Static Safety Factor (SKR)
Caged Ball LM Guide Actuator Model SKR consists of an LM Guide, a Ball Screw and a support bearing. The static safety factor and the service life of each component can be obtained from the basic load rating indicated in "Rated load of model SKR" (see Table4 detailed information for each model numbers [load rating] ).
Calculating the Static Safety Factor
LM Guide Unit
During actual operation, damage may be caused by an unexpectedly large load acting on the LM Guide that is caused in particular by sudden starting and stopping or a large moment created by an overhang. Therefore, a static safety factor fS must be considered.
The static safety factor fS is derived from the relationship between the applied load and the basic static load rating. The estimates of the static safety factor based on operating conditions are given in Table 8 .
| fs | Static safety factor |
|---|---|
| C01 | Basic static load rating (N) |
| Pmax | Maximum applied load (N) |
Ball Screw Unit/Bearing Unit(Fixed Side)
For the ball screw and the bearing, a static safety factor fS based on the relationship between the calculated maximum axial load and the static load rating must be considered. Vibrations, impacts, or inertia due to starting and stopping may result in an unexpectedly large load. Therefore, please confirm that a suffi cient static safety factor has been ensured when selecting a model. The estimates of the static safety factor based on operating conditions are given in Table .
| fs | Static safety factor |
|---|---|
| C0a1 | Basic static load rating (N) |
| Fmax | Maximum applied load (N) |
Table: Estimates of the Static Safety Factor (fS)
| Machine type | Load conditions2 | Lower Limit of fs |
|---|---|---|
| General industrial machinery | Without vibration or impact | 2 |
| With vibration or impact | 5 |
1 The basic static load rating is a static load with a constant direction and magnitude whereby the sum of the permanent deformation of the rolling element and that of the raceway on the contact area under the maximum stress is 0.0001 times the rolling element diameter.
2 The standard value of the static safety factor may vary depending on the load conditions as well as environment, lubrication status, mounting accuracy, and/or rigidity.
