MIG/MAG welding: description, information and equipment

Welding has a broad definition that includes permanently joining two elements, usually metal. There are various welding methods, each of them is suitable for different materials and conditions. One of the most popular welding methods is MIG/MAG. But what exactly is it and when is it used? Read the article below to find out.

What exactly is the MIG/MAG method?

First of all, MIG/MAG welding consists of two methods: MIG and MAG. Since they are both very similar, they are usually referred to together. They are classified as gas metal arc welding (GMAW) techniques. The difference between MIG and MAG welding is the type of gas used. MIG welding gas is an inert shielding gas, e.g. helium or argon. MAG welding uses active shielding gases such as carbon dioxide or its mixtures with argon, oxygen and helium. Shielding gases play an important role in the entire welding process and must be used based on the type of material to be connected.

With the exception of the difference in gas used, the basic principles of MIG MAG welding are the same. The welding torch of each wire welder is equipped with a special wire feeder. It gently ejects the electrode wire which will appropriate current is applied. The arc forms when the wire is close enough to the material. Melts both the wire and the treated surface. This then leads to the formation of a melt pool. Once the torch is withdrawn, the molten metal begins to solidify and forms a weld that connects the edges of both materials. The role of the shielding gas is to protect against the harmful effects of atmospheric air, which could affect the quality of the weld.

Using the MIG/MAG method

Since there is almost no difference between MIG and MAG welding, only one device can be used for both methods. All you have to do is connect an active or inert gas cylinder to the torch and you can weld dissimilar metals. So, in what cases can each method be used?

• MIG welding: for aluminium, copper, non-ferrous metals and alloys
• MAG welding: for unalloyed, low- and high-alloy structural steels and other non-ferrous metals.

As a result, MIG/MAG is the most commonly used welding method in the industry. The wide range of potential fields of use, however, is not its only advantage. Another advantage is the simple control of the process of joining the elements. It is also relatively fast and material deformation is minimal. The MIG welding torch is also notable for its high efficiency, as well as the possibilities for mechanization and automation. This method works best in enclosed spaces because the shielding gas could be dispersed by gusts of wind, which would significantly reduce the quality of the weld.

MIG/MAG welding parameters. What do you need to remember?

Before deciding to use the MIG/MAG method, you need to know its basic parameters. They have a significant impact on the quality and durability of the connection, as well as the MIG method as a whole. Below you will find the most important factors:

• Type and polarity of the welding current: usually a direct current of positive polarity is used, i.e. the welding torch is connected to the positive pole and the earth cable to the negative pole. This allows the electrode wire to melt quickly. Negative (reverse) polarity, can negatively affect the entire process.
• Welding current intensity: Determines how quickly the MIG welding wire will melt, as well as the shape and depth of the melt. If the current is too low, can cause a short circuit of materials, which in turn causes an oval-shaped melt. Instead, the high intensity can cause a fusion cavity formation.
• Arc voltage: the higher the arc voltage, the longer it is. Too high a voltage causes spattering, porosity and sticking. Instead, a too-low voltage, in turn, affects the quality of the weld.
• Wire feed speed: this is one of the fundamental parameters of MIG/MAG welding machines. The speed depends on the arc voltage level. It must be set appropriately to ensure stable wire fusion.
• Wire type and diameter: an appropriate wire must be used, depending on the thickness of the material being processed and the welding position. Normally the following diameters are available: 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.6 mm. In this case, the current density also plays an important role. The smaller the diameter, the greater the density and therefore deeper penetration is obtained.
• Welding gas flow rate: The suggested gas flow rate is usually 10 l/min for each millimeter of welding wire diameter. Values that are too low can lead to the development of imperfections, e.g. porosity. Too high a range can cause a bow blowout.
• Free grip: This is the length of extension of the electrode wire from its melting end to the current tip and is adjusted by setting the welding torch to the appropriate height. The length affects the intensity of fusion. If the free grip is too long, the stability of the bow is compromised, leading to shots and splashes. On the other hand, a small socket causes the wire to stick, causing damage to the current tip.
• Welding speed: the speed at which the wire moves with a hot electric arc. It must be adapted to the electric current, arc voltage and wire feed speed. The speed for manual welding is usually between 0.25 and 1.3 m/min.
• Torch angle: the angle at which the material is welded depends on the type of welding you want to obtain. If you hold the torch vertically, the depth and width of the weld will be medium. Tilting in the direction of the weld (pulling) increases the depth, but reduces the width. On the contrary, by positioning the torch in the opposite direction to the welding direction, it will be lower and wider.

Correctly determining the parameters is of great importance during MIG/MAG welding. Make sure you check them all carefully before using the welding torch.

MIG/MAG welding: correct and safe use

Now that you understand the basics of the MIG/MAG method, it's time to prepare your welder for the job and the material to be processed. Where to start?

First of all, check whether there is enough electrode wire available in the soldering iron and also if in good condition. If you detect any corrosion, replace it immediately. When installing a new spool, check the wire feeder pressure. This should allow the cable to slide easily but not unravel on its own. The first centimeters (about 8 cm) need to be straightened. When cutting the thread, make sure the tip is not chipped. It is important to hold the thread during this operation to ensure that the bobbin does not unravel.

The material must be thoroughly cleaned as part of its preparation. An angle grinder with an abrasive disc or steel brush would be ideal. You can also use a regular wire brush. Any visible rust or paint must be removed, they hinder the ignition of the arc, but they can also change the direction of the weld and affect the strength of the weld. The surface to be connected with the grounding terminal must also be clean.

You can hold the welding torch with one or both hands. It all depends on your experience level. If you want to weld with the MIG/MAG method using both hands, you must wear a welding helmet. Before you start, you need to find a position that allows monitor the weld pool. Welding torches often have an ergonomic shape that fits comfortably in your hands.

As mentioned before, the angle of the torch with respect to the welding direction largely depends on the type of joint and the thickness of the material. Then, its movement is the result of the positioning of the treated elements in relation to each other. For edge-to-edge welding, it is common practice to use a curvilinear zigzag motion. It is suitable for thin surfaces and allows you to use a weld on each edge. Welding is also characterized by its cleanliness. To begin, join the two elements at the chosen points every few centimeters. In this way, you can prevent the space between materials from becoming larger.

Safety first! Above all, make sure you protect your eyes. Welding arcs emit a very bright light and even brief exposure to the eyes can damage the cornea. To adequately protect your vision, always use helmets with special blackout visor lenses. You can choose between masks that are cheaper to wear and more comfortable helmets with full protection. The latter allows you to have both hands free. In addition, UV radiation from the arc can burn the skin, so don't forget about gloves, protective sleeves, special hoods, aprons and even welding jackets, which also protect against sparks and splashes. They are often made of split cowhide or other flame-retardant leather materials and are usually stitched together with Kevlar threads, which do not melt even at very high temperatures. Sparks also pose a danger to the workplace, as they can start a fire. To avoid this danger, you must remove all flammable objects from the surrounding space and have access to a fire extinguisher intended to extinguish electrical devices. Sand works here too. Never use water! Make sure you protect your respiratory system too. Poisonous fumes are often released during soldering, for example when processing tin alloys or coatings. In large workshops, you can often find industrial ventilation systems that eliminate harmful fumes. In-home garages, make sure you have good ventilation before doing any welding. Fortunately, many professional welding brands offer protective products for welders.

Isn't the MIG method overrated?

The universal range of applications and welding efficiency make MIG/MAG an extraordinarily popular method in many different industries. Additionally, the process of joining materials is relatively easy to learn. The best way to learn about this method is to try the MIG/MAG welder yourself.