7 MIG Welding Mistakes and How to Avoid Them

MIG welding offers numerous benefits for productivity without sacrificing quality of the finished weld, but there are many factors that can interfere with successful MIG welding performance.

You can improve performance and results in your MIG welding applications — and save money through reduced consumable waste — by taking steps to avoid common mistakes related to the MIG gun and consumables.

Consider these common causes of poor performance in MIG welding and learn how to prevent them, for a positive impact on productivity and the bottom line.  

Welding operator welding rotating tube while standing
Avoiding common mistakes helps you get the best results in MIG welding. It’s also important to properly maintain the MIG gun and consumables, including the contact tip and liner. 

No. 1: Improper liner length
Cutting the liner the wrong length is a common issue in MIG welding. In many cases, it’s a matter of the liner being cut too short.

When the liner is the wrong length, it can become deformed by the force of the drive rolls pushing the wire forward. This can cause an oscillation in arc length. Like a big spring, when the liner deforms, it takes up whatever free space there is in the conduit inside the gun. This can result in “chatter” or vibration in the MIG gun. Ensuring the liner is the proper length can help prevent this problem. Use a liner gauge as a guide. 

When installing a gun liner, make sure the gun is as straight as possible and that there is little to no twist in the cable.

Laying the welding cable as flat and straight as possible during welding will ensure the smoothest feeding. Twisting or coiling the cable can change the effective length of the liner and can cause the cable to take on a permanent set.

No. 2: Overheated consumables
When a MIG gun’s consumables become overheated, they can be the source of many problems. These consumables include the liner, contact tip and nozzle.  

To prevent consumables from overheating, use the proper wire stickout, mind the gun’s duty cycle and employ the right contact-tip-to-work distance. Any steps that keep consumables cooler will help limit the amount of vibration in the gun and reduce issues with burnback.

While a wire stickout that is too long is not desirable, keep in mind that too short of a stickout can result in the nozzle and contact tip being too close to the weld pool causing them to overheat. This impacts productivity by causing burnbacks and wire sticks, and can significantly shorten consumable life.

No. 3: A bad ground
Shortened life of the contact tip and other front-end consumables can also result if a solid ground isn’t in place when MIG welding.

Without a solid ground, the arc can become erratic and ultimately cause more heat buildup in the front of the gun. Any problem that creates more heat will also create more resistance and more wear — damaging the contact tip and other front-end consumables and possibly impacting weld quality.

To prevent these problems, place the ground cable as close to the workpiece as possible. If allowable, hook the ground cable on the weldment. If that is not feasible, hook it to a bench. But remember: The closer it is to the arc, the better.

Three Bernard BTB Semi-Automatic MIG Guns being held in a row by gloved hands
A key step to prevent a MIG gun from overheating is to choose the right gun for the application. Be mindful of the requirements of the job and select a gun with enough duty cycle and amperage capacity.

No. 4: Improper voltage or wire feed speed
An erratic arc can also be caused by setting the wrong voltage or the wrong wire feed speed.

Setting the voltage too high can create too much heat in the handle of the gun, which in turn can eventually wreak havoc on the contact tip.

When the wire feed speed is too fast, it can cause the wire to pile up instead of melting properly into the weld pool. This can also cause burnback or birdnesting. A wire feed speed that is too slow doesn’t feed the weld pool, so there is not proper penetration for a quality weld.

Always follow the manufacturer’s recommendations for the proper voltage and wire feed speed for the filler metal and thickness of the base material being welded.

No. 5: Poor cable management
Poor power cable management can lead to performance problems and cable damage.

To help prevent damage or other issues, don’t pull the welding machine around using the cable. When the gun is hot, everything is more pliable. Yanking or pulling on the cable can stretch the cable or the liner and even cause the conduit to pull away from the gas pin, which can result in shielding gas issues.

It’s also important to let the gun cool in a flat position, rather than draping or hanging the cable over a piece of plate or some other object. When a hot gun is draped or hung over something, it can bend the conduit. When the gun and consumables cool, they can be misshapen, leading to marginal shielding gas coverage.

Take care to lay the gun out properly to let it cool. Also, be sure to store the gun and cable properly when they aren’t being used to avoid damage that can occur if a cable is run over by a forklift or other heavy equipment.

No. 6: Selecting the wrong gun
A key step to prevent a MIG gun from overheating is to choose the right gun for the application. Be mindful of the requirements of the job and select a gun with enough duty cycle and amperage capacity.

If the application requires you to weld at 300 amps all day and you choose a 200-amp gun with a 30 or 40 percent duty cycle, this gun will not be up to the task. Exceeding the gun’s duty cycle leads to overheating — and doing this frequently will shorten the life of the gun.

In addition to choosing a MIG gun that has a high enough amperage rating and duty cycle rating for the job, you can also take breaks to let the gun and consumables cool to help avoid gun overheating.

A change in shielding gas can also help reduce the heat produced during welding. If you’re using an argon shielding gas, the higher the percentage of argon, the less cooling the shielding gas provides. However, keep in mind that many applications use argon shielding gas because it provides a cleaner process with much less spatter for reduced cleanup. So while reducing the argon can help the process run cooler, there are other tradeoffs that can impact productivity. 

Using the wrong type of drive roll or setting improper drive roll tension can be common causes of erratic or poor wire feeding in MIG welding. Consider the size and type of wire being used and match it to the correct drive roll. 

No. 7: Drive roll issues
Using the wrong type of drive roll or setting improper drive roll tension can also be common causes of erratic or poor wire feeding in MIG welding. Consider the size and type of wire being used and match it to the correct drive roll. 

Because flux-cored wire is softer — due to the tubular design and flux inside — it requires using a knurled drive roll that has teeth that can grab the wire and help push it through. Knurled drive rolls typically should not be used with solid wire, since the teeth can cause shavings to break off of the wire, clogging the liner and creating resistance in wire feeding. Instead, use U-groove or V-groove drive rolls with solid wire.

Setting proper drive roll tension is another important step. Without proper tension, erratic feeding can cause burnback or other issues. To set the proper drive roll tension, start by releasing the drive rolls. Then increase the tension while feeding the wire into your gloved hand until the tension is one half-turn past wire slippage. Always keep the gun as straight as possible to avoid kinking in the cable that could lead to poor wire feeding.

Proper maintenance is also key
Avoiding common mistakes helps you get the best results in MIG welding. It is just as important to properly maintain the MIG gun and consumables, including the contact tip, nozzle and liner.

Whenever you change consumables, check that the gas holes in the nozzle are clean and that the seat that holds the contact tip isn’t filled with spatter or debris. A clogged contact tip or nozzle can cause overheating in the gun and handle.

Also check frequently that all connections are tight and as concentric as possible. Keeping the gun and cable as straight as possible during welding — and laying them flat to cool — makes for an effective and efficient MIG gun.

Follow these tips to minimize downtime, improve productivity and quality, and save money in your MIG welding operation.