Why Is My MIG Welder Popping? (and How to Stop It)

When people start to learn to weld, especially MIG, one of the first problems they encounter is popping sounds while welding. The result of that popping isn’t good; it results in a very bad quality weld with a high failure rate. In this article we discuss why your MIG welder is popping and how to stop it.

A strong MIG weld should have a nice looking, slighty crowned and consistent weld bead. If your MIG is popping while welding will cause messy, inconsistent and failure-prone welds that are obvious at first glance.

Now let’s dive into how to identify and fix your MIG welder popping problem.

Why Is My MIG Welder Popping?

Why Is My Mig Welder Popping

Here are the reasons why your MIG welder might be popping:

Wrong Wire Speed

The most common reason MIG welders suffer from the popping is the wrong wire speed. It’s likely that your MIG gun is feeding the wire too fast or too slow. To test it out, touch the wire to a piece of clean scrap metal, hold the trigger as you move the gun, and listen closely to the sound.

If the wire speed is too fast you will get random popping with no consistent rhythm. The wire is moving too fast to melt into the weld pool and sections are breaking or melting off. This will lead to welds with unmelted wire embedded in them — not good.

If the wire speed is too slow you will hear consistent, rhythmic popping sounds. This occurs because the wire is melting back up toward the tip of the gun, then spatters and loses electrical contact. Then as the wire feeds, it regains contact again. This process of melting too fast, losing contact and starting up the arc again causes a repeating pop each time it happens. This leads to poor weld quality with insufficient material in the weld pool, inconsistent bead shape and spatter around the weld.

Material Thickness

The second most common problem that causes popping in MIG welding is the thickness of the pieces you’re welding together. As your metal thickness goes up, you need to slow down your weld speed, assuming the same wire speed and voltage.

You can move at a much higher rate welding thin 1/8″ sheet than 1/4″ plate, assuming you haven’t changed any other settings. It’s harder to penetrate thick metal, so you’re forced to slow down. This can often result in your MIG welder popping as the wire starts to melt back up to the contact tip and interfere with a clean arc.

Wrong Wire Size

The diameter of wire you’re using matters a lot and can contribute to your MIG welder popping. Assuming the same settings on your machine, a thin electrode wire like 0.23 can transfer metal to the weld pool faster than a regular 0.35 wire. You can easily move at 300 IPM (inches per minute) with thin wire but probably need to slow down to 150-200 IPM with thicker wire.

The problem is that the smaller wire doesn’t transfer enough heat or material into the weld pool on thicker metals, causing poor penetration. If you turn up the voltage and slow your weld speed down to get better penetration the thin wire will melt too fast and start popping.

A similar popping problem might occur if your wire is too thick for the base material. If you’re trying to weld 1/8″ steel with a 0.45 diameter wire, you may have trouble getting enough heat into the weld pool for the arc to fully melt the wire without blowing through the material. This will cause popping as pieces of cold wire embed themselves into the weld bead.

The ideal wire diameter may vary from one manufacturer to another. Be sure to match the recommended wire size to the metal thickness based on your manufacturer’s recommendation.

Wrong Amperage / Voltage Setting

Amps melt the wire, heat the work piece and join them together. An incorrect amperage or voltage setting will cause a lot of problems with your MIG welding.

If the setting is too low you will end up with a “cold weld” situation, with the arc failing to fully melt the wire into the weld pool. This will cause your MIG to pop and embed broken pieces of wire into the weld.

If the amps or volts setting is too high you end up with the opposite problem. The arc will be too hot and burn the wire back up into the gun tip, causing an inconsistent weld, popping and spattering.

Out of Shielding Gas

If you’re MIG welding with gas (GMAW) and start to run, the gas shielding around the arc will fail and you’ll start to get popping and oxidation in the weld. At first this won’t be immediately apparent, but the gas flow drops the problem will get worse. It’s critical to stop and replenish your gas supply, rather than continue on welding when this happens.

Worn or Mis-Adjusted Wire Feed Mechanism

On most MIG welders the wire is fed through the gun by two small wheels right in front of the wire spool. Over time, these wheels can wear out and lose their grip on the wire, causing wire slippage. This results in inconsistent wire speed. Your wire will alternate from going to slowly to too fast, even when you’re moving the gun at a consistent speed. The results of slipping wire feed are lots of popping and poor quality welds.

