So much slag!!

[atcig]

Ok I get almost all of my metal for art from different scrap places. This was stamped 12GA RA309. The slag on it is crazy and it doesn't chip off. I also can barley get it off with pliers, I had to grind it off. What the heck am I doing wrong? I haven't had this problem on anything else. Is it me or the metal?

[WookieWelding]

thats a exotic stainless with a HIGH Chromium content
http://www.rolledalloys.com/trcdocs/...309_Bul109.pdf
Cutting
Heat resistant alloys may be dry abrasive sawed, sheared,
laser or plasma arc cut. Shears will cut these alloys up to
about two-thirds the mild steel thickness rating. That is, a
shear rated 3/8" mild steel will generally cut 1/4" nickelchrome-iron alloy. Heat resistant alloys cannot be cut
by oxyacetylene or carbon air-arc equipment. Plate
through 3" thick is routinely plasma arc cut at Rolled
Alloys.

I am thinking it is the material not the machine operator

[Gadget]

I always get a lot of tough snot on the bottom of stainless cuts. I think it's just what you have to live with for that metal. I really don't like cutting stainless with plasma because of this.

[Charley Davidson]

Even with my little baby crapola plasma cutter I get good results with stainless, I cut all of my stainless for the tanks in my bus with my buddies Thermo-dynamics plasma cutter and it cut like butter and looked like it was sheared.

[atcig]

Thanks! I only have two pieces of it and I already used most of one - it's not that bad to just grind it down after I cut it. I just wondered what the heck was up.

[KHK]

I cut some .07 SS with my 200pi. The slag on the left side of the picture is when I was cutting free hand the slag was tough to remove. Center to right and vertical I used a guide. The slag there is minimal and easily removed with a file.

I think that your problem is due to the type of SS and torch movement. It could also be torch height, air pressure, current setting.

[ISKI]

I always use a four wheel holder on a guide rail for Stainless and go very slow. This yeilds a cut with very little slag. If I wobble side to side, I get a lot more slag. I wonder if you have the air too low and/or the current too low for the feed rate and are sort of melting vs oxidizing? It could also be some sort of exotic stainless that pulls the heat away too fast for a good cut to happen. It also looks like the cut is very wide and you may only need to put on a new tip to correct the cutting action.

[atcig]

The cut was wide but the tip was brand new. What you are seeing in the picture is not the cut, the cut wasn't nearly that wide. That is the piece laying on to of what I cut it from. Here is a different pic of it.

[LONGEVITY]

What PSI are you running? I believe you will need to turn it up or down depending on your setting. Also, make sure you crank the unit all the way.

[SICFabrications]

WHOA!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !! dood, high chromium content beware!!! if you arent wearing an approved metal particulate breathing apparatus, well, lets just say, dont cut that junk...

I'm going to do a little math problem to show you what you're up against.

The PEL for Cr[VI] is 5 micrograms/m^3.

Lets plasma cut a 1/8" thick sheet of 304SS.

304SS is 18-20% Chromium. We will assume it is 19% for the calculation.

We will also assume that in the plasma arc, all metalic chromium is oxidized to the +6 valence. We will use a 1/8" kerf for the calculations as well.

SS has a density of 8000kg/m^3 or 8g/CC. So each CC of stainless has 19% of 8g, or 1.52g chromium.

A cut 1/8" thick by 1/8" wide is .32cmx.32cm. To get 1CC, the cut needs to be 1/(.32^2) or 9.76cm long. This is 3.84" long. This is how long the cut must be to vaporize 1 CC of stainless (which vaporizes 1.52g of chromium).

1.52 grams is 304,000 times 5 micrograms, so you'd need to dilute it in 304,000 cubic meters of air to meet the PEL of 5ug/m^3.

Assuming 16' tall ceilings (4.88m), the empty building of air needed to dilute this amount of chromium would have to be 62,300 sq meters or 671,000 sq feet. This is a 15.4 acre building with 16' high ceilings.

Even if only 1% was oxidized to +6 and suspended in the air, you'd need 6,700 sq feet to dilute it to the PEL!

And thats for cutting about 4" of 1/8" stainless.

How much do you cut in a typical project? 10 feet? 100 feet?

A football field (including end zones) is 360'x160'. If you cut 100 feet of 1/8" stainless, and only 1% stayed airborne, you'd need the air contained over 36.4 football fields with a 16' ceiling to dilute it to the PEL.

So cutting, grinding, and stick welding will put you way over the PEL in a hurry. And drawing it out with negative pressure will put the people downwind above the PEL. But the PEL is so low that even TIG welding might do it.

this is a copy n paste from another of my posts, but whatever.... the stuff youre dealing with has a higher chromium content then 304 SS... ever watch the movie "erin brokovich"? all those peeps were screwed for life because of hex chrome poisoning