MIG Welding Aluminum

[sanddrag]

I know you can weld aluminum with a MIG welder, but do you absolutely need a spool gun? I've read a few manuals that just say use 100% argon gas and a larger tip for expansion and so on and so forth. No mention of a spool gun. So, does it really work? If not, how much do spool guns (and related/required accessories) cost?

[Jay H 237]

When I was shopping for a MIG welder last November all the ones I looked at, Lincoln, Miller, and Hobart, recommended a spool gun for aluminum. The problem with aluminum wire is that it isn't as stiff and can "bunch up" trying to go through the 8 or 10' gun cable if it's mounted in the welder where you normally mount the wire spool. I had no interest in welding aluminum so I never inquired anymore into the spool guns so I don't know how much they cost.

It can be done though with a standard MIG welder if you set the machine up correctly. Here's a link about welding aluminum that was given to me when I was asking about MIG welders on here. 100% argon is the correct gas to use.

[Andrew Rudolph]

Yeah jason pretty much hit it on the head there, once you get practice at setting a regular mig welder up to weld aluminum you will have less problems, but it takes a while to get it set up just right. Make sure that your welder even with the gas can do aluminum, some small welders even with the gas cant.

[Jeff Waegelin]

What would be the advantage of using a MIG welder over a TIG welder for aluminum? Does one have an advantage over the other?

[Cory]

Originally Posted by Jeff Waegelin

What would be the advantage of using a MIG welder over a TIG welder for aluminum? Does one have an advantage over the other?

MIG is a lot easier to learn than TIG, but I have no idea if that holds true while welding aluminum instead of steel.

[sanddrag]

TIG is the preferable choice for aluminum, but it is not cheap. MIG machines are generally much cheaper.

So, has anyone done it?

[Jay H 237]

Originally Posted by sanddrag

TIG is the preferable choice for aluminum, but it is not cheap. MIG machines are generally much cheaper.

So, has anyone done it?

Here's a site where you're likely to find your answers to welding aluminum with a MIG welder, Metal Meet. Thier forums have a lot of info. Plus there's plenty of other info on any type of metal work you can think of on there.

[Gdeaver]

Tig welding separates the heating from the filler material feeding. This allows you to place the arc and concentrate the heat where you need it with out excessive metal build up. The filler material can be added when and where its needed. It's more like a brazing process. This requires one to have 2 different hand motions at the same time. This takes allot more time to master. Difficult welds usually can be done better with Tig. Tig is expensive. The one piece of equipment I would spend some money on is a good wide view variable auto darkening welding helmet. It makes a big difference when your learning. > $150 but worth ever bit. I hate welding with a 115 volt MIG welder. I only use mine on jobs where I don't have access to 220. If you can afford it go with a good 220 unit. The more you spend the better the duty cycle. Learn to weld steel well first, then tackle aluminum. Most welding supply houses will have a book on welding and I think its Modern Welding. It includes several hours of step by step examples of welding techniques on DVD. The only way to learn to weld is practice and practice and practice.

[eugenebrooks]

Originally Posted by sanddrag

I know you can weld aluminum with a MIG welder, but do you absolutely need a spool gun? I've read a few manuals that just say use 100% argon gas and a larger tip for expansion and so on and so forth. No mention of a spool gun. So, does it really work? If not, how much do spool guns (and related/required accessories) cost?

SandDrag:

I did the welding on 1280's robot last year. There were both sections of 1/8 aluminum in 6061-T6, flanges on 1/2 axles in 4130 steel that we heat treated after welding, and other small parts. We used a Lincoln TIG-185 with a water cooled torch adapted to it. The rig was pretty close to topped out when welding the aluminun and the heaviest steel pieces. The water cooled torch was pretty essential at these currents.

The spool gun is optional, it's role is to avoid kinking in the wire feed when attempting to weld soft aluminum wire. If you already have a MIG welder, you can try it out with aluminum wire and see if the welder is capable of dealing with the welding you want to do before investing in a spool gun.

Inexpensive MIG welders can run a little short on voltage/current when attemtping to weld aluminum. Aluminum conducts heat away from the weld like a bandit. Aluminum is welded "hot and fast" in order to minimize heat input to the material so that the heat treatment is not unduly affected. Your typical 115 volt MIG welder will not be capable of welding 1/8 aluminum and this thickness of material is likely to appear on a FIRST robot.

