Siemens SINUMERIK 840D sl Function Manual page 53

Special features
● KONT only differs from NORM when the tool start position is behind the contour.
Figure 2-3
● KONT and G450/G451 (corner behavior at outer corners) has a general effect and
determines the approach and retraction behavior with TRC.
● When tool radius compensation is deselected, the retraction behavior is determined by
the NORM/KONT instructions.
Supplementary conditions
The approach and retraction blocks are polynomials in the following two variants. Therefore,
they are only available for control variants, which support polynomial interpolation:
● KONTT
With KONTT, approach and retraction to/from the contour is with a constant tangent. The
curvature at the block transition is not usually constant.
● KONTC
With KONTC, not only the tangent but also the curvature is constant at the transition, with the
result that a jump in acceleration can no longer occur on activation/deactivation.
Although KONTC includes the KONTT property, the constant tangent version KONTT is available
on its own, because the constant curvature required by KONTC can produce undesired
contours.
Tools
Function Manual, 06/2019, A5E47435126B AA
Example for selecting TRC with KONT or NORM in front of and behind the contour
W1: Tool offset
2.5 2D tool radius compensation
53