ZZ vs 2 RS Sealing Options
Posted at Marzo 03, 2022The primary function of a bearing seal is to keep lubricant in the bearing and contaminants out.
There are three common sealing types used on conveyor rollers – Open, 2RS and ZZ:
- Open sealed rollers as the name suggests, does not have a built-in seal. They rely solely on external seals to retain lubricant within the bearing and keep contaminants out. Open sealed deep grooved rollers are not an available option provided by CPS, however you may find these used by manufactures looking to provide a economically cheaper roller while jeopardising the roller longevity. Open sealed spherical bearing are used in some high load applications and are specified by CPS engineering. These rollers are fitted by external triple sealing to support the longevity of the bearing. In some applications a noncontact seal is an available option for spherical bearings.
- ZZ is a non contact seal and is the most commonly found bearing seal found on conveyor rollers. This non-contact seal produces much less friction (if any) and heating than a 2RS contact type. Unfortunately, non-contact seals also allow lubricant to leak out of the bearing chamber and can permit physically small contaminants to enter. External sealing is critical to support the longevity of the bearing by retaining the lubricant.
- 2RS refers to a contact seal on each side of the bearing and is required for conveyor rollers in some applications. These seals form an effective sealed interface by applying continuous pressure to the surface with a resilient material. These seals make it difficult for fluids or solids particles to penetrate the sealed area, but direct contact with the inner race of the bearing creates additional friction and heat. Additional friction and heat generation needs to be factored into the selection of a contact sealing arrangement. The additional friction will increase startup drag and rim drag factors for the conveyor roller and can affect conveyor start up and operational power requirements.
