Need a little help to get going

[ad-rock]

I have a brand new CNC esab shadow 250amp plasma/oxy-fuel torch, and i've had it going pretty good thing is im cutting 3/4 plain old carbon steel plate and (with the plasma head) i keep blowing out the sheilds and damaging the nozzles before their time. The electrode seems fine and i have all the paramaters set to the specs in the manual. The voltage is set right the electrode is new the shield and nozzles are new but within id say 20 min of run time the shield burns a slot to one side and the nozzle goes with it, the electrode is usually fine. if anyone has any solutions or advise for a total beginner to the plasma game i would be greatful.

[Torchhead]

Make sure your air is clean and dry. Make sure the workclamp is attached directly to the material being cut. Are you piercing in the plate or at the edge? Do you have a Torch Height Control? If not you need to make sure the material is VERY flat and level. Tip gap needs to remain constant across the sheet.

The piercing sequence will affect tip life if not done correctly. On thick material piercing at too low a level will splash molten steel back at the tip and cause nasty clogs or "tracks". 250A is a big unit and there is a lot of power there. 20 min of cut on 3/4 may be close to the lifespan of the nozzles. (question for the ESAB rep) I find electrodes outlast nozzels about 3:1.

Ask your ESAB rep to give you suggested pierce heights. The rule of thumb is to pierce as high as you can and still get penetration then lower the tip to the correct cut height after the metal has been pierced.

[accuratemike]

Sounds like the job is better suited to your oxy/fuel torch. Thicker stuff is the forte of oxy/fuel. Even my converted hand torch makes light work of 3/4" plate. Here is a 3/4" job I did with mine:
http://www.accuratepower.com/Rest/
I didn't even have to touch the edges with the grinder. Folks have looked at it and said the cuts look better than they can expect from their plasma. (no taper, no dross etc.) Give it a shot, I'll bet you are pleased, MIKE