Siemens sinumerik 840D sl Function Manual page 72

Detailed description
2.8 Orientation
Rotation of the tool
For six-axis machines you can program the tool rotation in addition to the tool orientation.
The angle of rotation is programmed with the THETA identifier (THETA=<...>).
NC blocks in which additional rotation is programmed, can only be compressed if the angle
of rotation changes linearly, meaning that a polynomial with PO[THT]=(...) for the angle of
rotation should not be programed.
The general format of an NC block, which can be compressed is:
N... X=<...> Y=<...> Z=<...> A3=<...> B3=<...> C3=<...> THETA=<...> F=<...>
or
N... X=<...>Y=<...> Z=<...> A2=<...> B2=<...> C2=<...> THETA=<...> F=<...>
If tool orientation is defined by rotary axis position, in the following format, for instance, then
copression can be done in two different ways, depending on whether large circle
interpolation is done or not:
N... X=<...> Y=<...> Z=<...> A=<...> B=<...> THETA=<...> F=<...>
If no rotary axis interpolation takes place, the compressed change in orientation is
represented in the usual way by axial polynomials for the rotary axes.
Accuracy
NC blocks can only be compressed if deviations are allowed between the programmed
contour and interpolated contour or between the programmed orientation and interpolated
orientation.
Compression tolerances can be used to set the maximum permissible deviation. The higher
the tolerances, the more blocks can be compressed. However, the higher the tolerances, the
more the interpolated contour or orientation can deviate from the programmed values.
Axis accuracy
For each axis, the compressor creates a spline curve which deviates from the programmed
end points of each axis by a maximum of the value set with the following machine data.
MD33100 $MA_COMPRESS_POS_TOL (maximum tolerance with compression)
66
Special functions: 3-Axis to 5-Axis Transformation (F2)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0