HEIDENHAIN TNC 335 Technical Manual - Manual (Page 126)

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TNC 360 1 Machine Axes 4-29
1.6.5 Temperature compensation
Exact measurements of machine thermal behavior (center of expansion in the axes, amount of
expansion as a function of temperature) are necessary to compensate the effects of thermal
expansion!
The words W576 to W582 were introduced for thermal expansion compensation As soon as these
words receive a value, the "follow-up tracking" becomes active.
"Follow-up tracking" means that the actual position value changes 1 µm/sec until it has changed by
the full value from the words W576 to W582. This does not change the value in the actual position
display.
The actual thermal expansion can be measured, for example, with a TESTOTERM unit. The values
are transmitted to the PLC through the PLC inputs, further processed in the PLC program and finally
transmitted to the words W576 to W582. The actual value display does not change.
Input range: +32 767 to –32 768 [µm]
W576 Follow-up axis error compensation axis X
W578 Follow-up axis error compensation axis Y
W580 Follow-up axis error compensation axis Z
W582 Follow-up axis error compensation 4th axis
Example: Temperature compensation in the Z axis.
Program description
The 13 TESTOTERM-BCD outputs are transmitted at the TNC control through the PLC inputs I128
to I140 and converted to a binary data format. Then the binary value is multiplied by a correction
factor (linear thermal behavior) and sent to the Z axis. The correction factor is located in MP4210.44.
Main program
L M 0
ON M 0
S M 1 M1 is always set
LW I 128 Read in from TESTOTERM outputs
LW M1180 Instead of inputs, non-volatile markers
A K+8191 Reset bits 13, 14 and 15
W= M1200 Intermediate register TESTOTERM BCD
A K +3840 Reset 1st, 2nd and 4th decade
>> K +8
X K +100 Multiply 3rd decade by 100
= W 252 Intermediate register TESTOTERM binary