Unsightly Mig Welds?

[zookymatt]

Hi Guys,

I've been having a problem lately with the look of my mig welds. I use a 180 amp gas rig, 0.030 wire and BOC Argoshield Light gas (which is 3.1% oxy, 5% CO2, 91.9% Argon). I can adjust to get the nice bacon frying sound and seem to be getting good penetration (I can burn through if I want to).

My problem is that the bead seems to sit up on the surface instead of the characteristic wide flat mig bead. Also the bead looks like a stick weld before the slag is chipped off. It has a sort of dull, rough, darker gray look to it, instead of a nice shiny mig weld.

I have tried to vary stickout, wire speed, gun angle, gas flow rate, voltage/amps and weaving and have had very limited success. My metal isn't always perfectly clean, but it's normally pretty good.

Can you guys suggest some tips?? Is there something I'm overlooking??

Thanks in advance,
Matt.

[Mike Sherman]

Are you using flux core wire? It sounds like you may be using a flux cored wire with bare wire settings. Please post the exact wire you are using and also the polarity settings on your machine.

[Arbo]

Slag on a MIG weld? That doesn't sound right. Sounds to me like you might be using the wrong wire for your application.

[zookymatt]

I'm using DCEP with normal mild steel solid wire.

Sorry if I wasn't clear enough in the previous post but the bead looks dull and gray. It doesn't actually have any slag on the bead, it just "looks" like slag on a stick weld bead.

I have already used the whole setup several months ago and it was welding fine, but now that I have a new project to work on I have come across this problem.

Thanks,
Matt.

[Roger]

That sounds about like bad gas. If you changed gas bottles before problem started or your bottle pressure is real low that could be your problem. If your getting reticulation which is swiss cheese holes in weld it is bad gas. Such could also be caused by missing/bad O-ring or anything that would let air get sucked into shielding gas. Shielding gas leaking out at bad connection causes turbulance sucking air into shielding gas. ***** of slag in gas nozzel can also cause problems because of turbulance. Turbulance problems often get worse with increased gas flow.

Wind blowing away shielding gas?

[Hobart Expert Rock]

zookymatt.......QUESTION IS ON MILD STEEL WHY ARE WE USEING SUCH A STRANGE GAS MIXTURE. IS THIS A SPECIFIC APPLICATION IF NOT TRY SOME 75/25, OR PERHAPS SOME STRAIGHT CO2.... HOW THICK IS THE MILD STEEL WERE WELDING ON?????/.... NEED TO KNOW TO FIGURE OUT THE PROBLEM.........ROCK
[email protected]

[zookymatt]

The strange gas is just a standard gas available in Australia. It is intended for mild steel up to 4mm (nearly 3/16").

There are two main gas suppliers here. One is Linde, and the other is BOC. You can check out BOC's gases by following this link:

https://pgw100.portal.gases.boc.com/...ate/zcpwp_b2c/!?~login=boccomau

BOC do have gas mixtures that tend to vary somewhat from the industry standards.

I have had the problem welding on several sizes of mild steel. From 0.03" to 1/4" and it still looks terrible.

Roger, I had begun to wonder if it was a gas problem. My current cylinder has nearly run out so this could definitely be a problem.

Is there a minimum pressure that I shouldn't run below? At low pressures is it possible to end up with an incorrect mix of the gases?

I will try and get a new cylinder this weekend and report back on the results. Thanks for everyone's suggestions, it's much appreciated.

Matt.

[Roger]

Don't know why but gas mix often starts to act bad just before running out. That's good if it keeps somebody from leaving valve open so water could condense inside.

[Mike Sherman]

It does sound like a gas problem. Each of my flow meters and regulators have been known to run out at different readings. They do not all say zero when they are empty.

[shaky]

BOC gas

I use the same BOC mix. Can I use the same excuse?

What about some pics Matt?

regards

shaky

[Al T.]

In the miller mig book is states that tall beads can be wetted out better using 75/25 or straight CO2 like Rock said. I have full control over bead height using 75%argon 25% CO2 or 75/25.

Post some pictures before and after, I bet all of us would like to see it.

[zookymatt]

Problem Solved....

Hi Guys,

Well low gas was only part of the problem. My bottle was pretty much empty so I got a new one on the weekend.

The low/bad gas mix was making the arc unstable at lower wire speeds, however I hadn't used my welder in a while. When I used it recently, I just adjusted the wire speed to get a good consistent arc with the frying bacon sound. It turns out that this wire speed was too fast and therefore depositing more metal into the puddle than necessary. This of course resulted in high beads.

Once I had the new gas, I tried to turn the wire speed down and found that the arc remained stable. Also, I was then able to achieve the nice flat typical mig weld bead.

So in a nutshell, I had the wire speed too high. If I was a more experienced welder, or had used my machine more often, I would have realised, bad gas or not, that my wire speed was causing the problem.

It was a great feeling to run several lines of great looking beads. Thanks everyone for their suggestions and help. Hopefully this thread will help other relatively inexperienced welders too.

Unfortunately I don't have a digital camera or a scanner around so I can't post any pics.

Regards,
Matt.

[shaky]

Hi Matt
Inspired by your success I will be off to my workshop this weekend to try this out. I understand that wire speed was your problem, but are you still using the same BOC argoshield light gas? mmmmmh........ frying bacon!