MIG or TIG When Frame Building?

Looking at B***'s stuff just makes me happy. Everything is done so well and purposeful. I normally like to shuffle through his builds once a month for inspiration and ideas. From what I can tell and have read he prefers TIG welding on most of the frame. I asked a friend who build cars for NASCAR and he said that they build their ch***is using MIG welders and only for small exposed brackets will a TIG be introduced into the equation. He told me that for the most part a TIG is stronger but also more brittle which makes is susceptible to breaking. Which do you prefer and why? Where would one use each type and is there a difference in the wire that makes it strong or weak? Post some pics if you can of where each method is appropriate.

 

How many timnes can this subject come up. There are many posts about various welding types. The answer is, all of them. Good penetration, good fit, and it doesn't matter whether it is arc, mig, tig or gas.
Search for the threads and every answer you want will come up. Choose the one you want.

 

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Easy Trigger. I did not find one that discusses the difference in wire type or why professional race teams would prefer one to another. Don't bother scolding me if your just going to answer my question in the long run. It's just perpetuates the need to make more threads where you deem them not useful.

 

TIG is state of the art process /aero space type stuff. It's the absolute best weld quality out of all the process'. But likewise...it's very over-rated.

MIG is a very good process also. The thing with MIG is travel speed. Facilities use MIG for production type work. Anything repetative, such as the booms, extension booms & fork lift platforms I normally weld together. Employer wants the product built & out the door.

Arc is for Maintenence.

If you don't mind spending a year and a day of your time TIG'ng an entire car frame, then go it. If you want to see the frame completed over the course of a weekend and not be in the garage the entire 48hrs, then MIG it.

Carl Hagan ......oh...straight CO2 is for beer, so stick with a mixture of Argon / CO2 for a nice quality weld.

 

Filler material (weld rod, tig rod, mig wire) is always equal to or greater than the base material your wanting to weld together.

All tig rods, mig wires & arc rods can be purchased as different hardness'.

You wouldn't want to weld something together if the wire or arc rod is purposely manufactured for say.....'Hard Facing' .....such as hard facing a spiral drill augger bit.

You just have to slowly learn these things & use what works for you as long as what your welding together will p*** a Destructive Testing Procedure (or nondescructive) . Carl Hagan

 

I Tig welded a bunch of tubing joints in a cage that is part of my ch***is. I liked being able to see the puddle and make sure everything was fused togeather. Maybe the joints are more brittle, but how much I wouldn't know. When I go back and put some gussets in I'll use the MIG. In my opinion it's nice to use both.

I fully agree that welding quality, no matter what type, is mostly up to the person doing the welding.

 

Gas welding produces the softest welds, then Tig, Then Mig.
The mig is fast, making a quick weld and less of a heat affected zone.
The faster the welding process the more brittle the weld.
Thats why gas welding is used to join complicated joints in chromoly aircraft tube, the slow heat up and cool down anneals / normalizes the joint so its less apt to crack.

Mig a couple pieces of sheet metal together, dress the welds, bend it and watch it crack......do the same with a tig or gas weld and if done properly it will work as a single piece of metal.

I can wheel out gas welds with my english wheel, Mig welds will tear the hell out of wheels, hammers and dollies.

Gas and tig welded sheetmetal is easier to work with a hammer and dolly.
Mig welded sheet metal is better served for the quickie bodyshop, weld it mud it, get r done and get paid.

 

I have been engineering in the racing industry for the last 15 years and all our stuff, frames, suspension, uprights, are welded with TIG welders. Our standard steel is 4130, rarely if ever is 1018 low carb utilized. Not sure why your buddy from NASCAR indicates that TIG welding causes the material to get brittle, I have never seen that happen and in fact we utilize the TIG process to prevent that from happening.

Working in my garage at home I have a small TIG welder but I am planning on purchasing a MIG welder for certain applications. I do agree with Carl you cannot go wrong with either process. In my industry which designs and manufactures to aerospace tolerance, TIG is the welder of choice.

