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  • #16
    Originally posted by stlyns
    another way to look at it...voltage =pressure , or force of current flow...current being the amount of electricity flowing through a conductor in a given amount of time....does that help?
    I try and think of electricity like water system. EMF= water pressure, amperage =water. I guess pressure washer would be CC power source? Unfortunetly still working on arc/current parables lol.
    Miller 251
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    • #17
      Do you agree with the formula that voltage should be (amps x 0.05) + 14

      By that calculation, at 110 amps you need 19.5 volts. According to the panel on my welder it only delivers 18 volts at 110 amps. Hmmm.

      Anyone else know the specs of their 110v migs?

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      • #18
        Basic electrical theory is a good starting point for understanding what is happening. E (Voltage) = I (Amperage) x R (Resistance) is the basic rule for circuits with pure resistive loads. Rnning the circuit theough an electric arc adds some variables that distort that "pure" resistive load.

        It's a lot easier to accept what welding machine engineers have determined to be the facts, and move on from there.

        We could get into the properties of electric arcs in an ionized gas envelope, and all that, but I sure can't see the good of it.

        Tim, where'd you come up with that formula??

        Hank
        ...from the Gadget Garage
        MM 210 w/3035, BWE
        HH 210 w/DP 3035
        TA185TSW
        Victor O/A "J" series, SuperRange
        Avatar courtesy of Bob Sigmon...

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        • #19
          i got a question....since we're on the topic....i was welding the other day at work, and my machine was set at about 26v and 550ipm wire feed speed....well a co worker of mine was using my welding machine, and had re adjusted it to about 24v and 540ipm, so i tried his settings, and i was getting better penetration with his settings than i was with my hotter settings...kinda weird...so i use those settings now...but i was thinking, if you set your machine to where you get good results, but wanna run hotter still, would a proportionate increase in voltage and wire speed, yield good results......example....say you have your settings at 23v and 475 wire speed.....if you were to want to jump up to 26 volts would you set your wire speed at 537ipm and have everything be the same....as far as the rate at which the wire is fed in and burned back.....would that be proportoniatly the same from one voltage/ws to the next....confused yet?

          regards,
          Nathan Hamler.

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          • #20
            What is Voltage

            The issue of what voltage is / does when GMAW welding can be complicated. All the answers brought up already are correct to some degree

            VOLTAGE - voltage changes mainly arc length. You typically set the voltage to yeild the arc characteristic you desire for a give WFS

            Voltage as Heat Input

            As already noted voltage affects your heat input so it is correct to state voltage is heat and therefore more voltage can yield higher penetration ( not always true though ! )

            BUT.... It is incorrect to assume that voltage is the governing variable that affect heat input

            HEAT INPUT - heat input into a weld is very simply calculated as current X voltage X 60 / linear travel speed ( units in kJ/inch ) All heat input calculations in welding are done using this formula

            It is not important to undertand the formula but rather the general idea on how V and amps vary the end result

            For example, a typical GMAW procedure guidline for short circuit w/ 100%CO2 on mild steel has the voltage ranging from approximately 17volts to 22 volts . These recommened produres cover material thickness from 24Ga to 1/4 "

            Again it is not important to undertand the numbers but rather to cover the voltage range for short circuting up to 1/4 you only vary the voltage about 5 volts . If you plug a 5 volt variation into the heat input formula the heat input goes up, but it only goes up about 30%

            However, if you look a the same procedure charts, from 24ga to 1/4 you can see the current range from approximately 40 to 200 amps . Plugging this variation into the heat input calculation yields a 400% increase in heat input

            CONCLUSION FOR HEAT INPUT

            From the exercise above, you can see that although voltage does increase heat, the governing variable that varies heat input ( therefore penetration ) is a amps ( which is dicatated mainly by Wire Feed Speed )

            Still not convinced , set up some 18 gauge material to a nice short circuit transfer . If you crank up voltage, your arc length gets long and the end of the electrode starts trying to blob off. The puddle will wet out but most likely will not burn through

