Siemens SINUMERIK 840DE Programming Manual page 353

Retraction behavior with G462 (see example)
With G462, the corner generated by N10 and N20 in the example program is not machined
to the full extent actually possible with the tool used. However, this behavior may be
necessary if the part contour (as distinct from the programmed contour), to the left of N20 in
the example, is not permitted to be violated even with y values greater than 10 mm.
Corner behavior with KONT
If KONT is active (travel round contour at start or end point), the behavior differs according to
whether the end point is in front of or behind the contour.
• End point in front of contour
• Endpoint behind the contour
Fundamentals
Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
If the end point is in front of the contour, the retraction behavior is the same as with
NORM. This property does not change even if the last contour block for G451 is extended
with a straight line or a circle.Additional circumnavigation strategies to avoid a contour
violation in the vicinity of the contour end point are therefore not required.
If the end point is behind the contour, a circle or straight line is always inserted depending
on G450/G451. In this case, G460-462 has no effect. If the last traversing block in this
situation has no intersection with a preceding block, an intersection with the inserted
contour element or with the straight line of the end point of the bypass circle to the
programmed endpoint can result.
If the inserted contour element is a circle (G450), and this forms an interface with the
preceding block, this is equal to the interface that would occur with NORM and G461. In
general, however, a remaining section of the circle still has to be traversed. For the linear
part of the retraction block, no further calculation of intersection is required.
In the second case, if no interface of the inserted contour element with the preceding
blocks is found, the intersection between the retraction straight line and a preceding block
is traversed.
Therefore, a behavior that deviates from G460 can only occur with active G461 or G462
either if NORM is active or the behavior with KONT is geometrically identical to that with
NORM.
8.11 Smooth approach and retraction
Tool offsets
8-57