What factors affect the service life of rolling bearings?

When it comes to rolling bearings, there are many external factors that can affect their service life, whether in terms of installation, operation or maintenance, such as improper installation or inadequate maintenance. Here, we would like to share some of the common factors that can affect the service life of bearings.

1. Analysis of installation factors

For example, the installation of bearing housing cover plates and seals on conveyor roller bearings are key factors affecting bearing performance. The installation of the bearing housing cover directly affects the radial clearance of the bearing. If the bearing clearance is too small, it will cause the bearing to overheat, accelerate wear, and prevent the bearing’s wear-resistant properties from being fully utilised. It may also lead directly to the bearing seizing up. Therefore, before installing the cover, use blue paper correctly to adjust its position.

The quality of the bearing housing seal (cage oil seal) installation affects the rate of corrosion of the bearing. As roller bearing housings operate in environments with high moisture content, damage to the seal during installation or incorrect installation methods can allow water and iron oxide impurities to enter the bearing, accelerating the corrosion of the bearing components. When installing the skeleton oil seal, mechanical damage must be avoided, and the lip should face the outer side of the bearing housing.

2. Bearing Maintenance Factors

For example: Maintenance work on conveyor rollers is divided into routine maintenance, operational inspections and fault rectification.

Routine bearing maintenance primarily involves lubrication. Provided adequate lubrication is ensured, even in complex operating environments, the service life of bearings can reach 5 to 10 years (approximately 20–30 million revolutions). However, under conditions of poor lubrication, bearing life may be reduced to around 3 months (approximately 9 million revolutions). The following table shows the service life of bearings under various grease supply methods. As shown in Table (1), continuous and adequate lubrication enables bearings to achieve a significantly longer service life. If lubrication is not applied in a timely manner, the service life of bearings in complex environments—such as those with high moisture, high temperatures, or dust—will be drastically reduced.

Operational inspections of bearings primarily involve monitoring the temperature of the bearing housing. The temperature of bearing housings on the roller conveyors before and after the rolling line is generally around 40°C. Even in the early stages of wear to the bearing cage and rolling elements, the temperature of the bearing housing does not rise significantly, remaining below 43–

45°C. However, as the internal components of the bearing wear further and become contaminated, the temperature of the bearing housing will rise to 45–50°C. At this stage, the load distribution across the rolling elements becomes increasingly uneven, and cracking or misalignment may even occur. Once the rolling elements crack or become misaligned,

the bearing housing will experience a sharp rise in temperature, accompanied by smoke emission and bearing seizure; the temperature at the bearing housing measurement point will rise to 150–170°C. At this stage, the bearing is completely beyond repair.

To ensure a longer service life for the bearings, during the early stages of wear, the bearings should be cleaned promptly, the grease replaced, and the position of the bearing housing cover readjusted by appropriately adding or removing shims. This will help to extend the service life of the bearings.

3. Environmental Factors

Although the operating environment for rolling bearings in medium and heavy plate production lines is complex—involving heavy loads, high speeds and high humidity, all of which affect the service life of the bearings—we can still strive to improve the on-site conditions to create a more favourable environment for the bearings (e.g. by adding cushioning pads to the bearing housing base or applying a waterproof coating to the housing) in order to extend their service life.

Rolling bearings are highly standardised precision mechanical components manufactured in specialised factories. Among the many economic and technical indicators affecting rolling bearings, the service life indicator is a direct, rapid and comprehensive reflection of bearing quality. Although careful and thorough consideration has been given to every aspect from design to overall structural layout, the service life of bearings is sometimes significantly reduced due to unforeseen oversights or certain external factors. Through a series of investigations, and by analysing extensive background material, analytical data and failure modes, the primary causes of bearing failure can be identified. This enables the formulation of targeted improvement measures to extend the service life of the bearings.