Six Advantages of Plastic Gears

zoomed in cropped image of plastic gears
Delrin® is a widely used engineering thermoplastic for gears.

Gears made from plastic—especially Delrin® acetal resin—avoid many of the problems common with metal gears. Here are six advantages of plastic gears in everything from automotive components to healthcare devices.

1.  Lighter Weight Components

Plastic gears offer weight saving advantages versus metal gears which results in less inertia in the gear system and lower assembly weight. This means less battery drain on devices such as e-bikes or robotic vacuum cleaners.

For comparison: Delrin® has a density of 1.4 g/cm3 compared with steel’s 7.8 g/cm3 and aluminium’s 2.7 g/cm3.

2.  Low Noise and Vibration

When designed with adequate clearance, plastic gear teeth will deflect slightly under loading. This deflection makes any small differences in pitch and profile less.

The lower modulus plastic gear teeth deform to compensate for inaccuracies, and the softer material provides a higher damping factor, making plastic gears quieter than more costly metal gears. For example, one manufacturer of home healthcare beds changed to acetal gears and significantly reduced operating noise.

3. No Corrosion in Moist Environments

Gears are often used in moist environments where steel would be prone to rust. In systems that are not used regularly, steel teeth can lock together. Plastics never rusts which avoids this problem.

Delrin® has One of the Lowest Coefficients of Friction for Gears

4. Eliminates the Need for External Lubrication 

Plastics generally have a lower coefficient of friction which means less horsepower wasted in heat.

Delrin® has one of the lowest coefficients of friction and this can be further lowered by friction modifiers that eliminate the need for external lubrication. So Delrin®  makes for cleaner assembly and disassembly for recycling.

5. Easily Mass Produced and Prototyped

Most plastic gears are manufactured by injection molding, which is very cost-effective for volume production. Plastic moldings generally do not need secondary operations such as de-flashing or anodising, making the final gear less expensive than an equivalent metal gear. Injection molding offers designers more flexibility since it’s easier to make a set of gears of different sizes mounted as a unit on the same shaft.

Prior to volume manufacturing, it’s often necessary to machine prototype gears, for which a suitable material needs to be chosen. Delrin® makes the ideal choice for ease of machining and for close mechanical performance to a molded part in the same material, which is not the case with glass filled materials.

Delrin® 100CPE Can Extend the Time Between Mold Cleanings by 33%

6. Less Deposit and Less Tool Cleaning

A new platform of POM homopolymers, Delrin® CPE grades enable optimum processing efficiency—and significant reductions in emission values to meet what are currently the most stringent automotive industry requirements.

Delrin® CPE grades, in addition to low emissions, offer a significant reduction in mold deposits during processing. This considerably reduces mold maintenance costs because more parts can be injection molded between two cleaning cycles, and cleaning takes less time.

In a successful launch, adopting Delrin® 100CPE acetal homopolymer enabled LIP srl, a leading manufacturer of standard and custom gears to extend the time between mold cleanings by 33 percent, supporting higher throughput and greater cost-effectiveness. Importantly, Delrin® 100CPE solution delivers the same high-performance properties that LIP had relied upon with the Delrin® 100 product.

Learn more about Delrin® materials for gears.