Mig Welding Technique.

[Caito]

Hello guys, I'm here to discuss the welding process in a chassis that's MIG welded.

It would be a Mild Steel chassis, for a low hp buggy. Round tube 50mmx1.6 (2inchesx 1/16) or something similar.

Let's imagine we have to weld this:


the upper one.


Would you:
a) Weld it all at once.
b) Do lots of small welds one beside the other
c) Other


How could you tell if you got enough penetration?

I believe that with a) you would get better penetration and with b) you would get better estethics.

Any input is more than welcome!


Bye bye


Caito.-

[Jersey Tom]

That's some really nice fit up. Shame to MIG it.. I'd TIG that up, would look beautiful.

Tack it all in place... and you can probably weld 1/4, 1/3, or 1/2 of each joint at once.

If you want to know about weld penetration it'd be worthwhile to weld a few test pieces and cut them. Otherwise.. pretty easy to tell so long as the filler is really blended in and wetted against the base metal.

[marcush.]

Nice weld fit ,but the zero gap will be not the best approach for mig Welding and weld penetration.(Cannot see the tube wall thickness, but it looks thin wall ).But normally you need material thickness gap to get perfect weld penetration or ,of course a very good chamfer to reduce material thickness in the weld area.
With the short tube you are welding two pieces of tube with a lot of mass to this
when welding all around ,the short tube will bend like a banana no matter what you try.
So the name of the game would be to go very slow have a lot of chamfer and really let the thing cool down after very short current input .Otherwise the thing will just go away from you dramatically .
So you start with tacks and work symmetrically to spread the loads ,take your time .
With TIG the warp can be made much less but still the short tube might get a bit out of round .
Unfortunatelly the tube is very close to the end of the short tube (less then 10mm
I´d assume ,so with mig welding it might be difficult not to burn the short tube as the heat will have to be reduced considerably to avoid this...
i would try and have this longer and finish for length later possibly?

You could as well try and manipulate the torch to not heat up the part too much ,but thats easier with TIG then with MIG ...

[Belatti]

Very close to your home (Villa Lynch) there is a magnificent welding school, just in case you want to do a course there.

http://www.esab.com.ar/ar/sp/educacion/ ... dadura.cfm

[mep]

Just a question:
How about pre heating the tubes before welding to reduce bending?

[xpensive]

I wonder how much welding there is on an F1 car thse days, anyone?

[marcush.]

preheating of tubes? you always try to get the right amount of heat concentrated in the welding area to minimise the heat affected zone..to retain the propertiess of the base material as much as possible.and you will try to take your time ,so not welding round in one go ,but work symmetrically to spread out the stress .

welding on a F1 car? apart from the headers /exhaust system and this year some wishbones ...it may be some brackets and possibly some Ti fabrication for pedals
I wonder if some parts of the front suspension rockers wetc are fabricated and not pure billet machinings..Newey specified a lot of ultra thin fabrications on the Leytonhouse cars a long time ago..but thats really offtopic.

[Jersey Tom]

I wonder how much welding there is on an F1 car thse days, anyone?

I'd venture to guess... zero.

[xpensive]

I wonder how much welding there is on an F1 car thse days, anyone?

I'd venture to guess... zero.

I'd say zip actually.

[marcush.]

http://www.gurneyflap.com/Resources/toy4.jpg
http://www.gurneyflap.com/Resources/rs27B.jpg

spot those MASTER tigwelds anyone??

http://www.gurneyflap.com/Resources/DSC_7421.jpg

[tjaeger]

I guess you got already lots of input. Suggest as well to take it easy, tag it in place, than start to weld 1/4 on one side, do another joint acc. the same. than come back do the 180 deg opposite side by a qtr and so forth. Allow cooling time.

Recommend to use TIG or MIG, but make some test pieces and practice to find the right power and wire speed settings that will give u best results.

Remember, most important part for a strong weld in the root. If u don't fill it proper it will break anyways.

Bending, can't avoid it when welding. However if you work out your staged approach, where u go first, how far, how long and than other side it will be less significant. Remember when the weld cools it pulls material together. So if u weld one side first it will pull it out, but then when you weld 180 deg side opposite it should pull it back to same extent but not as much...

I would not recommend to pre-heat, unless you got a special steel. SHould be able to look that up in a welders book or engineer (mech.) book.