Why POM is an ideal material for gears

POM is therefore one of the most important materials for modern plastic gears. A POM gear combines high dimensional accuracy with good sliding properties and low wear. The material is particularly interesting where a plastic gear is to replace classic metal gears.

Black PE300 rods belong to the group of high-density polyethylenes (PE-HD) and are characterised by excellent chemical resistance, high toughness and good machinability. As a supplier of PE rods, Martan offers PE300 in black for industrial applications and for use outdoors. The black colouring additionally protects the material against UV radiation and makes the rod interesting for permanently stressed components outdoors.

High requirements for gear materials

Gears are central components in countless machines and devices. They transmit forces, movements and torques precisely and reliably. This results in high requirements for the material used: it must not only be mechanically load-bearing and wear-resistant, but also ensure a long service life with minimal maintenance effort.

In addition to good noise damping, low weight and the lowest possible lubrication requirement are also in demand. Traditionally, metals such as steel or bronze are used. However, with progress in materials technology, high-performance plastics such as POM are increasingly coming to the fore. These enable a more efficient, quieter and more cost-effective implementation of many gear applications – especially in series production.

Properties of POM at a glance

Polyoxymethylene (POM), also known as acetal or polyacetal, is a semi-crystalline thermoplastic with outstanding properties for mechanically stressed applications. The combination of high strength, low friction and dimensional stability makes POM the preferred material for plastic gears.

Key material properties:

• High mechanical strength and rigidity
• Low coefficient of friction, good sliding properties
• Very good dimensional stability
• Low water absorption
• Good chemical resistance
• High fatigue strength

Advantages over metal

Weight

POM gears are significantly lighter than metal variants. This reduces the rotating masses, lowers energy consumption and contributes to increased efficiency in mechanical systems.

Smooth running

The damping properties of POM lead to quiet, low-vibration running. Especially in household appliances or office applications, this advantage is decisive for user comfort.

Self-lubrication

Many POM types have excellent sliding properties and can be operated without additional lubrication. This saves maintenance costs and prevents lubricant contamination.

Freedom from corrosion

In contrast to metals, POM is completely corrosion-free. It is therefore particularly suitable for applications in damp or chemically stressed environments.

Typical areas of application for POM gears

Due to their versatility, gears made of POM are used in numerous industries:

• Automotive engineering (e.g. in window regulators, seat adjustments)
• White goods (e.g. in washing machines, kitchen appliances)
• Office machines (e.g. printers, copiers)
• Medical technology (e.g. in dosing systems)
• Model making and precision engineering

Design notes for gears made of POM

Tooth width and module

The tooth width and the module must be selected so that the contact area between the teeth ensures sufficient force transmission. Larger tooth widths increase the load capacity.

Temperature range

Standard POM is temperature-resistant up to approx. 100 °C. For higher temperatures, modified types should be used in order to avoid deformation and loss of strength.

Bearing seats and shaft connections

These areas are particularly stressed and must be secured separately in plastic gears – for example by metallic inserts or positive-locking connections.

Moisture influences

POM absorbs only little water and remains dimensionally stable in most environments. In hygroscopically critical areas, however, a test should still be carried out.

Is PE-HD or PE300 UV-resistant?

Black PE-HD is particularly suitable for applications with UV exposure. The black pigmentation improves resistance to UV radiation and protects the material in outdoor applications. Black PE300 rods are therefore used, among other things, for technical components, guides, spacers and construction elements that are regularly exposed to sunlight and weather.

POM as a replacement for metal gears

POM and other engineering or high-performance plastics can replace metal gears in numerous applications. Applications with moderate mechanical loads, in which low weight, low friction, smooth running and corrosion resistance play an important role, are particularly suitable.

With regard to service life, too, correctly designed plastic gears can achieve very high running performance. Torque, speed, temperature, tooth geometry, counter-running partner and ambient conditions are among the decisive factors. A general comparison of the service life of plastic and metal gears is therefore not meaningful. For many applications, however, a gear made of POM offers a long-lasting and low-maintenance alternative to metal.

Comparison with other plastics

When selecting the suitable plastic for gears, designers are often faced with the decision between several materials. POM occupies a middle position here and convinces with a particularly balanced combination of properties.

Compared with PA (polyamide), POM has a significantly lower water absorption and offers higher dimensional accuracy, which makes it particularly suitable for precise components. Compared with PET, POM offers better sliding properties and higher fatigue strength. PEEK, in turn, is superior with regard to temperature and chemical resistance, but is also significantly more expensive. POM therefore represents an excellent compromise between performance and cost for many applications and reliably covers a large proportion of industrial requirements.

Property	POM	PA	PEEK
Friction	Very low	Medium	Very low
Moisture absorption	Very low	High	Very low
Temperature resistance	Up to 100 °C	Up to 120 °C	Up to 250 °C
Price level	Medium	Low	High
Dimensional accuracy	High	Medium	Very high

Conclusion: POM is the standard for many plastic gears

In recent decades, POM has established itself as the preferred material for gears in a wide range of industries. Its combination of good mechanical properties, excellent dimensional accuracy, low friction and high cost-effectiveness makes it an ideal all-rounder – both for series products and for individual technical solutions.

Thanks to its wide availability, good processability and proven reliability, POM is one of the most widely used plastics in the field of gear manufacturing. Whether in household appliances, vehicle interiors or industrial plants – wherever precise force transmission combined with high load capacity is required, POM proves to be particularly suitable.