Way off topic...Welding?

[jginalbany]

I am absolutely a huge fan of the "fabrication" reality shows on Discovery: American Chopper, American Hot Rod, Biker Build Off, Motorcycle Mania, etc. I love watching everything from raw fabrication to painting and fitting the interior/seat. One thing that I am intrigued by is welding. The only thing I know about welding, other than that it joins two pieces of metal through an arc, is that a good weld should look like a row of nickels standing on end. Other than that, I have no idea what a MIG weld is vs. a TIG weld. I've googled the topic, but most of the sites I found explain it at a level beyond my meager understanding of electricity and chemistry. Can anyone explain the types of welding for me?...aim for an 8th grade comprehension on this one. :-) Thanks!

Jim

[Gecko]

MIG welding uses a wire off a spool for fill and to carry the arc. TIG uses a tungsten to carry the arc and you use a filler rod. We use mig for steel and stainless steel mostly. TIG for aluminun. TIG is a cleaner welding process. I love to TIG aluminum. If you have any specific questions, I will try to answer them although I am by no means an expert. I just know how to it. :)

[cavey35]

MIG welding is sometimes called wire welding, as wire is fed from a spool to make the bead that joins the materials being welded.

TIG welding, heat is generated from a tungsten electrode to the material being welded. A filler rod is not always neccessary as enough heat can be applied to a small area, melting the materials together.


Hope this helps.


Jeff

[jginalbany]

Thanks for the explanations.

A few more questions:

Is it TIG welding when they are holding a long piece of filler in their hand and dabbing it on the joint as they go?

Can the same machine be used for MIG and TIG welding?

Thanks!

Jim

[FrankC]

Quite a bit of basic welding information here from Miller:

http://www.millerwelds.com/education...es/story18.php

Sawdust Making 101
http://sawdustmaking.com

[Gecko]

Yes that is TIG. And no. Two different machines are needed. You can only use a MIG welder for MIG but you can use an ARC welding machine to TIG.

[brent]

From my fuzzy memories of high school.. I think MIG is molten inert gas. CO2 and perhaps argon that flow around the wire as it melts. Keeps the Oxygen from being present when the weld is cooling and you get a very nice clean weld with no slag. (that crusty stuff left around a stick weld).
I have done MIG, but never TIG. A friend of mine was working with a TIG and said one of the big advantages of it is that it does not necessarily put so much heat into the metal. At OCC, you will see them tack a tank together with MIG and then fill it with TIG. I am guessing that the MIG is fast and holds it while they use the TIG to fill so the heat does not distort the thin metal. My friend said they were welding two small pieces together and when they were done you could pick them up by the edges. Looks cool.

[TDHofstetter]

Ah, REALLY close... "Metal Inert Gas" versus "Tungsten Inert Gas", referring to the kind of electrode used. Funny, since unless I'm mistaken Tungsten is a metal... it just doesn't melt at the temperatures we find in welding.

Metal Inert Gas welding gradually spends the electrode (mostly in the form of a wire but sometimes a stick) while Tungsten Inert Gas doesn't.

Loose filler metal held in the free hand is also used in torch welding, usually referred to as "brazing" 'cause the filler is brass or bronze... although such as nickel-silver filler rod (and some others) are also used. The primary difference here is that a torch is used to apply the heat instead of electricity, and torch welding is typically done at far lower temperatures than electric welding.

Benefits to 'em all - "arc" or "stick" welding, MIG, TIG, gasless wire welding, brazing. They each have their long trousers.

-- Tim --

A novice has many options,
An expert, only a few.

[rrich]

Jim,
I can explain a little. (I have a wire welder and use mostly flux core wire to weld rather than a gas set up. I don't do enough welding to make purchasing a tank of gas ecconomical.)

There are four parts to welding, the parts being welded, the heating mechanism, the filler material and the shielding mechanism. The parts to be welded are obvious. The heat may be electrical or burning gas. The filler is the welding rod, stick or wire. The shielding mechanism is what makes welding actually work.

As we weld, the parts are heated to the point of liquidity and these parts are melted together with additional filler material from the welding rod, wire or stick. As this cools the joint becomes as strong as if the pieces were originally made that way. But wait! There is a problem. When the metal is heated it tends to oxidize. (a.k.a. Burn) To prevent this oxidation a shielding gas is used. In a stick welder, the material around the welding stick burns and removes oxygen from the area of the weld. In a wire welder, the shielding gas is from an external tank (Argon or CO2/Argon mix) of from the core of the wire.

So, to weld, we heat the parts to molton metal, flow the metal together, add additional material all outside the presence of oxygen and we then have a welded joint.

Really it is a lot simpler than it sounds. Welding is a lot like woodworking, you have to practice to get good at it. (I don't get enough practice.)

[brent]

"long trousers" I like that one. Never heard that before. Ya' crack me up.
So there is also ac and dc is that right? If I remember right we used to weld MIG DC and reverse the current to fill larger gaps since the heat was in the wire and not the iron. Or did I just dream that up? It has been about 20 years since I held a welder.
Man that makes me feel old. Thanks a lot.