Aluminium Mig wire size?

[Fixer]

Hi, Ive had my Mig a few years now and fancy trying aluminium welding so I've ordered an argon cylinder and just about to order some wire and tips but not sure what size is best.

Most tof the jobs i want to do with it are welding pretty thick bits. I'd say 4mm plate would be the thinnest but most of it will be 10mm bits or there a bouts. The welder goes up to 160a.

All and any advice much appreciated

 

[shenion]

For 4043 go with 1mm. 0.8 is very hard to feed as it is so soft.

I find 5356 easier to use as it is stiffer and wire speed is not so insanely high but I tend to get cooling cracks on cast parts.

 

[wyn]

I use 1mm 5356 in my mig....it's 180 amps and will only weld 2.5 to 3mm thick.

I think the welder will struggle on 4mm with 160 amps.

 

[Fixer]

ok so 1mm 5356 wire, thanks.

About the cracking on cast - some of the jobs i want to do are with cast so how could i prevent/address this? post gas?

About the amps - will preheating, v grooves and multiple runs get me by? any tips on that? The plate parts can be done both sides if thats good?

One other thing - do i need a specific regulator for the argon? is a argon/co2 one ok? single stage dual gauge? The ones that say pure argon say for Tig and say fixed flow rate… that not for Mig though is it? i just need another like the one on my avon/co2 mix cylinder ye?

 

[BrokenBiker]

im not sure if you need to pre-heat cast ali parts to try and eliminate cracking on cooling.

160amps is fairly low for the sort of stuff you describe, I don't know much about migging ali but I would want a lot more amps, closer to 200-220 for 4mm, 250 for 5mm.

if you can get at the backs of the joints then grove it out, weld it, turn it over, groove it out again and weld again, or use one deep bevel and weld with more than one pass.

for the 10mm stuff you will probably need 3 passes, maybe more depending on how strong it has to be.

I was once told that migged ali is prone to cold lap without the right amps to run a bit hotter than needed, not sure how true this is though, im sure someone else will come along to clear that up

 

[wyn]

Preheating would help and it should make it easier to weld thicker stuff.

I should think any old argon/ argon mix regulator should do.

Have you got a teflon liner to go in the torch?

Check the feed rollers to see what groove you need to run aluminium in.

 

[Fixer]

Preheating would help and it should make it easier to weld thicker stuff.

I should think any old argon/ argon mix regulator should do.

Have you got a teflon liner to go in the torch?

Check the feed rollers to see what groove you need to run aluminium in.

Think I've got a teflon liner but i will get one ordered if not - forgot about that cheers

…and the feed rollers too, I'll look for some suitable ones.

Yes broken biker, I can get to both sides of all the bits i need to do. None of it is load bearing or stressed. One thing is a sump I have to close up where i cut it round a crossmember and the other stuff is fabricating a plenum/airbox thing i dreamt up.

As usual, top advice much appreciated chaps.

 

[BrokenBiker]

i wouldn't worry a great deal about full penetration then, just as long as the joints are all air tight should be fine

 

[Fixer]

goodo

Ive been looking for the rollers but can't find any for my SIP welder…. is there some place people go to for these? or could i adapt some meant for another welder?

 

[BrokenBiker]

the only difference for.the rollers is that mild steel rollers have a u shaped groove and Ali rollers have a different groove.

weld equip may be able to help, but not at this time of the morning lol

 

[Fixer]

I emailed him before i went to bed fingers crossed

 

[wyn]

You can probably get away with the rollers you allready have....it's just that some rollers may allready have a groove that's specified for aluminium.

 

[Fixer]

You can probably get away with the rollers you allready have....it's just that some rollers may allready have a groove that's specified for aluminium.

was wondering about that… use the 0.8 groove and just back off the pinching/roller tension. Think I'll try that before shelling out on new rollers - it might be fine, Cheers.

 

[PSweeney]

I've run ally in a mig to weld sheet. The success factors are basically very low tension on the wire, a 1mm tip for 0.8mm wire, a perfectly straight torch lead and pulling the inner liner back as much as possible to he feed roller to support the wire. The start on ally mig is cold, so weave about at the start or drag the arc back to the start of the joint and go over the starting point again. Rough rule of thumb is that you want 30-40% more wire speed for the same given amps on steel. When welding sheet, you have to weld very quickly and fit up between material is paramount otherwise you just blow holes. Forget tacking and any pulse techniques, you need a hot bead and move quickly and try not to stop otherwise you get another cold start. You will get birds nest in the rollers at some point, but keep the torch lead as straight as possible and only feed the ally wire into the torch with the tip removed.

 

[Fixer]

Thanks PSweeney, much appreciated - I will do my best to put all of that into practice. Practice being the operative word! If i was experienced I would probably only need a 1L disposable of argon to get the jobs done but I bought 10L so I can spend a week at least practicing on scrap.

Ive ordered everything now, teflon liner (1-1.2mm), regulator and hose (can't be bothered swapping the one i have over every time i want to do a different job) 20x contact tips, 500g of the wire recommended and the argon 10L. I should also by some uncontaminated abrasives and brushes too but i can get those local

 

[shenion]

the only difference for.the rollers is that mild steel rollers have a u shaped groove and Ali rollers have a different groove.

I think you have that backwards. you buy U-shaped rollers for aluminum. Standard rollers are often V shaped. If they are U-shaped, they are often knurled which really makes the soft wire hard to feed.

 

[Jan]

Only 10 Litres? At what pressure? Don't forget that you'll be using at a rate of not less the 10l/min!

 

[Fixer]

Only 10 Litres? At what pressure? Don't forget that you'll be using at a rate of not less the 10l/min!

hi Jan, 200bar (200 x atmospheric pressure) so I have 2000 litres of gas, enough for 200 minutes of welding at 10L/min.
If the cylinder was only filled to atmospheric pressure, with 10 litres of gas, you would get ZERO minutes welding as it wouldn't come out the cylinder!

Shenion - this is true - my rollers (for steel) are knurled. Need another roller don't I

OH, one other point i need to check with you guys - the torch stays connected as normal yes? torch posative?

 

[PSweeney]

I had no issue with the rollers been knurled, it does imprint on the wire but not enough to be a problem. You literally need the minimum tension on the rollers to feed and yes torch stays as per normal

 

[BrokenBiker]

I think you have that backwards. you buy U-shaped rollers for aluminum. Standard rollers are often V shaped. If they are U-shaped, they are often knurled which really makes the soft wire hard to feed.

my mistake, can tell I don't mig ali lol