Siemens Sinumerik 840D sl Programming Manual page 460

Tool offsets
7.11 Cutting data modification for tools that can be rotated (CUTMOD)
Explanations:
In blockN180, initially the tool is selected for CUTMOD=0 and non-rotated toolholders that can
be orientated. As all offset vectors of the toolholder that can be orientated are 0, the position
that corresponds to the tool lengths specified in $TC_DP3[1,1] and $TC_DP4[1,1] is
approached.
The toolholder that can be orientated with a rotation of 30° around the B axis is activated in
block N200. As the tool nose position is not modified due to CUTMOD=0, the old tool nose
reference point is decisive just as before. This is the reason that in block N210 the position is
approached, which keeps the old tool nose reference point at the zero (i.e. the vector (1, 12)
is rotated through 30° in the Z/X plane).
In block N260, contrary to block N200 CUTMOD=2 is effective. As a result of the rotation of the
toolholder that can be orientated, the modified tool nose position becomes 8. The
consequence of this is also the different axis positions.
The tool radius compensation (TRC) is activated in blocks N220 and/or N270. The different
tool nose positions in both program sections has no effect on the end positions of the blocks
in which the TRC is active; the corresponding positions are therefore identical. The different
tool nose positions only become effective again in the deselect blocks N260 and/or N300.
Further Information
Effectiveness of the modified cutting data
The modified tool nose position and the modified tool nose reference point are immediately
effective when programming, even for a tool that is already active. A tool does not have to be
re-selected for this purpose.
Influence of the active machining plane
To determine modified tool nose position, cutting direction and holder or clearance angle, the
evaluation of the cutting edge in the active plane (G17 - G19) is decisive.
However, if setting data SD42940 $SC_TOOL_LENGTH_CONST (change of the tool length
component when selecting the plane), a valid value not equal to zero (plus or minus 17, 18 or
19), then its contents define the plane in which the relevant quantities are evaluated.
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Programming Manual, 02/2011, 6FC5398-2BP40-1BA0
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