POM or PA6: three questions to help you decide which material to choose

Are you choosing POM-C, POM-H or PA6? Three questions make it easier to decide which material is right for your specific component. Both materials are engineering plastics with high mechanical strength, but they behave differently in service and during machining.

Where will it be sliding?

The first thing you should ask is whether the component will be sliding against metal or another plastic. POM, particularly POM-C, has low friction and good dimensional stability. This makes the material a common choice for plain bearings, gear wheels and gearboxes where the component moves a great deal. The coefficient of friction against steel is low and the surface wears slowly during dry operation.

PA6, or nylon, has slightly higher friction but withstands wear and impact better. If the component is subjected to impact, vibrations or momentary overloads, PA6 may be the right choice. Nylon also has a better ability to absorb energy without cracking.

Another difference is moisture. PA6 absorbs more moisture than POM. In a damp environment or underwater, PA6 can swell and change dimensions. POM is less affected by moisture and retains its dimensions better over time. For components with tight tolerances in damp environments, POM is therefore often the preferred choice.

What load is it designed to withstand?

The second question concerns mechanical load. POM-C has high rigidity and copes well with static loads. POM-H is even more rigid and stronger, which is suitable when the component needs to bear a heavy load without yielding. POM-H has lower water absorption than POM-C and is therefore particularly well suited to environments where moisture is present.

PA6 has good fatigue strength and withstands repeated load cycles. If the component operates under varying compressive or tensile stresses, PA6 may be the better option. For large dimensions, PA6 G is also available; this is cast and can be supplied in thicker sheets and larger rods than extruded PA6.

Also bear temperature in mind. POM performs well up to around 100 °C continuously. PA6 can withstand slightly higher temperatures, often up to 120–140 °C depending on the grade. For even higher temperatures, you’ll need to move up to PA66 or PEEK.

What can the material withstand in production?

The third question concerns machining and the environment. POM is easy to turn, mill and thread. It produces clean cuts and a good surface finish. POM is also suitable for parts with threads and mating surfaces as the material is hard and dimensionally stable.

PA6 is also machinable, but requires slightly more attention to clamping and cooling to prevent the component from deforming. Nylon can be tough to cut, which requires sharp tools and the correct cutting parameters.

If the component is to be used in a food-contact environment, food-grade variants of both materials are available. Always ensure you select the correct certified grade for your specific application. For chemical environments, you should compare resistance to oils, fats and solvents. POM withstands many organic chemicals well, whilst PA6 is more sensitive to strong acids.

Summary of the selection

Choose POM-C when you need low friction, good dimensional stability and ease of machining. Choose POM-H when loads are higher or the environment is damp. Choose PA6 when you need impact resistance, fatigue strength or large dimensions. Choose PA6 G when extruded profiles are not sufficient.

Next steps

Do you need help choosing between POM and PA6? Contact our materials advisers, try our range online or use VisualCutter to have the plastic cut to exact dimensions without waste.

Common mistakes when selecting materials

A common mistake is to choose a material based solely on price per kilo. PA6 is often cheaper than POM, but if the component is to be used in a damp environment, dimensional changes and increased maintenance can eat into the savings. POM may cost more to purchase but result in a lower total cost over time.

Another mistake is failing to consider surface quality and fit. POM produces finer surfaces when turned and is better suited to threads and bearing fits. PA6 can produce a slightly rougher surface and requires wider tolerances in precision applications.

Also bear in mind that there are several variants of both POM and PA6. Grades reinforced with glass fibre, dry lubricants or oil alter the properties significantly. You should therefore always choose a grade that matches the operating conditions.

Maintenance and service life

Both POM and PA6 have a long service life when used correctly. POM withstands dry operation and low lubrication requirements, which reduces the need for maintenance. PA6 withstands wear and impact, but may need to be moisture-adjusted prior to machining to prevent cracking.

When replacing worn components, it is worth considering whether a different grade might be more suitable. A component that wears out too quickly in PA6 may sometimes have a longer service life in POM with a dry lubricant, and vice versa.

How to order the right grade

Once you have decided on POM or PA6, the next step is to choose the right grade and dimensions. Both materials are available in several variants: oil-filled, glass-fibre-reinforced, food-grade and electrostatic versions. Choose a grade that suits both the operating environment and the machining method.

Bear in mind that filled grades are often stiffer and harder, but can also become more brittle. A glass-fibre-filled PA6 can withstand greater mechanical stress but causes more wear on tools during turning. Oil-filled POM is ideal for plain bearings that are to run dry for long periods.

Always check that the required dimensions are in stock or can be manufactured within a reasonable timeframe. If you need the plastic cut to exact dimensions, you can use VisualCutter to minimise waste and ensure you receive the correct length upon delivery.

Summary

The choice between POM and PA6 depends on how the component will be used. POM is best when you need low friction, good dimensional stability and smooth mating surfaces. PA6 is the right choice when the component needs to withstand impact, wear and momentary overloads.

Ask about sliding, load and environmental conditions before you order. Then choose the right grade and dimensions to ensure a component that will last over time.

Frequently asked questions

Can POM or PA6 be used outdoors? Both materials can withstand the elements, but UV light can cause the surface to become brittle over time. Choose a UV-stabilised grade if the component is to be left outdoors for a long time.

Which material is easiest to turn? POM is generally easier to turn to a fine finish. PA6 requires more attention to moisture content and tool selection to prevent cracking.

Are food-grade grades available? Yes, both POM and PA6 are available in food-grade variants. Always check the certification before ordering.