PM65 Machine Torch Problem

[Jacky Elliott]

During a cut my candcnc controlled DTHC IV jump up during cutting and the next cut even higher and leveled out there. Making the same cut it was high again and the arc volts were matching the set volts, so THC seemed to work. It was not cutting through so I slowed it down from 180ipm to 150ipm and lowered the set volts from 125 to 110. It still did not cut through. It was running 65 amps according to the DRO. I manually fired my torch from mach 3 to see what the DRO would show and the the pilot arc would not stay for more than a split second. Unless it connects with metal. Usually it would stay on for a bit before the Hypertherm would shut it off. At this I connected my hand torch and fired it. The pilot arc stayed and it had no problem cutting through the 10 gauge. Even while cutting it a little high. So question I have is what could possible be wrong? I changed my electrode and nozzle to no avail. I am concerned there is something wrong with my machine torch but I don't know how to check it. Any suggestions?

[Jacky Elliott]

Any Ideas on how to trouble shoot my torch?

[sphurley]

Is the electrode getting stuck in the swirl ring?
Material is connected to the Plasma return cable?

[jimcolt]

-Could be a worn out swirl ring, a worn retaining cap.

-Could also be a bouncing start input signal (electrical noise, to troubleshoot you would need to wire a switch in parallel with the start output relay on your CandCNC system....or to pins 3 and 4 on the PowermaxCPC port, activate the switch to fire the torch and see if the pilot stays active for the normal time.

Change swirl ring and cap separately (to determine the culprit).....if they do not solve the problem do the start input test.....which will isolate the problem to either the plasma (unlikely since the hand torch works) or the CNC output.

Jim Colt Hypertherm

[Jacky Elliott]

Thanks Jim I will do that and see what I can come up with.

[Jacky Elliott]

So I changed the swirl ring, no change, changed cap, no change, figured for the heck of it I'd fire it without the shield and it fired for the full 5 seconds. I then put my drag shield from my hand torch on it and again it went out immediately. Don't know if it would work anyway, just tried it. Then I put my fine cut consumables in with shield for it and it worked correctly again. Luckily I could cut the 10 gauge with the fine cut but obviously would be slow. Do you think it's just the shield? Or maybe in conjunction with something else? Air pressure or something? The only thing I would know to do at this point is to run to town and hope someone would have a shield in stock. Any thoughts?

[Jacky Elliott]

So I was able to find a shield. No change. Curious case I suppose. So thinking logically, what could be different with and without shield? Could air pressure be an issue? If so what do I need to check? Admittedly I am running higher pressure than what is recommended. Didn't realize this until I started digging. Not sure what else it could be hopefully Mr. Jim Colt you got some ideas.

[Jacky Elliott]

Spoke to a hypertherm expert. He give me a little more help. Schooled me up on how the consumables work inside the torch. Didn't know how the electrode moved with the air pressure. Which makes since if it's not retracting as it should, then the torch must raise up to maintain the correct arc voltage. Light bulb went off. Knowing this, we checked the air pressure from the utility screen on the pm65. It showed 78 as it was set for. After changing the swirl ring, cap, electrode, nozzle and shield to no avail, we came to the conclusion that the air line in the hose must have been kinked. He told me that there should be no less than a three inch radius on the torch hose. Another words, six inch circle minimun. I was greater than that radius but not much more near my Z axis. Maybe that was my problem area. Hypertherm is going to warranty the torch. I will post the results when I get it put back together. Thanks guys for your help. I just didn't know enough to comprehend what you guys were suggesting. I appreciate the feed back.