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  • GMAW transfer types

    I am a student teacher in a high school welding class. I am teaching GMAW (mild steel). What I want to know is the specifics that separate spray, globular, and short-circuiting transfers. My text book, "Welding Skills", is not very clear on the subject and often conflicts with what I learned in college. What are the shielding gases, voltages, electrodes, ect, that have to be in place to determine transfer type. Thanks, Ron
    Ronald 1

  • #2
    If the book you are refering to is "welding skills and practices" by Giachino and Weeks, the
    section that deals with arc transfer is fairly concise, as I see it.( Though perhaps a newer edition has changed the treatment of this subject, I last taught from the 1978 edition).
    Should this be the case, see if you can get an older copy.

    Basically, arc voltage is what seperates the transfer modes, shielding gas has an effect as well,as argon will allow the arc stability at a lower voltage.

    The Lincoln Foundation has many good titles for teaching texts, and you will find the prices very
    reasonable.
    work safe, always wear your safety glasses.


    Edward Heimbach

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    • #3
      Ron, this is the short answer (it could fill a book), the mode of transfer is the way that the molten wire is transfered from the tip to the work piece. It would take a long time to cover every wire size and gas combination and what mode of transfer you will achieve at what voltage. Tell me what wire and gas you have and we will go into specifics for that application. Following is some general information that I hope will help a little. In short circuit mode the wire is literally shorted against the molten puddle, up to a couple of hundred times per second. Penetration and heat input are low, spatter is moderate. This mode is ideal for light gauge steel and poor fit up in all positions but is not to be used for structural applications without a qualified procedure (it is difficult to qualify this mode for anything structural). Globular transfer is when the molten metal forms a glob at the point of transfer, the glob is larger than the wire. It has limited uses in the flat position only, penetration is good, spatter is very high. Spray transfer is much more complicated. The drops of molten metal detach from the wire and move through the arc column to the work piece. Penetration is good and there should be no spatter. Shielding gas composition and wire diameter will have an effect on if and when you make the transition from short circuit mode through globular into spray transfer. Shielding gases for these modes are really a whole topic by themselves. You need to do some research to fully understand these processes. It is difficult to cover everything or really much of anything other than the very basic principles here. A very good beginners reference and educational book to have is " THE PROCEDURE HANDBOOK OF ARC WELDING" from Lincoln Electric. It is hundreds of pages of valuable information for the low cost of about $15.00 call 1-216-383-2259 and the welding instructors at Lincoln will get you one. For the more advanced education try the "ASM HANDBOOK" it is 1200 pages of the most detailed information you could ever desire.
      Respectfully,
      Mike Sherman
      Shermans Welding

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      • #4
        I purchased the GMAW book from Miller. It covers all aspects very well for teaching.
        It's not an optical illusion...it just looks like one

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        • #5
          Can anybody who has done all three mode comment on the sound each mode creates?

          Bob

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          • #6
            sizzling bacon
            ploop. ploop-ploop-ploop. ploop
            whoooooosh
            my sincere apologies Bob. i couldn't help myself.
            chip
            chip

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            • #7
              Whoooosh! is the most fun! Some very impressive welds can be made in spray mode, the big pool of fluid metal limits the use of spray to flat position only, but what a time saver on thick material.
              work safe, always wear your safety glasses.


              Edward Heimbach

              Comment


              • #8
                Details

                Our book, Welding Skills, does a good job of illustrating the different transfer methods. What it does not do very well is tell the specifics of what has to be in place to get a given transfer type. As I understand it: Spray transfer requires an argon-oxygen mix with over 22 volts. Globular is nothing more than spray gone wrong, voltage too low or wrong shielding gas, and is a useless process. Short circuit uses an argon-CO2 mix or pure CO2. Is short-arc voltage specific? Is the only thing that separates it from spray the shielding gas? We are using .035" wire (ER70 S3). What would need to be in place to get the three transfer methods. Please be specific as to voltage, current, shielding gas, ect. Thanks for your help. Ron
                Ronald 1

