Mig wire size question
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From: baton rouge
Mig wire size question I am starting to do body work on my car and my mig welder is running .035 flux cored now and its tough to get good tacks on body panels without blowing through. I have .030 flux core and .025 solid wire. I prefer to run the flux core but would the .025 solid be that much different than the .030 flux? Would it help keep temps down by using gas on flux core wire? Also any quick tips on welding body panels?
On The Tree
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From: Ft. Lee, VA
Running gas will help prevent blow through by cooling the puddle. To balance it out you might have to increase the power to get a good puddle going. Play with the settings before laying down anything on the body.
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gas doesn't cool the puddle, actually, the C02 makes it hotter, and besides the actual flux covering the bead there is no reason for it to be dirty, in most cases it's actually smoother/cleaner (again, besides the actual flux coating).
The problem is that flux core does run forward polarity which puts more heat into the weld and gives more penetration, which is what you don't want to for body metal, as does larger diameter wire. Secondly, body work is usually a bunch of tacks run together, with flux core you'll have to use a flux core that is rated for multiple passes not to cause inclusions when your tack partially covers a previous one (in other words, no GS flux core wire if you want to use the right stuff and insist on flux core)
The problem is that flux core does run forward polarity which puts more heat into the weld and gives more penetration, which is what you don't want to for body metal, as does larger diameter wire. Secondly, body work is usually a bunch of tacks run together, with flux core you'll have to use a flux core that is rated for multiple passes not to cause inclusions when your tack partially covers a previous one (in other words, no GS flux core wire if you want to use the right stuff and insist on flux core)
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use .30 wire (solid) with argon/helium mix. it cleans the air surrounding the weld to keep it from popping and burning dirty gases. make sure the body panels are completely clean. rust free welding area. and are as close butt up together as possible. i used the lowest heat setting with a decent wire speed on my hobar 135 mig.
keep a wet rag by you to cool the weld after to make it. you want to keep the area as cool as possible to prevent warping the body panel. also each weld should be far apart to give it time to cool between welds. just do spots. like a tack weld.
good luck.
Billy.
keep a wet rag by you to cool the weld after to make it. you want to keep the area as cool as possible to prevent warping the body panel. also each weld should be far apart to give it time to cool between welds. just do spots. like a tack weld.
good luck.
Billy.
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we use .030 with 75/25 mix at work on body panels everyday. We never use a wet rag to cool the rag, because it makes an already brittle mig weld even more brittle. It makes the welded area almost impossible to hammer and dolly after welding. If you do get the metal to move, then you will get cracking along the weld.
Make sure you tack, tack and tack some more.
Make sure you tack, tack and tack some more.
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lee what is your thoughts on this i used to use air blowgun to cool the weld after tacking. that way didn't have the mess of water and cooled the panel rapidly. worked well for me. but haven't touched bodywork in a while.
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You have to let the weld cool down naturally. When you manually cool it down that quick it causes it to get weaker. Maybe not so important for body panels and non-stress related items, but Id imagine it would factor in there somewhere. When the metal expands from being heated and then cooled rapidly, things cant get back to their proper places fast enough. They end up being stuck, which makes the strength very inconsistent. Thats the easiest way I can think to explain it.
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jeff, I have seen many people do that including one guy at work now. I dont personally like doing it, because while its not as bad as water it will cause the weld to be more brittle and be harder to work with. I have also heard of people using a 60 series wire to weld body panels. This wire doesn't have as much tensile strength as a 70, but will be more plyable and easier to work with.
If at all possible I tig weld in patch panels because the weld is much softer. That means it is easier to grind and hammer and dolly after.
If at all possible I tig weld in patch panels because the weld is much softer. That means it is easier to grind and hammer and dolly after.
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