Problems with 1/2" A36

[onefjef]

Hello,

New to this forum. We have Amada 4020NT and regularly cut 1/2" material with this machine. I'm having trouble with a sheet 72"x144". Clean sides but thin dross bead on bottom. I think my problem is bottom surface quality but I was hoping for suggestions.
Current settings: 7" lens, 1.4D nozzle, 0.022 focus, 31 ipm, 2500 Watts, 1200 freq, 80 duty, 0.06 gas pressure, .055 gap.

I've tried 45 ipm, 4000 W, 2000 freq, 100 duty, .08 Mpa. but I get magma on top side like it cant push through.

Any help appreciated

Jef

 

[drossfree]

whenever i had trouble like this i generally used a larger nozzle dia and slightly higher assist gas pressure.

 

[jetrep]

3015NT user here. We can cut 1/2" plate all day long at 40-45"/min, 4kW, 2k freq, 100 duty. We have gone as high as .10MPa with the O2. Focus is set around +.050"

 

[onefjef]

Thanks for the help,

I've tried those settings and parts re weld to sheet. In fact changing my settings to each end of the normal operating scale doesn't affect it. Lens and nozzle fine, centering fine. I believe its an inferior material issue.

Jef

 

[msandoval]

What jetrep recommended should be fine. I think you need to move your focus up to widen the kerf and let the oxygen take care of the rest.

Have you tried replacing the lens? When was the last time the external optics were cleaned and aligned? How many hours in the current set of external optics?

Do understand A36 material is at the bottom of the barrel and won't cut as easy as A572-50 Grade so the material will make a world of difference.

 

[onefjef]

msandoval,

Optics cleaned and aligned 300 hours ago. Lens changed one month ago. Material was supposed to be Temperpest (TM?). I don't know what ISO classification this is. The sheet was shot blasted on both sides which could also make things worse. I know A36 is probably not the best for this machine but these days the material buyer is looking for deals and like I initially said we run 1/2 "mild steel" pretty often with little trouble such as this. The one thing I didn't try is focus up at 0.050". Job done but I saved a piece off the end to play with.

Jef

 

[msandoval]

Shot blasting, sand blasting. The worst things you can do to a rusty piece of plate. You're better off etching/engraving the parts first to get rid off the scale/bad surface and then try to cut it.

So much for getting a good deal on steel on the steel. You probably lost money trying to cut this material.

 

[onefjef]

agreed!