Plastic gear is a mechanical component of machinery used to transmit power and rotation. Many industrial sectors use these parts because they are lightweight, quiet and easy to maintain, in addition to offering a wide variety of applications that are not possible with metal gears. They also serve as a substitute for more expensive metals in cases where environmental or cost considerations are paramount. The most popular plastic gears are polyacetal and linear polyphenylene sulfides, but special blends created specifically for gear use, along with other plastic resins, can offer many additional benefits.
Injection molding enables the production of plastic gears at lower costs than their metal counterparts and allows for large quantities to be produced in a relatively short time. However, the process does require careful selection of the plastic material to ensure that the mechanical properties required for the application are met. In the case of iglide plastic gears, these include dimensional stability and the ability to handle a wide range of temperatures and moisture conditions.
The main drawback to using plastic gears is that their strength and stiffness are not as high as metal, which can impose restrictions on the load-carrying capacity of the gear. This limitation can be overcome by carefully selecting the resin to be used, and by designing the tooth shape to withstand stresses from load-carrying and frictional effects. In most cases, the tooth strength is calculated with a formula developed for MC nylon, but the same theory applies to other resins as well if the appropriate factors are used.
Another important feature of plastic gears is that they do not rust and are corrosion-resistant. This means that they can be used in wet environments, such as those associated with food production machines, without the fear of damage or deterioration from chemical contact. In addition, they are able to operate without lubrication, which reduces maintenance costs.
Although the dimensional stability of plastic gears is better than that of their metal counterparts, they are more likely to experience backlash if a mating metal gear is used. This is due to a larger coefficient of thermal expansion and a tendency for the plastic to absorb moisture, which causes it to swell. This can also cause stress concentrations and premature failure. It is therefore essential that the gear designer consider these issues when choosing a plastic resin for the application.
It is also necessary to understand that the dimensions of the plastic gear may differ from those specified on the CAD drawing, as the mold size and cooling characteristics will affect the final result. In addition, the lubrication used during the molding process will influence the dimensions of the finished gear. For these reasons, a good procedure is to fit the gears in the machine and test their performance under realistic operating conditions before committing to a design change. This will avoid costly mistakes and help to realize the full potential of plastic gears. iglide specializes in manufacturing tribologically optimized polymer gears for the medical, laboratory equipment and toy industries.