Stainless Steel dross!!! help

[exapprentice]

Hi everyone

Just started (Trying) cutting stainless steel (304, searched through loads of posts but couldn't find any answers to what to do next

Nothing like trying to make a hard job harder, just when I thought I had cracked this CNC plasma cutting thing it turns around and bites back.

Using 30 amp consumables on a m/c torch and a pm45 trying to cut 2mm / 14g st/st material.
checked through all the basics, clean air, enough air, new consumables etc etc all is good and as should be, I did start with book spec's but that gave me really bad dross and cut
did the initial test for cut height hence the 83 volt number (machine set up as per footer below)

settings: so far
CandCNCPlasma-rev11M1.scpost
PM set @ 30 amps
0.5mm / .020" cut height
1.5mm Pierce height
0.3 sec Pierce delay
2475mm/min feed
83 volts

front face of material looks good, minimal dross, not clean cut through, random stitches of dross remain and part is difficult to remove from sheet after cutting

Is there a rule of thumb to reduce the "Dross" on the back of the cut??? I think I should try going quicker but I am now running low on material left to play with
Does any one have a set up dialed in and working for 2mm / 14g st/steel who would like to share their experience with us??

[Thor]

I had to raise my cut ht up when cutting stainless as the .020" the torch kept running into the top side slag from pierce or whatever and messing up. In 14 ga though this is dross free on my machine with 45 amp finecut consumables.

Feed 170ipm
pierce ht .080"
cut ht .060"
volts 84
amps 45

[gamble]

I had to raise my cut ht up when cutting stainless as the .020" the torch kept running into the top side slag from pierce or whatever and messing up. In 14 ga though this is dross free on my machine with 45 amp finecut consumables.

Feed 170ipm
pierce ht .080"
cut ht .060"
volts 84
amps 45

Dross free stainless? I'm going to have to try that. I was cutting a lot of 14g stainless last night.
Book specs 280ipm, 45amps, 117v. Crap shoot most of the time. The torch was always too high unless sampling was on or it was just way too fast of a cut.I'm going to try your settings tonight

[jimcolt]

Use the 45 amp shielded consumables at the specs listed in your cut charts. The 30 amp consumables will not cut nearly as well. Stainless will never cut as good as steel...so use the book specs, if dross is excessive try faster and lower....be very vigilant about the height. Stainless needs good height control and likes to run very close to the material.

Jim Colt Hypertherm

[exapprentice]

Hi everyone

did a little more cutting based on Jim's recommendations above using book settings and it was ugly on the back
and then started plying with the settings
did loads of cuts at various settings and it stayed ugly until:

Biggest difference by far was turning the sheet over so the plastic film was on top or having no film at all
Really wished I had sorted that little issue out first as it would of saved shed loads of pain what a difference

best cut overall (dross, cut profile, cut finish etc) was:
CandCNCPlasma-rev11M1.scpost
PM set @ 45 amps
1.5mm cut height
2.0mm Pierce height
0 sec Pierce delay
4750mm/min feed
94 volts

Although @ 94v the cut height was lower than the 1.5mm book spec more like 1mm,
to hit the 1.5mm cut height the volts should have been 98v @ 6000mm/min and the part fell out into the tray but as said before the overall cut quality was better @ 94v (that didn't fall out though but it was loose and just lifted out)

The film on top made such a difference that I am going to go back and try the 30 amp consumable again (but with the film on top this time)

I will post the results when I have done some more cutting

[sphurley]

You shouldn't have the film on at all.

[SeanP]

Hi Pete,
I've never tried cutting with the plastic on, I just thought it would just melt and stick around the edge
Aye I'm not sure what I'm reading there
Must be loads of fumes at least?
Sounds like you getting closer though, better bet with the 45a parts if you can handle the speed I would say though.
Keep us posted

[muzza]

You're right Sean, it stinks but I leave it on and up. It's what I've had best results with and I don't find clean up any harder apart from a bit of glue residue right near the cut but that comes off easy enough with some thinners. Even when I'm welding it I only pull back the 100mm or so near the weld area.
Murray

[see&see]

If you have the capability to use the Hypertherm Fine Cut process it gave me the best quality on 14 ga 304 stainless at 45 amps. I tweaked the nozzle height up a bit and played with the speed and the result was almost zero dross on these connection clips using 1/4" flange bolts.

[exapprentice]

Hi see&see

good shout but unfortunately "Fine Cut" consumables are not available for use with my PM45 the next best thing will be using 30 amp consumables with the option of turning the setting on the PM45 down to 30 amps which is the next thing I am going to try (again)
what sort of cut speed did you use with those settings

[Hillbilly Stills]

I am really new to this . We have just received our new table from Ross at TruCut. The shop that has been cutting all of our stainless uses Nitrogen instead of Air when cutting stainless for this reason. The use Air on everything else but on the stainless they use the nitrogen.
Just what I have been told to do. I will know very soon..LOL

[see&see]

Hi see&see

good shout but unfortunately "Fine Cut" consumables are not available for use with my PM45 the next best thing will be using 30 amp consumables with the option of turning the setting on the PM45 down to 30 amps which is the next thing I am going to try (again)
what sort of cut speed did you use with those settings

Hi exapprentice,
Seems like I remember, sort of ?, that Jim Colt wrote a few weeks ago that Hypertherm was working on new shielded consumables that would improve quality like the fine cut but I'm not sure if he said it would be compatible with the PM45. I can't find the post now...

I had the PM85 with fine cut at 45 amps and 150 IPM with .079 cut height using air. I remember moving the cut height up using the stock 45 amp nozzle and that improved the dross on stainless slightly before I went to the fine cut.. 1.5 mm is .059 height.. .079 is 2 mm..

Also, on stainless when doing small parts the dross comes off real nice using a tumbler with ceramic media...

[Jaime Branco]

12mm stainless steel 65AMPS Powermax 105