What is MIG Welding? Understanding Gas Metal Arc Welding Thoroughly

Last Updated: March 12, 2021

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Welding is the procedure of connecting two metals by heating the metal surfaces to their thawing points. However, welding isn’t as easy as it may sound. It’s a highly technical procedure as it has many types and techniques that only qualified personnel can comprehend and practice.

There are numerous welding types. They include Laser, Friction, Arc, Electron Beam, and Resistance welding. The most common type is MIG (Metal Inert Gas), a type of Arc welding.

As earlier stated, welding isn’t easy as you might think. Therefore, you may not get it right the first time. If you want to accomplish a welding project, you need to be armed with so much information.

If you’re a novice and would like to learn everything you need to know concerning MIG welding, this detailed guide is your doorway to all the information you’re looking for.


What’s MIG Welding?

MIG (Metal Inert Gas) welding is an arc welding procedure that utilizes an incessant solid cable electrode heated by a welding gun and fed into the weld pool. The two basic materials are thawed together to create a joint. The welding gun feeds a shielding gas with the electrode to safeguard the weld pool from air pollutants.

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Image credit: Vadim Kulikov, Shutterstock

How Does it Work?

Metal Inert Gas welding is a versatile technique that suits both thin sheets and broad section parts. An arc is struck between the wire electrode end and the workpiece, which thaws the two of them to create a weld pool.

The cable acts as both a heat source and a filler metal for the welding hinge. Then, it’s fed via a copper contact tip that carries welding current into the cable. A shielding gas fed via a nozzle surrounding the cable safeguards the weld pool from the atmosphere around.

The choice of shielding gas relies on the welded material and the application. A motor drive is used to feed the cable from a reel, and the welder will move the welding torch along the connection line.

The cables may be cored (composites created from a metal sheath using a metal filling or powdered flux) or solid. Compared with those for other procedures, consumables are usually competitively priced. The process provides high productivity because the cable is constantly fed.

Manual MIG welding is frequently referred to as a semi-automatic procedure. It’s because the power source regulates the cable feed rate and the length of the arc. However, the traveling speed and the position of the wire are under manual regulation.

If the parameters of the process aren’t directly regulated by a welder, the procedure can be mechanized. However, you may still need manual adjustment when welding. The process can be referred to as automatic if there’s no manual intervention required when welding.

Usually, the procedure works with the cable positively charged and plugged to a power output delivering an incessant voltage. The choice of the cable diameter (typically between 0.6 and 1.6 mm) and wire feed speed ascertain the welding current since the wire’s burn-off rate creates a balance with the feed speed.

What are the Different Types of MIG Welding?

You can differentiate MIG welding types through the mode of transfer used. There are primarily four distinct types of transfer in MIG welding:
  • Short Circuit (Dip Mode)

The welding cable touches the metal in short circuit conveyance. Current flows via the gun and forms a short circuit. After the welding wire is melted, it leaks slowly onto the metallic surface, forming a puddle that creates a joint between the workpieces.

In this kind of MIG conveyance, Carbon Dioxide shielding gas is utilized with a low voltage combination. In this procedure, you require less shielding gas and, therefore, this is a cheap process.

The short circuit mode can deal with poor fit-up relatively well, and it’s fit for pipe applications. It’s a lower-heat input mode that lessens distortion of the weld.

  • Globular Conveyance

It takes place with a combination of argon shielding gas and high voltage. In this MIG welding conveyance type, the cable thaws and then gathers at the gun tip and leaks gradually onto the connection a couple of times every second. The main drawback of this type is that it causes spatter.

Several benefits of this mode comprise using affordable Carbon Dioxide as a protective gas, cheap solid electrodes or metal-cored, and equipment.

  • Spray Transfer

The wire thaws into very fine droplets and instead, it’s sprayed like mists onto the joints. Dissimilar to the popping and crackling of Globular and Short Circuit transfer respectively, Spray conveyance produces a hissing sound.

It’s useful when it comes to producing a clean arc between the materials being welded and the gun. This is accomplished using a combination of argon protective gas or a gas combination with 15% of Carbon Dioxide and high voltage. The protective gas is somewhat costly because it contains a large amount of argon.

  • Pulsed Spray Conveyance

This procedure needs a high-end MIG welder. Rather than giving a regular flow of voltage, the welder pulses the voltage. The consequence is a type of transfer that interchanges between Globular and Spray types.

To weld products, it doesn’t need a high voltage supply. It produces more effective welds and integrated greater suppleness with positions. The MIG welder is somewhat costly to offer such a performance.

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Where is MIG Welding Used?

MIG (Metal Inert Gas) welding is the welding type mostly used by industries and makers. However, several industries are more likely to utilize these welding forms (or provide more employment opportunities in this domain) than others.

Below is a summary of the industries where MIG welding is most widespread and, therefore, it’ll most likely employ welders with expert qualifications in the field:
  • Automobile Industry

MIG welding is frequently used to fix motorcycles, cars, RVs, SUVs, and vans. The fact that it can offer a powerful weld even with slender metals makes MIG welding the perfect technique for fixing and putting the body together or any car interior.

Also, MIG welded metals are versatile. It’s a prerequisite for vehicles that require enduring many years of use. Most vehicles are manufactured from aluminum, a metal that’s conventionally welded using a MIG welder.

With this in mind, there’s a possibility that MIG welding may be used to make vehicles in the future.

