. The plastic gears are also much easier to clean and sanitize.
The ability to withstand a comparable load while remaining quiet and light, as well as the more cost-effective production features make the use of plastic gears a very popular choice in manufacturing. In areas of high humidity or moisture such is found in many food preparation machines, the non-corrosive properties of plastic make it an obvious choice over its metal cousin.