LINEAR MOTION SYSTEMS
LINEAR MOTION SYSTEMS
LINEAR MOTION SYSTEMS
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Redi-Rail ® Steel Linear Guides<br />
Technical Information<br />
Linear Motion Systems<br />
SYSTEM LIFE<br />
Fc = coefficient depending on the actual length of the stroke.<br />
This is an important factor in the case of applications with short<br />
stroke and high frequency. In these cases total lifetime in km is<br />
much shorter, than if application with long strokes. The factor<br />
is equal to 1 for stroke longer than 2 meter, while for shorter<br />
than 2 meter, the value is derived from the graph shown below:<br />
fc<br />
1<br />
0.75<br />
0.5<br />
Technical Infomation<br />
The actual lifetime of the system (rails, slides, and rollers)<br />
depends on the applied load, but is also influenced by factors<br />
such as: correct lubrification, environmental conditions,<br />
assembly precision to avoid uncalculated component stress/<br />
wear and total cycle length.<br />
In order to estimate the expected system lifetime in km of<br />
operation, the following equation must be solved:<br />
L(Km) = 100 x (Co/P) 3 x fc/n x fa<br />
Where:<br />
Co = dynamic load coefficient of roller or slide<br />
P = is the equivalent load applied on the heaviest loaded roller<br />
or slide.<br />
For each single roller: P = P rad + (Pax / Co ax) x Co rad<br />
For the slide: P = P rad + (Pax / Coax + Mx / Mox + My / Moy<br />
+ Mz / Moz) x Co rad<br />
<strong>LINEAR</strong> PRECISION<br />
The linear precision of the running slide depends on the rail<br />
and, specifi cally, on the longitudinal parallelism between the<br />
raceways and precision of the surface to which they<br />
are mounted.<br />
As a result, two slide precision<br />
B<br />
values are determined, one<br />
referring to the surface the rails<br />
is fixed to (A) and the other (B) to<br />
the precision of supporting rail.<br />
Precision is achieved when the<br />
surfaces are aligned.<br />
When all screws are correctly<br />
tightened, the RRT rail aligns<br />
A<br />
with the fi xing surface, and this<br />
adds up to the construction linear<br />
precision of the same rail.<br />
When the RRT-rail is loose, it may result slightly curved.<br />
However, this does not give rise to any problem of alignment,<br />
once the rail is properly fixed.<br />
0.25<br />
0<br />
n = number of slides running on the same rail<br />
fa = coeffi cient depending on lubrication and environmental<br />
conditions. Recommended values are shown in the table below:<br />
160<br />
140<br />
120<br />
100<br />
80<br />
60<br />
40<br />
20<br />
μm<br />
0<br />
fa<br />
0.7 - 1<br />
0.5 - 0.7<br />
0.5 - 0.1<br />
250 500 750 1000 1250 1500 1750 2000<br />
APPLICATION CONDITIONS<br />
500 1000 1500 2000 2500 3000 3500 4000<br />
B<br />
A<br />
Stroke<br />
mm<br />
Good lubrication, availability of self-lubricating rail<br />
wiper system, no dust accumulation and no pollutants,<br />
precise assembly<br />
Random lubrication, environmental dust, thermal<br />
fl uctuations, vibrations<br />
Low lubrication, high environmental pollution, strong<br />
thermal fl uctuations, high vibrations<br />
Stroke<br />
mm<br />
The data and specifi cations in this publication have been carefully compiled and are believed to be accurate and correct. However, it is the responsibility of the user to<br />
determine and ensure the suitability of Pacifi c Bearing® products for a specifi c application. Pacifi c Bearing’s only obligation will be to repair or replace without charge,<br />
any defective components if returned promptly. No liability is assumed beyond such replacement. *Consult www.pacifi c-bearing.com for the latest technical updates.<br />
148<br />
800.962.8979 • www.pacific-bearing.com
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