Plasma Amperage Control Setting

[Errol]

Up till now I roll outside to do my cutting because of the smoke. But in this cold weather, minus 25 degrees for the past two weeks, I'm working inside the shop.

I have a Spectrum 625 with an Amp range of 15 to 40. I'm cutting up some 4' x 8' x 1/8" steel plate and the smoke is pretty bad.

A few years ago I had phoned the dealer about where to set the Amp control. He said just set to Max and leave it there. So that's what I have been doing until now. Fine outdoors, but not indoors.

So with a little experimenting, I tried lower Amp settings, and seem to cut with less smoke, but eventually there is a trade off. Lower Amp setting seems to produce less smoke, but then the time increases to the point that there doesn't seem to be a benefit. i.e. less smoke/second x more seconds = same quantity of smoke.

I eventually got it set it at 35, and get pretty quick cuts with none of that black/yellow smoke that you get at 40.

Question: Is there a "rule of thumb" for Amp settings vs smoke output?

[piniongear]

H-ummm, smoke using a plasma cutter?
That is a new one on me.
In all of the plasma cutting I have done, smoke has never been a problem. In fact I have not ever noticed any smoke from the process.
Question: You are not cutting galvanized metal are you? That's the only material (burning zinc) that would emit fumes that I can think of..........pg

[Errol]

Not galvanized for sure. Just mild steel plate.

[macona]

In general unless you are doing sheet metal its best to leave it at full power. With a lower current you will get a smaller kerf and less heat so less smoke. The smoke is mostly iron oxides and nitrides. And it sticks to everything. Even with a vent hood above you it can be hard to contain. If you have ever been to a shop with a CNC plasma look up. The ceiling will be stained even if they have a fume extractor.

[Errol]

Yes, thanks Macona. And you are right about the soot. My white painted walls are already yellowing. The fluorescent lights are totally yellow/brown.

What I find makes the worst smoke is high amperage, light gauge sheet metal and quick cuts. Slowing down travel seems to help, so does reducing the amp output.

I will carry on as I have been doing, but I always wondered why the range of control on the output.