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TIG Welding
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08-24-2012, 07:13 AM
I took a sculpture class recently with my sister and niece and we used a TIG welder to weld some steel plate together. That sure is a different process than MIG welding. I like the fact that you don't get showered in sparks nearly as much as with MIG. Can anyone tell me the advantages and disadvantages of the two processes and when you would use one process over the other?
Ed 
08-24-2012, 07:33 AM
I have never TIG welded but to my understanding the big advantage is being able to control the heat very precisely. I have heard of guys welding soda cans together with a TIG. It is similar to Oxy/Acetylene welding in that you have to have the torch in one hand and the welding rod in the other right?
Elijah
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08-24-2012, 08:07 AM
(08-24-2012, 07:33 AM)SnailPowered Wrote: I have never TIG welded but to my understanding the big advantage is being able to control the heat very precisely. I have heard of guys welding soda cans together with a TIG. It is similar to Oxy/Acetylene welding in that you have to have the torch in one hand and the welding rod in the other right? All we used in the sculpture class was the torch with the electrode in it. No filler rod. Ed 
08-24-2012, 09:52 AM
Elijah is right. It is somewhat similar to oxy-fuel welding in that one hand controls the torch and the other hand controls the filler rod. The big difference there is, an oxy-fuel torch doesn't act like a huge filler rod magnet and destroy your torch tip if they touch! (Ask me how I know..)
 Just kidding.... However - accidentally touching the tungsten electrode with any other material (filler rod, work piece, grease, oil, etc.) will contaminate the tip and cause all kinds of problems with trying to maintain a good welding arc.  MIG lays down a lot of weld metal, and does it fast - but with some spatter. TIG is slower, having to feed the filler materiel by hand. But it is much more refined and controllable, and capable of maintaining a very low amperage arc. That allows you to pinpoint the arc, and reduce the HAZ (heat affected zone) of your weld bead. If you get showered with ANY sparks from TIG, you are doing it wrong... TIG is also more expensive over all, considering the equipment and consumables costs. If you are building a structure go MIG. If you want to attach two sheets of aluminum foil together for the space shuttle go TIG. 
Willie
08-24-2012, 02:28 PM
Willie is right. No sparks allowed in TIG welding.
A real benefit of TIG over other types of welding is the ease of jumping from one material to another. All you need to do is change a few settings on the machine and the type of filler rod and you can jump from welding stainless to aluminum to copper to tool steel or even gold if you are so inclined. TIG is also incredibly controllable. I once watch a guy TIG weld two pieces of aluminum foil together. For that reason, it is very good for welding sheet metal because it the heat affected zone is small which keeps distortion to a minimum. The main drawback of TIG is that it's slow and it requires a fair amount of skill to do well. A little hand/eye coordination doesn't hurt either.  Tom ![[Image: TomsTechLogo-Profile.png]](http://tomstechniques.com/wp-content/uploads/2013/11/TomsTechLogo-Profile.png)
There are some materials that require a change of the type of shielding gas used as well, or an additional "back purge" of gas provided to shield the back side of the weld. Stainless steel being one of them. If the back side of a stainless weld is open to atmosphere it can cause "sugaring" of the weld bead on that side.
I think Tom is underplaying the hand/eye coordination needed though. Or maybe it's just the fact that I don't have any.... I do know that I went through a LOT of tungsten's when I first got my TIG machine. 
Willie
08-24-2012, 03:36 PM
How did we get away with TIG welding at the sculpture class with no filler rod? I'm perplexed, as usual.
 Ed 
08-24-2012, 03:44 PM
Hi
Lads On a close fitting joint with TIG you can fuse the edges together without using any filler rod TIG is very similar to gas welding (you use the ark like a flame) With a DC set and pure argon you san weld any type of steel stainless inconell titanium ect you can also weld copper To weld aluminium you need AC (expensive) Most dc stick welders can be used as a tig welder , with the adition of a TIG torch and some shielding gas You have to scratch start the arc but it is propper tig welding The latest inverter type welders are ideal for this John
08-24-2012, 03:53 PM
You can do it with steel as long as you have enough base metal to melt together and no gaps. Same with oxy-acetylene. But if you need to fill a gap between two pieces it isn't going to happen without a filler rod or wire.
For thin metal you can even use regular MIG wire as a filler. Aluminum isn't so forgiving though because it is "hot short" - meaning that it is almost guaranteed to crack if you don't add any extra filler metal to the weld. 
Willie
08-24-2012, 03:59 PM
It was 3/16" steel plate being T welded with little to no gap so that's probably how we got away with it.
I noticed I could see the puddle much better with TIG than I've been able to with MIG. That's why it peaked my interest. I think my dismal results with MIG so far have been due to the fact that I've been practicing on too thin of steel for a newbie. Does that sound like a reasonable assumption? Ed |
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