Siemens SINUMERIK 840D sl Programming Manual page 178

Measuring Cycles for Milling and Machining Centers
5.6 CYCLE979 workpiece: Measure hole/shaft/groove/rib at an angle
In all measuring variants the probe must be positioned at the required measuring height in
the applicate (tool axis) close to the first measuring point P1.
It must be possible to approach the first measuring point P1 via intermediate point P1' from
this position without collision using linear interpolation.
Recommended distance from contour: >_FA.
Procedure for hole, shaft
Note
When measuring circle segments of < 90 grd, it should be noted that, mathematically
speaking, measuring points that deviate from the circular shape exert a particularly great
influence on the accuracy of the results (center point, diameter).
For this reason, an especially high degree of care should be taken when measuring small
circle segments. Good results can be attained if the following procedures are used:
The circle segment to be measured should be:
• Free from production deposits.
• Have as exact a circular form as possible, as guaranteed by the production technology
• Have as smooth a surface as possible, as guaranteed by the production technology used.
• Be measured with high-quality probes, i.e, the shape of the probe ball is as
• Be measured with the 4-point-measurement measuring variant (_PRNUM=1xxx).
• Be measured with a recently calibrated probe
The intermediate positions of the measuring points are approached along a circular path
(G2, G3). The distance between the probe ball (ball circumference) and the hole or shaft is
_FA. The travel direction G2 or G3 is derived from the sign of _INCA: G3 is angle is positive.
The velocity along the circular path is programmed with _RF.
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used.
homogeneous as possible.
Programming Manual, 03/2009 Edition, 6FC5398-4BP10-2BA0
Measuring cycles