[LIGOOMBA]

What gas mix are you guys using? I have Miller 210.
In general what have you guys had the best results with.
I will be welding mostly steel and sheet metal.No thicker than 1/8 .3/16 on rare occasion.

[noddybrian]

Normal gas for thinnish material like that is 95% argon 5% CO2 - ( in the UK mostly supplied by BOC & now called Argoshield ligh)

[AKweldshop]

Normal gas for thinnish material like that is 95% argon 5% CO2 - ( in the UK mostly supplied by BOC & now called Argoshield ligh)

I dont know much about welding gases, but whats wrong with 75/25? I've never heard of 95/5 gas "uk special maybe"? Just wondering. John

[noddybrian]

Well I can only comment on gasses available here ( UK ) and BOC has pretty much a monopoly on supply - Air Products are also players though not locally - they match each other on most things & they supply only 2 main gasses for Mig welding - used to be called Argoshield 5 & Argoshield 20 ( approximate % CO2 - though rounded off as it's not that exact ) but apparently welders are getting dumber so they now call it Argoshield light or heavy - there has never been a 25% that I've heard of - I guess you just use what is available - but I do question why so many welders in the USA seem to think the only gas to use is C25 when they are asking questions about welding thin autobody material & very thin walled RHS etc as that is about the maximum amount of the hottest most biased towards penetration gas you can use ! maybe you guys know something that has eluded BOC !

[AKweldshop]

I was just asking most "sheet" metal work I've seen is "c25"
It's just what everybody uses thin and thick.
Could be wrong though.
Anybody else want to chime in?
John

[coldman]

Down here in Oz, our biggest gas player is also BOC, there are others as well offering similar products. For mig, I keep Agroshield Lite (91.9%Ar/5%CO2/3.1%O2) which is ideal for sheet steel and thin wall sections and Universal (81.25%Ar/16%CO2/2.75%O2) which is good for general fabrication. Most workshops and colleges use Universal that I have seen.

There is also Heavy (82%Ar/18%CO2) which is good for heavy fabrication/ship building/bridgework etc. I do work at the shipyards from time to time but I've never seen them use mig there, only stick on board.

[Bill Beauregard]

Why stick in shipyards? Years of practice with stick I produce welds much nicer first try with gas shielded MIG.

[coldman]

I have not asked. They probably use mig in the workshop. I can speculate. No new shipbuilding is done here in Brisbane anymore (or major refits), it is all done in China these days I believe. What is done here tends to be repairs, modifications and rework of materials and workmanship that did come out of China (don't even get me started!). So the welding leads (stinger and work return) run from the power shack on the dock onto the ship, over to the stairwell and up or down several or many levels and forward (or aft) to get to where the welding is required. These leads are freaking thick and hundreds of metres long. I guess they find it easier to do this than lug mig power sources and gas cylinders all the way or to run hoses and leads to remote feeders. Also I have only ever seen them use iron powder rods which I find strange because these rods are not all positional and I guess they would be welding all positions on board. I'm usually too busy with my own work to look closely at what other guys are up to in detail.
My work is always on board (never in the workshop) and always refrigeration related which means either oxy or tig work. I seem to be the only mug lugging cylinders on board and up/down stairwells.

[coldman]

Another thought just occurred to me is that on board, most locations are confined and also require forced ventilation to remove fumes and keep fresh air up. So using stick they avoid argon build up and also ventilation draughts don't affect stick but can affect mig. I've seen more than 20 welders working on board sometimes.

[Nils]

Just guessing, but in the ship building environment I would imagine the work is mostly done outdoors where the welding is subjected to wind and breezes. Bye bye gas shielding.

Assuming this is true, using stick is going to get the job done. But, a MIG using a flux-core wire (FWAC) setup with a Miller Xtreme Suitcase is a very workable and efficient process.

[MinnesotaDave]

For the gas question - I use standard 75/25 mix or straight co2.

I prefer the mixed gas though.

The MM210 is a nice machine - mine has done a lot of work for me

[noddybrian]

OK - I admit to never having used C25 as it's not available here - but logically CO2 is known to run hotter & provide more penetration when mig welding - so the BOC mixes ( which after checking I stand corrected by coldman's reply - thanks - I had'nt really checked on the exact mix since it changed name ) make more sense to the layman - 5% (ish ) for light gauge material as per the OP's question & 20% ( ish ) for regular fab shop type stuff - the % CO2 also effects the voltage at which spray transfer occurs a bit - have you ever thought of trying other mixes ? I know ChuckE2009 recently had 80 / 20 as his LWS was out of C25 - I don't think he's commented as to whether he's felt much difference - but maybe that little is not noticeable in general use.

