Bad plasma cut...why?

[quicken]

Background: I'm using a Multicam 1000 with a 1250 Hypertherm set at 80amps cutting 16 gauge cold steel.

Problem: I'm trying to cut out new ribs for the bed of the laser and when I'm cutting the steel it'll get about 60% complete and then the cut fades away for about 30" and then stops cutting completely.

Could this be from "dirty" steel (like oil on the surface)? Or some other phenomena?

Has anyone seen a cut like this before?

Thanks for any input.

David

[jimcolt]

By looking at the heat discoloration of the steel sheet it clearly looks like the torch height control on your MultiCam machine was not maintaining proper torch height. The Powermax torch needs to maintain .06" from the metal while cutting to maintain cut quality and penetration. The height controls function is to do this to compensate for warpage of the material, of for debriss buildup n table slats that will cause unlevel plate.

1. I suggest reviewing the operation of the torch height control functions on you system to ensure it is working correctly. MultiCam has a good tech service staff that can help you.
2. I also suggest that for 16 gauge steel you use a lower output power. For best cut quality switch to the Fine Cut consumables and follow the instructions for settings (speed, torch height, amperage, pierce height, pierce delay) that are in the Hypertherm operators manual. You cut quality will be much better. 80 Amps on 16 gauge will provide great cutting speeds but horendous cut quality.

Jim Colt

Originally Posted by quicken Background: I'm using a Multicam 1000 with a 1250 Hypertherm set at 80amps cutting 16 gauge cold steel. Problem: I'm trying to cut out new ribs for the bed of the laser and when I'm cutting the steel it'll get about 60% complete and then the cut fades away for about 30" and then stops cutting completely. Could this be from "dirty" steel (like oil on the surface)? Or some other phenomena? Has anyone seen a cut like this before? Thanks for any input. David

[PlasmaCraft]

I have seen this when the air pressure/air volume is restricted as well. First, watch the air guage on your regulator and see if it is dropping. Does the air compressor kick on as this starts to happen? Second, make sure the solenoids in the pasma are working properly. If your air quality is poor, water, oil, or excessive particles, this could clog those solenoids and also greatly affect the cut. Do you have a clean, dry, oil free air system? Air quality, Air pressure, and Air volume all affect the cut dramatically. This in turn affects the torch height control that Jim is reffering to. If the air flow or pressure is restricted or contaminated in some way, the torch will slag, not go all the way through, or shut off as well as start dragging the plate.

I hope this info helps.

Jonathan White
PlasmaCraft, Inc.