FAG NJ318-E-XL-M1-C4 CYLINDRICAL ROLLER BEARING

In applications with high temperatures and heavy loads, the choice of radial clearance is decisive for the service life of the rolling bearing. This FAG version features a C4 radial clearance specifically designed for large thermal expansions and very tight fits.

Explanation:
• NJ: Two flange ribs on the outer ring, one flange rib on the inner ring; axial guidance in one direction, floating bearing function in the opposite direction
• E: Increased radial load capacity through optimized internal geometry
• XL: FAG/INA X-life designation for higher service life and increased dynamic basic load ratings thanks to highly precise contact surfaces
• M1: Two-piece, roller-guided brass cage for improved heat dissipation
• C4: Increased internal radial clearance above C3 level, suitable for large thermal expansions and very tight fits

Features:
The NJ series is based on a separable design: the inner ring can be mounted separately from the assembly of outer ring and rolling elements. This allows both assemblies to be installed independently. The inner ring can first be mounted alone on the shaft, which is a significant advantage particularly for shrink fits.
The E version uses an optimized internal geometry to distribute loads more evenly on the raceways. In combination with X-life technology, the bearings benefit from improved surface quality, which reduces friction, lowers heat generation and places less strain on the lubricant. The result is higher dynamic basic load ratings and a longer nominal life compared with earlier generations.
The C4 radial clearance is greater than C3 clearance, which in turn is greater than the standard CN clearance. It was specifically developed for applications with high temperature differentials or strong press fits. This maintains sufficient freedom for deformation so that no harmful internal preload arises at operating temperature. The M1 brass cage complements this concept by providing stable roller guidance and efficient heat dissipation.

Maintenance:
For applications with C4 radial clearance, temperature monitoring is of highest priority. Unusually high temperatures can indicate excessive interference stresses, aged lubricants or insufficient lubricant supply. Regular temperature checks help detect deviations early and avoid bearing damage.
The type and amount of lubricant must be adapted to the actual operating temperatures. Although the M1 brass cage reduces internal heat generation in the bearing, it does not replace condition-based relubrication under real operating conditions.
In addition, vibration analysis and noise checks should be part of preventive maintenance. Even small changes in the vibration spectrum should be investigated. As this is an open rolling bearing, the bearing environment must be reliably protected from particles, dust and moisture.

Strengths:
• C4 radial clearance prevents harmful internal preload in tight fits and under large temperature fluctuations
• Higher load capacity allows accommodation of larger loads without changing the installation space
• Separable design reduces downtime during maintenance and servicing
• M1 brass cage improves heat dissipation and is particularly suitable for high-temperature applications

Applications:
The C4 version is especially suitable for heavy industry. Rolling mills, strip annealing furnaces, heat-treatment installations and high-pressure compressors are typical applications. In these plants, heating and cooling cycles alternate, subjecting the radial clearance continuously to thermal expansion. The C4 clearance compensates for these changes reliably without overloading the bearing.
High-power gearboxes as well as drive and transmission shafts in high-temperature environments also benefit from this increased radial clearance, particularly with very tight fit tolerances. Under these conditions the E version reduces stress on the raceways through optimized load distribution, while X-life quality enables longer service intervals and extended maintenance intervals.