MIG Welding and Common Mistakes Made

by Steve Darnell
MIG Welding

MIG welding is an essential skill for all welders. But what is it exactly, and what can go wrong when giving it a try?

To help you navigate the ins and outs of MIG welding, we’ve laid out the basics as well as eight common mistakes beginners make so you can avoid them and keep your projects on track!

MIG Welding Basics

MIG welding is one of the most popular welding methods used today. You’ll find this technique used on construction sites, at fabrication and auto shops, and in-home garages, among many other job sites. This method of welding is very versatile and an important skill every welder needs to learn.

MIG welding is more formally referred to as Gas Metal Arc Welding. But most welders stick to calling it MIG welding. MIG stands for “metal inert gas.” During this welding process, a wire is continuously fed through a welding gun to protect the weld pool from potential contamination. MIG welding can be done on various metals ranging anywhere from 24 gauge to ½ inch thick.

MIG Welding Equipment

You can’t MIG weld without the proper equipment. The three main components are the MIG welding machine itself, the wire you use, and the shielding gas. The thickness and type of the metal being welded will impact the type of wire you use. The same can be said for the type of shielding gas used to MIG weld (more on that below).

To MIG weld correctly, you’ll need to gather the following equipment:

  • MIG welding machine
  • Shielding gas tank and flow meter
  • MIG welding wire
  • Wire brush or grinder to clean and prepare materials
  • Good ventilation and airflow
  • Welding consumables to replace as needed
  • Welding tips
  • MIG gun liner

Shielding Gas for MIG Welding

Shielding gas is absolutely necessary for MIG welding. The shielding gas helps protect the weld from the hydrogen, oxygen, and nitrogen present in the atmosphere. These gases can contaminate the weld bead and impact the quality and strength of the weld.

Choosing the right shielding gas all comes down to the type of metal you are welding. Different metals require different types and ratios of shielding gas. Depending on the thickness of the metals being welded, these ratios may need to be adjusted. Certain gases will burn hotter than others which can have an impact on the quality of the weld.

Generally speaking, though, these are some common shielding gas ratios to stick to. Aluminum requires you to use 100% argon gas. If you’re welding steel, though, you’ll need to use a mixture of 75% argon gas, 25% carbon dioxide. For non-ferrous metals (meaning those without iron) or stainless steel, use a mix of 25% helium, 75% argon.

Safety Tips

You can’t MIG weld properly without the right safety equipment. Before you begin any welding operation, MIG or otherwise, make sure you are wearing the proper personal protection equipment (PPE). Failing to do so could result in painful and possibly permanent injuries as a result.

At the very least, you need the following:

  • An auto-darkening welding helmet
  • A welding jacket or thick long sleeve shirt
  • Welding gloves
  • Denim jeans or quality work pants
  • Steel-toed work boots (tied up properly)

Also, make sure that you are working in an area that has good ventilation. If you’re indoors especially, make sure to use fans, windows, and doors to help create proper airflow and remove harmful gases from the workspace.

8 Common Mistakes Beginners Make

MIG welding is a skill that every welder needs to have. This method of welding is very versatile and useful for a variety of welding projects. MIG welding is often one of the first skills that new welders learn. During that training period, you’re likely going to make some mistakes along the way. It happens to everyone, and it’s part of the learning process. 

To help make sure you make fewer of those mistakes, check out the tips below. 

Failing to Prep Your Materials

While MIG welding can penetrate past mill scale, oil, and other contaminants, you still need to clean and prepare your materials. This is a common mistake new welders make. They cut their materials and then head straight to the MIG welding machine. Failing to clean your materials only leads to poor penetration and weaker welds overall. It only takes a minute or two to prepare your material, so take the time to do the job right the first time.

There are several different ways to clean your materials before MIG welding. The easiest and fastest way is to use an angle grinder with a disk or wire wheel. Of course, you can always use a wire hand brush if the angle grinder isn’t accessible. 

By taking the time to prepare the materials beforehand, you’ll avoid hassles down the road. This will lead to longer-lasting welds and help you avoid having to make future repairs.

Gas Flow Issues

You’re just going to run into issue after issue if you don’t have the correct rate of gas flow. For most welding projects, the flow rate should be between 15-30 cubic feet per hour (CFH). If your gas flow is too high and above 30 CFH, you’ll end up using more gas than you need to and increase operations costs. 

On the flip side, you can’t have the gas flow too low either. This will lead to porous welds, which will crack or break over time. If you notice any tiny holes in your weld, you likely need to turn the gas flow rate up a touch.

On most machines, you’ll find a chart that recommends what the gas flow rate should be based on the method of welding you’re completing. 

Inconsistent Travel Speed

A lot of beginners just learning how to MIG weld often struggle with travel speed. This is the speed at which the welding gun travels across the weld. To achieve a consistent bead from start to finish, your travel speed needs to stay consistent. Travel speed directly relates to the width of the bead. The faster the travel speed, the thinner the bead. The slower the travel speed, the wider the bead.

