6 – 74 HEIDENHAIN Technical Manual TNC 426, TNC 430
6.5.3 Temperature Compensation with Tilting Axes
A change in temperature always causes a change in length. For tilting axes,
thermal growth of the spindle head must be compensated in the X, Y and/or Z
axes.
There are two possibilities for temperature compensation:
n Temperature compensation with a “tilted working plane”
• by entering a formula in MP7530.x
• by entering a formula in the MP7530 column of the description table
n Permanently effective temperature compensation
• by entering a formula in the TEMPCOMP column of the description table
In most cases, the formula to be used will be the formula for calculating a
change in length: ∆l = l · ∆T · α
∆l: change in length
l: Length
∆T: change in temperature
α: coefficient of expansion (steel: 11.5 · 10
–6
1/K)
Example:
Z
1
= 300 mm (at 20 °C)
α
steel
= 11.5·10
–6
1/K (coefficient of expansion of steel)
W486: Temperature measured by a Pt100 thermistor
MP7530.x or TEMPCOMP = 300 + 300 * 11.5e–6 * (W486 – 20)
better: MP7530.x or TEMPCOMP = 300 + 3.45e–3 * (W486 – 20)
If the front part of the spindle gets warmer by 40 K, it results in a spindle length
growth of
Z
1
∆l 300 mm 40 K 11.5 10
6–
1
K
----⋅⋅⋅ 0.138 mm==
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