HEIDENHAIN TNC 426B (280 472) ISO programming - Manual (Page 222)

8 Programming: Cycles 206
CONTOUR TRAIN (Cycle G125)
In conjunction with Cycle G37 CONTOUR GEOMETRY, this cycle
facilitates the machining of open contours (where the starting point
of the contour is not the same as its end point).
Cycle G125 CONTOUR TRAIN offers considerable advantages over
machining an open contour using positioning blocks:
■ The TNC monitors the operation to prevent undercuts and
surface blemishes. It is recommended that you run a graphic
simulation of the contour before execution.
■ If the radius of the selected tool is too large, the corners of the
contour may have to be reworked.
■ The contour can be machined throughout by up-cut or by climb
milling. The type of milling even remains effective when the
contours are mirrored.
■ The tool can traverse back and forth for milling in several infeeds:
This results in faster machining.
■ Allowance values can be entered in order to perform repeated
rough-milling and finish-milling operations.
Before programming, note the following:
The algebraic sign for the depth parameter determines
the working direction.
The TNC takes only the first label of Cycle G37
CONTOUR GEOMETRY into account.
The memory capacity for programming an SL cycle is
limited. For example, you can program up to 128 straight-
line blocks in one SL cycle.
Cycle G120 CONTOUR DATA is not required.
Positions that are programmed in incremental
dimensions immediately after Cycle G125 are referenced
to the position of the tool at the end of the cycle.
8.7 SL Cy
cles
Gr
oup II (not in
TNC 41
0)
Y
X
Z
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