Fagor CNC 8060 - Page 128

·128·
Installation manual
CNC 8060
CNC 8065
2.
MACHINE PARAMETERS.
(REF: 1402)
Machine parameters for the axes and spindles.
"Low passing" filter.
If the machine shows the resonance frequency at the end of its passing band, it will be enough
to eliminate it using a "low passing" filter.
These filters are also used to limit a jerk whose parameter has been set too high for the
machine but necessary to make it run faster. This way, the CNC smoothes the movements
out although it has the drawback of slightly rounding the corners off.
• The "low passing" filter, for the same frequency requires a lower order and consecuently
adds a shorter delay.
This type of filter inserts a variable (non constant) phase shift depending on the
frequencies. This phase shift can cause a change on the path if it is not executed at the
same feedrate as, for example, when changing the feedrate override percentage or when
moving back and forth on the same path.
• The "FAGOR low passing" filter inserts a constant phase shift regardless of the frequency.
This type of filter needs a higher order to apply the same amount of filtering.
Anti-resonance filter (band-rejection, notch filter).
If the machine shows the resonance frequency in the middle of its passing band, it will be
a good idea to eliminate it using a "notch" filter.
FREQUENCY
Cut-off or center frequency.
Parameter valid for linear and rotary axes and spindles.
Parameter valid for analog drive, Sercos and simulated.
Possible values: from0 to 500.0 Hz.
Default value: 30.0 Hz.
Associated variable: (V.)[ch].MPA.FREQUENCY[nb].xn
Parameter included in the FILTER table.
On "low passing" filters, this parameter indicates the break point frequency or frequency
where the amplitude drops 3 dB or it reaches 70% of the nominal amplitude.
-3 dB = 20 log (A/Ao) ==> A = 0,707 Ao
On the band-rejection filter (notch filter), this parameter indicates the center frequency or the
frequency where the resonance reaches its maximum value.
Ao
f
FREQUENCY
0,707·Ao (-3dB)
A
f
ff
1
2
FREQUENCY
A
Ao
0,707·Ao (-3dB)