MIG is a welding process that uses an electrical arc and a continuously fed electrode wire to join two base metals together. The MIG process uses a welding machine, a welding gun, and a shielding gas. Many people are interested in MIG welding because it’s one of the popular types of welding in the industry. In addition, it is relatively easy for DIY enthusiasts to welding basics, and it’s cost effective in manufacturing.
MIG welding is used for all manner of metal fabrication and repairs. You can use a MIG welder on a range of metals—carbon steel, stainless steel, aluminum, copper, other alloys, and non-ferrous metals. MIG welding is typically used in home workshops. But it’s also used in car repairs, ship construction, joining pipelines, and other small industries.
Are you a newcomer to welding or a welding amateur and want to know more about MIG welding? Do you want to know the difference between MIG and TIG (tungsten inert gas) welding processes? And what are the pros and cons of using a MIG welder to join metal plates? This article answers those questions and more.
What does MIG Stand for in Welding
MIG stands for Metal Inert Gas welding. The term refers to two characteristics of this welding technique.
- First, the electrode is a thin metal welding wire that feeds continuously through the nozzle of the welding gun.
- Second, the welding process uses a type of gas—usually argon or helium—to shield the weld puddle.
This welding technique is also called Gas Metal Arc Welding (GMAW). However, because the welding process uses a wire electrode, MIG welding is often referred to as wire welding.
What is MIG Welding
Metal inert gas welding is the process of joining metal pieces by heating them to a melting point over 5,000°F. The molten metal forms a weld pool, and a special inert or active gas protects the weld from contamination with gasses in the air. As the metal cools, it forms a strong bond, permanently joining the two metal pieces together.
MIG welding is described as a semi-automatic process. This is because the welding machine automatically controls the wire feed speed and arc length. However, the operator manually controls the wire position and travel speed. Some people liken the process to using a glue gun.
How does a MIG Welder Work
A MIG welder consists of a welding gun, a welding machine with a wire feeder, and a supply of inert shielding gas. The welder creates an electrical arc between the base metal and the wire electrode. At the same time, a flow of gas from the nozzle protects the weld puddle from contamination and oxidation.
A crucial aspect of a MIG welder operation is the wire feed speed. Because it’s a consumable metal electrode, the wire feeder must operate at a constant speed. Additionally, the wire speed depends on the type of parent metal being used and the speed of the operator.
What do you Need to MIG Weld
To weld metal using the inert gas welding method, you require a welder with MIG capabilities. Most welders for sale are MIG welders, and many have options for TIG welding. However, the welding machine is only one piece of essential equipment for MIG welding.
Here are additional pieces of equipment necessary for MIG welding:
- Solid wire electrode: It’s impossible to MIG weld without the suitable filler wire that melts into the puddle. Some electrodes are cored wires with a powdered flux or metal filling.
- Inert shielding gas: A shielding gas creates a protective environment to prevent contamination in the weld joint. Argon is one of the most common shielding gasses because its inert properties don’t react with other gasses.
- Additional tools: To create beautiful welds that are durable, you will also need a metal cutting tool, an angle grinder, clamps, and a suitable worktable.
- Protective gear: You must have protective gear for all types of welding. This includes a welding mask, eye protection, heavy-duty gloves, and fire-resistant clothing.
What is an Inverter MIG Welder
An inverter MIG welder is a welding machine that converts AC power supply to a lower voltage DC output. MIG welders use several electronic components to convert the power. The inverter MIG welder increases the original power supply from 50Hz to between 20,000 and 100,000Hz. This results in a smaller, more efficient transformer.
The advantages of inverter technology in MIG welding are that it uses up to 50 percent less electricity, they are lighter, easier to control, and have increased performance.
What Gas is Used for MIG Welding
Common shielding gasses in MIG welding are argon or helium. Typically, argon is the most common shielding gas used in MIG welding because it’s cheaper than helium. These gasses are described as noble gasses with inert properties. These inert gasses protect the molten metal weld pool from reacting with gasses in the air.
However, argon and helium are not the only gasses used in MIG welding. Sometimes carbon dioxide or oxygen can be used. These “active” gasses can be used in a mixture with argon. This is to boost arc stability and achieve deeper penetration when welding.
