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project: lowering flowrates for Dual-Shield Flux core

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  • project: lowering flowrates for Dual-Shield Flux core

    So ever since I learned about dual shield flux core, I had this nagging suspicion. The larger flowrates "required" by some literature might be due (in part) due to the very long CTWD necessitated by the DSFC process. With 0.045" E71T-1C/1M, the process needs about ¾ - 1" of "stickout" from the tip, so I could definitely understand needing upwards of 40+ CFH to make sure the shielding gas covers the spread considering that most MIG guns either have the contact tip flush or just slightly recessed; so the nozzle orifice itself is anywhere from 1" to perhaps 13/16" away if it happens to have a recessed tip. So I thought, what if the nozzle was simply longer, to the point where the nozzle orifice was approximately 3/8" away from the weld joint, similar to what one would use with short-circuit MIG with typical wire diameters? Would it still "work"? I'm only a hobbyist, so "work" has a looser definition for me than a professional, so what they heck, try it out.

    So I got bought some extra nozzles, chucked them up in the lathe sliced them up to make a predetermined nozzle length (in order to "bury" the contact tip with a huge recess) and cobbled together a longer frankenstein nozzle to try out.

    Here you can see my standard nozzle (the nickel-plated copper one), and the new mega nozzle. 82.2mm vs 92.5mm. With this setup, I only need 3/8" - 7/16" stand-off distance from the nozzle to the work. First try with only 27CFM of C25 worked great. Close enough to really cut down the shielding gas use, but far enough that it doesn't obstruct the view.


    I basically took a cylindrical nozzle, and took off a length, and attached the top of standard conical nozzle so as to have them meet on the flat part and not the taper, and just spot welded it all the way around. Didn't use any filler or anything, just autogenous tacks all the way around. It just needed to not fall off.


    Other than the nozzle getting hotter because it is closer to the arc, worked out great for me. I guess if I feel really ambitious I could add water-cooling to the nozzle to wick-out the heat, but that will be a project for another day.
    Last edited by OscarJr; 08-25-2019, 06:59 PM.
    HTP Invertig221 D.V. Water-cooled
    HTP Pro Pulse 300 MIG
    HTP Pro Pulse 200 MIG x2
    HTP Pro Pulse 220 MTS
    HTP Inverarc 200 TLP water cooled
    HTP Microcut 875SC

  • #2
    Originally posted by OscarJr View Post
    ...Other than the nozzle getting hotter because it is closer to the arc,...
    That was my first thought. This is a process often used in serious production work with high duty cycles.

    Comment


    • #3
      Originally posted by MAC702 View Post

      That was my first thought. This is a process often used in serious production work with high duty cycles.
      True, but that won't be the case here.
      HTP Invertig221 D.V. Water-cooled
      HTP Pro Pulse 300 MIG
      HTP Pro Pulse 200 MIG x2
      HTP Pro Pulse 220 MTS
      HTP Inverarc 200 TLP water cooled
      HTP Microcut 875SC

      Comment


      • #4
        I'm curious enough to ask... why not just shorten the length of the contact tip?

        Comment


        • #5
          I preferred to lengthen the nozzle because it is a 1-time modification. Tips are worn out at a much faster rate, so instead of cutting down a ton of tips, I only have to reach for the "dual shield" nozzle, and just grab any appropriately sized tip for the wire diameter. It also adds a bit more copper mass to the nozzle, so as to not get heat soaked as quickly as a stock length nozzle.
          HTP Invertig221 D.V. Water-cooled
          HTP Pro Pulse 300 MIG
          HTP Pro Pulse 200 MIG x2
          HTP Pro Pulse 220 MTS
          HTP Inverarc 200 TLP water cooled
          HTP Microcut 875SC

          Comment


          • #6
            Originally posted by Noel View Post
            I'm curious enough to ask... why not just shorten the length of the contact tip?
            Good question, but in addition to the permanent "fix" of the nozzle instead, the contact tip's entire length helps transfer welding current to the wire.

            It also allowed Oscar to show off autogenous welding of the nozzle.

