[Welding] Help me understand the relationship between wire speed and voltage.
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RPH
Well-known member
Duty cycle - a term meant to convey usage for a time period.
100% duty cycle means welding at full power continuously without faults.
Most equipment will not be able to run at that level that long. I worked on induction machines, our portable units had a 50/50 duty cycle described as such. 5 minutes full power on, then 5 minutes off. The off period allowed cooling to take place.
If the unit states 20% duty cycle then it can only output for 12 minutes in 1 hour time frame.
Duty cycle prevents the unit from overworking.
100% duty cycle means welding at full power continuously without faults.
Most equipment will not be able to run at that level that long. I worked on induction machines, our portable units had a 50/50 duty cycle described as such. 5 minutes full power on, then 5 minutes off. The off period allowed cooling to take place.
If the unit states 20% duty cycle then it can only output for 12 minutes in 1 hour time frame.
Duty cycle prevents the unit from overworking.
dr_clyde
Well-known member
On a mig welder, the wire is the current (amperage) conductor. The more wire you feed, the more current you can run.
The voltage is the pressure of the electricity. It is what’s required to maintain the arc and push the arc force through the conductor. The more current you’re trying to use, the more voltage you need to sustain the arc.
They are linear, and should be adjusted together. If you need more amperage (heat) turn up the wire feed first, then bring up the voltage to get a smooth arc.
If the wire isn’t arcing well or if you’re getting cold, lumpy welds, you probably don’t have enough voltage to sustain a good arc.
If the wire is burning back into the tip, or you’re getting erratic, hot spatter everywhere you’re running too many volts for your wire.
So to recap, wire feed controls the amperage on the weld, the voltage simply sustains the arc.
Duty cycle is just a rating at how long a machine can output 100% of its nameplate amps in a 10 minute period. So a 60% duty cycle (industrial standard) can run a full capacity for 6 out of 10 minutes before overheating.
The voltage is the pressure of the electricity. It is what’s required to maintain the arc and push the arc force through the conductor. The more current you’re trying to use, the more voltage you need to sustain the arc.
They are linear, and should be adjusted together. If you need more amperage (heat) turn up the wire feed first, then bring up the voltage to get a smooth arc.
If the wire isn’t arcing well or if you’re getting cold, lumpy welds, you probably don’t have enough voltage to sustain a good arc.
If the wire is burning back into the tip, or you’re getting erratic, hot spatter everywhere you’re running too many volts for your wire.
So to recap, wire feed controls the amperage on the weld, the voltage simply sustains the arc.
Duty cycle is just a rating at how long a machine can output 100% of its nameplate amps in a 10 minute period. So a 60% duty cycle (industrial standard) can run a full capacity for 6 out of 10 minutes before overheating.
dr_clyde
Well-known member
To add to this, some more modern machines have synergic pulse, which basically means the welder will take care of the voltage for you to maintain your settings for pulsed spray arc.
Simply adjust the amperage (wire feed speed) and the arc gap distance you want (wire stickout) and the machine will adjust the voltage automatically to compensate.
Simply adjust the amperage (wire feed speed) and the arc gap distance you want (wire stickout) and the machine will adjust the voltage automatically to compensate.
zmotorsports
ALLIANCE MEMBER
Think of the voltage setting as the potential needed to properly get the parent material and wire to the molten state where enough is needed to create a stable arc. Thicker metal will require more voltage obviously but will also determine the weld bead profile to some extent. More voltage will flatten the weld bead out vs. less will be more narrow and stand more proud. Metal thickness will require a certain amount of current for proper penetration and voltage is just one component in that formula, the other being wire speed. Wire speed is what determines the current that you are trying to achieve. I suggest start by using the charts equipped with your machine as a starting point for various thickness of materials and then adjust the wire speed to fine tune the current requirements.
I have found early on that what really helped me was to use some test pieces and try various voltage and wire speeds side by side by only changing one variable at a time. This made it easier when welding not only various thicknesses but also out of position welds as well.
