Mig welding aluminium

[Welderpaul]

I had a blast at MIG welding aluminum for the first time today - first photo - not too bad apart from an end crater - 3 runs there.
Messing about with AlSi and AlMg wires - AlMg gave us the best welds, but with no problems with feed etc, which i'd expected. Combination liner, oversize tips, U rollers and an expensive welding set seems to have sorted that

2nd/3rd picture - the parent material cracked right through at the edge of the HAZ. Why does it do this?

 

[malcolm]

Is it the corrosion of the aluminium that has caused the crack? I have found MIG doesn't do any cleaning so the top and edge of the aluminium needs to be cleaned immediately before welding. What cleaning did you do?

 

[Welderpaul]

Is it the corrosion of the aluminum that has caused the crack? I have found MIG doesn't do any cleaning so the top and edge of the aluminum needs to be cleaned immediately before welding. What cleaning did you do?

A reasonably new off cut of ally channel, 3mm thick, cleaned with a flap disc before welding.

The sample in the 2nd and 3rd pics was welded by someone else, but mine didn't crack.

 

[Jim Davey]

I think the problem is the massive weld to plate thickness ratio that's your problem there Paul.
Your sample could've been welded with one pass and survived. Three in succession on plate that thin was always going to cause a problem.

 

[Jim Davey]

You can see from the lack of definition on the surface of the welds that it went in monster hot too.

 

[DAPPH]

Paul , thanks for the pictures I now know what I should be aiming for /looking at

I too will be playing at MIG that aluminium in one , when I can afford a dedicated for Alu only torch & a reel of wire .

Is that end cracking to do with having need to reduce the arc once the area you are welding is hot ( I don't know what I'm talking about ) and gas purging the joint for a second or so after you finally cut the arc off to keep it a bit cooler ?

 

[Rrunnach]

As Jim Davey stated, far too many runs on 3mm T matl. Single pass is more than suffice. If you ever have the opportunity, try out same using a synergic mig. Results are very similar to producing a good tig weld bead.

 

[Jim Davey]

He's using a synergic Lorch Saprom I think Rrannach.

 

[Welderpaul]

Yes, we have a few Lorch Saproms. Good kit.

Yeah, the amount of weld is huge for small material, and the samples were only for messing about purposes to check we could weld it without a load of feed problems, but i was wondering what the mechanics were to cause the cracking

 

[Rrunnach]

It is the rapid cooling of weld that contributes to cracking. Crater cracks are also problematic. To eliminate this and, cold starts, run on/run off plates are utilised, same material of course.

I am not familiar with Lorch MIG/MAG plant. Kemppi synergics with pulse and double pulse facility, are the mutts nutz!

 

[Maxakarudy]

To eliminate cold start problems, use the hot start facility

 

[Rrunnach]

Back in the day, there were no such facility. It is good to skill up using bog standard equipment, this is how one learns the skill.

 

[8ob]

Back in the day, there were no such facility. It is good to skill up using bog standard equipment, this is how one learns the skill.

There is a bit in this comment, we were looking at the welds on my bulker bin that are 20 years old and must have been done with a basic mig set and spool on gun.

Bob

 

[Jim Davey]

I like a spool gun, but I wouldn't pick one over a pulse mig now.

 

[Rrunnach]

Agreed, pulse, double pulse facility, produces quality welds, in the correct/skilled, hands of course.

 

[matt1978]

Hi Paul, you can also turn on the crater fill in the back ground menu.

Put it on latch then you can have a hot start (125% factory setting) when you pull and hold the trigger, loose it and it will drop to your welding value and then pull and hold again and it will drop to your crater value (50% factory setting)

The percentages for the hot start and crater fill can be adjusted in the menu

 

[Welderpaul]

Cheers Matt, we all use hot start and crater fill on the mild steel programmes but i had latch switched off on this. It's a handy function.

 

[HughF]

There is a bit in this comment, we were looking at the welds on my bulker bin that are 20 years old and must have been done with a basic mig set and spool on gun.

Bob

Not necessarily, might have been a Combramatic on the end of a powcon/thermal arc inverter

 

[henry Kadzielski]

Good morning Welderpaul.
New kit these days does wonderfull things, so much so that it takes quite some time to get your head around it all. When setting up for alli, normal, synergic, hot start, the % of the hot start, duration, arc length for the hot start. This then followed by the main welding process and again repeated for the creater fill. All of which is available must be played with.
This must also be precceded by cleaning the material just prior to welding and then the technique. Do you use the straight along method as for steel, or the back and forward motion. This is all good but still requires the machine to be setup and calibrated correctly

 

[Maxakarudy]

Matt,
Is there a setup for 1050 wire in the S3, I'm using the 4043 wire at the moment for 1050 sheet ali, we just weld up corners.
Martin