Page 1 of 1

Mig welding at 28-30 volts not spray

Posted: Fri Feb 18, 2022 1:36 pm
by Fabworld welding
I've been listening to the podcast a lot and I've been looking at getting into stick welding and in doing so I've heard a lot of talk about stick being so much better because you can't weld anything thick with mig and it be reliable and it's just driving me crazy because I can weld 3/8 up to 1/2 on a single pass and get good penetration or depth of fusion. Thoughts?

Re: Mig welding at 28-30 volts not spray

Posted: Mon Mar 14, 2022 12:48 pm
by Oscar
The missing ingredient with MIG, as you probably already realized, is that it depends on the transfer mode. Spray Transfer and pulsed-spray are very high-energy processes that can weld thick sections if the power source is capable enough.

Re: Mig welding at 28-30 volts not spray

Posted: Tue Mar 15, 2022 5:27 am
by Gdarc21
There is a little debate in various camps about deposition and how its deposited.
For instance if I were welding a structure and needed 3/8 + fillet, no matter what I would go 3 run 2 layer to get there. Unless speccd otherwise.
On earthmoving equip probably just go as big as you could in one pass.
I was once told it had to do with fatigue cycles, ie structures with design life 30+yrs having more cycles than a scraper that will probably wear out around the weld anyhow.
Either way learn all the processes if you can, it does help. Can't count the amount of times being versatile helped out.

Re: Mig welding at 28-30 volts not spray

Posted: Tue Mar 15, 2022 7:17 am
by Jack Ryan
Fabworld welding wrote: Fri Feb 18, 2022 1:36 pm I've been listening to the podcast a lot and I've been looking at getting into stick welding and in doing so I've heard a lot of talk about stick being so much better because you can't weld anything thick with mig and it be reliable and it's just driving me crazy because
I think the ‘N’ words (never, no, not etc) are often used but are rarely accurate. It is “common knowledge” that “MIG” is prone to lack of fusion but less common is the realisation that this refers to the short circuit transfer mode (GMAW-S). GMAW-S is one of the coldest welding processes and as such, is great for thin materials like body panels. GMAW-S was not developed to replace SMAW in structural fabrication or ship building.
GMAW (ie spray transfer) is much closer to SMAW (which also uses a form of spray transfer) and can be used for structural work – especially in the form of FCAW (or perhaps GMAW-P) where the slag supports out of position welding. GMAW has replaced SMAW in many areas because of its improved productivity.
Each welding process has its limitations, and it is better to understand all of them than it is to know one and treat it as your hammer for which every problem is a nail.

I can weld 3/8 up to 1/2 on a single pass and get good penetration or depth of fusion. Thoughts?
Are you sure? What welder are you using?

Jack

Re: Mig welding at 28-30 volts not spray

Posted: Wed Mar 16, 2022 9:18 am
by drizzit1aa
I ma throw in my 2 cents too. not too long ago (20yrs) I certified with flux core MIG for structural. I believe it was 3/8" plate which allowed me to be certified for unlimited thickness. What I didn't know then is what Oscar and Jack have said, spray arc makes all the difference. https://www.youtube.com/watch?v=PI3pZxoPRvA
After thought, when you said you get good penetration, the only real way to see just how much your getting is to cut, polish and etch with acid. That clearly brings out the difference in base plate and weld.

Re: Mig welding at 28-30 volts not spray

Posted: Sat Mar 19, 2022 9:50 pm
by Louie1961
FWIW, there are no pre-qualified welding procedures for short circuit, hard wire MIG. There are pre-qualified procedures for stick, flux core, TIG, etc., but not short circuit, hard wire MIG. That ought to tell you a bit about what you are asking

Jody tells it better than I do. https://www.weldingtipsandtricks.com/mi ... dures.html