            Comment


            • #7
              lol, welds were nothing to look at, the fast termination of the arc caused some tiny cosmetic defects (tiny surface porosity) around the edges of the tacks, but it still sealed up the two parts together enough that it didn't matter. If I had to do it again, now having seen what I seen, I'd add a down-slope to the spot weld setting instead of no down-slope, as I was using a momentary push-button to get a quick molten pool, in order to not saturate the nozzle with too much heat.
              HTP Invertig221 D.V. Water-cooled
              HTP Pro Pulse 300 MIG
              HTP Pro Pulse 200 MIG x2
              HTP Pro Pulse 220 MTS
              HTP Inverarc 200 TLP water cooled
              HTP Microcut 875SC

              Comment


              • #8
                I ran skids of Dual Shield in the shop. The welding procedure set the gas flow whether we liked it or not. Plus our QC looked at every weld and if he didn't like it grind it out and do it again. Thats just the way it is someplaces.
                Bob Wright

                Spool Gun conversion. How To Do It. Below.
                http://www.millerwelds.com/resources...php?albumid=48

                Comment


                • #9
                  Originally posted by aametalmaster View Post
                  I ran skids of Dual Shield in the shop. The welding procedure set the gas flow whether we liked it or not. Plus our QC looked at every weld and if he didn't like it grind it out and do it again. Thats just the way it is someplaces.
                  Oh I bet. This is just hobbyist-level tinkering though.
                  HTP Invertig221 D.V. Water-cooled
                  HTP Pro Pulse 300 MIG
                  HTP Pro Pulse 200 MIG x2
                  HTP Pro Pulse 220 MTS
                  HTP Inverarc 200 TLP water cooled
                  HTP Microcut 875SC

                  Comment


                  • #10
                    Originally posted by OscarJr View Post

                    Oh I bet. This is just hobbyist-level tinkering though.
                    Thats fine. I used it at home and loved it
                    Bob Wright

                    Spool Gun conversion. How To Do It. Below.
                    http://www.millerwelds.com/resources...php?albumid=48

                    Comment


                    • #11
                      I'm of the understanding those copper nozzles are alloyed with Beryllium. I think something about retaining hardness at elevated temperatures? I'm also under the impression breathing the fumes and dust should be avoided. Just saying it in filler into the conversation?

                      As far as lengthening the nozzle or trimming the tip goes, there's going to be pros and cons to both if and when it's done.
                      I actually liked the idea of extending the nozzle over trimming the tip. Who would have guessed that eh? I'm however surprised it wasn't just a matter of matching a more correct nozzle and tip parts to the application if it was thought necessary? Availability maybe?

                      Reducing gas flow rates. I'm all for it. Unless there's a darn good reason, like someone who read it in product spec sheet, wrote it up on a WPS not taking into account weld size, type, position, voltage and WFS... just looking for quick fast and simple, I'd turn it down.

                      Just like I would the voltage, or increase WFS. Move as well a little quicker. Old habits are hard to break it seems and by that I was referring too keeping my opinions to myself. No harm or foul intended.



                      Comment


                      • #12
                        Originally posted by Noel View Post
                        I'm of the understanding those copper nozzles are alloyed with Beryllium. I think something about retaining hardness at elevated temperatures? I'm also under the impression breathing the fumes and dust should be avoided. Just saying it in filler into the conversation?

                        As far as lengthening the nozzle or trimming the tip goes, there's going to be pros and cons to both if and when it's done.
                        I actually liked the idea of extending the nozzle over trimming the tip. Who would have guessed that eh? I'm however surprised it wasn't just a matter of matching a more correct nozzle and tip parts to the application if it was thought necessary? Availability maybe?

                        Reducing gas flow rates. I'm all for it. Unless there's a darn good reason, like someone who read it in product spec sheet, wrote it up on a WPS not taking into account weld size, type, position, voltage and WFS... just looking for quick fast and simple, I'd turn it down.

                        Just like I would the voltage, or increase WFS. Move as well a little quicker. Old habits are hard to break it seems and by that I was referring too keeping my opinions to myself. No harm or foul intended.


                        If I'm not mistaken you're thinking of Tellurium. The only source I have is my guesstimate because some CK TIG collets are a tellurium-copper alloy which does as what you say: maintains hardness at high temperatures. The only other reason I'm pretty sure they don't use beryllium is that beryllium is stupid expensive. You can get these nozzles from China for $1.35ea. Also, they would likely produce toxic beryllium fumes in the case of an accident where the nozzle starts to melt away, and I'm sure companies don't want beryllium-related death lawsuits on their hands. And I always wear my respirator anyways, even during TIG welding, as I've seen wayyy too many youtube videos where an impeccably clean surface starts to smoke like crazy once the TIG arc lights up.

