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c25 or straight co2

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  • #16
    I just finished a MIG course an the books said 85% or more Ar is required to achieve spray transfer. Only short circuit or globular is possible with anything less than that. In our course it was mostly CO2 welding. Definitely more spatter than the C25 I have at home. I don't remember the exact details but the instructor said CO2 is practically free compared to C25 or straight Ar.

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    • #17
      Spray transfer with straight CO2?

      Weldmup,
      I, too, have NEVER heard that spray transfer is possible with anything containing more than about 15% CO2. It has to do with the ionization potential of the gas. What you are getting with anything higher that 15% CO2 (max.) is globular transfer. The primary difference being that in globular transfer the filler droplets will be 1.5 to 2.0 times the diameter of the wire. Whereas in true spray mode, the filler droplets will be about 0.5 times the wire diameter. Take a look at the end of your wire. If there appears to be a blob on the end, it's globular transfer. If the wire appears to taper to a point, it's spray.
      Be cool,
      Alex

      FREEDOM ISN'T FREE
      SUPPORT OUR TROOPS

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      • #18
        The Mix

        Cost of the gas and weld appearance are the main reasons I know of. We have 75-25 for our wire feeders and straight argon for aluminum. If you have ever changed tanks and got argon instead of 75-25 you would notice right away. As for glob or spray not a problem with our machine. It can provide the power to run a half dollar sized puddle and melt thru 3/4 in plate in 6 in of travel or weld the really thin tin.

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        • #19
          Just for the record......the "magic" number is 83% argon. The now defunct company called Liquid Carbonic carried a gas called Metal Match Steel. 83/17. This gas was the "go to " gas if there were questions. Great spray transfer at around 25 volts. Good short arc transfer down to about 16 volts. As for spray transfer with 100% CO2....can't be done. There are some folks out in the welding industry that will tell you that spray transfer can be achieved with C-25, and to some extent that is true, although the arc voltage required to achieve spray transfer with this mix is so high that it isn't plausible, and the transfer is more of an axial spray than a true spray transfer. I am of the opinion that you can actually do 99% of your steel welding with one gas, (C-17), but there are reasons that the big gas companies spend all this money on marketing new gas blends. Not because we want to charge more for the "smoke and mirrors" (as a few people call it), but the welding industry is changing. The equipment manufacturers are making advances in equipment that wasn't available 15 or 25 years ago. The ability to tailor the arc to suit a certain mix of gas (whether it is AR/CO2, AR/O2, or a 3 or 4 part mix with argon/helium/oxygen and C02, for example) has opened many new doors in the fabrication industry that allows and almost calls for these "exotic" blends.
          This is a great forum and a wealth of knowledge comes from some very experienced individuals, but as with anything....research is the key. Keep posting and asking and the people here are more than happy to share their knowledge and experiences.

          Just to finish off here......Wishing everyone a very Merry Christmas and safe and fun New Year!

          Sparx.

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          • #20
            The miix

            Thanks for the info Sparks. I am not up on the history of welding but would be nice to know why all these precesses come about. Keep your tanks full and wire clean. Good Seasoins to all . Steve

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            • #21
              judging by all the info on what transfer methods there are i would say my machine is set for globular transfer because i have a big blob on the end of my wire after i run a bead

              thanks for all the replies happy holidays to all
              to weld or not to weld that is the question

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              • #22
                Originally posted by Mike W
                I wonder where the c25 came from. Why not c50?
                c50 OR 50%AR 50%co2 is all I could use on a military contract we had...required for certification on A36 steel. The beauty of 50/50 is that it penetrates great and allows you to weld all position with out tweaking your machine...runs not as wet as C25...makes it good for vertical and overhead welding. I prefer it over C25.
                Arcin' and Sparkin', Rocky D

                "Experience is the name we give our mistakes"

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                • #23
                  Ah ha, thanks Rocky D. I have one text that mentioned using 80% CO2. I almost have my gas mixer finished. I will run some beads with different mixtures and take some pics.

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                  • #24
                    Another long term CO2 user here.

