Siemens SINUMERIK 840D sl Programming Manual page 757

Figure 3-8
Approach behavior
The approach behavior is always NORM for the 3D variant of the tool radius compensation.
Behavior at outside corners
The G commands of group 18 (corner behavior, tool offset) are evaluated at the outside corners
for circumferential milling with 3D TRC in the same way as for the conditions for the 2½D TRC:
● G450: Transition circle (tool travels round workpiece corners on a circular path)
In contrast to the solution for the 2½D TRC, the inserted contour element at an outside
corner is always a circle with a 0 radius, on which the tool radius compensation acts in the
same way as on any other programmed path. It is not possible to insert conics instead of
circles. In this case, the DISC address has no significance and is therefore not evaluated.
● G451: Intersection of equidistant paths (tool backs off from the workpiece corner)
The intersection is determined by extending the offset curves of the two participating blocks
and defining the intersection of the two blocks at the corner in the plane perpendicular to the
tool orientation.
The intersection procedure (G451) is not used when at least one block containing a change to
the tool orientation was inserted between the relevant traversing blocks. In this case, a circle is
always inserted at the corner.
Behavior for changes in orientation at outside corners
The ORIC and ORID G commands are used to determine whether changes in orientation
programmed between two blocks forming the corner are executed before the inserted circle
block (ORID) is processed or at the same time (ORIC).
Insertion depth
The insertion depth of the milling tool is the distance of the milling tool reference point from the
tip of the tool.
The milling tool reference point is the vertical projection of the milling tool machining point on
the programmed path to the longitudinal axis of the tool.
The position of the machining point on the peripheral surface of the tool is set with the insertion
depth.
NC programming
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
Circumferential milling
Work preparation
3.13 Tool offsets
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