Welding Aluminum with 110 V Welders

Date 01-16-2019 22:00

Recently, I have noticed that Lincoln, Miller, and several Asian makes, have made their 130 - 140 amp migs spool-gun-ready, and have advertised them as aluminum capable, with the gun, up to !/8" thickness.

However, after watching as many demos as I could stand of visually failing aluminum welds, I am of the opinion that the best of these were done with globular transfer, and most, with short-circuit transfer (from the sound, which is definitely not spray transfer or oxide crackle).

Is it correct that all code welds in aluminum must be spray transfer to obtain optimal fusion and low porosity, and these hobbyist class machines just don't seem to have the voltage or wire -feed-speed to get to spray. Or, are these machines capable of producing racing cart frames, hang-gliders, or other critical structural welds, with enough practice?

By Northweldor (***)

Date 01-23-2019 01:39

For some reason, I was unable to get a reply here, to my questions above, so I turned to another excellent resource, Frank Armao's "Aluminum Workshop", in The Fabricator. Mr Armao took some of his valuable time to provide an answer to the questions above.

Below is his reply:

"You ate asking good questions. In fact, all of these machines regardless of manufacturer are designed to weld 0.025" steel MIG wire. Do they have the guts to weld aluminum? Well, the transition current to spray transfer is only about 95 amps for 0.035" aluminum wire in pure argon shielding gas, but you also need to get the voltage up to 23-25 volts. Most of these machines can't do this. So you are correct. Most of the welds you see are made in short arc.

Many Codes indeed prohibit short arc aluminum MIG. AWS D1.2 used to. Now it allows it as long as you qualify the WPS. However, it is doubtful that short arc welds will pass bend testing. ASME Section VIII prohibits short arc aluminum outright

You ask if these small, cheap light duty MIG welders are capable of consistently producing acceptable welds for critical duty applications. The answer is "No". Let's put it this way. I wouldn't be driving any racing cart or flying in any hang glider that I knew was made using one of these machines. I'm afraid that, if you want to do critical duty aluminum welding, you need to spend more money (say $5000) for a more capable machine. Leave these small machines to what they are good at, which is short arc steel MIG and small diameter steel FCAW. By the way, they are really very good in these applications.

I hope this helps.

Regards,

Frank"

By jwright650 (*****)

Date 01-23-2019 15:23

"Leave these small machines to what they are good at,"-quote

I agree

By Lawrence (*****)

Date 01-24-2019 19:08

Frank is right... (as usual)

Another thing to consider when you talk about code work.

Those 110 units cannot really be calibrated or controlled in a way that AWS D1.2 or D17.1 could accept.

You certainly cannot set a particular voltage on them, nor can you digitally or by meter monitor amperage as the weld occurs.

I looked at the specs of a Millermatic 140 because I won one in a raffle... These are pretty much the Cadillacs of the mini-welder world and the max rated output is only 90 Amps at 18.5 VDC, 20% duty cycle..... Transition current for spray transfer and 3/64" aluminum electrode wire is about 135 amps... So yeah... Short circuit is all one of these will deliver and even that is going to be pretty limited by the feed system on those things. Now that little Millermatic is sweet with self shielded FCAW running in my garage... and I would bet it would be great with .023 solid wire and 75/25 on 16ga.

So even if you did have a short circuit WPS qualified by testing... I don't think one of these units could be used due to both technical compliance and performance reasons.

By Northweldor (***)

Date 01-25-2019 04:35 Edited 01-25-2019 04:37

The question that was originally asked about this, was the simple and common query: " am thinking of buying a 140 {110V GMAW}.....need to know if it will be able to do small aluminium welding jobs?? "

Given the fact that this is obviously coming from a hobbyist/beginner, my response was, not if you want aluminum welds with good fusion and low porosity, since I have never seen spray transfer achieved continuously by any of these machines. Then, I noticed the proliferation of spool gun connections and switches on newer 110V GMAWs, and thought that there may have been some sort of electronic break-through that made spray-transfer aluminum welding common on these machines. I am now convinced that this has not happened, and the comments of Frank, Al, and Lawrence reinforce this,

I think, still, to anyone who requires aluminum welding with structural integrity in GMAW, is to buy as Frank recommends, or, if production is not an issue, purchase one of the many cheaper AC/DC GTAW machines that will do everything well, but slowly.

I am still looking for a single video of a 110V GMAW machine welding aluminum in spray-transfer. Let me know if you run across any!

These machines are great for most light duty purposes, and a spool-gun-capable machine is even better, but quality aluminum welding is not one of their capabilities.