Calculation Rolling Bearings | Bearing Size | Static & Dynamic Load Rating | Life | Operating Hours скачать в хорошем качестве

Calculation Rolling Bearings | Bearing Size | Static & Dynamic Load Rating | Life | Operating Hours

The static load capacity is the decisive characteristic when a bearing is subjected to load while stationary, experiences short-term shocks, or operates at very low speeds. It describes the maximum load a bearing can withstand without causing permanent plastic deformation between the rolling elements and the raceways. Such deformations can impair the bearing's function and lead to vibrations, increased noise, and higher friction torque. The static load rating (C0) is specified by the manufacturer for each bearing and defines the load limit at which, under normal operating conditions, permanent deformations of 0.01 percent of the rolling element diameter occur. This value is considered acceptable, as it generally does not noticeably affect the bearing’s function. To ensure reliability, the full static load rating is not utilized for the actual load. Instead, a safety factor (static load safety S0) is applied. For normal operation, a factor of 1 is sufficient. In applications subject to heavy shocks or with high requirements for smooth running, higher factors must be used. For ball bearings, a value of 1.5 is typical, and in cases of particularly high demands, even 2.0. For roller bearings, the values can be even higher (3.0 to 4.0). Conversely, the safety factors can be lower under smooth, vibration-free conditions, for example 0.5 for ball bearings. When a combination of radial (Fr) and axial (Fa) forces occurs, the equivalent static bearing load (P₀) is calculated. This is done using radial factors (X0) and axial factors (Y0). In most applications, bearings are subjected to dynamic loads. In this case, the dynamic load rating C is the decisive parameter. It serves as the basis for calculating the expected service life of a bearing. The dynamic load rating C is the constant radial load at which 90 percent of a large number of identical bearings reach a life of one million revolutions before the first signs of material fatigue occur. The nominal life L10 is the number of revolutions a bearing is expected to achieve with a 90 percent probability. It is determined by the life equation, which takes into account the dynamic load rating C and the equivalent dynamic bearing load P. The life exponent k is 3 for ball bearings and 10/3 for roller bearings. The equivalent dynamic bearing load P is again calculated using radial and axial factors. For single-row radial bearings, the axial component only becomes relevant when the ratio of axial to radial force exceeds a certain limit. The video demonstrates the procedure using an example. The minimum load is critical because if the load is too low, frictional wear increases, which can lead to sliding instead of pure rolling motion, micropitting, and unwanted vibrations or noise. In practice, the shaft’s own weight is often sufficient to exceed this minimum load. If not, the bearings must be preloaded. The reference speed is a thermal guideline that indicates the speed at which a bearing reaches a stable operating temperature of 70 degrees Celsius under standardized conditions. It serves as a basis for assessing the bearing’s thermal capacity. In contrast, the limiting speed is a mechanical guideline and represents the absolute maximum speed of a bearing. It must never be exceeded, as doing so can lead to rapid wear and bearing failure. 00:00 Static Load Rating 01:32 Static Load Rating and Load Safety (Safety Factors) 03:18 Equivalent Static Load: Deep Groove Ball Bearings 05:15 Example for Determining Bearing Size under Static Load 06:35 Minimum Radial Load 08:49 Self-Aligning Ball Bearings 11:18 Dynamic Load Rating 12:07 Nominal Life (Basic Rating Life Equation) 13:11 Equivalent Dynamic Bearing Load 14:04 Example for Determining Bearing Size under Dynamic Load 14:57 Limit Value (Radial Factor & Axial Factor) 17:34 Required Dynamic Load Rating 18:02 Selection of a New Bearing 19:12 Reference Speed 19:56 Limiting Speed 20:20 Temperature influence, contamination, and lubricant