This page provides the life calculation formulas and static limiting load diagrams for AXCR cross roller bearings. This information is used to determine the expected life and safe operating range of the bearing under given load conditions.
Life Time and Load Safety Factor
General Notes
The following calculations are generally used for simple application cases and provide good approximations.
myonic Calculation Service
An accurate calculation of the nominal life time is possible via special calculation programs at myonic. The data required for calculation includes:
- Application details (drawings, sketches, technical specifications)
- Workpiece dimensions and weight
- Load cycle details (cutting forces, speeds, operating durations)
Dynamically Equivalent Load
In applications with radial and axial loads as well as speeds that have an effect on the bearing, all loads can be collected to form a single equivalent load. This "dynamically equivalent load" can be calculated using the following formula:
| When Fa / (Fr + 2M/Dpw) ≤ 1.5 | X = 1, Y = 0.45 |
| When Fa / (Fr + 2M/Dpw) > 1.5 | X = 0.67, Y = 0.67 |
| Symbol | Description | Unit |
|---|---|---|
| P | Dynamically equivalent load | [N] |
| Fr | Radial load | [N] |
| Fa | Axial load | [N] |
| M | Torque | [Nmm] |
| Dpw | Roller centre diameter | [mm] |
| X | Radial load coefficient | - |
| Y | Axial load coefficient | - |
Nominal Life Time
The nominal life time can be estimated with the following equation. The nominal life time designates the number of revolutions (in millions) at the same load and speed that 90% of all bearings of the same type achieve before material fatigue occurs:
| Symbol | Description | Unit |
|---|---|---|
| L | Nominal life time of the bearing | [106 revolutions] |
| C | Dynamic load rating (use Cr for mainly radial loads, Ca for mainly axial loads) | [N] |
| P | Dynamically equivalent load | [N] |
Equivalent Static Load
The static equivalent load collects all loads incurred during static application into one single load. This puts load on the bearing in the same way as the actual effective loads:
| Symbol | Description | Unit |
|---|---|---|
| P0 | Equivalent static load | [N] |
| Fr | Radial load | [N] |
| Fa | Axial load | [N] |
| M | Torque | [Nmm] |
| Dpw | Roller centre diameter | [mm] |
Static Load Safety Factor
The static load safety factor describes the relationship between the static load rating C0 (depending on the application case, C0r or C0a must be used) and the equivalent static load P0. Depending on the respective operating case, different static load safety factors are to be strived for. For more accurate information, please email sales@eb-system.com.
| Symbol | Description |
|---|---|
| S0 | Static load safety factor |
| C0 | Static load rating |
| P0 | Equivalent static load |
Limiting Load Diagram Explanation
The static limiting load diagrams serve to:
- Check the selected bearing size with mainly static load
- Determine the tilting moment Mk which the AXCR is able to absorb in addition to the axial load
The static limiting load diagrams take into account, for the roller element set, the static load safety factor S0 ≥ 4 as well as the screw and bearing ring strength.
How to Use the Load Diagram
- X-axis (Fa): Axial load [kN]
- Y-axis (Mk): Maximum tilting moment [kNm]
- 1 = Bearing/size
- 2 = Permitted range
- 3 = Unpermitted range
AXCR-U Limiting Load Diagrams
Limiting Load Diagram Cross Roller Bearing AXCR-U
The above load diagrams cover three size ranges:
- AXCR 80-U to AXCR 115-U - Small size series
- AXCR 160-U to AXCR 270-U - Medium size series
- AXCR 350-U to AXCR 540-U - Large size series
AXCR-S Limiting Load Diagrams
Limiting Load Diagram Cross Roller Bearing AXCR-S
The above load diagrams cover two size ranges:
- AXCR 130-S to AXCR 180-S - Small size series
- AXCR 220-S to AXCR 360-S - Large size series
Related Resources
Detailed Load Diagrams
The complete static limiting load diagrams can be found in the official product catalog:
Download AXCR Product Catalog PDF →