            Turn voltage back down and now peg the WFS . Assuming you have a decent size machine, it is easy to burn a hold right through the plate

            To increase your penetration ( heavier material for example ) it is generally best to increase WFS to increase the current and tweak the voltage to yield the desired arc

            If someone can let me know how to post into a reply a clip from a adobe file I can put up some cross sections of welds showing the effect of variables

            What Else Does Voltage Do

            Once voltage is set to yield a desired arc characteristic ( short arc , spray etc ) you can tweak the voltage to flatten the bead profile. In general, more voltage yields a flatter bead

            Although many people assume it flattens due to arc force etc, it is WAAAAY more simple than that

            A good analogy is spray painting. If you move the spray can closer the line gets narrower. If you move it away, it gets wider. It is geometry of a triangle. As the electrode gets further away ( higher voltage / longer arc length ) , the "cone or tent" it forms gets wider. It as simple as that

            Because the rate of wire feed is constant, if wire gets "spread out " more on the plate the bead gets wider and less high . This is why on a fillet weld excessive voltage will cause undercut. There is not enough material to be spread around to fill what the arc is digging out. Turning down the voltage reduces how much the material is getting spread

            Hope this clarifies some of this

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            • #21
              Originally posted by TRG-42
              HEAT INPUT - heat input into a weld is very simply calculated as current X voltage X 60 / linear travel speed ( units in kJ/inch ) All heat input calculations in welding are done using this formula
              Hmmm something's off with that formula:

              current (amps) x voltage (volts) = watts = joules/sec (this is just P = IV)

              multiply by 60 to get joules/min (I'm assuming that's where the 60 comes from)

              if linear travel speed is in inches per minute, then dividing joules/min by inches/min gives joules/inch -- not kilojoules/inch. So where'd the extra factor of 1000 come from? Or maybe just a typo?

              Asad

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              • #22
                Originally posted by asad
                Hmmm something's off with that formula:

                current (amps) x voltage (volts) = watts = joules/sec (this is just P = IV)

                multiply by 60 to get joules/min (I'm assuming that's where the 60 comes from)

                if linear travel speed is in inches per minute, then dividing joules/min by inches/min gives joules/inch -- not kilojoules/inch. So where'd the extra factor of 1000 come from? Or maybe just a typo?

                Asad


                Ooops !

                Sorry should have been more clear. This calculation yields J / in but in the welding industry heat input is always stated as KJ / in . For example you would not say you were driving at a speed of m / min but rather km / hr ( if you live in Canada ) The reason for this is heat input calculations generally run between 20 and 80 KJ / in . You would state " keep your heat input below 70 " It's assumed kJ

                In real world applications, having more accuracy than 2 thousand kJ is not necessary. I generally round up or down to the nearest 5 kJ

                Thanks for pointing out the mistake

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                • #23
                  Wow. That sure clarifies a lot of things for me. Thanks.
                  Miller 251
                  Miller Synchrowave 250 DX
                  Hobart Fabricator/No. 27 feeder
                  Hypertherm 45 Powermax
                  Hypertherm 190C
                  Miller XP 130
                  Princess Auto 400 amp DC Diesel Generator/project

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                  • #24
                    Lost me at "variations"
                    The Maniacal Migging Guy {as Hankj would put it}


                    HH180
                    Cutmaster 51

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                    • #25
                      MIG Voltage etc.

                      I didn't have time to read each and every repy but going back to the question asked and info given there made me wonder. Increasing the wire speed increases the amps? Now, I have this old Miller and got it used. Took welding classes but only on gas and stick. Is this upping the amps tied to speed a recent feature? I found that welding sheet metal or ornamental door tubing meant lowering the voltage from the setting I might have used for a heavier guage project.

                      Wire speed was adjusted down also so welding "felt" right. Regarding penetration. If I didn't lower the voltage (and wire speed) on light tubing I sure got penetration all right--zapped a hole right through the tube. I looked at my MIG and I have pencil marks all over the back of the voltage adjustment. "Sheet", 1/4", etc. Same for the wire speed control but I can set that dragging the gun across a scrap piece as I adjust it.