Although I would reccomend a TIG welder for aluminum, if you are going to buy a MIG rig for aluminum I would be very careful to check the process limits for the welder you are considering buying. The brochures available for the Lincoln SP-135 and SP-175 indicate that you will need at least the SP-175 in order to deal with 1/8 inch aluminum. Remember that power is voltage times current, and some welders might have impressive current figures while falling down a bit in voltage, and therefore come up short in delivering heat.

Have fun,
Eugene

[JAH]

Originally Posted by Gdeaver

TIG takes allot more time to master. Difficult welds usually can be done better with Tig. Tig is expensive. The one piece of equipment I would spend some money on is a good wide view variable auto darkening welding helmet. It makes a big difference when your learning. >Learn to weld steel well first, then tackle aluminum. Most welding supply houses will have a book on welding and I think its Modern Welding. The only way to learn to weld is practice and practice and practice.

Gdeaver is exactly correct on a lot of this. Welding aluminum takes a great deal of practice and time. An auto-darkening welding helmet is near must for a new welder. It helped me greatly when I learned. I however, learned to do aluminum before steel. It really makes me appreciate things more. I got good at welding aluminum then tried to do some steel real quick on a little project, I was amazed at how fast it would pool and stay so contained. I learned most of what I know from a new mentor for Cyber Blue, but Miller offers a guide to welding on their website, near 80 pages and you get it with any Miller welder, or you can download it offline for free. I recommend it. If you want to weld aluminum full time, TIG is the only way to go. On rare occasion, MIG would work. As many others have said, the amps just aren't there in smaller MIG welders to really be able to do aluminum. Aluminum takes a lot more power than steel. If you're interested, I use a Miller Syncrowave 180 SD. It's a great machine for the money. Hope I added something.

[ghansel]

Disclaimer: I am a crappy welder. That being said, I was my teams only welder in the 2005 season, and only because I was willing to take a chance and try to teach myself on the job. Autodidactic or not, this was a stupid (though necessary) thing to do which I would not recommend to anybody. I have never welded steel. Therefore any opinion below is completely honest and based on first-person experience but I make no claim to its veracity. You know what I mean. In addition I welcome any welding tips.

I used an autodarkening helmet. Absolute must. I can't imagine not using it, especially for those 2 hour 7am welding runs where time just disappears, but you have holes burned in your clothing.

MIG machines are generally much cheaper.

The cost advantages of MIG welding aluminum disappear when you have to get a spool gun. This year, ours broke (a discontinued-with-good-reason Miller model, the Spoolmatic 700 or something of the like, big honking thing) and we looked into replacing it. We're cheap, so we looked on Ebay - to buy a new model used would have run us over a grand. This is just for the spool gun itself - welder not included (the boxlike thing you plug all the wires into). We opted to repair it, but kinks continued to crop up every couple minutes.

I have never TIG welded but I'm sure that once I do, I'll have no desire to use MIG on aluminum ever again. In addition to the obvious cost disadvantage if you get a spool gun, a spool gun is a big thing, at least 16 inches long and always bigger, heavier, and more cumbersome than you think. After welding for a while (>20 min), you will get sore, tired, and irritated. I ended up holding it like a paintball gun - back of it resting on the top of my shoulder, wire coming out at eye level. This is probably terrible form (see disclaimer). Held like this, I had to crouch, which wasn't any more comfortable or any less cramping. Spool guns are big. If you're doing welds in small areas, they either won't fit, or you'll have to contort yourself to make a weld. Because the whole thing is so long, you won't be able to see what you're doing clearly, either.

So if your robot needs welds, go TIG or don't do it in-house. With TIG you'll get stronger, prettier, faster, easier (if you know how), welds that are less likely to burn through, especially on the thin aluminum we use in FIRST (if you pay attention and have a pedal etc.).

Regardless of your welding method, always clean and wirebrush or sandblast immediately before welding aluminum. Weld weakness, porosity, and crappy look of the weld smut if it's not makes it well worth the effort.

Another option is a spot-welder or resistance welder. Not as exciting, but simpler, much cheaper and easy to do without training (though you should be trained) and effective in many situations.

George

[Dick Linn]

A good source for welding information is http://www.hobartwelders.com/mboard/

Just search around before posting, as most beginner's questions have been discussed several times.

And here are some tips: http://www.lincolnwelding.com/knowle...icles/list.asp

I recently got a Lincoln SP-175+ MIG welder, primarily because I wanted to be able to do 1/8 to 3/16 Aluminum if necessary. If the cable is kept straight and the wire feed is set up correctly, a spoolgun is not absolutely necessary. The stiffer filler alloy is preferable (5356?), as is a larger diameter wire, to prevent kinking.