Siemens SINUMERIK 840D sl Function Manual page 56

W1: Tool offset
2.5 2D tool radius compensation
KONTT and KONTC compared
The figure below shows the differences in approach/retraction behavior between KONTT
and KONTC. A circle with a radius of 20 mm about the center point at X0 Y-40 is compensated
with a tool with an external radius of 20 mm. The tool center point therefore moves along a
circular path with radius 40 mm. The end point of the approach block is at X40 Y30. The
transition between the circular block and the retraction block is at the zero point. Due to the
extended continuity of curvature associated with KONTC, the retraction block first executes a
movement with a negative Y component. This will often be undesired. This response does not
occur with the KONTT retraction block. However, with this block, an acceleration step change
occurs at the block transition.
If the KONTT or KONTC block is the approach block rather than the retraction block, the contour
is exactly the same, but is simply machined in the opposite direction, i.e. the approach and
retraction behavior are symmetrical.
Figure 2-6
Note
The figure shows that a straight line bordering on the contour quadrant, e.g. to X20 Y-20, would
be violated with KONTC on retraction/approach to X0, Y0.
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Differences between KONTT and KONTC
Function Manual, 06/2019, A5E47435126B AA
Tools