Electrode Stuck in Torch Head During Cut, Damaging Threads—Need Help Diagnosing Issue

CrossFire ® PRO Troubleshooting
1

I’ve encountered a recurring issue with my Langmuir CrossFire Pro CNC plasma table and Everlast PowerPlasma 62i machine torch, and I’m hoping someone can help me figure out what’s going on.

The machine cuts fine at first, but partway through, the cut fails—either it stops cutting all the way through the material, or the cut quality drops significantly. When I inspect the torch and change the consumables, I find the electrode is almost stuck in the torch head. When I finally manage to unscrew it, I see the threads inside the torch head are damaged, making it impossible to screw in a new electrode.

This has happened twice now, and both times I’ve had to replace the torch head, which costs over $160. I’m trying to figure out what could be happening during the cut to cause this issue. Any advice or suggestions would be greatly appreciated!

Here are some details that might help diagnose the problem:

  • Electrode Installation: I’m certain I’m not cross-threading the electrode when installing it.
  • Cut Settings: Cutting 1/4" mild steel at 45 amps, 45 IPM. Pierce height is 1.4". Torch height is set to 0.038" in G-code (measured as 0.060" with feeler gauges).
  • Air Supply: Using 3/4" Maxline air lines with a Harbor Freight refrigerated air dryer, a 1-gallon desiccant dryer, and a Motor Guard filter. Air pressure is 75 PSI (machine reads 83 PSI, drops to and holds steady at 75 PSI during the cut).
  • Work Clamp: Attached directly to the workpiece.
  • THC: Enabled and working (using raw voltage).

Here’s what the damaged threads on the torch head look like after removing the electrode:

Let me know if any other information will be helpful

2

You can use an M5 tap to clean the threads up.

The main reason for that to happen is not enough post flow cooling. Set the post flow for as long as possible. 30 seconds, if possible.

Don’t use cheap electrodes, they sometimes don’t have the right thread pitch.

Permanent fix would be to switch to Hypertherm style torch like the UPM 105, which doesn’t use electrodes that screw in.

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3

so rather than getting angry, trying to force the electrode in and snapping it in half, I should next time clean up the threads… damn

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4

I had my post flow set to 24 seconds, ill increase it to 30 going forward (which, yes, George has told me to do before, I’m not sure why I had it lower…)

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5

If the electrode will not screw in by hand or after loosening it screw out by hand you need to clean the threads up in the torch head with a plug tip. If the threads are clean and the electrode is screwing in tight you need to clean the threads with a die as it may have a bent, nicked or chrome flashing in the threads. I have the taps and dies in stock if you need a kit.

I have used and dealt with the Trafimet and Tecmo style torch’s for over 25 years with the screw in electrodes and have only had this happen once and learned.

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6

Why so little post-flow?

You’re in good hands with George helping you, but anyone I talk to I always recommend at least 45 seconds of post flow.

This way in the event that you perform a long run, you’ve got plenty of air to help cool it. And if it’s a short run, that extra air isn’t hurting anyone…not like you’re paying for air anyway.

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