Welding aluminium.

[ted655]

I'm reading that impulse MIG machines are the way to go for aluminium. Anyone using an I-MIG machine? I'd like some thoughts on them.

[Dave Fleming]

Hmm, I was under the impression that IMPULSE MIG welding was for the manufacturing environment with Robotics.

Someone correct me please?

[ted655]

You are mostly right. Most searches take me to robotics. Lincoln does offer a couple of hand held/ wire feed migs at over 5k.
I was curious about other hand operated units. There are some in Germany, but I can't read the words. No spreckin da deauch, (can't spell them either)
I'm owning my first welded alum. boat. I'm loving it. Freshwater, no shore power, that helps. Taking into account the hidden costs of other materials, alum. cost is competitive. Impulse welding is supposed to be the way to go.

[Polarity]

Hi Ted
You might want to post this one on the Metal Boat society forum...

www.metalboatsociety.com they have guys over there that live and breath welding!

Paul

[flame]

Hi

MIG (with or without impulse) is used a lot in Europe - it's good for aluminium, too. The pulses help forming the right drop size of the melting wire being fed and cares for a good looking joint. My only reason not having such a box at home is that pulse transformers are very expensive here. I use a cheap old TIG transformer (Tungsten-Inert Gas)

Be VERY sure what alloy you want to MIG-weld and select the proper joiner wire, don't save money on the gas, use an Ar/He mixture, and don't overdo with the transformer power - Alu wants it cool

Some hints from German pages into English - let me know; you find my email address at http://www.dauda.at

Cheers
Mike

[ted655]

Thank you. It's these little tips that really help.
Ted

Mine was Mig welded..small home handyman machine made downunder by CIG (Commonwealth Indusrtrial Gasses).

It was the push wire feed type and we did have a few drama's getting it to feed right.

I'm told the ones with a push / pull feed mechanism in the hand piece are much better.

Feed problems seemed more prevalent if you tried to take the handpiece over the gunnel and to weld down inside where wire would have to feed Up againstgravity to get over the gunnel...so we solved that by hanging the welder from a rafter above the boat with a rope so the wire feed was always downhill!

Banged head on welder a few times!

It worked OK.

Short welds - no more than 2 inches at a time to avoid heat build up.

Then we also welded backwards, meaning...

Start the weld away from you and weld back away from you
from you for 2 inches.

Then stop, now come back 4 inches and weld away from you for 2 inches

This leaves a 50% stitch pattern.

Only weld about a foot each side of the craft this way at any time to avoid creating any hook in the hull thru uneven stresses.

So 1 foot of 50% stitch weld each side as you work your way along say each chine seam.

Then go back and stainless steel wire wheel the welds to clean em right back to shiney clean metal....and infill the 50% sticth the same way - 1 foot at a time..

This is how you keep it straight and avoid heat build up.

The heat is always building up away from you and you are always leap frogging ahead of any heat build up back toward yourself 4 inches each time..

Clean up the infill and your done.

For critical welds like keel and chine we continous welded the outside as well as inside using the 50% stitch 1 foot a time each side method.

After this we laid a 2 x 2 extruded aluminium angle over the chine seam and continuous welded that in place the same way...

The keel got a 1 inch extruded U channel welded over the same way...this way any water has to get past at least 3 of the 4 continuous welded seams to gain entry.

Transom is fillet welded in

Don't grind any critical below waterline seams, just wire wheel them.

Hope these tips help.

Cheers!

[ted655]

Yes, thank you.
Ted

The idea of pulse is that you only get spray transfer at high current. Spray is easier to control, gets better out of position transfer and avoids porosity.

But you can't run high current continuously on thinner (especially) metal.

So the idea is that the power supply pulses up to spray current, then back down rapidly.

Because pulsed spray is easier to control, it is frequently used with robotics, but it is a good process for aluminum. especially boat building, and a lot of professional shipyards will have pulsed equipment.

The only problem is that pulse spray equipment is expensive.

[kwarrick]

I have been a certified welder for over 17 years and a welding inspector for 2 and I just wanted to say that expensive or fancy welding of aluminium boats is not always needed.
I have worked on several aluminium boats and 7 out of 10 times I have gotten the job done quite nicely simply with good aluminium stick rod welding.
get back to basics guys, just because it is expensive does not mean it is going to be quality.

Just one mans thoughts.

pulse tecknology for welding is still in its infancy and extremely expensive to own and purchase and maintain. a good pulse welder and i stress the word good will cost 3 times what a normal wire feed welder will cost capable of running aluminium you need to ask yourself do i need such an expensive machine to do the work i will be doing. and please if you do end up buying a pulse welder....dont buy the cheapest machine on the market...... you will regret it

[phylus]

Hi, I've stick and mig welded a lot of steel over the years but never ali, except a little with AC tig. I like the idea of being able to use a stick welder on ali, but did not know this was possible. What is the polarity requirement for this ? Is this the same for mig as well ? How do the fluxes on stick welding compare to gas shielded as regards penetrating oxide layer and weld contamination etc ?
Any tips and info you could share would be much appreciated thanks

[Arty]

Hi guys, just my opinion...
Stick welding on ali is now banned in Australia due to health hazard. I run a business building ally and steel boats and always used the standard MIG due to the fact that PULSE cost a fortune and is a bennefit only with thin material as it doesnt heat the plate up. TIG is great but also expensive for AC/DC but a must. I use Kemppi equipment and havent looked back as they are specifically engineeredc for ally.

ONE IMPORTANT THING. Use only a CLEAN stainless wire brush or wire wheel!!! do not share the aluminum SS brushs or wheels on any other material, never, never. Also learn how to clean all the weld areas before you start. Pay a good welder $40 bucks to make you a pro in 15 minutes. Best money you will ever spend! Welders?? Thats how I learned in a shop.

I would thought that stick welding would cause a corrosion problems (at sea water) due to the left residuals. In any case, for anyting serious I would definitely suggest push-pull (at least 30feed long) and pulsed MIG. Its worth it. Recently we got a presentation from one leading welding company on their double pulsed MIG machine. And since then we dont want anything else, despite the cost of about $10,000. Its just brilliant, leaves welds looking like TIG, and gives much better positional welding characteristics. Well, 10k is not cheap indeed. There are few good books on boat Alu welding... look at amazon.com.