The advantages of plastic gears include light weight, no rust, quietness, lowering cost by injection molded, mass production can be achieved and able to operate without lubrication by mating with metal gears.
However, compared with metal, plastic gears have low strength and large dimensional changes, which need to be paid attention to. The dimensional change degree of plastic gear depends on their resistance to temperature changes, moisture absorption and chemical resistance. Factors such as load, temperature, humidity, price, etc. need to be comprehensively considered when selecting plastic gear materials.
Plastic gears are often made from POM and Nylon.
These materials are self-lubricating and usually do not require the additional lubricants. Engineering plastics are softer than metals, so they have high vibration absorption and noise reduction. Light weight and salt corrosion resistance also make plastic gears replace traditional metal gears in many special applications.
There is a big difference between POM and Nylon in terms of water absorption, and Nylon's water absorption is much greater than POM’s. Water absorption will reduce dimensional accuracy, which can cause noise or reduce torque transmission efficiency.
Plastic gears are more flexible than metal gears in terms of how they are formed. It can be injection molded, e.g. POM gears. POM is suitable for producing small gears in larger quantities. Also can be CNC machined, e.g. MC Nylon gears. MC Nylon is suitable for producing large gears or small lot gears.
PEEK, as the engineering plastic with the best comprehensive performance, is also often used to manufacture gears. Apart from the high price, PEEK has few disadvantages.
Plastic Spur Gear
Spur gear transmission relies on the meshing of the driving gear and the driven gear to transmit motion and power. This is a gear driven between two parallel shafts.
No thrust (axial force) is generated in the transmission, and it is one of the most common gears in actual production and use.
Plastic Helical Gear
Compared with spur gears, helical gears have the advantages of stable transmission, good meshing performance, high coincidence, high gear strength, quietness, and low vibration. And can transmit high power.
Helical gears differ from spur gears because their tooth lines are helical and generate axial thrust. Thrust can be eliminated by thrust bearing or combination of left and right helical gears. A pair of meshing helical gears must have the same helix angle and opposite helix directions.
Plastic Worm Gear
The precision worm gear transmission is a kind of gear transmission, which is composed of a worm and a worm gear. A worm drives a worm gear, a mechanism commonly used to transmit motion and power between two staggered shafts.
Even though the efficiency is low due to the sliding contact, the rotation is smooth and quiet.
Plastic Screw Gear
The screw gear transmission is a gear transmission between staggered shafts composed of two paired helical gears, also known as staggered shaft helical gear transmission. Because the tooth contact is a point, their load carrying capacity is low and they are not suitable for large power transmission. Features are low energy consumption, superior performance.
Plastic Bevel Gear
Bevel gears have a cone shaped appearance and are used to transmit force between two shafts which intersect at one point (intersecting shafts). Compared with cylindrical gears, bevel gears can change the transmission direction, the transmission ratio is often lower than that of worm gears, and the operation efficiency is higher.
Plastic Miter Gear
They are used to change the direction of power transmission without changing speed.
Miter Gear has longer life, high load carrying capacity, noise reduction and shock absorption.
Plastic Internal / Planetary gears
Internal gears are cut on the inside of a cylinder or cone and are paired with external gears. Internal gears are mainly used for planetary gear drives and gear couplings.
Plastic Gear Rack
Same sized and shaped teeth cut at equal distances along a flat surface or a straight rod is called a gear rack. A linear rack-shaped gear that meshes with a spur gear. It can be regarded as a special case when the pitch diameter of the spur gear becomes infinite. By meshing with a cylindrical gear pinion, it converts rotational motion into linear motion.