What is the Best Gas for MIG Welding Mild Steel
The best type of gas for welding mild steel with a MIG welder is a combination of argon and carbon dioxide. A mixture of 75 percent argon and 25 percent carbon dioxide is ideal for mild steel. This ensures the best weld bead appearance with minimal spatter. It also reduces burn through on thinner materials.
It is possible to use Co2 to achieve deeper penetration on thicker materials. However, 100 percent carbon dioxide produces more spatter and a weld bead that appears rough and messy.
What Gas for MIG Welding Stainless Steel
The most effective shielding gas for stainless steel is a mixture of argon and carbon dioxide. A gas mix of 98 percent argon and 2 percent carbon dioxide is ideal for producing the best results welding stainless steel. However, you can also use a combination of argon, helium, and carbon dioxide for MIG welding stainless steel.
What is MIG Wire
MIG wire is a spooled electrode that is continuously fed through the tip of the welding torch. The wire is typically a solid wire between 0.24” and 0.45” in diameter. The other type of MIG is a flux-cored wire for gas-less MIG welding. Flux inside the electrode creates a shielding gas to protect the weld integrity.
MIG wire is typically made from carbon steel, stainless steel, or aluminum. You should choose the type of wire the same as the base metal you plan on welding. However, modern manufacturers are making MIG wires with other elements like titanium, silicon, and manganese, along with the base metal.
What can You Weld with a MIG Welder
MIG welding is versatile and can be used for welding several types of metals. MIG welding works well for metals, including stainless steel, carbon steel, aluminum, copper, nickel, silicon bronze, and magnesium. Although you can use a MIG welder for cast iron, TIG welding is more effective.
What is Burn Back in MIG Welding
Burn back is a common occurrence in MIG welding. Burn back occurs when the arc burns back into the opening of the contact tip. The result is that the welding wire gets welded inside the tip. If this happens, you must remove the contact tip and start again.
Causes of burn back in MIG welding include the following:
- Wire feed is too slow
- The wire feed is not continuous
- Wrong contact tip size
- Poor grounding
- Using a damaged or wrong liner
Advantages and Disadvantages of MIG Welding
MIG welding is one of the most popular methods of welding. The advantages and disadvantages of MIG welding usually depend on the type of welding machine and the welding job. However, when comparing the pros and cons, most welders agree that the advantages of MIG welding outweigh the disadvantages.
Advantages of MIG welding
- Work faster and achieve greater productivity
- Easy to learn
- MIG welding results in high-quality welds
- Less slag and spatter to clean after welding
- Useful for a wide range of metals
Disadvantages of MIG Welding
- MIG equipment and consumables tend to be more expensive
- Not possible to do vertical or overhead welding due to the fluidity of the molten weld pool
- MIG welding is not suitable for outdoor use
- Burn back is an issue unique to MIG welding
Why is MIG Welding so Popular
Several reasons make MIG welding the most common type of welding process. For example, MIG techniques are exceeding simple to learn. And despite the initial cost, MIG equipment is coming down in price. Additionally, MIG welding produces bonds just as reliable as other welding processes.
The undeniable reason MIG is so popular is its versatility and speed. You can use a MIG welder for most average-sized jobs and different welding applications. Also, MIG equipment is usually compact enough for a home workshop.
Tips for MIG Welding
There are several things to keep in mind to achieve superior welds when using a MIG welder. Here are some top welding tips from the experts.
- Clean bare metal surfaces—Always ensure that surfaces are free from rust, paint, grease, and oil.
- Get a good grounding— Attach the clamp to a bare metal surface as close to the arc as possible.
- Keep the arc to the forefront—For best results, keep the MIG welding arc at the leading edge of the weld pool.
- Use both hands—Although MIG welding is touted as “one-handed welding,” two hands will always give you better control while you weld.
- Listen to the welder—You can tell a lot about weld quality by listening to the noise your welding creates. It should sound like gently frying bacon. Hisses, loud machine gun-like pops, or raspy sounds indicate the amperage is wrong.
- Stagger welding—When welding stainless steel or thin metal, it’s best to stagger welds to prevent bending and buckling.
Conclusion–MIG Welding Process
MIG welding is a popular welding method used by hobbyists and professionals. MIG techniques are straightforward to learn, are highly effective, and it is possible to create the ideal weld time and again.