I think I already responded to this question in a direct email...here was my response knowing that the cnc machine was using CandCNC equipment with Mach3 operating software:
A couple of things:
1. The air pressure setting on the front panel of the Powermax 45 should always be set at the optimum setting. This is the secondary (lower) cutting pressure for the torch…….it is different than the inlet pressure which is monitored by a pressure switch. By setting the pressure on the LED bars higher….you are shortening your consumable life rather dramatically!
The rear panel inlet pressure for a Powermax45 needs to be anywhere in the range of 85 to 125 psi….and this is with the air flowing at the torch with the front panel air pressure set correctly. I always suggest installing an air gauge right at the inlet (not upstream in your plumbing system….must be right at the rear)(see picture ). To make the air flow at the torch to set the front panel pressure and monitor the rear inlet pressure…turn the amperage knob fully counter clockwise.
If you have a gauge in place on the rear panel I would suggest monitoring it to see if your inlet pressure is dropping. If it gets to 85 psi or less during a cut….an internal pressure switch will shut off the DC power, extinguishing the arc. This is to protect the torch and consumables from catastrophic failure due to inadequate air flow. It is possible that your compressor may not be keeping up with the demand, and low air pressure may be shutting the system down. Measuring pressure closer to the compressor is not going to show the natural pressure drop through your air plumbing system.
So, if your Mach software is set up to refire the torch after the arc was lost, I suspect that the air pressure momentarily gets below 85 psi, the Powermax45 pressure switch shuts the unit down, the Mach notices loss of arc and releases the start then reactivates it. The plasma will not refire if the start input remains active, it will if the start signal opens then reactivates….so the Mach would have to play a role in this as well.
Hopefully this helps.
Best regards, Jim Colt