What is MIG welding?

Heating metal surfaces to a melting state is an integral part of welding. The latter is a process of joining two metals, which is considered quite complex. After all, it is a highly technical process. There are many varieties and methods that only specially trained MIG welders can understand and put into practice. If you want to know what is MIG welding, this article will be a source of information for you.

There are many welding techniques, particularly: contact, electron beam, laser, friction, and arc welding. Metal inert gas (MIG) welding has become one of the most commonly used when considering all of the above welding methods.

What Is MIG Welding: Basic Features

The abbreviation “MIG” also has another name – gas metal arc welding (GMAW). This type of welding is essentially an arc welding process. In it, 2 metals are joined together, which occurs directly by heating the metals with an arc. How it is formed: it occurs directly between the additive electrode, which is continuously fed, and the weldable surface.

The choice of wire diameter (typically 0.6 to 1.6 mm) is standard and the speed of the feeder wire determines the welding current, as the burnout rate of the welding wire will be in balance with the feed rate.

The melted metal must be protected from reacting with components in the air. There is a special electrode DCEP – reverse polarity. It is needed to perform quality MIG welding.

The difference with other technologies

Let’s analyze the different welding methods and compare them with each other to see if we can make the right choice – MIG welding work or choose another option. Each process has its advantages and disadvantages.

We will not consider their features, but highlight the most important and interesting differences from the welding method we are considering. So, next, we will analyze the difference between GMAW/SMAW, MIG/TIG, and MIG/STICK.

Difference between MIG and TIG 

Although MIG and TIG welding technologies are quite similar in several ways, they have key differences. One of the primary separations that separate the two types of MIG/TIG welding is that during MIG welding, the filler materials are supplied from a wire using the MIG torch. This wire allows the current to flow through it, and thus the welding process is carried out.

Let’s describe how the arc itself is created:

• the clamp, which is designed for the grounding function, is attached to the part you want to weld;
• after that, such an element as the MIG torch trigger is pressed;
• as a result, an arc is created at this stage.

The main advantage of MIG welding is that it produces high-quality welds at a much higher speed.

Difference Between GMAW and SMAW

In the late 1940s, after the tungsten electrode was replaced by a continuous-feed electrode wire, GMAW was born. The GMAW uses a gun that is used to guide a continuous solid wire electrode.

The shielding gas prevents the process from becoming contaminated. In this case, note that the main aspect that separates the considered methods is that in GMAW continuously fed electrode wire.

The discrepancy between MIG and Stick Welding

The biggest difference is that the MIG process we are considering is considered preferable for inexperienced specialists to stick welding, and it is also cleaner.

Metal Inert Gas Welding Technology

MIG welding can be found under the name “wire welding” due to the use of a wire electrode.

Thin wire (cored or solid) is most often used to create the wire electrode. There is a continuous feeding of this wire into the welding machine directly from the wire spool.

Consider the flux-cored version of the wire: includes composites, which are obtained from a shell of metal material with a filler metal or flux cored arc welding, as opposed to a solid – a simple wire.

• The arc occurs when the trigger of the welder is pressed down on the wire between the electrode tip and the blank. The resulting arc causes the workpiece and wire to begin to melt, forming a weld pool.
• The double action is performed by the electrode wire in the case of MIG welding, which is a kind of heat transfer medium and additive material for joining – thus its name is “welding with wire” (in this case we are talking about filler metal).
• The current to the wire is carried employing a copper slip line over whose wire is being fed in a continuous flow.
• Protective tungsten inert gas – to protect the workpiece or filler piece from interaction with the environment during MIG welding.
• The wire is surrounded by a nozzle, which is fed with MIG. The choice of gas depends on what kind of material is being welded. It also depends on the intended purpose of the activity.
• The power source monitors the wire feed rate, as well as the arch duration. That’s why welding with MIG is referred to as a process using semi-automatic welding technology. It is also important to note that the manual method monitors the wire feed rate and wire position.

The Meaning of Polarity and Voltage 

During MIG welding, a wire is charged with a positive pole and is plugged into a power supply providing a DC voltage. Additionally, the MIG welding is direct current from its negative pole to its positive pole, just like a battery pack in a car.

This is also the normal polarity. The “+” DC electrode, as previously described, indicates the MIG handle is connected to the MIG welder on the plus side of the electrical circuit. Current flows in a direction away from the main metal to the handle of the MIG welder.

The power supply used in the MIG welder procedure is called a DC power source. Adjustment and control are necessary concerning the voltage reading during the welding process.

What Metal Transfer Modes are available?

The following several types, what is the direct transfer of metal into the so-called weld pool via the electrode are possible:

Short-circuit mode

This principle, also known as immersion mode, is characterized by the fact that continuously fed metal is deposited on a flux-coated or solid wire electrode employing repeated short circuits several times. This transfer method has a low thermal load.

