Siemens SINUMERIK 840D sl Function Manual page 211

Requirements
● The smoothing of the path velocity is only effective in continuous-path mode with
LookAhead over multiple blocks with SOFT and BRISK. Smoothing is not effective with G0.
● The controller's cycle times must be configured in such a way that preprocessing can
prepare sufficient blocks to enable an acceleration process to be analyzed.
Activation/deactivation
The "smoothing of the path velocity" function is activated/deactivated with the machine data:
MD20460 $MC_LOOKAH_SMOOTH_FACTOR (smoothing factor for LookAhead)
Value
0.0
> 0
A change in the MD setting is only made effective through NEW CONF.
Parameterization
Smoothing factor
The smoothing factor is set via the channel-specific machine data:
MD20460 $MC_LOOKAH_SMOOTH_FACTOR (smoothing factor for LookAhead)
The percentage value defines how much longer a processing step without accelerations/
decelerations may be than the corresponding step with accelerations/decelerations.
This would be a "worst-case" value, if all accelerations within the part program, except the
initial approach motion, were smoothed. The actual extension will always be smaller, and may
even be 0, if the criterion is not met by any of the accelerations. Values between 50 and 100%
may also be entered without significantly increasing the machining time.
Consideration of the programmed feed
The path velocity can be smoothed with or without taking the programmed feedrate into
consideration. The selection is made via the machine data:
MD20462 $MC_LOOKAH_SMOOTH_WITH_FEED (path smoothing with programmed
feedrate)
Value
0
1
When considering the programmed feedrate, the specified smoothing factor (see MD20460)
is maintained better when the override is 100%.
Axis-specific limit frequencies
The axis-specific limit frequencies are defined via the machine data:
MD32440 $MA_LOOKAH_FREQUENCY (smoothing frequency for LookAhead)
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Meaning
Smoothing of the path velocity not active (default)
Smoothing of the path velocity active
Meaning
Programmed feedrate is not taken into consideration.
Programmed feedrate is considered (default setting).
B1: Continuous-path mode, Exact stop, Look Ahead
4.4 Dynamic adaptations
211