Calling all welders

[kamaroman68]

So I took a couple of extremely basic welding classes that the Snap On dealer puts on on a weekly basis. The teacher said many things some of which I didn't know some of which I thought was downright wrong. Anyways to the question. The teacher said that mig welding is the strongest from of welding. Stronger than tig stronger than arc welding. Is this true? If so why do people still make there rollcages with tig welds rather than mig? He also said that nascar uses mig welding although from what I see they all look tig welded. Come september I will be taking actual classes from the local boces. They start on basic arc welding moving into mig. The next class continues mig and starts tig. Thanks Chris

[parsonsj]

Uh. Yeah.

Hmm. Where to start? How about this: welding is a complex science/art that requires exacting knowledge of the material and tools to achieve optimum results. Lumping it all down as "MIG is the strongest weld" is nonsense. We need context to make such decisions. What material is he talking about?

There are lots of NASCAR racecars. Ask him how the radiators are welded. MIG? Or TIG? Why?

One thing that is often true is that production environments using mild steel are MIG-welded. Many circle track cars fit in that category. Why? Because MIG is much faster, and achieves the needed strength.

Have him look at a Top Fuel car chassis. Made from 4130 or other alloy steel, it is TIG welded (usually). Why? Because even though TIG is slower, it is necessary to achieve the proper welding for that material.

Have fun with your teacher!

jp

[Matt@RFR]

Apparently Snap-On instructors are no better than their welders. Promptly forget everything that guy said and go take a real class. He's an idiot.

Like John said, the Winston Cup guys build lots of chassis, and MIG is quicker. However, MIG on small tube is one of the hardest processes to do correctly. Harder than TIG on small tube.

[duece_bigalo01]

Tig is less hard on the metal and too me atleast it is easier to put down the right amount of filler rod and make the weld not only look good but be strong as well. As stated before the matierial that is used and time constraints dictate what process is used. Also matierial thickness is an issue. Mig usually puts down a very large heat pattern that tempers the metal alot different then the Tig. Tig has a small heat pattern. Tig consentrates its heat in a small concentrated area. Tig is used for delicate areas that can not have alot of heat tempering. Mig is used for production line alot becasue of simplicity and speed. Mig is also good (if you have the machine for it) for thick metals to do in one pass. Tig is traditionally cleaner then Mig but Mig is more portable.
As far as roll bars you dont want to boil some of the property's out of the metal and you dont want to have the metal more tempered (brittle) on something that is designed to save your life.

[FCRacing]

Well you got a lot of good info from the other folks above, but I might add MIG can be used on MILD or DOM 1020 Steel, but I do not and will not use for any Alloy welding @ 4130 many shops just weld the 4130 with oxweld 65 rod and call it good , but to properly weld this material you should use TIG with ARGON gas shield, You should also preheat the metal and post heat anneal when done............this adds a bit more time to the overall project, but gives your material the best chance at survival...........FCRacing