Plasma cutting thin gauge stainless steel

[HomerSimpson]

I need to cut thin stainless steel (<1mm) with a plasma cutter on a CNC machine. I have a CNCRouterParts Pro machine that I plan to upgrade with a Hypertherm 45XP, a water table, and height control. The stainless is cosmetic so I can't have any discoloration, and I'd like to avoid a secondary grinding or buffing operation. My local Hypertherm rep has no information to help me. A bit of searching has turned up a couple of useful articles:

https://www.thefabricator.com/articl...tainless-steel
https://www.thefabricator.com/articl...heet-and-plate

which point towards the right gas combination as a major factor. The first article references plasma gas and shield gas. What is the difference and is the 45XP capable of this?

Does anyone have experience resolving this specific problem? I have zero experience with plasma cutting and don't want to spend several grand on a system only to find out the process is not capable. Thanks!

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[Beefy]

Check the 45XP manual to see if it mentions the gases in question.

Also in the manual check the cutting speed for stainless that thin. Can the router table run at the required speed while having good acceleration at the same time.

Thin metal can also warp, so combined with the faster cut speeds you will need a decent torch height control. I cut some 2.5mm stainless a while ago and it was a nightmare. My Powermax 1250 has a cut gap of a quarter of a mm using Finecut nozzles. I kept getting minute bits of slag trapped between the sheet and the nozzle and my Z axis limit switch regularly tripped.

I can't see you having NO cleanup to do afterwards. If you are after that I'd subby it out to a laser cutter.

[LeeWay]

Plasma will not yield the results you are looking for. I have basically the same setup you are looking at and SS is my main material. I have cut a lot of .03" to .120" stuff. It all requires additional or secondary ops, though not nearly as bad with the water table. Laser cutting is what you are looking for and you will not get laser quality cuts with a plasma cutter.

We have some parts outsourced for laser cutting because of this. Cleanup just takes too long with plasma parts and we use a lot of those parts. That said, we can get those parts cut and delivered for less than what we could cut them out for with the plasma, so laser cutting is a very good option for parts that you need in volume.

[bytor]

Plasma will not yield the results you are looking for. I have basically the same setup you are looking at and SS is my main material. I have cut a lot of .03" to .120" stuff. It all requires additional or secondary ops, though not nearly as bad with the water table. Laser cutting is what you are looking for and you will not get laser quality cuts with a plasma cutter.

We have some parts outsourced for laser cutting because of this. Cleanup just takes too long with plasma parts and we use a lot of those parts. That said, we can get those parts cut and delivered for less than what we could cut them out for with the plasma, so laser cutting is a very good option for parts that you need in volume.

+1
Or better said, the 45XP doesn't have the ability to use F5, which is a mixed Hydrogen gas. Even then your cut quality won't be what you want. Water injection or VWI process will yield better results yet, but again. not for the equipment you have available. You want laser. One and done and no secondary process and no discoloration.
Outsource it.

[HomerSimpson]

Thanks for your input. I was afraid this would be the answer but I needed to hear it from 'expert witnesses' before I went down this path to determine it won't work for me in the end. I suppose I will have to outsource the parts for now until I can afford a laser. Thanks!

[LeeWay]

I suppose I will have to outsource the parts for now until I can afford a laser. Thanks!

Those machines are quite a hunk of cash.
If you have a business laser cutting for Industry or filling RFQ's, then they might be worthwhile. The ones I have looked at (not real hard) are approaching a million if not more. You may be able to get smaller sized imports though, so you would actually have to study up and ask for quotes.

As I mentioned, I cannot cut these parts out for what I get them delivered for. Post up a few RFQ's and test the waters. No obligation to do anything other than judge what your parts might cost.

[HomerSimpson]

Those machines are quite a hunk of cash.
If you have a business laser cutting for Industry or filling RFQ's, then they might be worthwhile. The ones I have looked at (not real hard) are approaching a million if not more. You may be able to get smaller sized imports though, so you would actually have to study up and ask for quotes.

As I mentioned, I cannot cut these parts out for what I get them delivered for. Post up a few RFQ's and test the waters. No obligation to do anything other than judge what your parts might cost.

I bought a small engraving laser a few years ago directly from G Weike in China and was pretty satisfied with the machine and the support. I've been looking at this one: 500W Fiber Laser

which is a 4x8 machine with a 500W fiber laser and will cut 1mm stainless at about 300 in/min. Here's the same machine in action:


I was given a price recently of $32,000, which is quite a bit more than what I would have spent on a plasma system but a lot cheaper than the million dollar systems my local laser cutting shop uses.

[HomerSimpson]

Just had a thought--I could use thin aluminum sheet in my application, instead of stainless. Would plasma cut aluminum with a clean edge, or would a secondary op still be needed to clean it up?

[LeeWay]

No.

Maybe a high definition plasma with the correct gas, but the 45 or the 45 XP will still leave a little dross, slag or otherwise unfinished looking edge.

[Torchhead]

Just had a thought--I could use thin aluminum sheet in my application, instead of stainless. Would plasma cut aluminum with a clean edge, or would a secondary op still be needed to clean it up?

You route thin aluminium. A good rigid table with a 2.2KW air cooled spindle with ER collets and using mist and air will cut up to 1/8" aluminium. We cut hundreds of plates from .060 AL and get clean edges and small detailed cutouts. Plasma is a great took for cutting metal but its not a precision machining tool. You have to as stated, use laser or water jet.

[HomerSimpson]

You route thin aluminium. A good rigid table with a 2.2KW air cooled spindle with ER collets and using mist and air will cut up to 1/8" aluminium. We cut hundreds of plates from .060 AL and get clean edges and small detailed cutouts. Plasma is a great took for cutting metal but its not a precision machining tool. You have to as stated, use laser or water jet.

I have the table and spindles to do that. I don't have any experience doing it though. What end mill, cut speed, and cut depth do you run at?

[Torchhead]

Deleted

[Torchhead]

How To Get Experience:
Get material.
Generate Toolpath from CAM.
Use largest diameter 2 flute up cut mill that will mill smallest features
Setup mister or flood
Make test cuts using different Spindle RPM and feedrates . Start slow and work up
Write down the results and save the optimum combination for that material and tool
Every material and every tool cuts differently .

[philgrady]

Hi,

I wouldn't say i'm an expert but I have no problems with stainless steel. We cut 0.7mm thick 0.67mm - 0.75mm 430 grade and 304 grade laser coated without any issues. We do get some warping but the THC adapts just fine.

I use standard air, rather than any Nitrogen or special mix, but pass it through a drier and then a tank and then through pipes to the plasma table. I use vertical takeoffs to avoid any condensed water in the pipes. I've tested the air and it's pretty dry, which following Jim Colt's advice is one of the main things to do. Electrical flame + water = Poor cut. This is the reason I opted for air rather than water tables, it does need more space and extraction.

I don't want to upset any laser people out there but I use to have access to an old CO2 laser and the current plasma cutting is superior. I also have current access to a 10kW fibre laser and it is a good cut. Although I have not compared under a microscope, comparing by touch and eye there is hardly any difference.

Hole quality < 5mm is poor compared to the laser but I simply mark and then drill by hand. I need to experiment with pierce height and speed and amps, but I think I can get better results than I currently get.

In summary thin stainless is fine on air plasma with a powermax 45xp. The hypertherm manual gives detailed setups for most materials and thicknesses.

I hope that helps.