Common Welding Mistakes

Presented by Gun Welding

Welding is a process that is beginner friendly and newcomers can have success with it very early on. Although the welding part seems straightforward, there is actually a lot going on inside the machine.

These tips will cover the MIG welding mistakes seen often at Gun Welding as well as the best ways to fix and prevent them in the future. We have all made these errors in the past but we persevered and learned how to correct them.

1 – Incorrect Contact Tip to Workpiece Distance

Often new welders will hold the MIG welder contact tip either too close or too far away from their welding piece. Just like all welding processes, the proper distance between your electrode and your workpiece can make or break a weld.

The thickness of the material you are welding is the same distance you should keep your contact tip from the job. This will ensure that the shielding gas can create a proper atmosphere to protect your weld puddle.

Contact tip diagram. Source: https://www.millerwelds.com/resources/article-library/how-to-choose-mig-welding-consumables

2 – Incorrect Liner Length

Cutting the torch liner to the wrong length is a common issue in MIG welding. In most cases, it’s a matter of the liner being cut too short.

When the liner is the wrong length it causes a poor wire feed, an erratic arc or wire chatter. For conventional liners:

1. Take out the tip holder
2. Feed the liner in the gun
3. Keep the torch straight
4. Install the liner nut
5. Snip the excess off the front of the torch
6. Remove the liner nut
7. Install the tip holder
8. Reinstall the liner nut.

Liner types example. Source: https://dynaweld.com.au/how-to-change-mig-welder-liner

3 – A Bad Earth

Not getting the expected life of the contact tip and other front-end consumables can be a result of bad ground when MIG welding.

Without good ground the arc can become erratic and ultimately cause more heat build up in the front of the gun. Any problem that creates more heat will also create more resistance and more wear on your parts — damaging the contact tip, other front end consumables and impacting weld quality.

To prevent these issues place the ground cable as close to the workpiece as possible. Grind off any paint to bare metal, ensuring your earth clamp is close. Magnetic ones are available to order through the Gun Welding website.

Earth clamp by Gun Welding. Source: Supplied.

4 – Selecting the Wrong Torch

A key step to prevent a MIG Torch from overheating is to choose the right Torch for the application. All Top Gun Welders come with the correct torch for the machine capabilities so you have nothing to worry about there.

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

A change in gas can also help reduce the heat produced when welding. If you’re using an argon based shielding gas, the higher the percentage of argon, the less cooling the shielding gas provides

5 – Incorrect Maintenance

It is important to properly maintain the MIG Welder, Torch and consumables including the contact tip, nozzle and liner.

Whenever you check and change the consumables check that the gas holes in the nozzle are clean and that the tip holder that holds the contact tip isn’t filled with spatter. Blow out your liner with compressed air. A worn contact tip or nozzle can cause overheating in the torch and handle.

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

Welding connections. Source: https://weldingpros.net/mig-welder-maintenance

6 – Incorrect Wire Speed & Voltage Settings

These are the two main settings that must work in harmony with each other. Beginners struggle with dialling these in perfectly but it isn’t too hard. The voltage is the amount of electrical power that is running to your welding arc. Depending on wire diameter and wire type (flux, sold wire etc) voltages generally range from 16-30 volts.

The wire speed is measured in inches per minute or AMPS. The higher the wire speed, the more wire material is flowing out of the nozzle. Higher wire speeds produce larger beads. Lower speeds are great for thin material and smaller welds. 

The only reason these two settings must work together is because they are heavily related. If you have a high wire speed and low voltage, there won’t be enough power to melt the amount of wire you’re putting into the weld.

If you have a low wire speed and high voltage your weld may get too hot and cause undercut or other weld defects. 

A Synergic MIG will automatically set up your wire speed and volts. Our Top Gun 210L is a fully synergic machine where you only select the material thickness and the type, the machine does the rest. – Check it out by clicking here.

The Top Gun 210L machine. Source: Supplied.

7 – Gas Flow Problems

Beginner welders can struggle to find the correct gas flow for their jobs. For MIG welding, common flows rates are between 12-15LPM (Litres Per Minute).

If you go outside of these parameters your weld may not be as strong. Make sure that you know your parameters so you can avoid a bad weld.

For most hardwire MIG welders we tend to have our gas set at 15 LPM. We find that this shields very well for most applications. If you bump up to 20 LPM or more, you will be going through a lot of gas which can be expensive. 

Porosity is a weld defect that is very undesirable. With MIG welding porosity is usually caused by low gas flows. If you find porosity (small holes) in your weld the best thing to do is to turn up your gas a little. If this does not work it could be an issue of contact distance (listed above), the angle of your torch or having bad consumables.

Example of porosity. Source: Supplied.