Siemens Sinumerik 840D sl Programming Manual page 271

Figure 11-3
Selecting the approach and retraction direction
Use the tool radius compensation (G140, default setting) to determine the approach and
retraction direction with positive tool radius:
● G41 active → approach from left
● G42 active → approach from right
G141, G142 and G143 provide further approach options.
The G codes are only significant when the approach contour is a quadrant or a semicircle.
Fundamentals
Programming Manual, 01/2015, 6FC5398-1BP40-5BA2
Approach movements with simultaneous activation of the tool radius compensation
Tool radius compensation
11.4 Smooth approach and retraction
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