cutting stainless/ dross issue

[twicecustom]

Im having problems cutting Stainless. I did a search but it wouldn't give me anything. I have a miller Spectrum 625 extreme, its an air plasma. I am getting dark brown/black dross that is real hard to get off. I looked at other sites and they say you can get good cut quality with an air plasma. The manual says I can cut stainless. does anyone have any ideas what I can try?

[greenweanie]

We use nitrogen and O2 on all of our stainless.

[DXF]

I have cut stainless steel for over 10 years with a Hobart AirForce 375 plasma cutter. I usually cut 304 stainless and connect the ground clamp directly to the piece. I think it cuts better than any metal I have cut but it is so expensive! I do get a little slag and I use a 4.5" grinder with a 100 grit pad to clean it off. It cleans up real nice. Here are some settings I use:

22 gage
speed - 44 ipm
pierce time - .76
amps - 18

18 gage
speed - 28
pierce time - .81
amps - 18

16 gage
speed - 26
pierce time - .94
amps - 18+

14 gage
speed - 26
pierce time - .92
amps - 19

12 gage
speed - 20
pierce time - 1
amps - 22

10 gage
speed - 12
pierce time - 1.2
amps - 21

Dave Hanks

[jimcolt]

If you can give me a little more information I can probably help you get better cut quality. The Miller 625 torch is manufactured for Miller by Hypertherm....it is very similar to the torch used on the older Hypertherm Powermax1000, 1250 and 1650 machines.....all of which cut stainless very well.

If you can let me know:

1. Are you cutting by hand or machine cutting?
2. If machine cutting....what type of cnc machine are you using? Does it have a height control system?
3. What thickness stainless are you cutting?


Jim Colt Hypertherm

Im having problems cutting Stainless. I did a search but it wouldn't give me anything. I have a miller Spectrum 625 extreme, its an air plasma. I am getting dark brown/black dross that is real hard to get off. I looked at other sites and they say you can get good cut quality with an air plasma. The manual says I can cut stainless. does anyone have any ideas what I can try?

[twicecustom]

Its a home built CNC and I have LCTHC height control. 18g stainless. From what DXF's settings are, Maybe I'm just way to hot. I'm Going to go cut a couple test pieces with less amps and see what happens.
Benjiman

[Eagle Mtn Metal Works]

Hey Ben
Ck your air supply that you don,t have oil or water in it

[twicecustom]

Well I cranked it all the way down, 20amps. And it still did the same black hard dross. Ill take a couple pictures this afternoon and go from there.

[jimcolt]

Ideally, with your torch running at 40 amps on 18 gauge stainless....you want to be running at about .06" (1/16") off the plate, using a machine shield (not a shield designed for hand held cutting as these are designed to drag directly on the plate) and at a cut speed of a little over 300 inches per minute. Slower will cause dross and warpage.

realizing that you machine may not be stable...or may not be able to achieve 300 ipm, you will have to experiment with a combination of lower amperage and speed. I suggest setting the amperage to about 30 to 35, try cutting at 150 ipm....adjust your height control so that during steady state cutting the height is .06" off the plate (lowering the voltage will make it closer, raising will make it higher). Running the torch close to the plate is absolutely critical on stainless....and if you are using the hand cutting shield (the hand shield has castelations machined into the face, the machine shield is smooth on the face) the torch will be too far away from the plate unless it is dragging.

Jim Colt Hypertherm

Its a home built CNC and I have LCTHC height control. 18g stainless. From what DXF's settings are, Maybe I'm just way to hot. I'm Going to go cut a couple test pieces with less amps and see what happens.
Benjiman

[MrFurf]

finding some of this information very useful and going to give some it a shot next time i get to shop to cut.

i use a vicon plasma cutting system and the boss just left me 30 pieces of 20 by 48 18 gauge stainless steel he cant use so it all mine to play with. been burning several items members have posted here yesterday, but after initial cuts ive found the stainless warps quickly with the cuts so close together.

fortunately i have lots of metal to waste but still trying to perfect close cutting without warping the metal.
ill probably mount the rollar ball shield on torch to help keep proper distance when metal warps.