What is the main difference between a Mig and a Tig in plain English?

I know Tigs produce a cleaner nicer weld but are the welds stronger then a mig?
If you want to weld aluminium you should get a tig correct? But do all tig welders weld aluminum? Or only certain ones?

Do they still make welders that do both? Weld Mig and Tig? My one friend had a snap on that did both. Do these still exist? And if so what is the price range on something like this?

What are some good sites to read up on the different machines and where do most people recommend buying them from?

Sorry for the stupid NOOB questions but I would like to purchase a machine for my father for his b-day and also over time learn how to weld. Right now he has this cheap mig welder that does not even use gas and lays down some crappy welds.

Thanks for your help.

 

The main difference in mig and tig is, Mig feeds the wire for you and Tig you use a filler rod and do it by hand. As a result the welds are a little different but both are strong.

You need a machine with AC to do aluminum. Most guys use tig for Alum. but you can do it with Mig also. Look for a mig with a spool feed gun if you want to go that route.

The best thing to do would be go to a welding shop and have them show you some things.

 

the above is correct. Also machines called multi-process machines will do several different types of welding such as mig and tig but usually these machines are DC only not AC and DC which means no aluminum. but what is really strange is on a tig machine you need AC to do aluminum but on a mig you can weld aluminum in DC mode and just add a spool gun. both mig and tig are very strong if done properly. Tig is slower , more costly and requires more talent/practice to do.

 

Okay so if I want to get a dual machine mig/tig I can not do aluminum? How much do those machines go for? Also do you use different gas for mig/tig?

 

You can do aluminum with DC. it just isn't as easy. The AC is what cleans the metal and the DC is what welds it. Or something like that. If you clean the metal really good you can do it with DC. The mig will be DC I think.

Do you know what he will be using it for? A mig has to be the most veristle thing there is.

I have a fairly cheap lincoln mig, sp 125+ and a miller 180sd tig. I would take the mig over the tig any day. Probably 75% of the projects I do I use the mig. A spool gun mig will do aluminum pretty good. They tend to cost more though.. Like $1500 for a mig.

 

The only reason I am worried about the tig with aluminum is b/c we got a rollback and the bed is aluminum and most of the welds are cracked or broken. I figured this would give him something to practice on and keep him busy for a while.

Other stuff that he would be welding not really sure at this point in time.

 

A good mig will do aluminum nicely. They are a little more mobile, since they only use the gun and a ground.

 

DC Electrode Negative (-) ~ The arc goes from the electrode to the base metal. This concentrates the heat onto the piece being welded and produces a deeper weld penetration.

DC Electrode Positive (+) ~ The arc goes from the base metal to the electrode. This concentrates less heat onto the base metal and is useful for welding thinner materials. DC (+) also provides a cleaning action to the base metal since the arc is rising from the base metal to the electrode.

AC/DC ~ A combination of DC (+) and DC (-). Provides medium penetration and the benefit of cleaning the base metal.

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Aluminum has to be really really really clean to produce a good weld. Aluminum should only be cleaned with a stainless steel brush and should be brushed until the metal has a satin finish and the brush slightly sticks while scrubbing back and forth. It is best to use an AC/DC machine to weld aluminum because the DC (+) wave will clean off the oxides from the metal.

This being said, you can use a Mig or a Tig machine to weld aluminum. When Mig'ing aluminum it helps to have thicker metals and/or uniformly thick metals. When Tig'ing aluminum the welder (you) can manually adjust the amperage while welding to adjust to different metal thicknesses and base metal temperatures.