The transfer of metal occurs only if the electrode is in contact with the electrode a fraction of the molten metal or base material.

The method of the transferred metal used in the short-circuit case can be carried out in any position.

It copes well with insufficient adhesion, can be used for pipes, is one of the methods with less heat, which provides less welding strain, is easier to use, and has an electrode effectiveness of 93% or greater.

Spherical Method

With the spherical transfer technique, the electrodes are fed continuously with metal cores or solid wires and are applied by gravity not only for short circuits but also for short circuits and large drops.

The large droplets are irregularly shaped. As a result, the short circuit becomes a spherical duct. This begins at the point where the short ends.

In this case, the electrodes do not come into contact with the substrate material.

Among the many, merits of a spherical transfer metallic are that it can be welded at high speeds, the availability of low-cost protective gases such as carbon double oxide, metal powders, or cheap hard electrodes, and the availability of MIG welding equipment.

Sputtering or Spray-Modal

Sputtering is a high-energy transfer of metal technique in which a central electrode or continuous wire is at all times supplied with relatively high energy.

The result is a uniform flow of small drops of molten metal, unlike the weld bead transfer process, resulting in irregularly shaped droplets.

Thermal spraying has many advantages, including electrode yields of up to ninety-eight percent, a high metal removal rate, an excellent weld pattern, a wide variety of additive metals or metal diameters of electrodes, simple cleaning after welding, and simple weldability. It leaves no weld spatter and is suitable for robotic, automation, and quasi-automated use.

Pulse mode

This method is a tightly controlled version of the spray method. The welding current alternates between different amperages. At a high current, it moves the metal as a melted droplet.

Pulsed metal transfer in MIG welding has the greatest direct superiority over all other metal transfer methods known today.

A low so-called “splashing” index, should be noted for a rather high level of stability, absence of penetration defects, the excellent appearance of the weld, very attractive for operators, low thermal distortion, off-site welding capability, ideal for robots and automated.

What is the MIG Welding Procedure?

Before we get to the welding process itself, there are some important terms to familiarize yourself with which you will be able to understand more about the MIG welding process.

First, it’s a good idea to get familiar with the basic principles of the MIG welding machine.

Seam characteristics

• Base Metal joined by welding processes.
• Overlay metal. This material is used in the process to bring metal parts together.
• Heat exposure area. There is a certain portion of the main metal. It is directly affected by the metal, but its melting is not affected by the heat that occurs during the welding processes.
• Fusion line. This line is called the boundary. It is between the high-temperature influence area and the MIG weld metal. Fusion line is an unusual term used to define the connection of welds.
• The weld metal is to be welded. The weld comprises a metal seam that is molten together and held in place during the formation of that seam.
• Seam weld area. The weld area encompasses the metal of the weld, as well as includes the HAZ.

MIG Welding Machine/Gun

It is important to know the structure of a MIG welding gun to understand the function of gas metal arc welding.

• As well as many other elements: this is the so-called gas hose and a special electronic (or mechanical control switch), as well as the contact tip itself and the metal active gas, power supply with electrode channel, and gas flow for protection.
• The gas nozzle is responsible for ensuring that the shielding gas flows uniformly in the welding area. If the gas flow is not uniform, the arc will not be adequately protected. It is the protected (or shielding gas) that protects the weld pool from any contamination.
• Copper is used as the material for creating the contact tip. In certain situations, there is a need to chemically treat this tip. In this way, the number of spatters produced during welding operations can be significantly reduced.
• The contact tip is plugged via an AC cable back into the main power supply, which transfers the electricity to the electrode. It is necessary, if possible, to choose the right size of the tip because it provides the necessary area of contact of the electrode with the base metal.
• The electrode rod is guided and shielded. This prevents bending and ensures a smooth wire feed speed.
• If you use a larger gas nozzle, you can achieve a larger shielding effect, which is useful for high-current operations and for getting a larger melted metal pool for welding. There is sometimes a water hose attached to the welding gun, which is used to cool the MIG welder following higher-temperature applications.

The wire feeder is the device that energizes the workpiece and feeds it through the wire and inserts and contact tip.

Shielding Gas

And as mentioned previously throughout our blog, MIG welding gas prevents the melt from interacting in the atmosphere with oxygen and various elements. But shielding gas isn’t everything. Shielding gas has a big impact on metal migration and arc stability.

Other functions:

• Formation of the arc plasma. Stabilization of the arc root on the surface of the material.
• To ensure a smooth flow of the molten metal on the wire to the weld pool.

Welding gas for MIG welding type determines the penetration depth of weld metal, its mechanical features, and the characteristics of the welding arc.

The shielding gases commonly used in MIG welding are special mixtures of argon, carbon dioxide, oxygen, and helium.

