Mig gasses

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i am new to welding and just learnig, be easy on me! lolwhat gasses work best for what metal?  Is there a all around gas that will work with them all?  Reason i ask this is i dont want to have to buy two cylinders! and will only be doing a little Alu welding? thanks guys i tried to search but was wanting to purchase this weekend and have not found my answer yet!
Reply:You're not going to find one gas that does it all.  Sorry.For steel, your best bet is going to be what is call C25... 75% Argon, 25% CO2Aluminum would be 100% argonStainless uses a tri mix...90% helium 7.5% argon and 2.5% CO2There are other mixes that work with all the above but these are the most used.  Such as 100% CO2 with steel - produces more splatter and doesn't produce as pretty a weld
Reply:Generally there are 3 std mig gasses. (there are other specialty gasses for SS and such, but lets skip those for now)1) CO2 Pros: cheap, heavy penetration. Cons: heavy penetration (poor for sheetmetal), lots of spatter.2) 75/25 ( 75% argon/ 25% CO2) Pros: good consistent clean welds with minimal spatter, useful for most welding in steel. great for thin sheetmetal thru 1"+    Cons: More expensive than CO2, Sligtly less penetration (down side on small 110v migs where max pen may be critical (you will find the chart for pen is higher with CO2 than 75/25).3) 100% argon required for alum. Also useful for tig if you have 2 machines.Personally I use 75/25 for everything except alum (100% argon). My LWS will allow me to swap my 75/25 for 100%  and vice versa if I choose. I never tried to swap it for CO2 but bet the guy would do the swap if I asked.If I were you I would get a bottle of 75/25, Unless you do alum you most likely can do every thing you will want with that.
Reply:I have to agree with these guys on everything but the 75/25. The 75/25 sure has its place in welding, you can run a nice short circuit with it, it makes flux core very easy, but I prefer a 90/10 mix. (90% Argon & 10% Carbon Dioxide. My reasoning for this is because 90/10 not only will allow you to have a nice beautiful spray transfer, but you can also get a pretty good short circuiting arc with it too. In fact we never turn the 75/25 on for ppl who come in to take the sheet metal test (cuz we are lazy sometimes) and they never tell and their tests come out just the same as with the 75/25!
Reply:In the manual for my 350P, Miller recommends 90/10 as the all-around gas for short circuit, spray and pulsed spray.  I've never run it, so don't know personally how true that is in practical use but I doubt Miller would specify that if it didn't work good.  I run 98/2 and use the 350P for spray and pulsed spray on steel.  I use pure argon for aluminum.  If  you're going to be welding both aluminum and steel with the one machine, you're going to have to have 2 gas bottles, no way around it, unless you only use self sheilding fluxcore for steel and argon for aluminum.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:THANKS GUYS!I GUESS ILL JUST HAVE TO BUCK UP AND GET 2 BOTTLES ONE FOR ARGON AND ONE  75/25
Reply:http://www.weldreality.com/MIG_welding_gases.htm
Reply:Straight argon will work for everything, straight co2 works for carbon steel, but not AL and is cheapest.   Mixes give mixed results.        Our group used to do a lot of exotic metalurgical testing with mixes and published the results, AWS etc, helium, argon, oxygen, co2, all sorts of proportions, robots, pulsing, titanium, aluminum alloys, superalloys. It can drive you nuts.        We run straight Argon for tig, and mig Al and stainless, straight co2 for carbon steel. Now we have lots of low time welders and not a lot of training time.        We ran straight argon last spring for a few months on a machine with a spool gun, just changed wires - it worked well with aluminum, stainless, dual shield and solid carbon steel. Sometimes you just give up and use what works.         We had a very bad day last fall, somebody recomended a 3 way mix, co2, argon, o2 for steel. not good. made lots of slag sponges, porosity city,  looked good on top, junk inside, bad steel, bad gas. And we were training new welders, nuts. wasted a lot of time.         ar 75% co2 25% works good on carbon steel,  just expensive.Last edited by wesdavidson; 02-06-2009 at 06:40 PM.Reason: clarity
Reply:Go herehttp://www.weldreality.com/MIG_welding_gases.htmA butterfly without wings, is just an ugly bug