Self-lube integrated bearing units from NSK
New bearing units help reduce build maintenance costs for OEM manufacturers
NSK’s RHP range of Self-Lube-housed bearing units are designed to help OEM manufacturers and end users to improve their competitiveness, cutting build and maintenance times by reducing bearing complexity and mounting costs.
Self-Lube bearing units provide integrated benefits in general manufacturing industry, materials handling and agricultural applications. By providing units that are ready assembled to bolt into place, they allow designers to easily and economically solve specific bearing problems relating to component complexity, mounting, and also bearing maintenance and life in difficult environments.
A simple comparison supports the case for ‘bolt-on’ convenience. The typical mounting arrangement for a standard ball bearing includes a number of separate components, some having to be accurately machined. These components include a housing, stepped shaft; inner and outer ring retainer and lock nut and thread. This arrangement is both expensive and time consuming to install. In contrast, one of NSK’s RHP range of Self-Lube units employs the same basic bearing, but integrates all other elements needed to assemble the bearing, together with facilities for sealing and relubricating.
Self-Lube bearings conform to ISO standards and are available in different materials and configurations. Cast iron pillow block and flange types are used for normal- and medium-duty applications, while zinc-plated press steel units are available for lighter duty operations. In addition, as many Self-Lube units are called upon to operate in harsh environments, NSK have introduced the Silver-Lube range of corrosion-resistant bearings and housings.
Silver-Lube bearings and housings are particularly suitable in applications where frequent washdowns are necessary, optimum hygiene standards are required and good chemical resistance is important. Together with the RHP Life-Lube range, Silver-Lube bearings can also benefit from the sealed-for-life lubrication provided by NSK’s Molded-Oil technology.
Self-Lube-housed bearing units consist of an insert, normally a 6200-series deep groove ball bearing with cast iron (pillow block, flange or take-up unit) or pressed steel housings. The bearing insert can carry a combination of radial and axial loads in the same way as a standard ball bearing. It has an extended inner ring with integral shaft-locking device and a spherical outer ring that matches the spherical bore in the housing to overcome initial housing misalignments up to 0.030 radians.
A number of insert types are available for use in light and heavy applications and high and low temperature operating conditions. Heavy-duty types are used widely in equipment such as pumps and fans. Designed with a wide inner ring they facilitate a wide range of locking methods. The simplest of these, set screw locking, is suitable for most applications excepting those where vibration is a problem. Where vibration does occur an eccentric locking collar mechanism is supplied. Alternatively, in applications where positive concentric lock is required, or when heavy vibration or shock loads are present, a taper lock system is preferred. With all these locking arrangements, standard shafting can be used – there is no need for a precision interference fit.
Inserts for high or low temperature operation
In applications where Self-Lube bearings are required to operate in high or low temperature conditions, HLT inserts are used. These inserts provide opportunities to reduce maintenance, downtime and replacement costs at temperatures as high as +180 degrees C and as low as -40 degrees C.
Suited to high-temperature applications, HLT inserts are designed with C5 radial internal clearance and high-temperature grease and seals to give maximum life - even at +180 degrees C.
Effective sealing systems
As Self-Lube bearings are widely used in operating environments that are dirty and wet, they are provided with a choice of sealing systems. The standard S-type seal consists of a robust steel pressing with a nitrile sealing lip that is designed to retain grease within the bearing and keep contaminants out.
For more hostile environments a flinger seal has been developed. This gives increased levels of protection to the standard single lip seal to extend bearing life in arduous conditions without any loss in speed capability. Finally, offering the highest levels of protection of all is the triple lip seal; a highly efficient seal having three nitrile sealing lips. This component is recommended where a high degree of contamination is present.
The Self-Lube range can also be supplied with a protector end cover for easy fitment to most standard Self-Lube housed bearing units. Manufactured in mild steel, the protector is difficult to dislodge, yet can be removed without damage and used again repeatedly.
