Plastic vs. Metal Bearings: Which Should You Choose?

Choosing between plastic bearings and metal bearings is one of the most talked about decisions when choosing bearing materials, it is no longer just a material preference—it specifically affects performance, maintenance, and cost throughout the lifetime of your application.

Traditionally, metal bearings have been known for strength and load capacity, an area where modern high-performance plastic bearings were seen to be at a disadvantage. However, plastic bearings now offer advantages in corrosion resistance, weight, and maintenance-free operation.

This guide compares the two, metal v's plastic. The goal, to try and help customers quickly understand where each option performs best and how to select the right bearing for your specific operating conditions.

The comparison- Metal plain bearings vs. igus plain bearings

Metal composite bearing vs. igus plain bearing

What is a metal composite bearing?

A classic metal composite bearing essentially consists of a metal cover and a very thin layer of polytetrafluoroethylene (PTFE).
Typically, these types of bearing have a maximum wear zone of approx. 0.05 mm or approx. 0.002 inches.
During operation, the PTFE layer is worn out.
In extreme cases, it is completely worn away until metal runs on metal, resulting in shaft damages or "seizing up" of the bearing.

What is an iglidur® polymer plain bearing?

iglidur® plastic bearings are made of modern polymer compounds, which consist of base polymer, solid particles and so-called solid lubricants.
These help reduce the iglidur® plain bearing's coefficient of friction.
A transfer to the shaft is not absolutely necessary, but improves functionality.
With this homogeneous structure, theoretically the entire wall thickness is available as wear zone.

Sintered bearing vs. igus plain bearing

What is a Sintered bearing?

The oil is absorbed by the body of the porous sintered bearing and provides lubrication, especially at higher rotation speeds.
The oil film necessary to ensure that sintered bearings function effectively does not work in the case of slow and/or linear or pivoting movements.
In addition, the amount of oil available for the duration of the operation decreases.

How do iglidur® plain bearings compare to sintered bearings?

The homogeneous and consistent structure with solid lubricating and reinforcing materials but without oil saturation ensures that the solid lubricants incorporated in the material are always available irrespective of the kind of movement.
Very low coefficients of friction and wear over the entire life cycle of the product.

Needle bearings

What are Needle bearings?

Due to the line contact between needle rollers and raceways, needle bearings have, compared to the point contact of the ball bearings, a better load distribution at the contact point during rolling
Despite this, the line contact requires a high Hertzian pressure.
Therefore, like all rolling bearings, they are sensitive to vibrations and shocks. In addition, wear of the shafts can occur, which is why usually hardened shafts have to be used.
Needle bearings can only absorb radial forces.

How do needle bearings compare tp iglidur® plain bearings?

Due to the large load-bearing surface and the comparatively elastic properties of the plastic, iglidur® plain bearings are also suitable for heavy shocks and edge loads.
Reinforcing fibres provide an additional improvement of the mechanical properties. In combination with iglidur® plain bearings, "soft" shafts can be used in many applications.
Even with edge loads, the risk of shaft wear is significantly lower than with needle bearings.

Conclusion:

In conclusion, all bearings ultimately do the same thing. The primary differences between the metal bearing types and the igus plain bearings is simply the material compound and the fact that metal bearings need lubricating in order to prevent ceasing and igus plain bearings don't.

The preconception that metal is "stronger" or "better" than plastic is diminishing. There is a lot of test data and proof with real-life applications which proves that plastic plain bearings are more than capable of competing with metal bearings.

Customer examples-| igus plain bearings replace metal bearings

High temperature

The temperature resistance of high-performance polymer plain bearings is usually underestimated. igus® plastic bearings prove their suitability at up to 250°C.

Learn more about plain bearings in applications with high temperatures

Heavy duty

The iglidur® plain bearing materials for high loads combine high wear resistance with the ability to withstand high (static) loads, shocks and edge loads. They have proven themselves in different heavy-load applications for many years.

Learn about plain bearings in heavy duty applications

Dirt

iglidur® plastic plain bearings are characterised by their robustness and high service life, especially in dirty applications. An important reason: as no lubrication is necessary, dirt and lubricant cannot stick to the bearing locations.

Learn about plain bearings in dirty environments

Chemical resistance

Extreme environmental conditions, such as chemicals combined with high temperatures, require special properties of the plain bearings in use. All iglidur® plain bearings can be used in diluted acids and diluted alkalis. Differences occur in particular with higher concentrations or higher temperatures. For this, special iglidur® materials are available.

Underwater

igus® has also developed plain bearing materials for continuous use in water and other liquid media. In addition to corrosion resistance, minimised moisture absorbency and high wear resistance in liquid media are necessary.

Learn about plain bearings in water

Frequently asked questions

Depending on the application, some plastic bearings are as strong as metal bearings. We have a range of both composite and polymer bearings that often replace metal equivalents in applications such as agriculture, automotive and medical

Absolutely! Many of our bearings are designed for high loads and are often used instead of metal ones for this exact reason, alongside the fact they require no lubrication!

This will depend on the application and whether or not the correct bearing has been chosen. We always strongly recommend all applications are put through our configurator

This ensures the right bearing, based on parameters such as loads and speeds are taken into consideration. If this is done, there is no reason that plastic bearings wear faster than metal.

A hard wearing plastic is best for bearings however, depending on the parameters such as speed, load, temperature range really depends on the best plastic for bearings.

Oil impregnated sintered bronze bearings are the most common self lubricating metal bearings. The downside to these is the cost of the bearing, the cost of the lubrication and the mess, oil is messy!

This is why a lot of customers are choosing self-lubricating plastic bearings as an alternative, no mess, cheaper and no lubrication

Bearing overview