I have found early on that what really helped me was to use some test pieces and try various voltage and wire speeds side by side by only changing one variable at a time. This made it easier when welding not only various thicknesses but also out of position welds as well.
zmotorsports
ALLIANCE MEMBER
dr_clyde stated it better than I did.
Others may correct me, but the explanation I received when learning to weld was that wire speed vs amps is arbitrary. There are no rules.
Don’t forget, there’s also more factors in play, weld speed and weld duration.
Depending on what is being welded, you want to set the amps to achieve good weld penetration, but not blow a hole in the material. You can set your machine to high amps on thin sheet metal as long as you keep the weld duration short, or if the material allows, move quickly.
The advice I was given for choosing wire speed was “less is better”. Always try and use the least amount of wire for the job. Too much wire can cause too much heat buildup, too large a HAZ and leave you with a lot of grinding. Unless it’s a situation I’m already familiar with, each weld project starts with a few test welds where I try out slower and slower wire speeds.
Welding is fun but every machine is different. Experiment, see what works and keep notes. I maintain a notebook of each new weld project and record the material, thickness, amps and wire speed to use a reference down the road.
My MIG welders are short duty cycle and each has a 5 position amp control (rheostat) with infinite speed control (potentiometer). This past weekend, welding 1/8” aluminum, **** joint, I set my MIG to the highest amps, and kept the wire speed low to create full penetration, flat welds. The project required about 80” of weld, but I kept the weld bead lengths to under an inch to avoid building up too much heat and stitched the project. The technique yielded very little warping and the welds were grounds flush.
Don’t forget, there’s also more factors in play, weld speed and weld duration.
Depending on what is being welded, you want to set the amps to achieve good weld penetration, but not blow a hole in the material. You can set your machine to high amps on thin sheet metal as long as you keep the weld duration short, or if the material allows, move quickly.
The advice I was given for choosing wire speed was “less is better”. Always try and use the least amount of wire for the job. Too much wire can cause too much heat buildup, too large a HAZ and leave you with a lot of grinding. Unless it’s a situation I’m already familiar with, each weld project starts with a few test welds where I try out slower and slower wire speeds.
Welding is fun but every machine is different. Experiment, see what works and keep notes. I maintain a notebook of each new weld project and record the material, thickness, amps and wire speed to use a reference down the road.
My MIG welders are short duty cycle and each has a 5 position amp control (rheostat) with infinite speed control (potentiometer). This past weekend, welding 1/8” aluminum, **** joint, I set my MIG to the highest amps, and kept the wire speed low to create full penetration, flat welds. The project required about 80” of weld, but I kept the weld bead lengths to under an inch to avoid building up too much heat and stitched the project. The technique yielded very little warping and the welds were grounds flush.
You're going to have a few different additional parameters to consider. One being wire diameter. Thinner metals require smaller wire, thicker metals, thicker wire. 0.030 or 0.035 is pretty common for most materials. 0.023 for thin sheet metals (18-20 gauge). 0.045 for really thick stuff. Some guys can do thin gauge metals with a thicker wire - I can't
You're going to have a range of both voltage and wire speed that's going to be capable of making a good weld. It'll depend on your style of welding. Some guys like to run hot and fast, other will run a bit lower voltage and take their time. You'll have to experiment to see what works best for you.
Generally, as you increase voltage for a given wire diameter, you'll increase the wire speed as well. For a given voltage, if you run too low of a wire speed, the wire (which is also your electrode) will burn back and could fuse to the tip, or you'll just end up with a very intermittent weld. So, you can either increase your wire speed or, you could reduce your voltage. However, reducing your voltage may mean you're not getting enough penetration for a decent weld. If your wire speed is too high, you may actually feel the wire hitting the base metal. So again, you can increase the voltage or you can decrease the wire speed. Increasing the voltage could result in burning through the base metal.
Between those two extremes, you'll fine tune it depending on the profile of the bead you're looking for. Too much wire speed with not enough voltage and the weld will sit very high with little penetration. Too much voltage and not enough wire speed, you can end up burning through the backside or end up with undercutting on the sies of your weld.
