404LXR Series Product Manual
Chapter 4 - Performance
34
Thermal Effects on Repeatability
Repeatability will not be effected as long as the temperature remains constant. However the
repeatability will be effected as the temperature changes from one level to another. This is most
commonly experienced when starting an application cold. Then as the application runs the 404LXR
comes to its operational
temperature. The positions defined when the unit was “cold” will now be
offset by the thermal expansion of the unit. To compensate for this offset, all positions should be
defined after the system has been exercised and brought to operational temperature.
Causes of Temperature Increases
One or more of the following conditions may effect the temperature of the 404LXR
base:
•
Ambient Temperature
This is the air temperature that surrounds the 404LXR.
•
Application or Environment Sources
These are mounting surfaces or other items which produce a thermal change that effect the
temperature of the 404LXR base (i.e. Machine base with motors or other heat generating devices
that heat the mounting surface and thus thermally effect the 404LXR base).
•
Motor heating from 404LXR
Since the 404LXR uses a servo motor as its drive, it produces no heat unless there is motion, or a
force being generated. In low duty cycle applications heat generation is low, however as duty
cycles increase, temperature of the 404LXR will increase, causing thermal expansion of the base.
With very high duty cycles these temperatures can reach temperatures as high as 30
C above
ambient.
Temperature Effect on Accuracy
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0
100
200
300
400
500
600
700
800
900
1000
Travel (mm)
E
rr
or
(
m
m
)
5 degrees C
10 degrees C
15 degrees C
20 degrees C
25 degrees C
30 degrees C
