Aluminium

[JLP]

Plasma on aluminium - is it any good for a garage based guy or not worth your time, especially when switching between aluminium and steels?

 

[hotponyshoes]

It cuts through aluminium easily enough.
It can leave a nasty kerf on the back side which can be hard to remove.
Can also need quite a bit of clean up before welding the alloy compared to some other cutting methods .
Depends what you are doing as to weather it's the best tool for the job?

 

[JLP]

It cuts through aluminium easily enough.
It can leave a nasty kerf on the back side which can be hard to remove.
Can also need quite a bit of clean up before welding the alloy compared to some other cutting methods .
Depends what you are doing as to weather it's the best tool for the job?

I thought the nasty stuff was just due to using air rather than a helium/argon mix?

I am only asking as my cutting of aluminium tends to be large sized whereas my steel and stainless cutting is small enough I can do it on a small guillotine

 

[hotponyshoes]

I had a big cebora plasma once that I ran on gas bottles and it was a pretty clean cut on alloy but an expensive way of cutting as the bottles didn't last long. Consumable life was pretty good though..

Since switching to inverter based machines I tend to get a fair bit of kerf. I am running from a compressor now though and it does not have a decent drier fitted so others may be getting better results than me but I haven't really spent much time messing to see if I can improve it.
Most of my stuff is 3mm< on alloy and if cutting up sheets etc I normally get better results with a cordless circular saw. If you need to follow templates or do curves/circles then plasma would obviously be better

 

[Hood]

Cut Alu all the time on the plasma, personally I have no probs with dross on the back really. Edges clean up very quickly with a quick skim over with the flap disk and no issues with Mig or Tig welding for me.
Today I cut quite a few bits of Alu some of which I welded, below is one of the things I did today.

 

[JLP]

Cut Alu all the time on the plasma, personally I have no probs with dross on the back really. Edges clean up very quickly with a quick skim over with the flap disk and no issues with Mig or Tig welding for me.
Today I cut quite a few bits of Alu some of which I welded, below is one of the things I did today.

View attachment 169124

was that just with air?

 

[Hood]

Yes, only use air with the plasma.

Here is some I cut, right off the plasma. It was for the new control panel for my CNC lathe, 5mm 5083

Some 12mm 5083 for a davit, again right off the plasma before clean up, you can see the hairy dross on some parts but a quick scuff with the flap disc takes that off.

Here is it cutting the above parts.

 

[Hood]

This is a pic of a bit that I Migged, you can see the surface finish that is left by the plasma in the holes, the dross has been taken off with the flap disc but the insides are untouched.

 

[hotponyshoes]

I'm hand cutting with mine , I expect travel speed and other operator factors have something to do with my problems!

 

[Hood]

I'm hand cutting with mine , I expect travel speed and other operator factors have something to do with my problems!

Oh that is a definite, the 12mm above was actually cut too slow as I had been having issues with the plasma and although I had them sorted by the time I cut that particular one I was still a bit too scared to up the cut speed as a chunk of 12mm plate is, although not massively expensive, not something I wanted to screw up. I think I was only feeding about 600mm/min in that vid, should really have been about the 1000. Due to that there was a lot more dross than I get now, really the only bits I get it at now are where it goes over the slats on the table. I keep meaning to order a sheet of 3mm steel and cut some slats out of it with small points so that the majority of the material is above the slats.

 

[Richard.]

Aluminium and plasma is fine but it does come with its issues if your welding it after the cut. Tig is pretty awful if welding directly on to the cut edge because there is no getting away from the fact plasma leaves oxides which play real havoc when trying to weld with a completely inert process. Although the aluminium mig is also completely inert the process seems to be more forgiving than tig in such cases. What is a fact and can be an issue depending on what is needed from a weld and that is plasma creates a Haz. Welding also creates a HAZ. Aluminium doesn’t do as well with over sized haz’s on joints. I’m not saying it will cause an issue but something to know is that a cold cut welded joint will be mechanically more sound than a hot one simply to do with the fact the haz will be smaller

 

[Hood]

As I was cutting some Alu to make a tank I thought I would post a pic of one of the cut parts.
As you can see the only dross is where the support slats on the plasma table are.

Close up of the cut edge, it is 5mm 5083.

Lastly a pic of the tig weld, this was with a quick skim over the plasma edge with a ceramic flap disc prior to the welding. Not totally contaminate free but not bad either.

 

[KemppiFrog]

I was asked to cut out a bunch of hatch dogs from 8MM alloy. So I made a template to follow round and tried one. The result was awful and I refused the job. Part of the prob, was that he supplied the chunk of used plate and had no idea what it was from. The dross and roughness would have wasted loads of time to clean up, so I told him to find a lazer outfit. (he is a serial cheapskate and has tried my patience in the past.)

My plasma is a Cut 50, but with a better torch (thanks Hugh) and does well on steel. Would different types of ally make a difference?

 

[Hood]

....
My plasma is a Cut 50, but with a better torch (thanks Hugh) and does well on steel. Would different types of ally make a difference?

I have only ever cut 5083 and 6082 so not really sure if the silicon alloys cut fine or not.
The correct speed makes a big difference or rather a consistent speed and that is where the CNC shines. The above was done at 2000mm per minute.