CNC deviation error

[Alex S.A]

Hi everyone,

I have one problem that let me crazzy!!!
There is one CNC that show on its display deviationn error in axies.
The CNC controls one machine that execute cutting with oxyfuel process.
At most time the error happens when the CNC actives the solenoid and ignition so that I conclude that some interference can be causing that problem.
I checked the grounding of equipment and it is okay. The resistence ground is less than 1 ohm.
The machine block diagram shows that there is one board between solenoid, ignition and the CNC. It works like this: The CNC sends a signal to this board that close one contact from relay then actives the solenoid or ignition. On this board there's many relays that actives the devices. The function of relay when it is used as interface is isolater to avoid interference. Am I right ?
Does someone has any suggestion to avoid this problem at CNC?
The CNC is one Vision Le manufacturer by ESAB. I think in change the board that cointain the relay or improve the grounding of the board.



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[Al_The_Man]

You should have interference suppression on both control relays and solenoids, in the case of DC operated devices it can be a Rectifer Diode wired across the coil (diode + to supply +), and in the case of an AC device a R/C (resistor capacitor 'snubber') connected in series and placed across the coil. Typical values are 220ohm and .5mfd cap. rated at the voltage you are using.
My experience is that alot of this kind of interence comes from AC contactors and solenoids being caused by not using the above mentioned snubber.
Al

[arvidb]

You should probably use an 0.5 uF (microfarad) cap, not a 0.5 mF (millifarad) one. The latter will be very expensive, too.

(Al, please correct me if I'm wrong.)

Arvid

[Al_The_Man]

I guess I will have to remember to use alt 230 (µf).
Al

[arvidb]

Thanks for the tip! (When I need a special character, I always use the Windows "Character Map" program, which is something of a pain...)

I'll remember the alt 230!

Arvid µ (yep it works )

[Alex S.A]

Al,
You meant to say across as parellel?
Sorry but my english is not so good at times :-)

[Al_The_Man]

Alex, Yes, the suppression device should be wired in parallel to the coil you are trying to supress.
Al