MIG question

Bret4207

Well-known Member
I think I know the answer, but- I'm getting burn through with .035 solid core wire with amperage set as low as I can go, 8-10 lt/min CO2. I've got the feed set about where I think it should be, a little fast if anything and I'm trying to hold my gun as close as I can. I think the answer is heavier wire as it will take more amps to make the arc. Or have I got it backwards? This is on steel, trying for a vertical weld, practicing for a car frame repair. Also have some sheet metal to do. I'm not worried so much about the frame, but the lighter stuff is a concern.
 
I'm far from being a welder but I picked up a few things during my years in the lab at Lincoln. First you should be welding down for vertical. Going to larger wire will require more amps. And try welding in short bursts with some cool down time between. Hopefully somebody with more experience will correct me.
 
You are taking too long and creating heat in the surrounding metal. Need to move faster. what type of
weld but corner makes a difference.
 
here at the body shop for most automotive work we run .023 wire. also, we use 75/25 argon co2 shielding gas.
 
>'m getting burn through with .035 solid core wire with amperage set as low as I can go, 8-10 lt/min CO2. I've got the feed set about where I think it should be, a little fast if anything...

Bret, the "current" control on your MIG welder is labeled "Wire Speed". The other knob controls voltage, not current. To reduce current, you need to SLOW down the wire speed.
 
Hello Bret4207,

Slow down the speed, if it does not work use smaller wire.

Guido.
 
Bret, I had to weld the door latch on a 4450, a vertical weld. I started practicing on similar metal but kept burning through. I took my welder to the Welding Supply House and had it checked out. There was a slight kink in the liner and the handle was an older design. They replaced both, checked the amperage and voltage at all the settings which were on specification and I was good. It ran like it used to.

I had also noticed my welder sounding like small pops rather than bacon sizzling. Now it sounds like bacon sizzling. So you might want to check your liner, feed, etc. There are some really good YouTube videos on welding also that were helpful to me. My welder is a Miller Challenger 175 Mig, I use .035 wire since I mostly weld bigger stuff, and I use 75% Argon/25% CO2. My son had to weld some thinner stuff and put on 0.023 once.

My two cents.

Paul
 
When you are holding the gun, is it 90 deg to the surface of the metal? If so, the wire will probably push the molten puddle right through leaving you a nasty hole. I lean the gun over about 45 deg, strike a quick arc on one piece of metal and carry the puddle over to the other piece, and get off the trigger insty quick. Do not try to follow the seam between the 2 pieces, your metal will heat and flow away. What I am doing is like stitching with a sewing machine, with a pause between each stitch. Others will disagree, but I use this technique in vertical mode going up hill. Then if any flow begins, it usually stays in place. And the slight flow can be easily repaired because the molten metal has not been lost and there is not a big hole. If you have a piece of copper bar, you can clamp it behind the seam to be welded. For the thicker steel of the frame, you can probably use a piece of steel flat bar as backup. You might accidentally weld the back plate to your seam, but if you are aiming the gun from one side and moving quickly to the other side of the seam, then you can usually knock the back plate loose with a hammer.

Wire size: .035 for the frame metal. and .023 for the sheet metal.

Mig likes clean metal, so grind the flat area next to the seam. Some MIGs will do OK with rusty metal if you are using a ER70 series S 6 wire.

Disclosure: I am not a certified welder, but I have been welding in our farm shop for over 50 years.

It is good that you are practicing before you attempt the precious metal. Best wishes!


Paul in MN
 
Need smaller wire, lower current for the thin stuff. Be quick on/off the trigger, very short time with cool
down between welds.

If you can get to the back side, use a thick piece of nonferrous metal as a heat sink/backup to keep from
burning through, especially if there is a poor fit between the pieces.
 
(quoted from post at 18:59:12 03/01/18) >'m getting burn through with .035 solid core wire with amperage set as low as I can go, 8-10 lt/min CO2. I've got the feed set about where I think it should be, a little fast if anything...

Bret, the "current" control on your MIG welder is labeled "Wire Speed". The other knob controls voltage, not current. [b:8f958ee91a]To reduce current, you need to SLOW down the wire speed[/b:8f958ee91a].

Okay, not to get off on a tangent, but that makes no sense to me. If I slow the speed, the wire is going to maintain a longer, hotter arc. I've got the "voltage", as you say, as low as it goes. Names aside, a longer arc is hotter, is it not?
 

Smaller wire seems like the opposite of what I need, but okay.

I am doing tack welds and trying to move right along. I'll try more tipping of the nozzle.

Thanks to all.
 