 

use whatever your more proficient with

 

Likewise, TIG is the way to add 25hrs of labor to the bill. Carl Hagan

 

The thing about nascar teams is they spend HUGE money to understand how ch***is flex translates to on-track dynamics. Some of the ch***is construction and suspension variables are determined by the rulebook, so the teams take things like welding methods to the extreme, in an effort to make the ch***is more rigid or compliant in specific areas. Wouldn't suprise me at all to see different weld methods or different filler wire used depending on which corner of the car you're looking at.

 

This is total BS. If that's what they're experiencing, then they are doing something wrong. Just because the guy works for a team doesn't mean he's an expert or even competent welder. I've seen guys who call themselves fabricators but couldn't glue two popsicle sticks together without screwing it up.

 

Raceworks, a local builder specializing in Nascar Modifieds, tigs their ch***is together, according to them, the extra time is not too bad, and the quality of their cars is outstanding. I like to use tig, especially for smaller stuff, as I can use stainless for alot of it, and when you are done, you are done, no plating, powder or paint needed. Still like the mig for stuff that's heavy, or does not easily fit on the bench, as I'm not quite as good as those guys. If I could only have one machine, it would be hard to choose, but using the tig more and more, as it's usually so much prettier. Your local supply house is your best bet for info on rod etc.as long as they are used to dealing with pros. Lotta good info on here too...

 

I don't know if I agree.

A proper MIG weld with do the same thing (act like a single piece of metal) in my experience.

 

ICAR sheet metal certification with MIG is to weld the coupons together and do a bend until it breaks test. If it breaks at the weld, you don't p***. The weld joint should be stronger than the base metal.

 

Similar for structural when I certified on MIG. The test consisted of welding together two 1/2-inch thick mild steel plates with a 45 degree chamfer at the joint using 0.045 wire, CO2 and up to 8 p***es. The weld areas on the plates were then ground flat, the plates were sliced through the welded seam into 4 strips, 2 bent into a U shape in a press with the root of the weld out, and 2 bent with the root of the weld in. Forming the strips really stretched the welded seam, and any inclusions or cracking found = you failed. Took some people many hours of practice before their first success on this test, especially with the multiple p***es required. An acid solution painted on the cross section clearly showed the depth of penetration of the weld into the base material. Later I worked in field test and sometimes found structural failures on frames in overstressed base material on either side of a MIG weld, but none through the weld itself. MIG is excellent for structural work, but TIG also works well. TIG is usually prettier because there is more control over the filler material, and the overlapping fishscale style of weld typically seen doesn't reveal stopping or starting points like a string of MIG welds. Continuous MIG welds can be very pretty.

 

Use a jig so your frame won't turn into a pretzel. Make your tacks with a MIG and finish weld with a TIG. For the most part TIG welds are stronger and they look better. There is a reason why professional ch***is builders TIG their ch***is... my 2 cents.

 

I think the Nascar dude was talking out his rear end - probably isn't even a certified welder.

The most likely reasons they use MIG has got to be time/cost. It is much faster to use MIG, than TIG . . . but I sure wouldn't agree that TIG is less structurally sound than MIG. If that was true, you wouldn't see it in professional ch***is work, aero-space, nuclear, etc.. Everybody I know would take TIG over MIG any day of the week - ***uming they didn't have to worry about time and $$$

 

I am a better MIG welder than I am a TIG welder. It takes practice and I'm working more often now with the TIG............I think, eventually, I will use the TIG whenever I can.

You can't beat a MIG for quick & dirty blacksmith stuff though.

 

AHEM, Well I've been thru all the phases of welding since1951, & each of you has a very legitimate answer, I started welding in the USN in 1951, gas welding & brazing to start, then into arc/ stick welding, later into certified pipe welding (stick), then when MIG came out in 1964 for pipe welding (certified), then TIG for Brewery quality SS pipe welding, I can say that the simple answer for mild steel car related, is MIG, & yes , TIG does have a tendency to make the molecules "draw up" tighter, so each application DOES require a different approach,---Right?-----------Don

 

MIG (Mud gun) is for trailers and TIG is for race cars and hot rods!

