Materials used in plastic gears are, in general, engineering plastics such as polyacetal (POM) and MC Nylon which is essentially polyamid resin. In addition, U-PE and PEEK can be used.
When there is a large temperature fluctuation in the application environment, when the diameter is large or when there is load on its keyway, metal hub made of S45C or stainless steel may sometimes be used. In these cases, the teeth portion and the hub portion are attached together with screws. If it is not possible to screw together, two parts are fused together and made into fused gears. KHK’s fused gears are designed in such a way that the holding strength of the fused surface is stronger than the tooth strength.
The positive characteristics of plastic gears include being lightweight, non-rusting, quiet, injection molding enabling low cost and large production, and able to operate without lubrication by mating with metal gears. On the other hand, low strength, tendency to hold heat, large dimensional change including backlash compared to metal, etc. are some of the points requiring caution. The degree of dimensional changes that occur with plastic gears depend on the ability to resist temperature change, moisture absorption rate and resistance to chemicals.
As far as the applications of plastic gears, they are used in varying industries such as food production machines, consumer electronics, chemical, toy, and medical equipment industries.
