Siemens SINUMERIK 828D Programming Manual page 315

Motion steps between start point and end point (G340 and G341).
The approach characteristic from P
In cases which include the position of the active plane G17 to G19 (circular plane, helical
axis, infeed motion perpendicular to the active plane), any active rotating FRAME is taken
into account.
Length of the approach straight line or radius for approach circles (DISR) (see figure
"Selecting approach/retraction contour")
● Approach/retract with straight lines
● Approach/retract with circles
Fundamentals
Programming Manual, 07/2010, 6FC5398-1BP40-0BA0
DISR specifies the distance of the cutter edge from the starting point of the contour, i.e.
the length of the straight line when TRC is active is the sum of the tool radius and the
programmed value of DISR. The tool radius is only taken into account if it is positive.
The resultant line length must be positive, i.e. negative values for DISR are allowed
provided that the absolute value of DISR is less than the tool radius.
DISR specifies the radius of the tool center point path. If TRC is activated, a circle is
produced with a radius that results in the tool center point path with the programmed
radius.
10.4 Smooth approach and retraction
to P is shown in the figure below:
0 4
Tool radius compensation
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