Various shielding gases are also used for welding thin metals. Gas mixtures consisting of 5-25% carbon with argon and 2-5% oxygen are usually used for welding steel. For non-ferrous metals, argon and mixtures of helium and argon are usually used.

What kinds of metals can be welded with MIG?

The primary reason that MIG welding has been so widespread is the fact that you can use it to weld (almost) any metal.

Although MIG welding does not differ in quality from other welding methods, it is one of the fastest welding methods and is notable for its low cost.

The most popular metals that can be welded with this method are aluminum, and carbon steel. Of these two varieties, it is carbon fiber (carbon steel) that is the easiest for the MIG-welding process.

MIG welding applications

Due to the high popularity of MIG welding, its applications can be varied and quite extensive.

The following are the most current applications for MIG welding:

1. The automotive industry is the area in which this technology is most common.
2. MIG welding is used to repair cars, as it provides very high-quality MIG welds. Their thickness is half a millimeter, which gives them high strength.
3. Welding of metal sheets. MIG welding also finds application in pipe welding, as it allows the formation of efficient and durable joints, as well as significantly saves time.

Advantages of MIG welding

The cheapness of the welding procedure and the high quality of the welds for non-ferrous and ferrous alloys are the main reasons why MIG welding has become very popular with MIG welders.

Many advantages of MIG welding:

• Suitable for joining different types of materials together.
• Welding materials of different thicknesses
• The availability of MIG welding equipment components on the market is due to their simplicity
• MIG welding provides higher efficiency of the electrode.
• In MIG welding a higher level of efficiency of personnel and welder
• The technology is easily applicable for complex automation, the use of high-speed robotics, and semi-automatics.
• In the MIG welding process, the wire is used continuously, resulting in shorter waiting times for electrode changes.
• The welding technology provides high productivity when working in different positions.
• The type of bevel formed during MIG welding is characterized by its excellent features.
• MIG welding produces less fouling
• Requires less heat compared to other welding methods.
• Fast and easy cleaning of the weld is guaranteed because the number of spatters and the amount of slag is minimized.
• The MIG welding procedure is great for tacking and spot welding.
• MIG welding produces less welding fumes, increasing the welder’s safety.
• Cost efficiency is high because the cost of the weld metal/stretch is lower than with other methods.
• The qualification level needed for MIG welding is lower than for other types of welding methods, which allows the method to be used by beginners.

Disadvantages of Gas metal arc welding

MIG welding machines have an impressive weight, and given the power of the coil and wire, there is a need for portability, because the versatility of MIG welding makes it in demand both for small production shops and enterprises, as well as for huge industrial facilities. The method of MIG-welding, if you have enough of the right electrodes, which allows obtaining different welds, can perform welding of many metals and alloys.

The initial cost of MIG welding equipment is relatively high. MIG is generally not suitable for outdoor welding, except when using cored wire.

Gas metal arc welding (GMAW) has certain limitations, despite its widespread use:

• The metal transport mode is a mode of low thermal conductivity, which limits its use to thin materials.
• Since metal transfer by sputtering uses a high heat transfer mode, it is only suitable for heavy materials.
• Because spatter transfer is a high heat release mechanism, only for horizontal and flat position welding.
• Argon is generally used as shielding gas in spraying and pulse transfer modes, which is considerably more valuable compared to pure, one hundred percent carbon dioxide.
• The welder needs to stay close to the MIG welding machines.
• The use of MIG welding is limited to work in enclosed production facilities or workshops, as wind becomes the main factor outdoors.
• A gas cylinder is always required.
• Because contact tips are often contaminated by spatter, they get stuck.
• Every part of the MIG-welding machine must function perfectly so that high-quality welds are obtained. But to determine what exactly is wrong with the machine is very problematic.

Compared to DCEP, this method has higher deposition rates, but it has several disadvantages, such as the lack of deep penetration and insufficient heating of the weld pool.

Many novice welders prefer to start learning the GMAW method because it requires little skill compared to stick welding. In addition, the work is easier due to the lower amount of slag than in stick welding.

As a result, beginners can handle this task very easily. MIG welding combines efficiency, simplicity, speed, and economy – all this ensures its application in many industries.

FAQ

What is MIG welding in simple terms? The term stands for Metal Inert Gas. In simple words, this is gas-fusion electric arc welding.

Which gas is used in MIG welding? Pure carbon dioxide or mixed gases (oxygen, argon) are used in MAG welding in a variety of compositions. These gases are highly reactive. MAG is used for both over-alloyed and unalloyed or low-alloyed materials. Inert gases are also used: a mixture of argon, helium, and pure argon. This process is used for welding titanium as well as copper and magnesium.

What is MIG welding technology? MIG welding technology is suitable for smaller, less demanding welding jobs in metal fabrication workshops and factories. MIG welding machines work at a very lower voltage, which keeps the welding bead size quite small.