Understanding Static and Dynamic Load in Industrial Bearing Applications
At the most basic level, industrial bearings are designed to facilitate smooth rotational motion while reliably accommodating static and dynamic loads. Though the equipment applications may be incredibly complex, this basic functionality is at the core of how virtually all industrial bearings operate.
Below, we take a look at static loads vs. dynamic loads, how these different types of loads affect bearing components, and how we account for these factors in manufacturing quality high-performance bearings for the specific application at hand.
The Basics of Static vs. Dynamic Loads for Industrial Bearings:
Static Loads Explained
Static load generally refers to a load exerted on a bearing when it’s stationary or at rest. However, static loads can also include operational conditions where a bearing undergoes very slow movement which is not sufficient to dynamically disperse the loads via rolling action. In other words, the bearing is rotating so slowly that sudden loads are still “felt” statically, not rotationally.
A crucial specification to keep in mind is the static load capacity of the bearing. That refers to the maximum load or weight the bearing will reliably hold before permanent deformation (such as brinelling) or damage is likely to occur.
Of course, the maximum capacity is especially crucial for bearing applications in which shock loads or heavy weighting are expected to occur while the bearing is not in motion – e.g. industrial conveyors and other factory material handling systems, or pretty much any machine that utilizes an emergency stop feature.
Dynamic Loads Explained
Dynamic load refers to a load exerted on a bearing as it undergoes continuous movement – i.e. generally whenever the attached equipment is operational. Essentially, a bearing’s dynamic load capacity is its functional life within the expected use case.
Radial and axial loads are both crucial considerations from a dynamic perspective, as these different types of loads will cause different types of stress and wear to the bearing. Carefully determining reliable operation under these conditions gives us a bearing’s “L10 Life” – a measurement derived from testing identical bearings under given loads/speeds to determine the ratings at which 90% of the bearings are still operational.
How Static Load Capacity Determines Bearing Life and Performance
One way to look at a bearing’s static load capacity: it’s essentially the bearing’s maximum weight limit at rest. Of course, you also have to consider the effects of sudden impact loads or shock loading (such as machine emergency stops), which can damage bearings and raceways just like exceeding the weight limit will. The major issue that occurs when exceeding static load capacity is brinelling.
Brinelling causes permanent indentations in the bearing raceway as the metal is deformed under an excessive load. As you can imagine, any amount of deformation within these precision bearing components impairs the bearing’s overall performance and drastically reduces its service life. Brinelling prevents the bearings from rolling smoothly, which results in machine chatter or excessive vibration. Excessive noise and persistent rattling are other common resulting issues.
How Dynamic Load Capacity Determines Bearing Life and Performance
Dynamic load capacity is mostly determined by the load rating, the load magnitude, the bearing speed, and the lubrication conditions. Because these conditions are constantly changing, choosing an optimum bearing type to accommodate dynamic loads means you have to consider the most extreme end of operational conditions if you want to maximize service life.
For example, higher speeds mean more wear. Heavy loads combined with high speeds further exacerbate any wear issues. Dynamic loads also include irregular vibrations and shocks, which add complexity to the load calculations but must be accounted for to ensure reliability.
Ultimately, we calculate a hypothetical dynamic equivalent load, which gives us the expected life of the bearing if it were subjected to a constant level of combined radial/axial loads. It’s a delicate balancing act of choosing reliable, high-performance bearings that do the job dependably without adding excessive costs to your equipment.
Quality American Manufacturing and Bearing Distribution Since 1933
BSC is one of America’s leading and longest-standing manufacturers of industrial bearings and other power transmission products. By carefully considering your equipment application and static/dynamic load requirements, we will help ensure you receive the highest quality bearings optimized for your specific performance needs.
If you have any questions regarding the static and dynamic load conditions of your unique application, get in touch with the experts at BSC!
