POM, PA, and HMPE: Which Plastic Should You Choose for Your Machine Part?

For machine parts, plastic is often a smart alternative to metal. The material is lightweight, easy to machine, and can offer excellent properties in terms of wear resistance, friction, and chemical resistance. But which plastic is best suited for your application?

POM, PA, and HMPE are among the most commonly used plastics in mechanical engineering. At first glance, they may seem similar, but they differ significantly in their properties and potential applications. Choosing the right material therefore starts with the component’s function.

First the application, then the material

A guide, bearing sleeve, gear, or wear plate often must meet specific requirements, such as load, speed, friction, moisture, temperature, or contact with chemicals. The desired dimensions and tolerances also play a role.

At Lakwijk, we therefore look not only at a part’s dimensions but, above all, at its application. Will the part come into contact with water? Does it need to be wear-resistant? Is precise dimensional accuracy important? Or is low friction the key requirement for a moving part?

Based on this, we recommend which plastic material is the best fit.

POM: Suitable for Precise and Dimensionally Stable Parts

POM, or polyoxymethylene, is a widely used engineering plastic for machine parts where dimensional stability is important. The material is strong, rigid, and easy to machine. As a result, POM is highly suitable for parts that require a precise shape or fit.

Examples include:

• Gears
• Bearing sleeves
• Rollers
• Guides
• Precision parts
• Small mechanical components

POM also has good sliding properties. This makes it a logical choice for parts that move relative to one another, such as guides or bearing sleeves.

Are dimensional accuracy and precision machining (milling or turning) important for a part? Then POM is often a strong candidate.

PA: Strong, Tough, and Wear-Resistant

PA, also known as polyamide, is widely used when a part is subjected to heavy mechanical loads. The material is strong, tough, and wear-resistant. PA can withstand impacts and dynamic loads well, making it suitable for parts that are used intensively.

Common applications include:

• Wear parts
• Guides
• Bearing components
• Gears
• Wheels and rollers
• Structural machine parts

PA is a good choice when strength and impact resistance are more important than extremely precise dimensions. The material can absorb moisture, which may cause its properties and dimensions to change under varying conditions. For parts with very tight tolerances, it is therefore important to take this into account when selecting materials.

HMPE: Ideal for Wear Resistance and Low Friction

HMPE is a high-molecular-weight polyethylene best known for its wear resistance and low friction. The material is widely used in applications where parts move against each other or where there is continuous contact with another surface.

HMPE is suitable for, among other things:

• Wear strips
• Chain guides
• Slideways
• Conveyor guides
• Impact and wear parts
• Protective machine components

Due to its low friction, material glides easily over HMPE. This makes it particularly suitable for conveyor and guide systems. HMPE is also impact-resistant and can withstand intensive use.

While POM is often chosen for precision parts and PA for heavy-duty parts, HMPE’s strengths lie primarily in its wear resistance, sliding properties, and impact resistance.

POM, PA, or HMPE: A Practical Comparison

Which plastic is right for your part?

In practice, the choice can often be summarized as follows:

Choose POM when precision, dimensional stability, and good machinability are important.

Choose PA when the part must withstand high forces, impacts, or dynamic loads.

Choose HMPE when wear resistance and low friction are key considerations, such as in conveyor or guidance systems.

However, no application is entirely standard. Factors such as temperature, moisture, UV radiation, chemicals, food safety, and the desired service life of the part can also influence the right choice.

Custom plastics for mechanical engineering

POM, PA, and HMPE are commonly used materials in mechanical engineering and are often processed into custom parts. Depending on the application, plastic sheets or bar stock can be cut, milled, or turned to size.

Do you already have a working drawing or 3D model? If so, we can work with you to determine the right material and the most suitable machining process. Do you have a specific functional issue, such as a part that is wearing out, jamming, or needs to be replaced? In that case as well, we’d be happy to help you find a suitable plastic solution.

Would you like to know which plastic is best suited for your machine part? Contact Lakwijk for advice on material selection, customization, and machining.