                Comment


                • #9
                  Re: Details

                  Originally posted by Ronald 1
                  Our book, Welding Skills, does a good job of illustrating the different transfer methods. What it does not do very well is tell the specifics of what has to be in place to get a given transfer type. As I understand it: Spray transfer requires an argon-oxygen mix with over 22 volts. Globular is nothing more than spray gone wrong, voltage too low or wrong shielding gas, and is a useless process. Short circuit uses an argon-CO2 mix or pure CO2. Is short-arc voltage specific? Is the only thing that separates it from spray the shielding gas? We are using .035" wire (ER70 S3). What would need to be in place to get the three transfer methods. Please be specific as to voltage, current, shielding gas, ect. Thanks for your help. Ron
                  Ron,

                  To produce spray transfer, the shielding gas has to a have a minimum of 80% Argon and the remainder is either oxygen or CO2. However, the oxygen content should not exceed 5%. Some common gas mixtures are: 80% AR/ 20% CO2, 85%AR / 15% CO2, 90% AR/ 10% CO2, 95% AR/ 5% Oxy, and 98% AR/ 2% Oxy. Now remember this, the higher the argon level is in the mixture the lower the arc voltage that is needed to produce the transfer. Because of this my personal preference is 98Ar/2oxy. For an .035 wire the 24-30 is the voltage range.
                  Your pretty much right about globular transfer. Globular transfer is either produced by using spray transfer settings with the wrong gas or 22-24 volts spray transfer wire speed settings, and CO2 or an AR/CO2 mixture normally 75/25 also known as C25. Now globular transfer is pretty much useless for the professional weldor because of the spatter that it creates. However, for the home hobbiest weldor who doesn t have the financial means to purchase a machine like a Millermatic 251 that is capable of producing spray transfer, globular transfer is an acceptable alternative on thicker material. To make globular transfer useful in this such case a person would need a machine at least similar in size to a MM 210. Excellent penetration would be acheived by using CO2 as the shielding gas, actually deeper than acheived by spray transfer, there is all that spatter. However, spraying the base metal surface with anti spatter spray prior to welding should make the removal of most of the spatter easy.

                  Short circuit transfer occurs at voltages lower than 22 volts. Common shielding gases are 75/25 or CO2. Voltage and amperage settings are main difference between spray transfer and short circuit transfer. Short circuit transfer can be performed with certain shielding gases that are used to produce spray transfer. Each wire diameter has a specific amperage at which point the mode of metal transitions from short circuit transfer to spray transfer. For an .035 wire this is around 170 amps.

                  Now for an .035 wire short circuit transfer occurs at 16 - 22 volts and 80 - 380 IPM on the wire speed. And with a Ar/ 1-5%O2 shielding gas spray transfer occurs at 24 -30 volts and 340 to 625 on the wire speed. What you need to keep in mind is that the voltages mentioned are arc voltages. Reason I state this is because on the machines that I use the voltage that you set the dial at on the machine is actually the open circuit voltage. In my experience, the arc voltage is usually about 2 or 3 volts lower. To give you anything more specific then the above parameters you need to mention material thickness.

                  Also, Im not familiar with E 70S-3. E70S-6 has pretty much become the most popular wire used
                  MigMaster 250- Smooth arc with a good touch of softness to it. Good weld puddle wetout. Light spatter producer.
                  Ironman 230 - Soft arc with a touch of agressiveness to it. Very good weld puddle wet out. Light spatter producer.


                  PM 180C



                  HH 125 EZ - impressive little fluxcore only unit

                  Comment


                  • #10
                    Smaller wire?

                    Thanks for the information; it is very helpful. Our machine is a Millermatic 200. We are using .035" wire to weld .250" mild steel. Our shielding gas is 75-25 argon-CO2, and pure CO2. Could we get spray transfer if we used an argon-oxygen mix and a smaller diameter electrode wire such as .030" or .023"? Is it correct that it takes less voltage and current to get spray transfer with smaller wire? If we could get spray transfer with the smaller wire would it be useful, or would the wire be to small? Thanks for your help. Ron
                    Ronald 1