It's also all going to vary depending not only on the thickness of material that you're doing and the type of joint. A T joint is going to require more heat than a **** joint, for example
You're going to have a range of both voltage and wire speed that's going to be capable of making a good weld. It'll depend on your style of welding. Some guys like to run hot and fast, other will run a bit lower voltage and take their time. You'll have to experiment to see what works best for you.
Generally, as you increase voltage for a given wire diameter, you'll increase the wire speed as well. For a given voltage, if you run too low of a wire speed, the wire (which is also your electrode) will burn back and could fuse to the tip, or you'll just end up with a very intermittent weld. So, you can either increase your wire speed or, you could reduce your voltage. However, reducing your voltage may mean you're not getting enough penetration for a decent weld. If your wire speed is too high, you may actually feel the wire hitting the base metal. So again, you can increase the voltage or you can decrease the wire speed. Increasing the voltage could result in burning through the base metal.
Between those two extremes, you'll fine tune it depending on the profile of the bead you're looking for. Too much wire speed with not enough voltage and the weld will sit very high with little penetration. Too much voltage and not enough wire speed, you can end up burning through the backside or end up with undercutting on the sies of your weld.
It's also all going to vary depending not only on the thickness of material that you're doing and the type of joint. A T joint is going to require more heat than a **** joint, for example
Other bits of advice for a noob welder...
Don't grip the torch too tightly that you limit your wrist action. A lot of success in welding comes from reading the result during the weld and making torch position changes to accommodate. If you're gripping the torch handle like its an angry snake you're trying to kill, your wrist will be locked and you won't be able to make adjustments.
Before you start throwing sparks, (with the welder unplugged) tape a pencil to the torch end and practice drawing weave patterns. Wear your weld gloves and press the trigger while doing this.
Until you're a seasoned pro, use two hands. I've been welding as a hobby for over twenty years, and I still use my non torch arm as a steady rest.
Don't look at the arc. Look at the puddle right behind it to read how the weld is going.
Don't grip the torch too tightly that you limit your wrist action. A lot of success in welding comes from reading the result during the weld and making torch position changes to accommodate. If you're gripping the torch handle like its an angry snake you're trying to kill, your wrist will be locked and you won't be able to make adjustments.
Before you start throwing sparks, (with the welder unplugged) tape a pencil to the torch end and practice drawing weave patterns. Wear your weld gloves and press the trigger while doing this.
Until you're a seasoned pro, use two hands. I've been welding as a hobby for over twenty years, and I still use my non torch arm as a steady rest.
Don't look at the arc. Look at the puddle right behind it to read how the weld is going.
dr_clyde
Well-known member
VOLTS ARE NOT AMPS! These are not the same thing as the current on a stick welder. Turning up the voltage will not make the weld "hotter". It will increase the arc gap between the work and the end of the wire, and it will appear hotter to our human skin and eyes due to the increased arc flash, but there is not any more amperage being put into the work.
VOLTS ARE NOT HEAT!
You use wire diameter to control the size of the deposit, and you use wire feed speed to control the amount of amperage being put into the weld. All the voltage adjustment does is provide a sufficient amount of pressure to push the current across the wire and make the arc.
Stick welding and TIG welding are CONSTANT CURRENT, where you set an amperage value on the machine and the volts automatically adjust to maintain the amps for a given arc gap. Short circuit wire welding is CONSTANT VOLTAGE, where your volts are set on the machine and the wire is a second independent variable. TOGETHER, they make the weld. On a wire welder, you adjust both volts and current, but everyone gets confused because the amperage adjustment is labeled "wire feed speed".
When you need more heat, turn up the wire feed then bring the volts up to get the desirable arc. If you're making too much weld deposit for the speed you're running, use a smaller wire. Using too little wire feed speed will make cold welds or welds that don't penetrate properly. I've seen guys lay a bead on a piece of plate that you could chip off with a hammer, no penetration. "But it sounded like bacon frying!" So what, you didn't have the right amps and it just sat on the base metal.
Volts follow the wire.
VOLTS ARE NOT HEAT!
You use wire diameter to control the size of the deposit, and you use wire feed speed to control the amount of amperage being put into the weld. All the voltage adjustment does is provide a sufficient amount of pressure to push the current across the wire and make the arc.
