Clarification on MIG Settings for Plate Thickness and Real-World Applications

[Erdling]

Hello,

I’m looking for some clarification on MIG welding settings for different material thicknesses and how to best match these to real-world welding scenarios. My goal is to ensure I’m using the correct voltage, amperage, and wire speed combinations for reliable, strong welds, rather than just following tables blindly.

Firstly, I’d like some general guidance. How do voltage and amperage typically relate to different material thicknesses? For example, what ranges are common for thin sheet metal versus thick structural plate? Are there any rules of thumb to help scale from, say, 6 mm plate up to 25 mm?

Secondly, I want to understand how to apply this in practice. For example, if welding a structural rectangular section of 203 × 133 × 30 mm with a 15 mm end plate, what would be the recommended approach regarding voltage, amperage, wire speed, and welding technique (multi-pass, weaving, etc.) to achieve strong, consistent welds?

Finally, any practical tips would be appreciated. Are there common pitfalls when moving from thin to thick material? How should settings be adjusted when transitioning from tack welds to full penetration welds?

Thanks in advance for your time. Any advice, charts, or reference resources would be extremely helpful and very much appreciated.

Kind regards

 

[zzr1200]

You'd be looking at a 400 amp mig minimum (ideally a 500 amp mig) with pre-heating the 30mm section at least and welding in spray transfer mig, so horizontal welding position.

So you'll probably need a 415 volt 3 phase mains supply or a 63 amp 240 volt mains supply for a single phase mig of the size required, or possibly a 300+ amp stick welder, both mig/stick would require multi-run welds.

You would also have to weld prep the joints for full penetration welds, if you haven't done any welding before, contract it out to a welding company.

 

[eddie49]

Hello and welcome to the Forum!

From this other post, it looks like the OP has a PowCon 300 with 1.2mm wire:

E

Thread '8mm Fillet Weld - Powcon 300SM'

Yesterday at 10:23 PM

Hi, I'd just like some thoughts on this weld of mine. My settings were 80 (about 27 to 30V) and 6.0 (about 250A). Gas was an Argon mix, at 20l/min. I executed a slight weave. I tried to nudge just at the leading edge of the puddle, watching the toes of the weld to maintain an even fill. What can I improve here? There was some patter, everything you see is uncleaned. About a 45 degree work angle and maybe 15 degree travel angle. I think the tie ins at the end of the weld could be better, and perhaps the start of the weld. Maybe hold it more, or back into it after start for better fusion? Am...

• Erdling
• Replies: 2
• forum: Learning MIG Welding

 

[Erie Fred]

Ed Craig over at Weldreality.com used to have charts that should answer your questions.
I've not been over there in a few years.....

 

[Jackimus]

Ed Craig over at Weldreality.com used to have charts that should answer your questions.
I've not been over there in a few years.....

Well, that was an experience!

 

[Erdling]

Cheers for that, yeah, I’ve read quite a bit of Ed Craig’s stuff on Weldreality, including the Powcon info. There’s some great detail in there on transfer modes and machine setup, but what I’m really trying to understand is the practical side - how you guys actually think through real-world jobs where you’re welding different thicknesses or structural sections.

For example, let’s say you’ve got a 203×133×30 beam with a 15 mm end plate. I’m not chasing chart numbers anymore - I’ve got plenty of those - I’m more interested in how experienced welders decide on heat input, pass sequence, and whether to go with multiple passes, a weave, or just crank it up for a single run. Basically, I want to understand the reasoning process behind setting up for something like that, not just the machine settings themselves.

I’m trying to move past “turn knob A to 7 and knob B to 5” and get a feel for how people approach different scenarios in the real world.

 

[Erie Fred]

At work, we have welding engineers, and they create the weld procedures.
As a welder, you set the knobs to what they wrote.

Also the gage calibration people come around every year or so, with a tow behind load bank
and calibrate the machine and it's meters.

 

[Erie Fred]

Well, that was an experience!

Need some eye bleach ?