I do best with .030, even on thick metal.....just stay on the spot and let it build up. I am learning how to use my MIG and find that I do most
of my welding with it these days. Exceptions are old, rusted up implements that need a lot of cleanup before drawing the bead.

I have a 115v Farmhand 75 flux core I bought from TSC years ago and never had it to work right. When I started using the smaller diameter
wire on my HF 151 (with argon/Nit) and seeing how much better I could weld with it, I got some for it. Amazed at the difference in ease of
use and quality of the joint.

That works for me and may not work for you. Just injecting what works for me.
 

A long arc, more stickout, is cooler in a mig welder. For stick, a longer arc is hotter. Pure CO2 shielding gas is hotter and gives more penetration so use an argon/co2 mix to cool the arc. Larger wire size gives more penetration so use the smallest wire your rollers will support. For sheet metal, use a stitch weld technique to reduce the heat and reduce burn through. Then practice to learn the time it takes to get a weld bead without burn through.
 

Okay, a long arc, ie- more space between the filler metal (be it stick or wire), is going to have more resistance and take more voltage/amps/magic lightning/whatever to cross the larger gap, right? I don't see how wire and possibly be different from stick in the that regard.

I can grasp that less "magic lightning" is required for smaller diameter stick/wire to jump the gap at the same distance. I just thought the more power through a smaller diameter stick or rod meant a hotter pool of metal.

BTW- I believe I'm actually using 75/25 CO2/Argon, if that makes a difference
 
> Okay, not to get off on a tangent, but that makes no sense to me. If I slow the speed, the wire is going to maintain a longer, hotter arc. I've got the "voltage", as you say, as low as it goes. Names aside, a longer arc is hotter, is it not?

Whether or not it intuitively makes sense, that's how the way it is. MIG welders are constant voltage devices. (Stick and TIG are constant current.) So you can control the voltage with the knob that looks suspiciously like a current control but is never labeled as such. But it is the wire feed rate that controls the current. What happens is when the electrode comes in contact with the base metal, there is a short circuit for an instant, which melts a bit of electrode, breaking the short circuit and interrupting the current. Then as the wire feeds out, it creates a new short, repeating the cycle. If you increase the speed, eventually you'll reach a point where the wire is constantly feeding directly into the weld pool and keeping a constant short circuit. That will be the maximum current you can get at that voltage, so the voltage will need to be increased to further increase the current.

This is a rough description of how consumer-grade MIG welders work. Industrial-grade welders can operate in modes other than "short-circuit", but I won't get into that.
 
I think the .023 works better on sheet metal. Had an instructor once who didn't believe in ever going under 20 on the gas. I'm usually about 15. Any wind and it goes way
up.
 
Do you have recommendations for your welder either in the owner's manual or a chart inside the cover?

I was having the same problem with my new Hobart welder. I even wound up with a wire jam. While straightening that out, I looked at a chart inside the door that gave recommendations for settings for different types and thicknesses of metal. Their recommendations weren't close to what I was using, but I used those settings and immediately had beautiful welds with no problems.

It pays to read the book.
 
> Okay, a long arc, ie- more space between the filler metal (be it stick or wire), is going to have more resistance and take more voltage/amps/magic lightning/whatever to cross the larger gap, right? I don't see how wire and possibly be different from stick in the that regard.

Well, they are different processes! Constant current for stick, constant voltage for MIG.

Google "short circuit MIG transfer", there are plenty of articles that explain it. Here's one from ESAB:
MIG short circuit transfer
 
(quoted from post at 19:41:51 03/02/18) Do you have recommendations for your welder either in the owner's manual or a chart inside the cover?

I was having the same problem with my new Hobart welder. I even wound up with a wire jam. While straightening that out, I looked at a chart inside the door that gave recommendations for settings for different types and thicknesses of metal. Their recommendations weren't close to what I was using, but I used those settings and immediately had beautiful welds with no problems.

It pays to read the book.

No, nothing much in the book. That was the first place I looked!
 
(quoted from post at 08:03:51 03/03/18) > Okay, a long arc, ie- more space between the filler metal (be it stick or wire), is going to have more resistance and take more voltage/amps/magic lightning/whatever to cross the larger gap, right? I don't see how wire and possibly be different from stick in the that regard.

Well, they are different processes! Constant current for stick, constant voltage for MIG.

Google "short circuit MIG transfer", there are plenty of articles that explain it. Here's one from ESAB:
MIG short circuit transfer


Thanks Mark. I guess all this magic lightning stuff is just too much magic for me to grasp... :oops:
 

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