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View Full Version : Teach me about welding (TIG, MIG, ARC, etc.)


Spritle
06-11-2002, 12:02 PM
I want to learn to weld. I'm pretty confident with oxy-acetylene.

What's the difference between MIG, TIG, ARC and other types of welding? (I've used a MIG welder with flux core, but not a solid core/bottled gas system. What's the difference between these two?)

thanks in advance!

Spritle
06-12-2002, 08:28 AM
Anyone? Anyone? Bueller? Anyone?

Gosh, people, I don't want you to teach me how to weld, I just want to know the functional/practical differences between the types.

For example:

I know that you can't braise with MIG, TIG, ARC but you can w/ Oxy/Acet.

The M in MIG stands for Metal and the T in TIG stands for Tungsten. Why this is important is beyond me...

Please help....

Padeye
06-12-2002, 09:03 AM
If you've mastered OA you're well ahead of things. Everyone says TIG is the hardest process to master but I find the technique to be pretty similar to OA but with better puddle control. The only tricky part is getting both hands and a foot pedal all coordinated.

The tungsten electrode has an extremely high melting point so it's not consumed. The eleectrode is ground to a fine point which gived very fine arc control. The electrode is in the middle of a nozzle that feeds sheield gas to displace the oxygen and nitrogen from the puddle. TIG machines except for cheap hobby boxes have radio frequency arc starter. That starts the arc without touching the electrode preventing you from cross conaminating the base metal and electrode. I'm still a neophyte at TIG but hope to get more practice next year. I've got a Miller syncrowave 180 which is closer to an industrial machine than a hobby machine. I personally find stick welding on thin stock, 16ga steel, to be the most difficult for me. I need morepractice to get just the right amount of heat to get a full depth puddle without blowing through.

MIG welding adds shielding gas to the wire feed process. It's just as easy as flux core but you get pretty smooth welds with little or no spatter.

FWIW you may see some other terms for welding processes. GTAW (gas tig arc welding), GMAW (gas metal) and SMAW= stick

GaryM
06-12-2002, 09:22 AM
Aren't thay all considered "Arc Welding" in that the heat is supplied by an arc between an electrode and the base metal? Sure in some cases the electrode is deposited in the weld and in some cases not. But they are all types of arc welding.

Spritle
06-12-2002, 09:35 AM
OK, I'm getting this, I think....

If GaryM is right (and I have no reason to believe otherwise) what's the difference between the welders with the stick attached to the handle (what I thought was ARC) (is this "stick" welding?) and the MIG type with the wire feeding out of the handle?

Here's the real question. I have the opportunity to buy a MIG welder (slightly used but in excellent condition). My primary use would be to weld sheetmetal (auto body repair, mostly) and occasionally thicker stuff. Is the MIG better than Oxy/Acet for this purpose? I imagine I'd have problems with the thinner sheetmetal and OA blowing through it. Is this eliminated with the MIG? What about control and depth of weld? How does this fit into the whole MIG thing? In short, is the MIG system ($150) worth the purhcase of welding gloves and better helmet (autodarkening - $250) worth the "investment" over Oxy/Acet?

Spritle
06-12-2002, 09:40 AM
Oops, should have read that the entire rig would be about $250; I can get a AD helmet for $100 +/- $20.

GaryM
06-12-2002, 09:54 AM
The "wire feed welder" I have is a a consumer grade made by, or marketed by, Campbell-Hausfeld. It was fairly inexpensive and within my finances at the time. I called it a wire feed because I can use flux filled wire, or solid wire with gas. I use it for repair jobs, not for heavy work. Last week I repaired the handle on my friend's Honda mower.

I am not an expert, but I have read/been told that a wire feed welder is easier to learn than "stick" welding. It's not too hard if you have a grinder handy to clean up with. As Padeye said, when using gas and solid wire you get nice beads and no flux to chip off. But gas supposedly can't be used if there is a breeze as the gas is pushed off the weld before it's time. So being able to use both types of wire is an advantage.

If a welder is advertized as "able to weld up to 3/16 material", you can be sure that's it absolute limit. I get poor results with that thickness of material.

The autodarkening helmet is money well spent. You'll not regret that one bit.

Spritle
06-12-2002, 10:06 AM
Thanks! I found some good explanatory info on stick vs wire feed welding at popularmechanics.com and toolsofthetrade.com

I'm reading this stuff now.

Padeye
06-12-2002, 03:06 PM
FWIW arc welders can in fact be used to weld in a straight line. :D

One of the other big differences is in the power supply. Tig and stick are done with a constant current power source. You set the desired current flow and voltage will vary with arc condition to maintain that current level. Wire feed is done with a constant voltage power source.

MIG is probably going to be the best choice for your kind of work but be wary of cheap machines as the wire feed mechanisms are sometimes unreliable. Still $150 sounds like a bargain. I'd hop on it. You can always trade up.

Gary, blowthrough isn't eliminated with any arc welding process including MIG but IMO it's easier to control than with gas. YMMV

Padeye
06-12-2002, 03:08 PM
BTW, what make and model is the machine you might be buying?