                        I think this type of stuff doesn't exist because it tends to over-complicate things, and would require additional inventory. It's easier for everyone to just say "oh just turn up the flowrate to 40-50CFH".
                        Last edited by OscarJr; 08-28-2019, 08:28 AM.
                        HTP Invertig221 D.V. Water-cooled
                        HTP Pro Pulse 300 MIG
                        HTP Pro Pulse 200 MIG x2
                        HTP Pro Pulse 220 MTS
                        HTP Inverarc 200 TLP water cooled
                        HTP Microcut 875SC

                        Comment


                        • #13
                          Well I heard it was the B not the T... all good. If someone looks up both those words they'll learn something.

                          Not that I need to think any harder on the subject, but when I do, my thoughts revolve around arc plasma gas theory and the effect to lengthening the nozzle as you have done as well what effect it has on metal transfer, deposition and penetration/fusion profiles. It comes with my need to question stuff.

                          I'm assuming you were using CO2? I did a couple of welds the other day the likes of which I attached pictures from. Not the same wire, or gas as I was using a 75/25 mix, but the toes of the weld stood out enough in blending that I was forced to think about why? The arc plasma effect thing going on was my guess.
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                          Anyways, my thoughts were that if you did lengthen the nozzle, you would in effect change the profile of the arc plasma. To what effect, while open to discussion, it opens up questions to me how my welds appearance could have changed had I simply raised or lowered the nozzle due to the effect of Arc Plasma gas profiles.

                          All good.






                          Comment


                          • #14
                            I see what you mean, but since dual shield in the E71T-1C/1M flavor is not full-on 100% spray arc, but rather a part globular-spray animal on it's own, the arc cone isn't too much larger than an equivalent short-circuit arc depositing the same amount of metal. Of course with larger dual-shield wire diameters that changes, but the parallel is still there; a 1/16" dual shield wire would still need more clearance that my super-nozzle offers, because I am restricted to about 0.045" on my machines. .The nozzle orifice is still far away that it won't pose much of a problem, for me. None of this discussion applies to professionals who are following a WPS, of course. This is strictly hobbyist-level tinkering.
                            HTP Invertig221 D.V. Water-cooled
                            HTP Pro Pulse 300 MIG
                            HTP Pro Pulse 200 MIG x2
                            HTP Pro Pulse 220 MTS
                            HTP Inverarc 200 TLP water cooled
                            HTP Microcut 875SC

                            Comment


                            • #15
                              Actually this discussion does apply to those guys following a WPS, as well those that write them. You are in some respect, going through the hoops and hurdles of qualifying a procedure.

                              My researching and limited knowledge suggests if the theory of the arc plasma profile is considered with the type of gas shielding, voltage, WFS and CTWD, transition current for droplet formation, metal transfer and deposition rates are affected. Yada,yada, that in turn has an effect on depth of penetration and fusion profile changes.

                              So in the picture I posted of an all thread with a nut welded on top, on grinding the weld flush, my blended edge has done little for me yet I want to have penetrated and fused a deeper depth in the joint of the two pieces.
                              You did a fillet in a corner. I'm of the belief that your lengthening of the nozzle had the effect of creating a slightly deeper penetrating weld deposit. This achievement was by modifying the plasma profile. Sounds plausible doesn't it?

                              And as mentioned, with reduced flow rates.
                              Now, when I suggested a reduction in voltage, it was that increasing voltage typically increases CTWD. That in relation spreads the fan of metal being deposited. To over come that is WFS increases or electrode stick out lengthening.
                              The width of the nozzle and gas coverage is for consideration. as it's purity and dilution effects other variables in metal transfer.

                              I'm thinking a wider nozzle diameter could have produce a flatter weld deposit with better blending on the toes all thing other wise being the same? I'm also thinking you could change the nozzle end profile and change the plasma profile and still reduce gas flow further?

                              The resulting metallurgical properties...that's like deciding do I load the cart before attaching the horse or after as the horse waits? I say discover if it's do able, then see if it is repeatable, then try and break it. You mostly have, results are favorable. Being a betting man, I'd gamble thinking your welds will be less hard, offer greater elongation and increased ductility with an improvement in low temp impact properties. Not a bad thing but not prequalified without testing. But more then enough for 98% of what needs welding and with reduced shielding gas consumption.

                              For hobby level tinkering, in my opinion, you did pretty good.

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