MIG Welding Wire Speed and Voltage Calculator

That’s when most problems on the shop floor begin: Spatter all over your shoes full of iron shavings. You pick up the gun, pull the trigger and what do you have? It is a violent sputter where there should of been a smooth bead. Time to turn up the voltage knob; that’s what it seems like anyway. But more often than not, voltage isn’t the culprit.

Most likely, it’s the balance between heat used to melt the wire and the speed at which wire is fed. You provide the wire diameter and material thickness and the rest is done by the calculator. You no longer have to guess with coefficients for deposit rate and amperage. It converts physical parameters such as shielding gas mix and base metal thickness into concrete settings for voltage and wire feed speed range. Then it calculates the amps required based off the metal thickness, and converts those amp requirements to inches per minute for a particular wire size.

How to Fix Welding Problems

Why does this matter? Because amperage is the real power behind the arc, it’s what makes it go! Wire speed just delivers that power. The tricky part comes in selecting proper transfer mode. For thin sheet metal, short circuit transfer, known as low heat input. Are the default setting. That’s because the arc will re-establish itself quickly after the weld pool breaks. This keeps the weld pool relatively cool, preventing thin sheet metal parts from melting. Standard shielding gas mixes (such as a 25-percent CO2/75-percent argon) operate this way. Another plus is that it operates quietly and is less picky about dirty metals. One minus: it tends to be spattery if the voltage is too low for wire speed. When out-of-whack, you’ll know…you’ll actualy hear it, like a sharp crackle.

This one needs way more argon in the mix of gases as well as more ampers to keep the arc stable. With spray transfer, the wire doesn’t drop big chunks of melted metal onto the workpiece. Instead, it sprays it across the arc, so there is very little or even no spatter and a much smoother bead. It is great when depositing lots of metal and working on flat surfaces on larger pieces of steel. The caveat here is you can’t do this setting on thin metal without burning right through the piece. The heat applied from spray transfer are just too great for thinner gauges. You must also have argon rich gas to help keep the arc stable in the transfer process. If not you’ll get into the globular zone which is inefficient and messy.

Aluminum conducts heat away from the arc much faster than steel, which require some special considerations. It also develops an oxide layer which is more difficult to melt with a higher melting point than the underlying metal. A mix of argon and helium or pure argon work best to break down this layer. Aluminum will appear to have a really fast wire feed speed on the calculator, mostly because the wire is physically larger and less dense than steel wire of the same diameter. Don’t be concerned by these large numbers; they does not show huge heat input. Amperage stays relatively low for thin aluminum sheets, so energy transfer is actually moderate.

Another factor that quietly sabotages welds is the contact tip to work distance. How far the stick out is also a factor and one that goes into the wire’s resistance. The wire’s electrical resistance start heating it up as soon as it leaves the tip, before it even hits the arc. That early heating will affect the feeding consistency and may even cause the wire to buckle. While you don’t have to get exactly the right number here, it’s more critical to maintain consistency with every weld. So if you vary the stickout just an 1/2-inch, you should adjust your voltage accordingly to account for resistance differences.

All of this is linked to your travel speed. The calculator estimates a reasonable travel speed based on the bead size you are targeting. Too fast, and you’ll end up with a narrow, ropey bead that wasn’t fused well at the toes. Too slow, and you risk either burning through the dough or adding so much reinforcement that you end up with something resembling a worm on top. You just need to find a beat at which the molten puddle flows smoothly in front of the arc. As long as you can watch the puddle close back over the arc as you continue forward, you’re good to go.

There’s no substitute for testing on scrap metal. There are too many variables, like the room temperature, a draft in the shop, or just how dirty my piece of work is. Nothing takes the place of experience, no matter how accurate calculations. Dial it in by cranking up the wire speed a bit if the arc is rough, and back off the voltage if the bead isn’t right. It’s a balancing act. When you get it dialed in, you’ll hear that smooth arc and know things are right. Your shoes will be clean, the bead will lay down evenly and there will be no more spatter.