                      On the Miller there is just one more dial. "Stabilizer" Never could get any change in the weld regardless of how I set it. What is it? Thor

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                      • #26
                        Originally posted by Thor Odinson
                        Increasing the wire speed increases the amps? Now, I have this old Miller and got it used.... Is this upping the amps tied to speed a recent feature? Thor

                        Hi Thor, turning up the WFS does NOT " turn" up the amps on a constant voltage power supply . You don't turn up amps on a CV welder, but rather, for a given wire speed, there is a resultant amps required to melt the electrode off

                        This is nothing new . Its been like this since the development of CV welders decades ago.

                        For a given wire diameter , wire alloy and electrode stick out you can always determine the current that will be drawn to melt the wire off


                        For example ( I will try to attach the charts showing WFS vs Amps ) a .045 electrode at 200 ipm WFS and a standard electrical stick out, you will ALWAYS get about 200 amps. This is regardless of the make of machine, model of the machine ( assuming it has 200 amps to give ! ) what planet you live on etc

                        A interesting note : if you run both ER4043 and ER5356 ( the two most popular alloys ) aluminum MIG wire at the same wire feed speed, the ER4043 will "draw" more amps. That is why ER4043 is said to be deeper penetration in GMAW applications

                        I will try to include a graph of WFS vs Amps

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                        • #27
                          thanke you hankj

                          thanke you hankj
                          thank to you now i undrstand it. happy new year
                          Originally posted by hankj View Post
                          Basic electrical theory is a good starting point for understanding what is happening. E (Voltage) = I (Amperage) x R (Resistance) is the basic rule for circuits with pure resistive loads. Rnning the circuit theough an electric arc adds some variables that distort that "pure" resistive load.

                          It's a lot easier to accept what welding machine engineers have determined to be the facts, and move on from there.

                          We could get into the properties of electric arcs in an ionized gas envelope, and all that, but I sure can't see the good of it.

                          Tim, where'd you come up with that formula??

                          Hank

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                          • #28
                            voltage

                            No one has mentioned heat input to the weld yet. Voltage is part of heat input. Heat input in Joules is Amps x Volts x 60 / Travel Speed. While amps in theory controls penetration, voltage plays a lesser part. Amps is a squared function. That is why it is emphasized. At the same time, Voltage plays a large part in crossing the line between short circuiting mode welding and spray arc welding. A high dep process like spray arc welding does not start until 28-30 volts. Of course, this does not come into play when using a cheap 110V flux core welder.

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                            • #29
                              Wow, this is a old (though good) thread. Are we still using volts and amps these days? I would have thought by now we'd have something with an orthogonal flux density detector for sensing the input particles and for providing the multiplier output signal through a process of electron multiplication by secondary emission of electrons within an interior portion of the detector; perhaps even a conversion dynode for assisting the detector in the sensing of the input particles to prevent orthogonal decomposition of the current of non-sinusoidal voltage sources applied to non-linear loads. Or at least something without knobs.
                              --- RJL ----------------------------------------------

                              Ordinarily I'm insane, but I have lucid moments when I'm merely stupid.
                              -------------------------

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                              • #30
                                Originally posted by usmcpop View Post
                                Wow, this is a old (though good) thread. Are we still using volts and amps these days? I would have thought by now we'd have something with an orthogonal flux density detector for sensing the input particles and for providing the multiplier output signal through a process of electron multiplication by secondary emission of electrons within an interior portion of the detector; perhaps even a conversion dynode for assisting the detector in the sensing of the input particles to prevent orthogonal decomposition of the current of non-sinusoidal voltage sources applied to non-linear loads. Or at least something without knobs.
                                Ya. The machine I just got imported from China has all of that. And it fits in my pocket and runs on a pair of AA batteries. Good for 1.2*10^21 electrons/second, just like a MM180
                                I may not be good looking, but I make up for it with my dazzling lack of personality

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