Stick welding and TIG welding are CONSTANT CURRENT, where you set an amperage value on the machine and the volts automatically adjust to maintain the amps for a given arc gap. Short circuit wire welding is CONSTANT VOLTAGE, where your volts are set on the machine and the wire is a second independent variable. TOGETHER, they make the weld. On a wire welder, you adjust both volts and current, but everyone gets confused because the amperage adjustment is labeled "wire feed speed".
When you need more heat, turn up the wire feed then bring the volts up to get the desirable arc. If you're making too much weld deposit for the speed you're running, use a smaller wire. Using too little wire feed speed will make cold welds or welds that don't penetrate properly. I've seen guys lay a bead on a piece of plate that you could chip off with a hammer, no penetration. "But it sounded like bacon frying!" So what, you didn't have the right amps and it just sat on the base metal.
Volts follow the wire.
Opa
Well-known member
thanks dr. Clyde. I really appreciate your explanations. helps a lot.
BigLeagueSmoes
Well-known member
following
Pretty much what dr. clyde said.
Amps is the 'heat'. Just call it amps though.
And the amps is from the wire feed speed (wfs).
The volts is what pushes the amps through the wire and through the ionized shielding gas and makes the arc. The specific shielding gas used and the specific welding transfer mode being used (short circuit transfer mode, globular transfer mode, or spray transfer mode) and the specific wire diameter and specific wire alloy being used all affect the specific required voltage needed FOR THAT SPECIFIC WFS.
Wire diameter affects how much metal is deposited and what volts and amps are needed to get that wire and gas to properly make a weld. Bigger wire dia needs more amps and smaller wire dia needs less amps, so you don't try and weld 1" thick plate with 0.025" wire and you don't try and weld 22 gauge sheet with 1/16" wire.
Set the amps (wire feed speed or wfs) for the thickness of metal you are trying to weld together (general rule of thumb is 1 amp per 0.001" thickness). Then set the voltage that lets that wfs run smoothly. If the wire stubs into the workpiece and pushes the gun physically back means the volts is set way to low for that wfs and wire dia. If the arc is erratic and spits globs of metal around means that the volts is too high for that wfs and wire dia.
And +99 on watch the puddle of molten metal in the weld bead and NOT the bright arc itself.
With a wire feed welder, the wire will (almost always) melt. But to actually make a weld, you have to get the molten wire and at least some of the workpiece to melt together to form an actual weld bead and not just have melted-and-resolidified-wire-sitting-on-top-of-the-workpiece (aka cold-lap, aka lack of fusion, aka lack of penetration, aka crappy wire feed snot sitting on top of the workpiece and not an actual weld).
Check the Miller and Lincoln and ESAB websites for tons of info about welding.
www.lincolnelectric.com
esab.com
training.esabna.com
training.esabna.com
Ten minute online course on the basics of GMAW/FCAW (free course from ESAB University) https://training.esabna.com/mod/scorm/view.php?id=1865
Amps is the 'heat'. Just call it amps though.
And the amps is from the wire feed speed (wfs).
The volts is what pushes the amps through the wire and through the ionized shielding gas and makes the arc. The specific shielding gas used and the specific welding transfer mode being used (short circuit transfer mode, globular transfer mode, or spray transfer mode) and the specific wire diameter and specific wire alloy being used all affect the specific required voltage needed FOR THAT SPECIFIC WFS.
Wire diameter affects how much metal is deposited and what volts and amps are needed to get that wire and gas to properly make a weld. Bigger wire dia needs more amps and smaller wire dia needs less amps, so you don't try and weld 1" thick plate with 0.025" wire and you don't try and weld 22 gauge sheet with 1/16" wire.
Set the amps (wire feed speed or wfs) for the thickness of metal you are trying to weld together (general rule of thumb is 1 amp per 0.001" thickness). Then set the voltage that lets that wfs run smoothly. If the wire stubs into the workpiece and pushes the gun physically back means the volts is set way to low for that wfs and wire dia. If the arc is erratic and spits globs of metal around means that the volts is too high for that wfs and wire dia.
