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350P Contact-to-Work Distance on 1/8" steel; 0.035 wire; 90/10; 250 ipm

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  • 350P Contact-to-Work Distance on 1/8" steel; 0.035 wire; 90/10; 250 ipm

    I'm very new to Pulse MIG and truth be known, not a particularly good welder (yet). Welding Tee Joint on 1/8" thick mild steel and have had a couple burn backs where the wire fuses with the contact tip. Further, my beads look too tall and they don't wet in to the edges very well. Couple quick questions:

    1) What is a good range for the contact tip to work distance? I've read (and heard) everything for 1/8" to 1/2" and 1/2" to 3/4" - both of these cannot be right!

    2) When I slow down my travel speed to wet in the edges, the bead seems to get unreasonably tall - sort of like squirting molten metal from a fire hose.

    3) Should I consider adjusting either the Arc Length, or the Arc Width?

    Sorry for such basic questions, but there isn't a whole lot of information that I've found on Pulse MIG on steel, and again, I'm generally new at all this. Naturally I'm experimenting, but hoping some pointers will accelerate my progress (and waste less practice material).

  • #2
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    They say a picture is worth a 1000 words, this close to Christmas my gift is 4000.

    You have to do some serious learning. Post pictures. Seriously, your embarrassment isn't something we haven't seen before. You have to show us what you've done, so we can best offer advice and guidance on how to if not correct it, improve it.

    Comment


    • #3
      When you have questions always head to Miller's resource page at the top of the page for videos and help articles. Miller has a great library of information available. Click on the MIG welding guide, then on the Mig Tips folder.

      https://www.millerwelds.com/resources/welding-guides

      I recommend learning on regular Mig, not pulse Mig, you need to learn the basics first.

      This is the wire I run in my MM251. https://www.lincolnelectric.com/en-u...ncolnElectric)
      Last edited by tackit; 12-10-2019, 11:27 AM.

      Comment


      • #4
        In Tackit's link to the wire he uses check under "Typical Operating Procedures". Recommended CTWD (Contact Tip to Work Distance) is specified. Check with the wire manufacturer for the wire you are using for their recommendations.

        ---Meltedmetal
        ---Meltedmetal

        Comment


        • #5
          Good idea, Check out page 17 https://www.lincolnelectric.com/asse...L-56/c4200.pdf

          Comment


          • #6
            According to what I've read contact to work distance can be as much as twice for pulse as for short-arc. Meaning the 1/2" to 3/4" is reasonable. I adjust the arc length so the wire melts in the air close but not on the puddle. If it's too short, you'll melt or foul the contact. If you have spatter you're either too close or the arc is too close to the puddle. I find I have to change the arc length as the wire speed changes. My machine isn't a miller though.

            What gas are you using? I'm using 90/10 and it works pretty well. My gas place didn't carry it so I had to wait a week to get a tank mixed up.
            I found a miller chart that shows wire speeds for different metal thicknesses for pulse. It's pretty close even on my non-miller welder. Most of the machines seem to prefer .035 or thicker wire. The chart I use doesn't even have .023 wire range listed even though my machine has a setting for it.

            The primary reason I use pulse is that it doesn't spatter.

            You're right that information is pretty sparse.

            Comment


            • #7
              Part of the problem when having a discussion surrounding the pulse process is the lack of understanding to how it affects metal deposition and composition. The terms of short circuit, globular, spray not only describe a visual display in effect, but account for a range to that effect in occurrence taking place.

              PuIse is a term used that describes something... but that something means very little to most other then high and low, up and down, hot and cold.

              Changes resulting from such things as CTWD, arc length, increase or decreasing Voltage/WFS while meaningful, in conjunction with base current values, (transitions from one current to the next), shielding gas composition, the resulting changes to mechanical and chemical composition of the deposit stands out in being effected yet most see a pretty bead and no splatter.

              It's a term used that describes something, but that something means very little to most because the basis of the process is misunderstood. The mention of allowances for 1/2' to 3/4" stick out, in simplicity fails to account for wire size, nozzle size, shielding gas density.

              Example would be as asked:


              1) What is a good range for the contact tip to work distance? I've read (and heard) everything for 1/8" to 1/2" and 1/2" to 3/4" - both of these cannot be right!

              2) When I slow down my travel speed to wet in the edges, the bead seems to get unreasonably tall - sort of like squirting molten metal from a fire hose.

              3) Should I consider adjusting either the Arc Length, or the Arc Width?
              1) Depends as I mentioned on wire size and type, where the upper and lower ranges are set for voltage and WFS, shielding gas, material thickness, size and shape of the required deposit with travel speed considerations. The generic nature of these informative articles don't always elude to these variables for consideration.

              2) If it was normal GMAW and the edges weren't wetting, how would you fix it? Increase voltage, reduce WFS. Adjust gun angle, maybe it's tipped increasing stick out? Or shorten stick out resulting in the same occurrence but through inductance heat and resistance lost in the wire.

