Have you got the right bearings?

To avoid equipment breakdowns, industry professionals must improve their knowledge of bearing materials — this is the cautionary view from SMB Bearings. The company has identified a trend related to the terminology used for ceramic bearing types, with many end users failing to differentiate between hybrid and full ceramic variations.

Due to lack of clarity in terminology, what are often referred to as ceramic bearings are actually hybrid bearings. As the name suggests, hybrid bearings use a combination of materials in their design, usually encompassing steel rings and ceramic balls made of silicon nitride.

While there are clear differences between the two bearing types, a worrying amount of end users are unaware of this. As a result, many are incorrectly purchasing hybrid bearings under the premise they can be used in applications that actually necessitate the use of full ceramic versions.

Full ceramic bearings do not include any steel or plastic in their design. Due to the material, these bearings can perform in extremely harsh environments, such as those with high temperatures or corrosive substances. Hybrid bearings do not carry these same characteristics, and therefore their use in these environments could have detrimental consequences.

“Hybrid bearing capabilities differ extensively from full ceramic,” explained Chris Johnson, managing director of SMB Bearings. “For instance, despite having ceramic balls, the corrosion resistant properties of hybrid bearings are inadequate for use in many submerged and underwater applications — even when using a marine grade metal, such as 316 grade stainless steel.

“Marine grade stainless steel relies on a high rate flow of water, as the passive film of the metal requires frequent oxygen to retain its corrosion resistance. Without this, the bearing will begin corroding when fully submerged. Ultimately, this misunderstanding about material types could cause the bearing, and the entire application, to fail.”

While improving bearing material knowledge may not be a priority for many end users, the threat of downtime caused by bearing failure should be motivation to differentiate between hybrid and full ceramic.

SMB Bearings noted that, while there are frequent misinterpretations about the different ceramic bearing types, end users will have complete clarity on the end application for the bearing. Therefore, it is recommended to discuss the intended application of bearings with the supplier before placing an order.