Smoothing Tolerance Ctol, Otol, Atol; Path Reference Upath/Spath - Siemens SINUMERIK 828D Manual

3.7
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Important functions for 3- to 5-axis machining
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3.7.4 Smoothing tolerance CTOL, OTOL, ATOL

The tolerance for linear and rotary axes for smoothing was previously set with CYCLE832. As of
SW 2.7 this is implemented via the functions CTOL (contour tolerance), OTOL (orientation
tolerance), and ATOL (axis-specific tolerance).
The CTOL, OTOL, and ATOL commands can be used to adapt the machining tolerances defined
for the compressor functions (COMPCAD), the smoothing types G645, and the orientation
ORISON using machine and setting data in the NC program.
The tolerance value for CTOL is set by CYCLE832. OTOL is calculated in the cycle. Since OTOL
also has an effect on ORISON by default, it is important when activating ORISON in the cycle (or
manually) to ensure that the orientation tolerance is not too great, because otherwise too much
orientation smoothing will result. In most cases, over-smoothing occurs during roughing
operations.

3.7.5 Path reference UPATH/SPATH

During polynomial interpolation, there may be a requirement for two different relationships
between the velocity-determining FGROUP axes and the other path axes. The path axes that are
not included in the FGROUP should either be routed synchronously to the path of the FGROUP
axes or to the curve parameters. Therefore, for the axes that are not contained in FGROUP,
there are two ways to follow the path:
SPATH synchronous to path S
UPATH synchronous to the curve parameter
Both types of path interpolation are needed for different applications and can be changed over
via G codes SPATH and UPATH.
UPATH is recommended for programming with active 5-axis transformation (TRAORI) and
is preset in the manufacturer cycle CUST_832.
© Siemens AG All rights reserved SINUMERIK, Manual, Mold-Making with 3- to 5-Axis Simultaneous Milling
Feedforward control.
In cases where axes are not feedforward-con-
trolled, the following error results in a contour
error whose severity is determined by the
velocity
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in the form of a narrowing of the radius
curved contours. The following error depends
on the servo gain factor that is set (dependent
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on mechanics) and the axis velocity.
1
The FFWON feedforward control function
brings the velocity-dependent following error
down toward zero during path traversal. Tra-
versing with feedforward control permits
.
higher path accuracy and thus improved
machining results.
.
. Generally, this will manifest itself
on
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