              Sounds like your upper voltage range needs reduction or a change to WFS is required. Could also be too short a stick out and the wire over heating?

              3) Not changing anything but one thing will have an affect. How do you change arc length? Increase or decrease WFS. Or the arc width? Increase or decrease Voltage.

              You could also increase or decrease wire size. Lengthen or shorten stick out. Change your shield gas mixture. Adjusting your gun angle will have an effect.

              The chart I use doesn't even have .023 wire range listed even though my machine has a setting for it.
              It used to be, before invertors anyways, that .023 couldn't be brought to a "true" spray. I can say that even with a 75/25 mix on a 135, .923 will burn like it's spraying. Not a true spray by the definition, but close enough for most to think they are.

              https://app.aws.org/forum/topic_show.pl?tid=33928

              Comment


              • #8
                Noel, I thought because Mig machines are constant voltage welding machines, differences in wire to work distances within the machine's designed range shouldn't change chosen voltage settings that much or at all? Am I not understanding correctly? Thanks
                Last edited by tackit; 12-11-2019, 03:31 PM.

                Comment


                • #9
                  Increase voltage,
                  I'm not aware of any pulse MIG machines that aren't "synergic" or whatever the manufacturer term is for automatic voltage setting. Typically you tell the welder what the wire thickness is, you pick a feed rate based on the material being welded, change the arc-length to control where in the air the wire melts and that's about it for settings. The machine picks voltage and pulse parameters based on the wire speed and thickness. The pulse rate changes with wire speed. The frequency goes up as the wire speed goes up.


                  Comment


                  • #10
                    When we talk Constant Current and SMAW the idea of Amperage being adjusted as a value equating to "heat" is what we associate when turning the dial up or down. If we thought of that not as heat, but volume of electrons, little amps if you will think so, then we have more or less of them.
                    This of course is based around the principle of electron travel, those +/- values and which terminal the greater number of electrons are traveling from or too.
                    Voltage then would be the variable. Raising the rods end further away or closer to the surface would change voltage because the distance the electrons have to travel is diminished with a close arc, or increased due to a long arc.
                    I should bring in a mention of volt/amps curves to such change in arc length but I won't. I will say though that the longer arc length scatters a greater percentage of those electrons and that typically is shown as a wider, wetter deposit of metal. It doesn't occur though without a loss of electrons, heat, or is it amperage?
                    Now accounting for the idea the SMAW electrode is a consumable, to be used up, as it shortens, the rod appears to burn hotter. The reason is, less resistance in the rods length from the electrode holder,(point of contact) to the end of the rod. Longer to shorter stick out assuming the length of the tip of the rod is held consistently for arc length.
                    Back to GMAW.


                    differences in wire to work distances within the machine's designed range shouldn't change chosen voltage settings that much or at all? Am I not understanding correctly? Thanks
                    Your understanding it correctly just I'm not being clear enough in my explanation.
                    These "new" invertor based machines do some wonderful things to compensate and correct for us, our mistakes. I can't argue that. What I can discuss is what is still occurring.
                    When you set voltage on a CV machine, even the old ones, it should hold fast, there shouldn't be any variance far past holding steady +/- 1 volt? So what's voltage? A pressure or force moving electrons. Pushing cattle thru the chute.
                    So for the sake of discussion, if the machine was not of the abilities to self correct operator inconsistencies, and to a limited degree even if it was, variations to stick out will add more or less still from proximity and further in time due to a number of variables.
                    Longer the chute, the longer it takes to load cattle. You got a corral
                    (Contact tip)
                    a cowboy ( Voltage) trying to move cattle ( AMPS) and he may get them in the chute (Wire size) but the longer the chute the slower the lead cattle move. Resistance.
                    With the length of chute or wire size, it's the volume of cattle that can be moved at one time.
                    We were talking GMAW-P, the change in two values. Like the SMAW rod melting shorter and appearing hotter, if it isn't lowered what are the effects? if we look at the process aside from the upper and lower transitioning range, is it so far fetched to think turning voltage up or down is much different than thinking hotter or colder? It isn't, but it appears almost so. It's not like the WFS is going faster or slower, but it when adjusted adds more or less, yet amperage is changing they say?
                    Food for thought... Regardless of voltage, if the wire speed is slowed down, arc length increases. Sped up it decreases. That is a noticeable attribute to stick out changes as well. Since your not adding more or less wire, it becomes in effect, hotter colder, or seen maybe as a similar effect to/as more voltage or less voltage. What is happening however, is those cattle will not just leave the chute on there own, so when the cowboy zaps them with the prod, a group of them jump out, a large droplet. Spray transfer is nothing more the a narrower chute and more cowboys with prods to move them faster nd singular in file.


                    Synergic power sources.
                    https://www.youtube.com/watch?v=z7xWYmVd3EA
                    I don't know if I answered your question Tact? But I tried to offer an explanation for it. Dazzle them with brilliance or baffle them with BS.

