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mig welded

Posted By: sixpackgut

mig welded - 05/23/11 03:48 PM

i was in a plane this past weekend doing loops and all kind of crazy things. hit 3.5 G's. and the one thing i noticed was the plane had mig welds.

another note, as soon as we were done, i had to check what the G's are in a Top Fuel dragster and according to the internet it is 5-6 on launch which must be totally incredible

Attached picture 6646744-051901_1642[00].jpg
Posted By: MR_P_BODY

Re: mig welded - 05/23/11 05:13 PM

Quote:

i was in a plane this past weekend doing loops and all kind of crazy things. hit 3.5 G's. and the one thing i noticed was the plane had mig welds.

another note, as soon as we were done, i had to check what the G's are in a Top Fuel dragster and according to the internet it is 5-6 on launch which must be totally incredible



That plane must have been made out of mild steel...
all moly tubing should be tigged... also the decell
on the top fuelers has a greater G force than on the
acceleration... supposedly 5 Gs on accell and 6 Gs
on decell
Posted By: sshemi

Re: mig welded - 05/23/11 05:21 PM

are you joking or what??
Should be made out of aluminum?
Posted By: MR_P_BODY

Re: mig welded - 05/23/11 05:24 PM

Quote:

are you joking or what??
Should be made out of aluminum?



Seen alot of airplane stuff made in moly... a buddy
has a copter that is moly
Posted By: maximum entropy

Re: mig welded - 05/23/11 05:32 PM

the nascar stuff is all wire feed. they have giant, globby welds. the eagle has landed (that's what we say when a huge, ugly weld has been executed).
Posted By: sixpackgut

Re: mig welded - 05/23/11 07:49 PM

Quote:

the nascar stuff is all wire feed. they have giant, globby welds. the eagle has landed (that's what we say when a huge, ugly weld has been executed).



Yes, i also noticed a NASCAR car on display this past weekend with mig welds and chaulked that up to being a display car and really wasnt sure about it
Posted By: RobX4406

Re: mig welded - 05/23/11 08:07 PM

Aren't cup cars chassis/cages mild steel, no CM in them.
Posted By: maximum entropy

Re: mig welded - 05/23/11 08:12 PM

Quote:

Quote:

the nascar stuff is all wire feed. they have giant, globby welds. the eagle has landed (that's what we say when a huge, ugly weld has been executed).



Yes, i also noticed a NASCAR car on display this past weekend with mig welds and chaulked that up to being a display car and really wasnt sure about it


check out the welds on tv- big und phat!
Posted By: MR_P_BODY

Re: mig welded - 05/23/11 09:59 PM

Quote:

Aren't cup cars chassis/cages mild steel, no CM in them.



Correct, thats why they mig plus its easier to fix them
after a crash
Posted By: rickstershemi

Re: mig welded - 05/23/11 11:00 PM

Quote:

i was in a plane this past weekend doing loops and all kind of crazy things. hit 3.5 G's. and the one thing i noticed was the plane had mig welds.

another note, as soon as we were done, i had to check what the G's are in a Top Fuel dragster and according to the internet it is 5-6 on launch which must be totally incredible



I used to own and fly a 1948 Luscombe 8F Silvaire with a 115 Lycoming Conversion....aluminum structure & skin .... stress rated to +6 -4 g's fun ride ... it was actually the first all-metal small plane produced

Rickster
Posted By: Stanton

Re: mig welded - 05/24/11 04:17 AM

Quote:

are you joking or what??
Should be made out of aluminum?




Many small planes are made of chromoly. I think mild steel would be very uncommon due to the weight. Hey, they used to be made out of wood !!!

The welds in roundy-round cars are usually migged because they're mild steel and a mig weld is fine in that application. The weld itself is big and fat because they lower the heat and weld in a circular pattern. The lower heat gives less distortion and maintains the metal integrity while the circular pattern provides the penetration. You will see tig welds but they'll often be used to attach a thick bracket where the amperage required for adequate mig penetration on the bracket would just blow holes in the cage tubing.
Posted By: Cab_Burge

Re: mig welded - 05/24/11 07:06 AM

The FAA allows gas(oxy aceleteneSP?) welding to be used in repairing chromemoly in airplanes, seen it done on a Taylor Craft and a early Piper Most of the newer spam cans are all rivited aluminum monoque construction except for the wing spars, landing gear and motor mount cages A lot of the earlier airplanes that where fabric covered where wood and steel tubing combined or all of one or the other
Posted By: Bob_Coomer

Re: mig welded - 05/26/11 03:17 AM

Quote:

The lower heat gives less distortion and maintains the metal integrity while the circular pattern provides the penetration.


I hate to agrue but as a State certified Union Welder some of these statements I cant agree with...
I would of coarse need to look at the weld but I larger weld bead is simply that more weld. Penetration is more or less controlled by heat range... Fact. Now the speed at which one moves will help "under cut" which is when the weld is not held long enough on the sides. Your always pausing on the sides with a Mig and move across the center faster and hold on the sides... Same with arc welding... This keeps the bead from humping up, ties in the sides good just lays down better. Heat dictates everything, how fast you move, Idea is to weld hot as you can and still control the bead in a uniform fashion.
I still dont under stand why the sanction body doesnt allow stick/arc welding of the cage. Done properly will be just as strong, actually stronger than MIG.
Posted By: MR_P_BODY

Re: mig welded - 05/26/11 04:00 AM

You will see tig welds but they'll often be used to attach a thick bracket where the amperage required for adequate mig penetration on the bracket would just blow holes in the cage tubing.