If you want to create strong and better-looking welds, make sure to practice your travel speed. A great exercise for beginners just starting out is to prep a scrap piece and practice laying down consistent beads of different widths. Once you get comfortable with this, you’ll be able to make better welds when it really counts.

Poor Wire Tension

Your preparation before starting a weld doesn’t just mean cleaning your materials. You also need to make sure the machine is set up properly. Part of learning to MIG weld includes changing wire spools inside the machine.

Every MIG welding machine has a control setting to adjust the wire tension. This controls how much pressure is placed on the wire inside of the machine. If the tension is too high, the wire could end up breaking or jamming in the nozzle of the welding gun. If the tension is too low, however, the entire spool could unravel. Neither situation is ideal.

To get this right, you need to spend time practicing and understand your machine. This setting will be different for every machine, so make sure to check out the owner’s manual when you’re first starting out.

Incorrect Wire Speed or Voltage Settings

Your wire speed and voltage settings need to work together if you want to make great welds. Voltage is the amount of power that is running to the arc. Wire-speed is exactly what it sounds like – how fast the wire is fed through the machine to the torch.

These two settings need to work together. If your wire speed is too fast and the voltage is too low, there won’t be nearly enough power to melt the wire needed to complete the weld. On the contrary, having these settings reversed can cause the weld to get too hot and create defects.

Your MIG welding machine should include a chart to help you dial in these settings. In most cases, your voltage should be set around 16-30 volts. The wire speed should be anywhere from 100-500 inches per minute.

Improper Contact Tip to Workpiece Distance

One of the most important parts of MIG welding is the contact tip to workpiece distance. This is something a lot of beginners struggle to get right. Essentially, it’s how far away the contact tip is from the metal being welded. If the distance between these is too far or too close, you’ll end up with weaker welds full of defects.

When the distance between the tip and workpiece is too much, there won’t be enough shielding gas reaching the arc. This is how you create weaker welds that will eventually need to be repaired. If the contact tip is held too close to the workpiece, you will create some other issues. The main one being that the tip of the nozzle will get clogged up and jam the wire. Holding the contact tip too close also makes it difficult to see the weld puddle and maintain a consistent bead width.

Generally speaking, you want to hold the contact tip about ¾ of an inch above the workpiece. This will ensure the shielding gas can do its job and create an atmosphere to protect the weld puddle.

Incorrect Nozzle Angle Positions

It’s not just the distance between the contact tip and workpiece that impacts the quality and appearance of a weld, the nozzle angle does too. Welders will often push or pull the weld puddle when MIG welding. In order to do this properly, you need to hold the nozzle of the torch at the correct angle. Most beginners often have it too shallow or too steep.

If the nozzle is too shallow (as is often the case for most beginners), the penetration of the weld is severely limited. This results in a weaker weld. If you make the angle of the nozzle too steep, though, you’ll end up creating holes through thinner workpieces.

To get this right, it takes some practice. When practicing with scrap pieces, experiment with different angles until you get a feel for what’s right. The majority of the time, this angle should be about 5-15 degrees. Anything beyond 25 degrees will result in plenty of splatter and poor penetration. 

Difficulties with Bead Patterns

When you’re first starting out MIG welding, you’ll likely stick to creating straight beads by pushing or pulling the torch. What you’ll quickly learn after working alongside experienced welders is that different bead patterns are needed for different types of welds. For instance, a vertical weld should be completed by using a side-to-side weaving pattern instead of dead straight.

A lot of new welders have trouble with bead patterns when just starting out. By taking the time to learn these patterns, you’ll be able to create flatter and better-looking welds. To get started, use the cursive “e” pattern. This involves using the torch to write a series of lowercase “e’s” in cursive. You can also practice circle or triangle patterns as well.

To truly get this technique right, you need to practice. As is the case with most of the mistakes mentioned already, practice can solve most of these issues. If you really want to learn how to MIG weld properly, spend time working with scrap pieces to master your beads and create stronger, long-lasting welds.

Make Fewer MIG Welding Mistakes

MIG welding is something that anyone can learn how to do. In fact, a lot of people will tell you it’s easier to do than working a glue gun. While that may not be one hundred percent true, it is a useful skill to have.

By enrolling in the Welder 101 course, you can learn how to MIG weld properly. This comprehensive course gives you lifetime access to a growing library of training videos and resources. With over 30 years of professional welding experience distilled into one program, you’ll learn how to complete different welding operations properly. Better yet, you’ll make fewer mistakes when starting out and have a place to turn to anytime you have a question.

Enrollment includes access to our private Facebook group and discounts on WelderUp merchandise and on equipment from some of the most reliable manufacturers around. 

Get started today and improve your welding skills faster!

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