Static Load Capacity - NTN-SNR LINEAR AXIS AXC Series Manual

2.6

Static load capacity

The values of the static load capacity given in the data tables of
the Linear Axis (except AXBG) represent the maximum load that
can be applied.
The loads (radial and tangential) and moments can act
simultaneously from different directions on the Linear Axis
(Figure 2.2).
In this case, a maximum equivalent load, consisting of radial,
tangential and other loads, used for verification. For this, the
position must be located within the movement cycle in which the
combination of all loads has the maximum value.
For complex loads, we recommend to contact our NTN-SNR
application engineers.
A minimum safety factor for static load capacity is not given here.
The static load capacity should not be mixed up with the static
load rating that is specified in calculation of linear guides. Only for
the axis of the series AXBG the static safety is to be determined
because the loads affect here on the carriages directly.
2.7 Life time
2.7.1 Dynamic load capacity / Nominal life time
The catalogue data to the dynamic load capacity of the Linear Axis
(except AXBG) based on the nominal life time of 50,000 km for
toothed belt axis, of 25,000 km for screw drive axis and of 10,000
km for Linear Axis with polymer track roller guides. The change of
the nominal lifetime depending on the load is shown in Figure 2.3.
If the loads are lower than the described limits, no further
investigation is necessary.
100 000
90 000
80 000
70 000
60 000
50 000
40 000
30 000
20 000
10 000
0
50 60 70 80
Dynamic load capacity [%]
Figure 2.3 ___ Nominal life time
In case of higher dynamic loads, please contact at on our NTN-SNR application engineers or use for complex loads our calculation
service.
2.7.2 Influence factors
For a calculation of the nominal life, it is often very difficult, to determine the real acting loads exactly.
• Linear Axis are usually subject to oscillations or vibrations caused by the process or driving forces.
• Linear Axis are to be dimensioned so that the load peaks of shocks do not exceed the maximum permissible loads.
This applies to the dynamic and the static state of the system.
90 100 110 120 130 140
The static load capacity of a Linear Axis results from the maximum
load capacity of all related components in their interaction and is
lower than the static load rating of the guiding system.
An additional check the static safety of the guiding system is not
necessary.
If a Linear Axis is subjected in static alternating loads use, the
values of the dynamic load capacity shall be recognized as the
maximum values.
Figure 2.2 ___ Equivalent load
If the nominal life time of the Linear Axis should be calculated,
the calculation basics for linear guides, ball screws, racks and
track rollers, which are described in the relevant catalogue, must
be applied.
For Linear Axis of the AXBG series this calculation rules are always
applicable.
150 160 170 180 190 200
17
F F
E Z
Toothed belt axis / Rack
and pinion axis
Screw drive axis
Linear Axis with polymer
track roller guides
F
Y