What Does
Static Load Capacity Mean?
Static load capacity is the amount of load that a bearing can endure before a bearing raceway causes a permanent distortion of 0.01% of the diameter of a rolling element.
The static load capacity of a bearing is always denoted by Co, and this value is given to make sure the load does not cross the static load capacity.
Safeopedia Explains Static Load Capacity
Static loads are usually the result of unplanned and unquantified shocks to a bearing. This is why static safety factors are determined by ball screw manufacturers on the basis of application and operating conditions. The static safety factor is a ratio that ranges between minimum to maximum load bearing. The minimum range can be 2 for smooth operations and the maximum can be 5 to 6 for high shock loads.
Static load capacity is always used in a non-moving state and hence is not used in bearing life calculations. Exceeding the load capacity will certainly deform the bearing and compromise its performance, yet static load capacity is an imperative benchmark for recirculating linear bearings.
Linear bearings are mainly related to motion—for instance, moving a tool and shifting load from one point to another—and therefore require dynamic load capacity. However, some linear bearings also work under static conditions.
If the static load case is not considered, a bearing will fail much earlier than its predicted life on account of distortion caused by static loading. Static loading generally occurs when the bearing is immobile but loaded for a long time, when the bearing is loaded and moving at a very low speed, or when the bearing experiences high shocks.
Some common examples of static loads are shock loads, pressing forces, and holding forces. Shocks and vibrations are generally caused by conditions that are unpredictable, random, and difficult to quantify.