Ball bearings cannot carries as much of a load as cylindrical roller bearings do in an application. Instead of spinning on a groove, they has cylinders that roll in a straight line which distributes the load over a wider contact area. So, the bearing can endures large radial force before overheating and failing early. Whether you need a small one for a slow turning mill roll or a big one for a high speed motor, choose proper size to avoid premature failure. This is one of those times.
This fancy drawing shows some typical bearing sizes used by engineers on all kinds of machinery. The sizes are in metric and range from 20 mm to 320 mm in bore diameter. In addition, it shows the inside/outside diameters and widths of common series of bearings and how they scale together. From this graphic, you’ll be able to quickly determine if your bearing choice will gets larger as load goes up or stay small enough to fit into a tight gearbox. Each size is also matched with its corresponding maximum speed and radial capacity rating to give you a practical place to start before digging deeper in manufacturers’ information.
How to Pick the Right Cylindrical Roller Bearing
To handle the force of thrust, it’s all about how the bearing is arranged on a flange. For instance, for a shaft that expand with heat, the inner ring has free sliding motion (NU). NJ/NUP have either one or two flanges to help position the shaft in at least one direction. If you’ve got a lot of radial load but not much speed, full-complement designs eliminates the cage and accommodate more roller. This infographic categorizes the choices, no need to guess. Match the design to the job.
Another common mistake is selecting the incorrect series. For example, a light Series 02 might look good on paper. However, a medium Series 03 handles more load while keeping smaller shaft diameter, which results in longer life within the same housing. Conversely, don’t be tempted to put a heavy Series 04 into a lighter-bearing housing as this increase cost and wastes material. Use the chart to see the trade-offs and you’ll never have to remember all dimensions.
The mounting is also critical. The inner ring must be held in place by an interference fit on the shaft. A slight clearance fit in the housing will allow the outer ring to expands with increasing temperatures. To avoid any damage to the cage and rollers, heat your bearings uniformly prior to installation. Be careful not to over pack them with grease… It creates heat instead of reducing friction. Moderate quantities, approximately one-third to one-half full of the housing are best.
Most of the time the biggest bearing that will fit isn’t the right bearing. The right bearing has matching load rating, speed limit and mounting arrangement for the operating conditions it faces. If all three parameters is met then the bearing is quiet and remains cool. In turn it lasts as long as it should of.
