Gears

What is a Plastic Gear?

Generally made from Ertalon 6PLA or Ertacetal C, gears are toothed mechanical components to transmit motion and power. Even though plastic gears can be paired, for the best wear life performance pairing with another non-plastic (general steel) gear is ideal.

Benefits of Plastic Gears vs metal gears

Eliminating Lubricants – Due to the low friction and lubricity properties of plastics, it is often possible for plastics gears to operate without lubrication.
Dirty & dusty conditions – plastics tend to be more tolerant to non-ideal conditions, such as dirty and dusty conditions, especially when external lubricants are eliminated.
Low Friction – This reduces energy consumption due to lower driving forces, as well as contributing to longer service life.
Reduced wear – particularly when plastics are paired with steel, the wear on both materials are lower than metal-on-metal and plastic-on-plastic.
Sacrificial – plastics can be used a sacrificial component in a drive system, to protect other more expensive parts being damaged in the event of system failures or jams.
Fatigue – Plastics don’t suffer from fatigue in the same way that metals, but materials such as Nylatron MC901 can provide additional resistance.

Dotmar has qualified engineers that can provide direct support with plastic gear material selection and recommendations.

Spur or Straight Cut Gear - the most common style of gear used to transmit motion and power between parallel shafts.

Helical Gear - teeth are cut at an angle, providing smoother operation due to the gradual engagement and disengagement, resulting in less noise and vibration.

Split Bearing - segments are used to make a full ring gear, generally for larger gears, for ease of manufacture.

gearrack-gear-rack-and-pinion_2 - non-depp

Rack & Pinion - used to transmit rotational motion to linear motion or visa-versa.

Bevel Gear - can be both straight cut or spiral, and a designed for transmitting motion via non-parallel shafts

Worm Drive - particularly used when there is a high reduction ratio required.

MATERIAL SELECTION CONSIDERATIONS

Material selection is a critical consideration when choosing a plastic for gears, as it directly impacts the ability to transmit power and durability. Here are some key material selection considerations for plastic gears:

Load

Understanding the surface pressure from the load is critical when selecting a plastic, that is to ensure that the stress is within the long-term load capability of the material.

Wear and Abrasion

The surrounding temperature (opposed to heat generated from friction) for both short- and long-term exposure is important, as materials can withstand higher temperatures for short term periods compared to long term or constant exposure, which in turn affect their load and power capacity. In the case of extreme temperatures, materials such as Ketron HPV PEEK and Techtron HPV PPS can be considered.

Wear & Abrasion

Abrasive conditions provide different challenges to clean environments, and therefore the material selection, which can include Ertalon LFX and Nylatron NSM.

Friction

The co-efficient of friction of materials will vary depending on the conditions (load, speed, counter-face etc), and will influence the operation the system.

Regulatory Requirements

Does the application have regulatory requirements such as food contact, drinking water, anti-static or flame retardant. The food industry may also require materials to be metal detectable, x-ray detectable and/or visually detectable by being coloured blue.

Other considerations

At times there may be other considerations such as chemical resistance, dimensional stability and machinability. Also, the tooth profile can influence the material choice, especially for small moduli gears.

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