With a mig its all in the angle of attack... you aim
towards the thick material and circle/sweep to the
thinner stock

Posted By: astjp2

Re: mig welded - 05/26/11 05:28 AM

That airplane was probably Oxy Acteylene welded, Most steel tube aircraft that were built before 1986 were. Boeing still Oxy hydrogen welded Aluminum until the mid 1990's. One manufacturer mig welded and then had to heat treat the entire airframe in a huge oven. Think of 6'x6'x22' oven that got the tubing to a dull red. When those airplanes crashed, they usually broke in the weldment.
Tig used to be required to be pre and post heated to a dull red with a torch and then left to air cool to normalize 4130. Some will argue this topic but many airplanes are built from 3/4"x.035 wall 4130 normalized tubing. Engine mounts are .049 or .058 wall. They hold a 500 lbs 500+ cubic inch engine that puts out 750 lbft of torque at 2700-3000 RPM. They only get around 235-350 horsepower. All of this on around 8.0-1 compression.
I actually read how NHRA got to require tig, the called a welder up and he suggested TIG. They make great welds. Read the attached article. Tim

http://www.netwelding.com/Welding%204130.htm
Posted By: DaKuda

Re: mig welded - 05/26/11 02:34 PM

What does it really matter. MIG welding is PLENTY strong enough. That argument gets so old to me. GRANTED my Cuda just got a TIG welded cage but really...only for looks.
Posted By: Stanton

Re: mig welded - 05/26/11 03:39 PM

I don't think "strong enough" is the issue. Its only strong enough if done properly. Anyone can go out and buy a $200 mig at Harbor Freight and slap down a "good looking" mig bead. Having one done so its "strong enough" is a different thing altogether. By requiring tig welds you've just cut down the number of do-it-youselfers tremendously and a poor tig weld will be much easier to spot.
Posted By: DaKuda

Re: mig welded - 05/26/11 04:24 PM

So what about the millions of us who can MIG weld correctly...its absolutely strong enought then.
Posted By: MRMOPAR622

Re: mig welded - 05/26/11 05:31 PM

You can very well buy a mig-gun for $200.00 even @ Wal-Mart,but it will not be good enough to weld a roll cage. Not if you want it to hold up if ever in a crash. You can Mig weld a mild steel cage with a good Mig and it will hold if welded right. You run a bead down hill (welders know)with a mig,it won't hold!!!! Like someone said earlier you can buy a $200.00 arc (220 amp)and weld any M.S. cage and it will hold better than any mig weld.Take you forever to weld it,but will give you a stronger weld. I was a supervisor in the weld-bay @ Varco-Pruden for 14 yrs. been a welder for 25+ yrs.

BEWARE of who you trust to do any welding on your Race-Car. A poor weld is about like sticking bubble-gum on your cage or what ever you have welded,just because it is stuck on it does not meen it will hold.
Posted By: MR_P_BODY

Re: mig welded - 05/26/11 06:38 PM

Quote:

So what about the millions of us who can MIG weld correctly...its absolutely strong enought then.



Tig welding on moly is to keep the heat down(a very
concentrated heat point) because your welding on thinner
material
Posted By: MRMOPAR622

Re: mig welded - 05/26/11 10:14 PM

Tig & arc is 3 position welding,mig is 1 position welding flat.
Posted By: Evil Spirit

Re: mig welded - 05/31/11 01:43 PM

Quote:

You can very well buy a mig-gun for $200.00 even @ Wal-Mart,but it will not be good enough to weld a roll cage. Not if you want it to hold up if ever in a crash. You can Mig weld a mild steel cage with a good Mig and it will hold if welded right. You run a bead down hill (welders know)with a mig,it won't hold!!!! Like someone said earlier you can buy a $200.00 arc (220 amp)and weld any M.S. cage and it will hold better than any mig weld.Take you forever to weld it,but will give you a stronger weld. I was a supervisor in the weld-bay @ Varco-Pruden for 14 yrs. been a welder for 25+ yrs.

BEWARE of who you trust to do any welding on your Race-Car. A poor weld is about like sticking bubble-gum on your cage or what ever you have welded,just because it is stuck on it does not meen it will hold.



Anybody that can't weld the side or the bottom of a tube needs to go back to a GOOD welding school. NASCAR cages are mild steel and MIG welded on surface plates and jigged - they certainly don't turn them over to weld the sides and bottoms. You can bet if those welds weren't strong enough they wouldn't take the abuse that they do.

I used to make stock racks (2" sq tube, .120 wall) for a corrugated company for about 5 years. Forklifts typically destroyed the racks, but we never had a tube tear the weld apart - it would always tear out the whole tube itself - the weld was stronger than the .120 wall mild steel. Again, they were welded horizontally, vertically, and across the bottom. I don't buy that a MIG weld is for top surfaces only.
Posted By: MR_P_BODY

Re: mig welded - 05/31/11 02:51 PM



I used to make stock racks (2" sq tube, .120 wall) for a corrugated company for about 5 years. Forklifts typically destroyed the racks, but we never had a tube tear the weld apart - it would always tear out the whole tube itself - the weld was stronger than the .120 wall mild steel. Again, they were welded horizontally, vertically, and across the bottom. I don't buy that a MIG weld is for top surfaces only.



Thats called the "heat affected zone" thats the reason
that moly tubing is tigged to keep the heat down...
it will always tear in the "HAZ" unless its a junk
weld and it breaks the weld
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