[coldman]

Back in my school day from memory we were told that the addition of a little oxygen in the Agroshield Lite and Universal helped stablise the arc or some such thing. I find it a bit weird though because one of the contaminants we want to keep out of the weld pool is oxygen. Maybe someone out there in the know could answer this one for me please.

[coldman]

Was able to answer this one myself by a quick search on the web. Here is the link:
http://www.mig-welding.co.uk/welding-gas.htm

Oxygen apparently improves the wetting of the puddle and gives a smoother finish to the bead.

[Bill Beauregard]

Thank you for the answer to the "why stick" question. I'm an electrician, my experience welding in a factory situation is limited to adding brackets to mount motors or conduit. I choose either TIG or MIG. With less skill I can make a good looking weld. The fabricator I work around does everything with stick unless I have another machine sitting there ready. His mig welds make me jealous, yet he chooses stick. He doesn't have much of an answer to the question.

[Antorcha]

Why stick in shipyards? Years of practice with stick I produce welds much nicer first try with gas shielded MIG.

Penetration. MIG and Decking go together like US and intelligence. They don't. Nicer, in appearance, doesn't necessarily mean quality.
Back on topic. I've use C25 since 1985 on light structural.

[rake]

Hmmm? I spent most of my adult life in the shipyards.

A good rule of thumb is 16ga carbon steel and thicker 75% Argon - 25% CO2 is preferred.
On 18ga and thinner a mix around 95% Argon - 25% CO2 is preferred.

I know, I know, y'all been using C25 for years but there are advantages to switching gas.
With the 95-5 mix you will get a smoother, cooler more controllable puddle with less heat input,
distortion and blow holes. You can actually run passes instead of just stitching every 3/4" to 1"
at a time.

If you have 75-25 and 100% argon and a "Y" fitting you can blend the two and not have to shell out
for an additional tank.

Reducing the CO2 has it's benefits. Try it, you might like it.

[jimbob]

Back in my school day from memory we were told that the addition of a little oxygen in the Agroshield Lite and Universal helped stablise the arc or some such thing. I find it a bit weird though because one of the contaminants we want to keep out of the weld pool is oxygen. Maybe someone out there in the know could answer this one for me please.

I weld structural steel everyday, from 4in c channel to 12in. C channel for the bases on commercial HVAC. We use 95/5 argon oxygen. The problem with it Is without the co2 it doesn't cut through the mill scale very well. So the shop has all the channel wheel abraided. And for the 1in. Lifting lugs we grind down to Shiny bright. The o2 gives a hotter weld and is a bit more stable when we use spray for the lugs.

[mcoe]

I will add a question to this confusion, what would it be like to run straight argon through the mig? I know you use straight argon on aluminum but what about steel?
Matt

[Otto Nobedder]

I won't speak to carbon steel, but I once sent my helper to change my gas (tri-mix), and he accidentally hooked me up to 100% argon, while I was welding SS with 308. The results were disastrous, and required an hour of grinding for five minutes of "what the f#$%".

Steve S

[AKweldshop]

I will add a question to this confusion, what would it be like to run straight argon through the mig? I know you use straight argon on aluminum but what about steel?
Matt

with plain old s6 it runs okay, but a high crowned bead with little penetration and washin
John

[mcoe]

Thanks John

[AKweldshop]

It's not an awful set up to run, give it a try if you get a chance.
John

[mcoe]

The reason I was asking was I was thinking about purchasing a Tig welder for my horseshoe art business and I have a tight budget to work with and was thinking that if I got a bottle of argon to run on the Tig just hooking it up to my Mig welder when not running Tig. Right now I am running straight flux core and was wanting to hook gas up to my welder and run solid wire but thought if I was going to buy a Tig that I could just get argon instead of argon and mix. That was my thought, just buy one bottle instead of two.
Matt

[Otto Nobedder]

Matt,

For art, where you don't have to certify everything or meet a standard beyond your own quality satisfaction, you could get a bottle of CO2. With mixing valves, you could make your own 75/25, or close enough, as you use it. I've done this with helium and argon for aluminum TIG.

Yes, that's still a second bottle, but straight CO2 is cheap compared to argon or mix-gas, and you could mix as you need when you're using hard wire. For that matter, you'll probably be satisfied with the results from straight CO2 for most of your carbon-steel work.

Then again, once you have the TIG bug, you might do all your work with it, and only need argon.

just a thought.

Steve S