Compared with plastic gears of the same size, metal gears work well and have good dimensional stability when temperature and humidity change. But compared with metal materials, plastic has many advantages in cost, design, processing and performance.

Compared to metal molding, the inherent design freedom of plastic molding ensures more efficient gear manufacturing. Products such as internal gears, gear sets, worm gears can be molded from plastic, which is difficult to mold from metal materials at a reasonable price. Plastic gears have a wider application area than metal gears, so they push the gears towards higher loads and more power. Plastic gears are also an important material to meet the requirements of low-quiet operation, which requires high-precision, new tooth profile and materials with excellent lubricity or flexibility.

Plastic gears generally do not require secondary processing, so compared to stamped and machined metal gears, a cost reduction of 50% to 90% is guaranteed. Plastic gears are lighter and more inert than metal gears and can be used in environments where metal gears are subject to corrosion and degradation, such as the control of water meters and chemical equipment.

Compared with metal gears, plastic gears can deflect and deform to absorb impact loads, and can better disperse local load changes caused by shaft deflection and misalignment. The inherent lubrication characteristics of many plastics make them ideal gear materials for printers, toys, and other low-load operating mechanisms. Lubricants are not included here. In addition to running in a dry environment, gears can also be lubricated with grease or oil.

Strengthening effect of materials

In the description of gears and structural materials, the important role of fibers and fillers in the performance of resin materials should be considered. For example, when an acetal copolymer is filled with 25% short glass fiber (2 mm or less) filler, its tensile strength is increased by two times and its hardness is increased by three times at high temperatures. The use of long glass fiber (10 mm or smaller) fillers can improve strength, creep resistance, dimensional stability, toughness, hardness, abrasion properties, and more. Because of the required hardness and good controllable thermal expansion properties, long glass fiber reinforced materials are becoming an attractive alternative in large-size gear and structural applications.