Metal, plastic or ceramic ball bearings: when should I use which one?

Choosing the right material for ball bearings is not always easy. In this article, you will find a brief summary of whether and when ball bearings made of metal, plastic or ceramic are suitable.

Limits of metal ball bearings

Metal ball bearings are mainly used in most classic mechanical engineering applications. They are number one in terms of global sales volumes and are suitable for a wide range of different mechanical engineering applications. However, they always reach the limits of their application when, in addition to load bearing and speed, further requirements are placed on the bearing. This applies, for example, to various sectors such as the food industry or medical technology. Here, specifications such as suitability for contact with food or suitability for use in cleanrooms are crucial. System manufacturers often require food certification in accordance with EU standard 10/2011 or FDA (American authority: Food and Drug Administration).

plastic and its advantages

The advantage of plastic lies in the variety of materials. This means that different base polymers can be selected for a wide variety of applications, which are precisely suited to the application in terms of their specifications. In recent years, base polymers such as POM, PP, PEEK and other plastics have become established. Ball bearings made of plastic can be suitable for the following industries and applications:

• Food industry (advantage of food contact)
• Medical technology (advantage FDA conformity)
• Chemical industry (advantage of chemical resistance)
• Textile industry (no dust and dirt adhesion)
• Vacuum / high temperatures (no destruction of the lubricant)
• Special applications such as MRI or metal detectors (advantage metal-free)

In addition to the fact that xiros plastic ball bearings are corrosion-free and heat-resistant, they can also be used in chemical environments. Maintenance costs for plant and machinery can be reduced and reliability increased. The plastic ball bearings are characterised by low-friction dry operation, which means that xiros ball bearings do not require lubrication. This minimises rolling resistance. The reason: the balls do not have to overcome the resistance of the lubricant so that they can start up with a low breakaway torque.

However, plastic ball bearings can also reach their limits. For example, speeds in excess of 5,000 revolutions per minute can only be realised for a short time, as plastic deforms more quickly than metals at higher speeds and the resulting heat development. Bearings made of metal, on the other hand, have the edge when it comes to higher speeds and absorbing higher loads. This is where the metal variant scores points thanks to its combination of hardness and flexibility.

135 trillion test movements in our in-house test laboratory

Yes, metal ball bearings are ahead in these disciplines, but the evolution of ball bearing technology is allowing the cards to be reshuffled. What exactly does this mean? igus® has always conducted basic research and a test laboratory that carries out around 135 trillion test cycles every year. In addition to investigations into friction coefficients and wear rates, corrosion behaviour is also on the agenda, for example.