[Mikeover]

I'm trying to join hand railing - 2x2 .063 wall mitered tubing. Extremely frustrating as I can't seem to find a technique to prevent burn through on the "cheeks" of the weld. I'm using .030 wire, straight CO2, have tried settings all over from 16-20V, 200-320 IPM - just not succeeding.

The closest workable approach seems to be short stitches, maybe 1/2" or so, and pulling the weld.

Any ideas on doing this?

Thanks!

[LtBadd]

7 effects of shielding gas
Blend composition makes a difference

4. Bead Penetration, Potential for Burn-through
When welding thin material—16- to 22-gauge—a gas blend's welding characteristics become important. One characteristic of pure CO2, for example, is that it results in increased weld pool energy when compared to an argon/ CO2 blend. By controlling the blend's CO2 content, you can control burn-through and increase welding productivity. Use argon/ CO2 blends in the 85 percent to 95 percent range to minimize burn-through.

From this article on The Fabricator.com

[Mikeover]

Thanks for the reply & link. In the interest of brevity I didn't mention I had tried another machine with 75/25, similar results.

I must be doing something ... wrong. Question is what is it?

[tweake]

I'm using .030 wire, straight CO2, have tried settings all over from 16-20V, 200-320 IPM - just not succeeding.

just looking at the charts ( i don't do much mig and i'm in metric) its suggests about 100 IPM for that size wire and work thickness.

edit: if your machine doesn't go that low, try using 024 wire. or a machine with pulse.

[cj737]

Contact to Work Distance comes to mind as well. A “long arc” will create a much hotter puddle. With 0.030 wire, you should be struggling to keep the bead down, not burning through. Says technique to me... I’d use a fairly short stick-out and make darn sure the gas isn’t being disrupted due to breeze. CFH around 30.