Cutting 7Ga mild steel with nitrogen

[jjl1210]

I was asked to find some solutions for cutting 7ga mild steel with nitrogen. We have no problems with 10 ga or less we do it all the time and the feed rate is still fast. I was given some things to try from Amada but had no luck and the feed rate was so slow. So I want to find out what others are doing when the 7ga parts they cut have to be laser scale free because buffing by hand stinks.

 

[Foostrap]

Try to cut it like stainless steel.

 

[JeanFreli]

use oxygene around .07 bar. Is that a fiberlaser and how many watts do you have?

 

[jjl1210]

We have 3 lasers I can use all 4000w, one Amada 4020 and two Amada 3015 but they are 15 years old. The problem isn't cutting it's what can I do to cut it faster because one week of cutting will now take two and I don't have that time.

 

[LaserSpyder]

why do you cut steel with nitrogen? I get a beautiful finish on my 188 Steel without nitro and we also have an AMADA FO 3015 I can share cutting conditions if ud like

 

[jjl1210]

We get a great cut also but when it comes to paint the scale will chip off and the paint with it. We cut most of our 12 ga with nitrogen because the paint process is a ton better.

 

[Chalked]

what speeds are you currently cutting at ? If you're looking to get up to the 140ipm average that oxygen cuts you may be seeking the impossible. At our shop we nitrogen cut 7ga P&O at speeds of about 70-80ipm on ext, and around 60ipm on internal. on amada FO3015 NT and 4020NT lasers. we have found, how fast you can push depends on the material, when we get higher carbon material. speed at times is reduced for a clean cut by 20%. also if your cutting mild steel that has mill scale. you will have a hard time getting a burr less edge. regardless of speed.

 

[jjl1210]

Thanks for all the help. Our normal 7 ga, A36 or Gr50 cuts between 140 ipm and 150ipm on the 3015 with Oxy. With T1 the feeds drop but with the quality of the material the cut is great all around. The normal feed with nitro is between 70ipm and 80ipm but I can't accept that, it will not work, I need to see if someone found a trick that will bring the feed up to 110ipm. When we first started cutting 19 years ago I was told we could not cut a .097 notch in 1/4 with our Amada 2000w Altair or a .098 hole and I made it work. We even turned the old laser into a shutterless cutting laser and run multiple programs with different thickness sheets on one bed. So I need to find someone that didn't accept that you can't run past 80ipm with nitrogen and did something about it.

 

[Chalked]

well if ya find the answer post it. by years end we are suppose to be getting a 6000watt fiber laser. management tells me it will cut our 7 ga and 1/4 inch 4 times faster with nitrogen. then our 4000watt co2 lasers. but still anytime I can ramp up speed. it's a win. back to the issue at hand. I have been able to push 7ga up to the 90-100ipm feed rate, but because of some of the intricate parts we cut, I would lose the cut on small profiles,I was able to fix the issue with tweaking and adding edge data. but we found that the extra time added by the edge data, it actually slowed the cut time dramatically. we were in the same boat you're in when we switched to nitrogen cutting our carbon steels 3 years ago. and the companies solution, doesn't help you one bit. but their answer to the problem was we added another shift.

 

[JeanFreli]

Change your focal lens. With a 2000watts we reach perfect cut 7 ga ss 201LN at 70 inch per minute. This sunday i cut 27 sheets 20 feet long at 170 inch per minute using nitrogene. We just change the focal lens after 820 hours of cut. Normally the speed should be around 138 and 154. Slowly our old lens was loosing. At the end we were cutting at 88. Here some parameters....nitrgene gas 13.25 bar.....focal -3.15 to -3.45......power 4000 watts......nozzle 3. Th e kind of ss will affect the cut a bit too. By heart i think the 11 ga speed is 325. can give you more if you need.