How to MIG Weld Like an Expert

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Frank Wilson

Frank Wilson

Senior Editor

MIG welding is popular with beginner welders because it is relatively easy to learn compared to other techniques. A solid wire electrode travels through a welding gun, reaching the welding pool to join the base metals. To reduce the risk of contaminating the weld pool, a protective shielding gas also moves through the welding gun.

This straightforward process makes MIG welding an appealing option for many DIY and home repair enthusiasts and is suitable for many industrial applications. Although aspiring welders can become competent using a MIG welder in a short period, it’s necessary to follow the proper procedures to achieve the best results.

Last Updated on March 17, 2021

Learn the Safety Guidelines

Safety is the priority when using a MIG welder. Read the manufacturer’s handbook, consider taking some online courses, and purchase the correct safety clothing. You can choose between helmets with a fixed-shade lens or an auto-darkening lens helmet for head and eye protection, and always wear flame-retardant clothing. 

Clear your welding workspace of papers and knickknacks, and ensure you have a fire extinguisher and sand bucket in the vicinity. It can be a good idea to put signs up to alert others you are welding, and they should not enter the room.

Prepare Your Metals

Solid MIG wire finds it challenging to weld metals that contain contaminants such as dirt or rust. You can use a stiff brush to clean the area. If the surface is in inferior condition, a grinder can remove more stubborn contaminants. Attach the work clamp to clean metal to prevent any electrical interference that could impair wire feeding performance.

Prepare Your Equipment

When learning how to MIG weld like an expert, it’s essential to prepare your equipment correctly. Ensure your cables aren’t frayed and turn the shielding gas flow rate to between 20 ft³-25ft³ per hour. Use the manufacturer’s handbook to adjust the tension on the drive rolls and wire spool hub to ensure the wire feeds smoothly through the welding gun. 

Select Your Wire and Gas Types

Refer to the American Welding Society (AWS) classification system for guidelines on the most suitable wire for your requirements. A wire thickness of 0.023” is ideal when welding thin metals, while a 0.035” thick wire is a solid choice when welding heavier materials at higher heat levels.

An excellent all-purpose shielding gas has a 75% argon/25% carbon dioxide mix. While a 100% carbon dioxide gas offers deeper metal penetration, it also results in higher levels of spatter that affect your weld’s neatness.

Set Your Volt and Amp Levels

Choosing how much voltage and amperage to use depends on many factors. The metal thickness, metal type, welding position, shielding gas blend, and other factors all enter into consideration. 

It’s essential to consult the MIG welder manufacturer’s handbook to find the approximate settings you should use at the start. As you become more experienced, you can fine-tune the voltage and amperage to suit your personal preferences.

Choose a MIG Welding Technique

Some MIG welders prefer to push their gun ahead of the welding puddle, which results in a flatter bead. However, this technique is best suited for low penetration welding and does not work well with thicker metals.

Pointing the welding gun back at the welding puddle and dragging it away from the deposited metal results in deeper penetration but produces a narrower bead with increased metal deposits. 

Both welding techniques are useful, and you can experiment with both methods to find which one you prefer.

Choose a MIG Welding Position

Flat MIG Welding Position 

When MIG welding metals in a flat position, you are working on the joint’s top side. A flat position butt-weld involves holding the welding gun at 90° to the base metals and depositing the filler metal straight into the joint. Try to maintain a travel angle of between 5°-15° when butt-welding. The travel angle is the angle relative to the gun in a perpendicular position. 

When MIG welding a flat position 90° joint, maintain a steady 45° gun angle. For a lap joint, when two pieces of metal are on top of each other, hold the gun at a slant of between 60°-70°.

Horizontal MIG Welding Position 

Horizontal MIG welding is an out-of-position technique that requires more skill than flat welding. When you place the joint’s filler metal, it is still molten, and gravity could make it drip. 

When horizontal welding, you need to move slowly and make multiple passes to deposit small filler metal amounts each time. Aim to hold the welding gun position between 0°-15°, relative to the angle of the welding joint, and hold the travel angle between 5°-15°. It’s essential to be patient when performing a horizontal weld.

Vertical MIG Welding Position

The vertical down welding technique involves starting at the top of a joint and moving towards the bottom. The arc does not penetrate deeply because of the rapid travel speed, making this an excellent technique when welding thin metals. If you worry about burning through the metals, point the wire away from the weld puddle. 

When working with thicker metals, a vertical up welding technique produces a deeper penetration. Reduce the gun travel angle by around 5°-15° from the perpendicular position. 

Overhead MIG Welding Position

Because you are working with the joint’s underside, your filler metal can drip when MIG welding in an overhead position, so it’s vital to keep a relatively high travel speed. You can push or pull the welding gun, and it can be useful to reduce the voltage and amperage settings to produce a smaller welding puddle. Should the welding puddle become too large, remove the heat to allow the filler metal to cool and harden. 

The overhead MIG welding technique requires the most skill, so you may want to try it after learning how to MIG weld with the less complicated techniques. 

Final Thoughts

When you first start learning how to MIG weld, you may find it challenging. Learn from your setbacks, and you may be performing neat and intricate welds quicker than you imagine.