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I had a guy contact me about cutting out a grill for his tractor from 16 gauge stainless steel. His only concern is that there will be discoloring along the cut edge from the plasma, i havent cut stainless yet but read that if you cut it in water you eliminate the burn marks? if so does the peice need to be submerged in water when cutting?
EDD
All steel changes color when heated beyond a certain point. It's hard to see in mild steel with black mill scale. The heat effected area varies based on the time of exposure and amount of heat. The discoloration is a form of oxidation so the air surrounding the cut feeds the process. You can limit the heat discoloration by keeping the metal on either side of the cut below the temperature that causes the reaction. By having the stainless setting on water (water touching the back of the material or slightly submerged) you can keep discoloration to a very narrow area or none at all. You can also remove minor discoloration using several acid based pickling agents.
TOM CAUDLE
www.CandCNC.com
Modular CNC Electronics
Have when cutting stainless, that cutting on a water table stop materiel warping but no so much discoloration, using N2 as a purge, which can be used on air torch, helps with oxidation (no O2, except for whats in the water, which is what causes oxidation). I do a fair amount of polished stainless, and even with all the troubles I have had recently with Fine Cuts, running regular 40A seem to do okay. A little buffing and the discolor is about as noticeable as a laser cut. I'll even add, I leave the laser coat on the stainless when cutting. Just a little more cleanup. But It's better than scratches or arc marks.
Just polish it up with a palm sander when your done. I would start with 100 grit, move to 220 then 400, it will look nice. If you run 16ga dry, I would expect warpage, water table is the way to go.
Thanks guys, i think i may make a water tray to sit on my slats and try it out.
EDD