To TIG or not to TIG....

[cornflakeMini]

... that is the question!

I have an Aluminium intercooler with a cracked mounting bracket which I'd like to repair.

The bracket is around 2-3mm but I would guess that the wall thickness on the intercooler is closer to 1-2mm. I can't be certain of the intercooler wall thickness as I don't want to cut into it ideally.
I'm considering buying an AC TIG to do this job but would appreciate your opinions on whether it might be possible with MIG?

I've never worked with Aluminium before but I have a good amount of experience MIG welding thin steel (0.8mm) and some limited experience TIG welding thick steel (2 - 3mm).

I already have a bottle of Argon so it might be cheap/easy to take a punt with MIG if I stand half a chance.
I normally use a SIP Migmate 100 although I can get access to a 160A MIG welder if current will be a limiting factor.

Here's a picture of the job as well in case it helps:

Thanks in advance everyone!

 

[Paul.]

That needs tigging, but tbh its pretty poorly made, looking at the gap in the joint suggests the plate is too short and the joint is under constant tension, I would probably make a new one complete using 3mm minimum for the box, or you could try a mechanical repair, make a new tab with a bent flange on it and bolt it to the box

 

[Hood]

If you had lots of experience with Mig in Aluminium then it could be done but I would certainly not be doing it without lots of experience. Tig would be better but that also needs a fair bit of practice so the mechanical fix as suggested by @Paul. would probably be the easiest and best route for you unless you really want to splash some cash on an AC Tig and do a lot of practicing first.

 

[Robert Weaver]

MIG with aluminium is not particularly good. Needs AC to create a cleaning phase and a penetration phase to get through the oxide layer.

Would you use the TIG machine after you've finished this job? If not, it's an expensive fix.
An ac TIG set will be at least £400, then there's practice and filler rods etc. Is there a fab shop near you that might entertain the job for some beer tickets?

Edit; found this on fleabay...
https://www.ebay.co.uk/itm/Ac-dc-ti...2349624.m46890.l49286&mkrid=710-127635-2958-0

(Looks like it's made by BMW, so stay clear)

 

[northwest]

You would be best taking that to someone who knows what they are doing and pay them to fix it, not a great deal. OR you can invest at least a grand in an AC set and Gas and lid and rods and plenty of practice.

There is an alternative as you could possibly Alu solder it. Then mount it better.

 

[carbon]

MIG with aluminium is not particularly good. Needs AC to create a cleaning phase and a penetration phase to get through the oxide layer.

Are you sure about that all my aluminium mig welding is done with dc. Definitely ac for tig

 

[Hood]

MIG with aluminium is not particularly good. Needs AC to create a cleaning phase and a penetration phase to get through the oxide layer.

...

I beg to differ. Mig is an excellent method of welding aluminium but ideally 3mm or thicker. The reason you need AC for Tig is you need, as you said, the positive for cleaning but if you used DC positive then your tungsten would get too hot and melt. With Mig that is not a problem, the electrode is positive so you get the cleaning but as the electrode is also the wire you want it to get hot and melt so it is ideal.
Problem is however you really want to be in spray transfer for a good Mig weld and thus anything less than 3mm is not easy to do.
Pulse Mig solves that issue as you can weld way down to 1mm or less but pulse migs, good ones anyway, are very expensive and make even a top end AC tig look reasonably priced

 

[Robert Weaver]

Differ accepted - my experience with MIG aluminium is with thin section, low current and a torch with spool. It had very little penetration, probably because current was too low.

 

[Hood]

Differ accepted - my experience with MIG aluminium is with thin section, low current and a torch with spool. It had very little penetration, probably because current was too low.

As said spray transfer is really needed so unless you have a pulse Mig 3mm is really the thinnest you can weld satisfactorily with Mig. With experience you can go thinner but it is not easy and really thinner than 4mm, in sheet, was something I avoided if at all possible.

 

[carbon]

I don’t take many pictures of my welds, definitely not one of my better ones. Approx 250amps dc spray 6mm plate lap joint

 

[Barking Mat]

I'd pay someone competent to fix that for you. Personally.

 

[slim_boy_fat]

(Looks like it's made by BMW, so stay clear)

 

[Robert Weaver]

I don’t take many pictures of my welds, definitely not one of my better ones. Approx 250amps dc spray 6mm plate lap jointView attachment 301170

I'd be very happy with that.

 

[Hood]

Regarding penetration, these are some welds I did as a test, the first 4 from left are various Mig processes the others, if I recall are Tig.

 

[Robert Weaver]

Thread 'BMW i3 spares or repair' https://www.mig-welding.co.uk/forum/threads/bmw-i3-spares-or-repair.113489/

Milkfloat was written-off because inverter box (EME) was too expensive to repair. It's a sore point and I've nothing good to say about that particular German company.

 

[Robert Weaver]

Regarding penetration, these are some welds I did as a test, the first 4 from left are various Mig processes the others, if I recall are Tig.


View attachment 301180

This deserves a thread of its own.

 

[Hood]

This deserves a thread of its own.

It does have one

 

[cornflakeMini]

Wow, loads of responses in a short time. Thanks for the input everyone!

Sounds like like MIG is a no-go and TIG is obviously an expensive option. If I do buy a TIG welder then it will get used for other projects but only one I have in mind would be in Alu so perhaps buying an AC TIG would be slightly silly.

I'll weigh up the options including paying a local fab or Aluminium "brazing" and go from there. Unfortunately bolting is a no-go as the box needs to be airtight but that would otherwise have been a good suggestion.

Regarding the bracket construction, I completely agree that it needs some improvement. It's just a flat tab poking out at the moment so I'll take this opportunity to triangulate it back to the intercooler to add some stiffness.

Thanks again

 

[willie.macleod]

Edit; found this on fleabay...
https://www.ebay.co.uk/itm/Ac-dc-ti...2349624.m46890.l49286&mkrid=710-127635-2958-0

(Looks like it's made by BMW, so stay clear)

It looks likes Draper have taken an ancient Chinese WMSE 200 machine and put it in a snazzier case, that's making strong money for what it is.

 

[Robert Weaver]

I bought an ac/DC TIG set several years ago (an Apex TIG 200 for £450) and it's one of the useful things in the workshop. If it lets go and emits its magic smoke tomorrow, I couldn't do without an ac TIG set. It's a very useful tool once you've got one.