                    Comment


                    • #11
                      I see.

                      Comment


                      • #12
                        Lol. Really... or are you just saying that?

                        From Lincoln:

                        For most of the diameters of filler metal alloys, the change to axial spray transfer takes place at the globular to spray transition current. A stream of fine metal droplets that travel axially from the end of the electrode characterizes the axial spray mode of metal transfer.
                        This is part and parcel to the problem. Probably buddies problem by the sounds of it. He's gone past the range required. Now, let's assume he bobs in and out a bit, doesn't support the gun well in technique (who knows? ) and while the machine is set and will make rapid changes, all it takes is a variation and parameters change further as I mentioned with in and out or weld profile changes for that matter. Doing a fillet and weaving across the middle to the sides as an example. We don't know. Maybe the pre set was for 1/4" plate and he's using a 1/4" plate, but his is on a table acting as a heat sink and the factory did theirs in free air on a smaller piece being welded? We don't know. I got 6" but depending on the angle viewed it looks longer.

                        And the thing with a longer stick out, at some point no matter what those setting are, the shielding gas still has to provide an environment with gas coverage for those transfers to occur.

                        What holds true however is the basics of the process. Guys see that spray transfer occurs between X volts and x volts, x WFS and x WFS yet fail to account for the process variables of wire size, type, material, joint design and CTWD. The latter and longer would mean a change to those parameters for such to occur.

                        Lastly from Lincoln:

                        During the use of all metal-cored or solid wire electrodes for GMAW, there is a transition where short-circuiting transfer ends and globular transfer begins. Globular transfer characteristically gives the appearance of large irregularly shaped molten droplets that are larger than the diameter of the electrode. The irregularly shaped molten droplets do not follow an axial detachment from the electrode, instead they can fall out of the path of the weld or move towards the contact tip. Cathode jet forces, that move upwards from the work-piece, are responsible for the irregular shape and the upward spinning motion of the molten droplets.
                        Not of all it was BS you know. Not to say it was brilliance either but...it was something.

                        The highlighted, those cathode forces...those are over come by reducing voltage, increasing WFS, or lengthening stick out. All with limits attached of course.






                        Comment


                        • #13
                          Originally posted by Noel View Post
                          Lol. Really... or are you just saying that?

                          From Lincoln:



                          This is part and parcel to the problem. Probably buddies problem by the sounds of it. He's gone past the range required. Now, let's assume he bobs in and out a bit, doesn't support the gun well in technique (who knows? ) and while the machine is set and will make rapid changes, all it takes is a variation and parameters change further as I mentioned with in and out or weld profile changes for that matter. Doing a fillet and weaving across the middle to the sides as an example. We don't know. Maybe the pre set was for 1/4" plate and he's using a 1/4" plate, but his is on a table acting as a heat sink and the factory did theirs in free air on a smaller piece being welded? We don't know. I got 6" but depending on the angle viewed it looks longer.

                          And the thing with a longer stick out, at some point no matter what those setting are, the shielding gas still has to provide an environment with gas coverage for those transfers to occur.

                          What holds true however is the basics of the process. Guys see that spray transfer occurs between X volts and x volts, x WFS and x WFS yet fail to account for the process variables of wire size, type, material, joint design and CTWD. The latter and longer would mean a change to those parameters for such to occur.

                          Lastly from Lincoln:



                          Not of all it was BS you know. Not to say it was brilliance either but...it was something.

                          The highlighted, those cathode forces...those are over come by reducing voltage, increasing WFS, or lengthening stick out. All with limits attached of course.





                          Perhaps Miller can come put with a nozzel that has a guide wheel to keep the torch at the proper distance from the work, and gold contact tips for those weldors who want the most electrical + and - thingies traveling down the wire and through the shielding gas money can buy?

                          Comment


                          • #14
                            https://www.youtube.com/watch?v=WNRBSUNvFEs

                            You want to know what stubs my electrode. I watch these video's of people with all the high tech and higher education but who seemingly fail to apply it in a manor that's of value to the viewer. This video is an example of that.

                            That was produced, shot...at the U of A here in Edmonton.

                            Cool as it is, looking at the irregularity of droplet formation, droplet transfer, somethings out of sorts.
                            While it's quite a visual display, it's an example of CTWD being over extended, or other parameters being out of wack. Does it matter, no. But it could be adjusted and tweaked to be done better, yielding more uniform droplet formation and a more consistent transfer.

                            https://www.youtube.com/watch?v=drCSLgfvY8I

                            Around 5 minutes things are dialing in. Note the setting.
                            While I would describe his technique in forward progression as jerking the dog off not walking it along, as he mentions, the arc becomes needle like.

                            Comment


                            • #15
                              Tack, you are correct.

                              MasterKwan, you are spot on with the pulse mig as understand the operation as well.

                              AlphaBob, increase your WFS and practice. Pulse mig is an incredibly versatile process.

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