Setting the machine parameters, 1 f undamentals – HEIDENHAIN TNC 640 (34059x-01) Cycle programming User Manual
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Touch Probe Cycles: Automatic Tool Measurement
20.1 F
undamentals
Setting the machine parameters
When measuring a rotating tool, the TNC automatically calculates the 
spindle speed and feed rate for probing.
The spindle speed is calculated as follows:
n = maxPeriphSpeedMeas / (r • 0.0063) where
The feed rate for probing is calculated from:
v = meas. tolerance • n where
probingFeedCalc
determines the calculation of the probing feed rate:
probingFeedCalc
= ConstantTolerance:
The measuring tolerance remains constant regardless of the tool 
radius. With very large tools, however, the feed rate for probing is 
reduced to zero. The smaller you set the maximum permissible 
rotational speed (maxPeriphSpeedMeas) and the permissible tolerance 
(measureTolerance1), the sooner you will encounter this effect.
probingFeedCalc
= VariableTolerance:
The measuring tolerance is adjusted relative to the size of the tool 
radius. This ensures a sufficient feed rate for probing even with large 
tool radii. The TNC adjusts the measuring tolerance according to the 
following table:
Before you start work with the TT cycles, inspect all 
machine parameters defined in ProbeSettings > 
CfgToolMeasurement
and CfgTTRoundStylus.
The TNC uses the feed rate for probing defined in 
probingFeed
when measuring a tool at standstill.
n
Spindle speed [rpm]
maxPeriphSpeedMeas
Maximum permissible cutting speed in 
m/min
r
Active tool radius in mm
v
Feed rate for probing in mm/min
Measuring tolerance
Measuring tolerance [mm], depending on 
maxPeriphSpeedMeas
n
Spindle speed [rpm]
Tool radius
Measuring tolerance
Up to 30 mm
measureTolerance1
30 to 60 mm
2 • measureTolerance1
60 to 90 mm
3 • measureTolerance1
90 to 120 mm
4 • measureTolerance1