                    Comment


                    • #11
                      RONALD1......A NUMBER OF YEARS AGO I WAS ASKED TO ASSIST IN THE MAKEING OF A MOVIE.......THIS MOVIE SHOWED EXACTLY WHAT ALL FORMS OF THE WELDING CHARACTERISTICS YOUR ASKING ABOUT LOOKED LIKE........... WHEN I AND I BELIEVE BRIAN BASHORE PREVIED THE MOVIE (STEVE WHO STILL WORKS AT THE HOBART INTSITUTE OF WELDING TECHNOLOGY WAS THE PRODUCER) I THOUGHT THEY WERE WELL DONE (THE MOVIE). WELL ACTUALLY HE GIVE US A NICE RIGHT UP FOR HELPING OUT IN THE SCRIPT..........HAHAHA.........BUT I DON'T THINK IT WAS IN THE MOVIE HE MADE, PROABABLY LAYING ON THE CUTTING ROOM FLOOR..........IF YOU CALL 1-888-462-2789 THAT IS THE INSTITUTE AND ASK TO SPEAK TO STEVE IN THE SCHOOL BOOK DEPT.... HE IS A MANAGER THERE.............STEVE HOUSTON IS HIS NAME AS I RECALL..........I'LL BET HE WILL HELP YOU OUT FROM ONE INSTRUCTOR TO ANOTHER...........WORTH A SHOT........HOW MANY STUDENTS YOU TEACHING IN YOUR CLASSES..................?..ROCK
                      [email protected]

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                      • #12
                        Re: Smaller wire?

                        Originally posted by Ronald 1
                        Thanks for the information; it is very helpful. Our machine is a Millermatic 200. We are using .035" wire to weld .250" mild steel. Our shielding gas is 75-25 argon-CO2, and pure CO2. Could we get spray transfer if we used an argon-oxygen mix and a smaller diameter electrode wire such as .030" or .023"? Is it correct that it takes less voltage and current to get spray transfer with smaller wire? If we could get spray transfer with the smaller wire would it be useful, or would the wire be to small? Thanks for your help. Ron
                        Ron,

                        Im not familiar with the Millermatic 200, so I downloaded the manual for it from the Miller website. The manual is showing me that the machine has a 60% duty cycle at 28 volts and 200 amp. So, what this means to me is that you should be able to use the .035 wire in a spray transfer mode on your 1/4" material. Here are the parameters that I use for spray transfer on a T joint constructed from 1/4" material. I run an open circuit voltage of 29 volts which drops to a load voltage of about 27 volts. The wire speed is around 410-420 inches per minute . Now my Millermatic 250 doesn t have meters on it , so I have a co- worker measure the voltage settings for me with our shop digital multi meter. If you dont know how to do this just reply back and will try to explain it to you. Now measuring the inches per minute is quite easy. Cut the wire flush with the contact tip. then run the wire for 6 seconds. shut the power to the machine off. Then measure the length of wire that is extending out past the contact tip. Multiply this measurement by 10 and you have your inches per minute. Now obviously, you probably won t get the correct wire speed on the first try. So after you take this measurement, just roll the wire back onto the spool. I recommend rolling it back on to the spool because other wise your students might end up wasting a lot of wire cutting it off until they reach the proper wire speed range.

                        Remember, my parameters are based on using 98/2 shielding gas and an E70S-6 wire.

                        Also, Im attaching a picture that contains some important info for you on stickout and contact tip location as compared to the end of the nozzle.
                        Last edited by Dan; 05-01-2009, 08:16 AM.
                        MigMaster 250- Smooth arc with a good touch of softness to it. Good weld puddle wetout. Light spatter producer.
                        Ironman 230 - Soft arc with a touch of agressiveness to it. Very good weld puddle wet out. Light spatter producer.


                        PM 180C



                        HH 125 EZ - impressive little fluxcore only unit

                        Comment


                        • #13
                          Here is MIG welding Parimeter Chart.
                          http://www.esabna.com/ESAB/showdetl....=1323&CATID=22

                          Let me know if link doesn't work.
                          I haven't found a better chart on web.


                          Hobart should provide this type of info for their wires.
                          Last edited by Roger; 11-25-2002, 08:48 AM.

                          Comment


                          • #14
                            that's a great chart Roger. thanks for the link ... even if the Hobart wire specs aren't identical that's a great point of reference.

                            - jack

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                            • #15
                              Here is another chart from that site.

                              http://www.esabna.com/ESAB/showdetl....=1325&CATID=22

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