Rex

 

I'm not a faby, but have been in the racing industry since 1986, and have never seen anybody use MIG on anything but pit equipment. Nas**** uses it all the time, it's quick and ez and they build a lot off cars at the same time. TIG makes a nice weld. There'e my 2 cents.

 

I usually stay the hell out of these welding threads but I just have to say that MIG is not only for trailers and stick is not only for maintainance. All procedures will make beautiful and strong welds if the welder knows what he's doing. Reminds me of the cutting torch, most people think of it as some kind of butcher tool but if you know how to use it properly you can make perfectly clean cuts.

 

What I found after becoming proficient in tig welding back in the late 60's it made me want to throw rocks at gas and arc welding (no mig in those days that I know of) When I certified for my SEMA cert. I had to weld up what was called a wing strut ***embly (a piece of 1/4" 4130 chromoly plate with (3) 1" o.d. .063 wall (I think) 4130 slotted tubes that were welded in from the side 2 on angle and 1 straight) I bought 3 of the ***emblies 2 for practice and one for testing. Think I still have one around somewhere, if so I will take a picture of it and post it. All NHRA AA/FD, TF/FC, TA/D and TA/FC are required to be constructed of 4130 chromoly and tig welded. You will find a lot of .063 wall thickness used race car ch***is construction because no matter the O.D of the tube .063 will slip fit into the next size tube, up or down with a tight fit. And if needed for a joint you can make a beautiful tight fitting rosette weld in the chromolly in addition to the weld at the splice that was always cut on an angle for more weld surface area. Tig is my choice on any ch***is work if its affordabe and you are proficient. There were a lot of dragster ch***is in the early days that were constructed on a garage floor from mild steel and gas welded (and for the most part they stayed together) I drove some mild steel gas welded cars when I first started driving dragsters. Would I do it today? NO...... Maybe there should be "How To" thread started on welding round chromoly tubing and how to fish mouth the tube for proper fit. Something Ed Mabry taught me was always put your tubing in tension and never in compression. BTW.....Ed's rear engine dragster design was used by SEMA for the first standards. Sorry for going a little O/T and being long winded. Just my .02 cents. "Skid Inn" and "Pearl", if you know Ed you will understand, Ha.
408 AA/D

 

Are you trying to tel us what your MIG welds look like?

 

I'd love to see a thread started on welding techniques for chrome moly tubing, ch***is building, suspension components, etc.. I'll bet that most of us "HAMB Welders" could learn a TON from guys like you who have been doing high-performance race car work for years.

You should start a thread - maybe just starting with the basics of types of tubing you use, rod types, prep work, TIG welding settings (electrode setup, amps, gas, etc) and application techniques. I've read about many of these things, but am NOT a certified welder - though I'm getting fairly proficient in mild steel and stainless with my TIG. The books and videos help, but they tend to be more general than specific.

I can't say that I'm qualified to be a big contributor, but I'd be more than happy to "work along" with the post, try some things and give feedback from a student's perspective.

 

I agree well said.

 

Actually .058 tubing will slide into the next size, .065 will not slide.

 

I've been TIG welding forever and Carl is right, there is many different filler materials so idon't know what they mean by brittle. The reason ch***is builder use TIG is that we have to, SFI certification of a chrome moly ch***is requires TIG welding.
TIG welding is akin to needlepoint s***ching, each little 'dot' is a seperate weld. That little spot is heated until molten, the base materials joined and a touch of filler added; then the next spot is heated and so on. I believe that welding estimates of MIG is in feet per day and with TIG it is in inches per day.
All that said, the best resean we TIG over MIG is pure pride in our workmanship. And thats' that.