Siemens SINUMERIK 828D Function Manual page 1463

W1: Tool offset
18.5 Tool radius compensation 2D (TRC)
Figure 18-14 Approach and retraction with constant curvature during inside machining of a full circle: 3D representation.
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
blocks 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.
Basic Functions
1463
Function Manual, 09/2011, 6FC5397-0BP40-2BA0