                    Originally posted by Mike W
                    I have been using CO2 for 20 years. Since I also have an argon tank I am going to build a gas mixer just for the fun of it.
                    I have been using straight CO2 for 20+ years. Yikes. Guess it all depends on your work type and how much cleanup you want to do. As my collection of welders has grown, including TIG, I have toyed w/ making some kind of mixer, but am not sure how best to procede. would be interested to exchange ideas on making a DIY mixer. The gases are on hand so why not take advantage of that! Seems like this computer stuff may come in handy afterall!!!!!

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                    • #25
                      Welcome Captbob! I am putting together one along the lines of this one: http://www.star.bnl.gov/STAR/pmd/sta...as_system.html

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                      • #26
                        BCarlucci,

                        I am as lost you you guys concerning spray arc with CO2 . I've sprayed with argon/CO2, argon/O2, argon/helium/CO2 (2.5%) and various patented mixes from several companies, but never straight CO2. I never even considered it.

                        Check out PRAXAIR'S website regarding gases used for various GMAW applications.

                        This quote is direct from the PRAXAIR link listed above:

                        Carbon Dioxide
                        Carbon dioxide (CO2 ), a reactive gas, dissociates into carbon monoxide and free oxygen in the heat of the arc. Oxygen then combines with elements transferring across the arc to form oxides from the weld pool in the form of slag and scale, generating a great deal of smoke and fumes. Although carbon dioxide is an active gas and produces an oxidizing effect, sound welds can be consistently achieved with pure CO2 .

                        Carbon dioxide is often used in its pure form with welding of carbon steel, because it is readily available and produces good welds at low cost. However, this may be a false economy as the low cost per unit of gas does not always translate to the lowest cost per foot of deposited weld. Other factors, such as lower deposition efficiency due to spatter loss, can influence the final weld cost and should be carefully considered.

                        Carbon dioxide will not support spray transfer. Metal transfer is restricted to the short circuiting and globular modes. A major disadvantage of carbon dioxide is harsh globular transfer with its characteristic spatter.

                        The weld surface resulting from carbon dioxide shielding is usually heavily oxidized. An electrode with higher amounts of deoxidizing elements is needed to compensate for the loss of alloying elements across the arc. This may cause problems when the completed part requires paint. The advantages of carbon dioxide are good width of fusion and the achievement of good mechanical properties.

                        Check out the entire site. It's good reading.

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                        • #27
                          Originally posted by Mike W
                          Ah ha, thanks Rocky D. I have one text that mentioned using 80% CO2. I almost have my gas mixer finished. I will run some beads with different mixtures and take some pics.
                          I should've added in my last post, that I used a Smith gas mixer at work...with it, I can dial precisely what flavor of Ar to CO2 I need...or run either gas straight....it's a little pricey, but the results are right on every time. It's easy...and I like easy!
                          Arcin' and Sparkin', Rocky D

                          "Experience is the name we give our mistakes"

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                          • #28
                            Rocky D,

                            Do you have link to the Smith Gas mixer you used or use at work?

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                            • #29
                              To Sparx,

                              I would like to add a little to your mention of spraying with C25. I have done it at around 36 volts pushing 400 amps. It is a spray, not a true spray, as you used axially for the adjective. Even at that it is in consistent and not feasible.

                              I would like to say a 98 argon/2%CO2 will do most everything needed in the GMAW process if you have either adjustable slope/inductance and enough amperage to run it. It is not as easy to control as 83%argon/17% CO2, but works well and is readily available.

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                              • #30
                                Originally posted by Alex
                                Weldmup,
                                I, too, have NEVER heard that spray transfer is possible with anything containing more than about 15% CO2. It has to do with the ionization potential of the gas. What you are getting with anything higher that 15% CO2 (max.) is globular transfer. The primary difference being that in globular transfer the filler droplets will be 1.5 to 2.0 times the diameter of the wire. Whereas in true spray mode, the filler droplets will be about 0.5 times the wire diameter. Take a look at the end of your wire. If there appears to be a blob on the end, it's globular transfer. If the wire appears to taper to a point, it's spray.
                                Alex,

                                Spray is possible with 75/25 but it takes a big welder. Your 251 would probably do it but higher % Argon is better.

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