  • Construction

In construction, the most used metal is steel. More than half of the steel in the world is used to build homes, wind turbine towers, office buildings, bridges, and other structures. Although MIG welding was designed for aluminum and other non-ferrous metals, presently, it’s also increasingly used for steel.

Since MIG welding is the preferred option for welding structural steelwork, it’s not astonishing that the building industry requires MIG welders. 

  • Mass Production Manufacturing

It includes the mass production of stuff. For instance, this manufacturing type is used to produce auto components, computer parts, ship parts, and numerous other items. The fact that MIG welding is inexpensive and fast makes it fit for use in high production manufacturing.

The other reason why MIG welding is usually utilized in this sector is that it’s used in numerous metal types. They comprise carbon steel, magnesium, steel, nickel, and a variety of alloys.

Advantages of MIG Welding
  • It can connect numerous material types with distinct thicknesses.
  • The components used in MIG welding are readily available and, therefore, you can find them in the shops at a cheap cost.
  • It has higher electrode efficiencies (92 to 98%) when compared to other welding types.
  • You can adapt it easily for semi-automatic applications, high-speed robotic, and hard automation.
  • It offers the option of all-position welding.
  • The weld bead’s appearance created from MIG welding is excellent.
  • When compared to other welding types, it needs a lower heat output.
  • The weld spatters and slag stay at a minimum and, therefore, cleaning the weld is fast and easy.
  • It creates fewer welding fumes, which makes it secure for welders.
  • The weld metal’s cost is lower, making MIG welding an affordable procedure.
  • It’s suitable for novices since the skill level is low.
  • It’s great for spot and tack welds.
Disadvantages of MIG Welding
  • The initial setup cost is high.
  • The atmosphere around the welding procedure must be stable (as a result of the shielding gases) and, therefore, the procedure is restricted to draught-free conditions.
  • The maintenance cost is high because of additional electronic parts.
  • It has more severe effects of radiation.
  • A high skill level is needed when it comes to adjusting plant variables.
  • It’s not effective if high duty cycle requirements are needed.
  • It can create heavy smoke and fumes.
  • The method may lead to rust deposits.
  • It’s not as potent as TIG welding.

FAQs

What’s the difference between TIG and MIG welding?

The major difference between the two is the method the arc is utilized. Metal Inert Gas welding (MIG) utilizes a feed wire that moves incessantly via the gun to form the spark. It then thaws to create the weld.

When it comes to Tungsten Inert Gas welding (TIG), two metals are fused directly using long rods.

What leads to excessive spatter in MIG welding?

Excess spatter is caused by several factors. The main factor is an interruption in the melted weld pool while the wire is being transferred into the weld. In such a situation, the arc is too chilly to keep the pool and the wire melted, and this leads to a stubbing effect on the cable. It can take place in both low and high current ranges.

What gas type is used in MIG welding?

The four shielding gases most commonly used in Metal Inert Gas welding are Helium, Oxygen, Carbon Dioxide, and Argon. Each offers incomparable advantages and disadvantages in every application.

What’s the most suitable gas pressure for MIG welding?

MIG shielding gas flow is determined and measured as CFH (cubic feet of gas per hour). Dissimilar to cutting and oxyfuel welding, the flow rates of MIG gas are low. The pipe’s gas pressure that flows into the cable feeder/welder when welding usually varies from 3 to 8.

What safety equipment is needed for MIG welding?

You require leather gloves and a colored welding helmet at the very least. It’s also advisable to put on leather shoes and a leather welding jacket also. Sultry sparks and metal will fly everywhere during welding.

Apart from the fact that non-leather shoes and t-shirts don’t provide protection, they’ll rapidly develop holes in them caused by sparks burning through. Even if you weld in an area with adequate ventilation, the fumes emitted by numerous metals are bad for you, particularly galvanized steel. Also, ensure that you have a fire extinguisher as it comes in handy.

Quick Reference Guide

When to Use MIG Welding
  • If you have thicker metals that require longer, constant runs
  • If you have projects that need higher production rates, use this method as it’s faster and easier to manage than TIG welding
  • If you’re a novice
  • If you don’t want to begin and stop frequently, use this method as it’ll lessen the chance of a defect due to its continuous nature
When to Use TIG Welding
  • If you’re using thin metal
  • If you want to offer a high level of detail, use TIG welding as it’s slower
  • If you’re a professional and understand how to balance materials using both hands
  • If you have an automotive project, or you need a clean, artistic finish
  • If you have numerous types of metals such as copper and aluminum. However, you cannot use cast iron with this method.

Conclusion

Among the main reasons why MIG welding is common is that it’s used to weld nearly any metal as compared to TIG welding. Though the quality of weld in MIG welding isn’t superior to other welding types, MIG welding is among the quickest and most affordable welding procedures.

Additionally, MIG welds are excellent, if not flawless. The most commonly used metals in MIG welding comprise carbon steel, aluminum, and stainless steel. The simplest metal to MIG weld is carbon steel.


Featured image credit: Danil Evskyi, Shutterstock

Cameron Dekker
 

Cameron grew up in Allentown, Pennsylvania, a once-proud steel town on the Lehigh River, where he got a taste of TIG welding in his high school shop class. He holds certificates for Certified WeldingEducator (CWE) and Certified Resistance Welding Technician (CRWT) from the American Welding Institute. His interests include scuba diving, sculpture, and kayaking.

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