[IPSracing]

Hi everyone, our plant is currently having issues with arcing or grounding on the retaining caps of our plasma center. We have a Messer setup...running the Hypertherm HPR400XD...with the Hypertherm 220637 200amp retaining caps. I'll post up a pic so everyone can see what I'm talking about. I talked to Technical support at Hypertherm and they said this is a common issue if the material being cut follows sideways and arcs against the retaining cap when it starts to cut.....the company owner here wants me to pursue the issue though. Wanted to get everyone's opinion on the matter.

[s-euteneier]

Do you pre pierce what you are cutting. If not it could happen when the torch touches the slag puddle. Also are you cleaning the slag off the tip of the torch often, or letting it build up? How good is the connection between the plate and the table? Do you have a lot of slag on the slats? When you are cutting does the scrap bow up and touch the side of the torch?

[IPSracing]

We do some pierce cutting yes. I'm honestly not sure if the operators are cleaning the tips or not. The table is only 2 months old...pretty clean. I checked the grounding strap going from the plasma head to the main unit...it is in like new condition. Yes...I didn't notice that sometimes the scrap does bow up.

[jimcolt]

The arcing to the side of the cap generally occurs if you are cutting...and the retaining cap comes in contact with a piece of metal that has bowed up. This will cause the internal cutting arc to double arc through the cap to the metal....and eventually will destroy the cap.

This is not always avoidable, however the following tips will minimize the chance of this:

- be sure that if you have thin sections to cut...that they are done in an order that will minimize contact.
- If you see a piece of scrap that is bowed upwards....stop the torch, remove the scrap then resume cutting.
- Nest your parts with wider scrap webs to minimize bow.
- If you use a water table...raise the water to minimize warpage.

Jim Colt Hypertherm