And +99 on watch the puddle of molten metal in the weld bead and NOT the bright arc itself.
With a wire feed welder, the wire will (almost always) melt. But to actually make a weld, you have to get the molten wire and at least some of the workpiece to melt together to form an actual weld bead and not just have melted-and-resolidified-wire-sitting-on-top-of-the-workpiece (aka cold-lap, aka lack of fusion, aka lack of penetration, aka crappy wire feed snot sitting on top of the workpiece and not an actual weld).
Check the Miller and Lincoln and ESAB websites for tons of info about welding.
Welding & Cutting Resource Center
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Ten minute online course on the basics of GMAW/FCAW (free course from ESAB University) https://training.esabna.com/mod/scorm/view.php?id=1865
welder4956
Well-known member
Short answer - voltage is directly related to the arc length. Increasing voltage increases the distance between the wire and the puddle, decreasing voltage results in a shorter arc. Amperage is directly related to wire feed speed. Increasing wire feed speed increases the amperage, decreasing wire feed speed decreases amperage. Finding the optimum voltage and wire feed speed for a particular metal thickness, shielding gas mixture and wire diameter is the difficult part. The settings chart usually found inside the door of the wire feeder is the best starting point, then modify as needed to get the bead appearance that is desired.
welder4956
Well-known member
Somewhat true, but voltage does contribute to heat input. Heat input per inch of weld is measured by (volts x amps x 60) divided by travel speed (inches of weld bead per minute). The result is given in Joules of heat per inch of weld bead length. This does not account for thermal efficiency of the arc or heat lost to the atmosphere, but is a good point of reference for comparing the effect of changes in voltage, amperage or travel speed.
dr_clyde
Well-known member
I mean, yeah, it has to contribute, you can't have one without the other.
What I mostly mean by this is to address the old timers who just yell "turn up the heat!" and expect you to turn up the volts. Back in the day this was on a stick machine that had just one knob, the amperage. Since it is hard to discern an amperage change with a wire welder if the voltage doesn't change along with the wire, most people associate just voltage with how "hot" the weld is. If you turn the voltage up WAY too high, the wire basically explodes all over the place and you're left with the impression of "that was too hot" instead of "that's too much voltage for this wire".
Overall heat input is a different thing entirely like you've described. Usually much more a function of travel speed if everything else is set correctly.
Most people associate "heat" with penetration and overall soundness of a weld. "Need more penetration? Just crank up the volts!" Nah dawg, you need to up your amperage, and you adjust the voltage to get the arc characteristics you're after. Lots of factors affect penetration, not just volts.
When I was a teenager I worked at a general repair and fabrication shop. We mostly fixed cars, but we did machining and welding too. The guy who was showing me how to MIG weld for the first time told me "it runs best if you starve it a bit for wire". What I think he meant was he liked enough voltage to get a clean separation and good short circuit instead of pushing too much wire for the puddle to handle. And yeah, that's a roundabout way of finding out where you want to be. He did a lot of auto body work, and if your volts are too low it doesn't play nice on thin sheet metal.
All that to say, amps and volts are directly and proportionately related. If you increase your wire feed to get more amps, you need more volts to sustain the arc. Set the wire where it needs to be, then fine tune the volts until you get the desired arc characteristics.
welder4956
Well-known member
Yes, I agree. Changes in voltage are a small number compared to amperage, so they don't result in as much change in heat as amperage. If you are running short circuiting mode at 16-17 volts and kick it up to 18 volts, that doesn't change the heat input as much as increasing the amperage by say 10-20 amps.
Walkers
Well-known member
It is not important to understand minutiae regarding why certain voltages or amperage are required for mig welding to work, it is only important to understand that they are required. Get the Miller welding calculator app on your phone and you can have the numbers at your fingertips when needed. Then you can cheat and look them up for the wire size and gas that you generally use, and for metal thicknesses that are common for you, and write them with sharpie on your machine.
Translating from voltage and wire speed to dials on your machine that are numbered 1-10 is a whole nuther trick. Ask when you are ready.
Translating from voltage and wire speed to dials on your machine that are numbered 1-10 is a whole nuther trick. Ask when you are ready.