You may also have a mis-adjustment of the tensioning mechanism. Normally there is a small screw adjuster on one of the wheels that presses it against the wire to create grip and tension. If this adjustment screw is too loose, the wire will slip, causing popping when you weld. If the adjustment is too tight, it can deform the wire, causing it to feed too slowly and hang up in the wire feed tube running to the gun. The result will be a popping MIG and bad quality welds.

MIG Wire Tangled

It’s very common for MIG wire to snag or kink slightly in the feeding mechanism and cause a backup. If you don’t catch it quick enough, a minor backup can turn into a major rat’s nest between the feeder and gun tube. These snags are hard to get to, and require you to cut the wire and re-feed it through the gun again.

When the MIG wire snags, it will initially cause fits and starts in the wire speed, which will cause your MIG to start popping. Eventually the wire will stop altogether when you pull the trigger, and you’ll know it’s time to take your MIG apart.

Wrong Type of Wire

This doesn’t happen often, but if you change work pieces and unintentionally use the wrong wire for the metal, all kinds of popping, smoking and spattering is likely to ensue.

Occasionally you’ll hear of a welder switching flux core for plain metal wire, thinking he’s still welding with solid metal wire. The combination of MIG shielding gas with flux core electrode wire will produce a tremendous amount of gas, popping and smoke.

If you use aluminum wire with steel it will pop and break up. Steel wire will do similar unexpected noisy things.

How to Stop a MIG Welder From Popping?

Popping in MIG welding is a common problem that weakens the quality of the weld’s final output. Here are the best steps to take to stop your MIG welder from popping:

Start With the Manufacturer Recommended Settings

You should always start off with your welder’s recommended amperage / voltage settings, wire type, diameter and wire speed matched to the metal type and thickness you’re welding.

Then run a few test beads on some scrap metal of the same type to fine tune the settings.

If you make any changes, such as replenishing your wire spool or gas supply, you should always do some short test welds on scrap pieces. Doing this basic recalibration will save you a lot of grinding bad welds off later.

Use the Right Amperage or Voltage

This goes back to following the manufacturer’s suggested settings as a starting point. The table inside your MIG welder’s access door will get you in the ballpark. The right amperage / voltage settings for the metal type and thickness will help avoid an overly hot or cold arc, and associated popping and splatter problems.

To figure how much amperage you need, multiply the thickness of the metal by 1000. For example, if you’re welding a mild steel 1/4″ sheet, this formula will give you 250 amps as the ideal setting.

Again, once you’ve got a starting point, you should always do a couple test runs on some extra material to fine tune things.

Use the Correct Wire and Wire Speed

Most manufacturers include a wire size vs. metal thickness chart inside the access door of the machine and in the user manual. After setting your MIG up with the right spool of wire, feed the wire through the tube and set the feed tension so it grabs, but isn’t too tight.

Then start your gas and run a weld some extra base metal, listening to the sound as you go. Adjust the wire speed higher or lower until you hear a constant buzz or sizzle without any popping.

Hold the Gun Tip the Correct Distance From Your Work

Most MIG welders operate best with the tip around 1/2″ to 1″ from the joint you’re welding. If the tip is held too far away, the gas shielding will expand too much before it reaches the arc, resulting in popping and oxidation of the weld bead. If the tip is held too close to the weld pool, the wire will melt back up into the gun tip, popping, splattering and potentially welding itself to the tip.

Check the Contact Tip, Gun Feed Liner and Wire

If you’re still having problems getting a consistent and smooth wire feed and your MIG welder is still popping and splattering, then you need to check these areas:

  • Check the welding gun contact tip to make sure it’s in good shape. The wire should feed out smoothly. The tip should be straight and smooth and not have any globs of metal or burrs around the wire hole. Replace the tip if it’s burned back, plugged with splatter or has a lot of burnt crust. Clean it if possible with a wire brush or small file, or change it. Tips are cheap and you’ll be surprised how much it affects the wire feed quality.
  • Next, examine the wire feed liner. Look to see if it’s been bent or kinked anywhere. Unscrew the gun tip and examine the inner lining. Take a look at the area where the wire feeds into it — this is usually where tangles happen which can lead to damage. Check if it’s the right diameter for the wire. Pull and push wire through the gun tube to see if it hangs up. If so, change it.
  • Finally, check the wire itself for dirt, rust or other imperfections. Wire can often get crossed when rolling off a spool that hasn’t been tensioned properly, leading to inconsistent wire feeding. If there’s any gunk or rust on the wire it will clog the tube and will decrease the weld quality. If you see any issues, cut out the offending wire or replace the spool
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