Rounding In Compliance With Defined Tolerances (G642/G643) - Siemens SINUMERIK 828D Function Manual

3.3.3.2

Rounding in compliance with defined tolerances (G642/G643)

Function
In continuous-path mode involving rounding in compliance with defined tolerances, the rounding normally takes
place while adhering to the maximum permissible path deviation. Instead of these axis-specific tolerances, the
maintenance of the maximum contour deviation (contour tolerance) or the maximum angular deviation of the tool
orientation (orientation tolerance) can be configured.
Note
Expansion to include contour and orientation tolerance is only supported on systems
featuring the "Polynomial interpolation" option. When rounding in compliance with the
orientation tolerance, the additional option of "orientation transformation" is also necessary.
Activation
Continuous-path mode with rounding in compliance with defined tolerances can be activated in any NC part
program block by the modal command G642 or G643.
Selecting the exact stop which works on a block-by-block basis enables rounding to be interrupted (G9).
Continuous-path mode with rounding in compliance with defined tolerances (G642/G643) can be deactivated by
selecting:
• Modal exact stop (G60)
• Continuous-path mode G64, G641, G644 or G645
Differences between G642 - G643
With regard to their rounding behavior, commands G642 and G643 differ as follows:
G642
With G642, the rounding path is determined on
the basis of the shortest distance for rounding all
axes. This value is taken into account when
generating a rounding block.
With G642, the rounding area results from the
smallest tolerance setting.
Parameter assignment
Maximum path deviation
The maximum path deviation permitted with G642 / G643 is set for each axis in the machine data:
MD33100 $MA_COMPRESS_POS_TOL
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
B1: Continuous­path Mode, Exact Stop, LookAhead
G643
In the case of G643, each axis may have a
different rounding path. The rounding travels are
taken into account axis-specifically and block-
internally ( ⇒ no separate rounding block).
Very different specifications for the contour
tolerance and the tolerance of the tool orientation
can only have effect with G643.
3.3 Continuous-path mode
163