Welding is a term associated with metalwork (although thermoplastics and wood can be welded). It is the joining of at least two metals using heat, pressure, or both causing them to melt together, cool off, and resultantly become fused together. There are different types of welding, some more common than others. So what is the most common welding?
Gas Metal Arc Welding (GMAW) is the most common type of welding. This type of welding is used for the repair of vehicle exhausts and home and building constructions.
This article will explain the important things you need to know about Gas Metal Arc Welding (GMAW). You’ll also get a rare chance to explore the pros and cons.
What is Gas Metal Arc Welding (GMAW)?
Gas Metal Arc Welding (GMAW) is sometimes known by its variants, metal inert gas (MIG) and metal active gas (MAG). It’s a term used to refer to a welding procedure in which an electric arc originates between a flammable MIG wire electrode and the workpiece metal. This heats the workpiece metal, melting and joining (fuse). Alongside the wire electrode, a protective gas is channeled through the welding gun, protecting the process from environmental contamination.
What is the Process of Gas Metal Arc Welding (GMAW)?
The Gas Metal Arc Welding process is either automatic or semi-automatic. A steady voltage with a direct current power source is often used with GMAW, but steady and intermittent current networks can be used. There are four basic methods of metal transfer in GMAW: globular, short-circuiting, spray, and pulsed spray. Each of them has a unique properties and associated benefits and drawbacks.
Initially, GMAW was developed in the early 1940s for welding aluminum and metals other than iron. Before long, it was applied to steels because it welded for a shorter period of time compared to other welding techniques. The hike in the price of inert gas became a limitation to its use in steels until many years after, when semi-inert gases like carbon dioxide became commonly used.
In the 1950s and 1960s, the process gained universal popularity, and it became a widely used industrial process. Right now, GMAW is a widely used industrial welding process. People prefer it because it is swift, universal, and the ease of making the process fit for robotic automation.
Is there a Difference Between MIG and MAG?
One major difference between MIG and MAG is the type of protecting gas used. The components of this protective gas are critical as they impact the firmness of the metal transfer, arc, weld profile, access, and spatter.
Metal Inert Gas(MIG) welding: The MIG process uses inert gases and gas mixtures as protective gas. Examples of inert gases typically used in the MIG welding of metals other than iron (such as aluminum) are Argon(Ar) and Helium(He) mixes. Inert gases do not change with the filler metal or weld pool.
Metal Active Gas(MAG) welding uses active protective gases. These gases can change with filler metal moving across the arc and the weld pool, impacting its chemistry and/or outcome simulated properties.
MIG / MAG Metal Transfer Mode
The way and manner in which the metal travels from the filler wire to the weld pool greatly ascertain the functional features of the procedure. The metal transfer has four predominant modes: short-circuiting or dip transfer, Globular transfer, Spray transfer, and Pulsed transfer.
Short-circuiting metal transfers are used for minimal heat intake jobs. This mode of transfer requires skill to prevent a lack of fusion. In the case of short-circuiting or dip transfer, the molten metal that forms at the tip of the wire is transmitted by the wire descending into the weld pool. This is accomplished by applying a low voltage.
A higher voltage and current are needed for spray transfer, causing a significant heat intake. The molten metal at the tip of the wire transmits to the weld pool in what looks like a spray of small droplets (smaller than the radius of the wire).
However, there is the lowest current level or baseline, below which droplets are not forcefully extended across the arc; this is called the globular transfer. In the case of welding at a level way below the baseline current level, the low arc forces are insufficient to prevent large droplets from forming at the wire tip. These droplets move in an erratic way across the arc under standard gravitational force, often yielding a tangible quantity of spatter.
The pulsed mode evolved to minimize the heat intake of spray transfer while sustaining its advantages. Spray-type metal transfer is performed by utilizing pulses of high current, each pulse having enough power to separate a droplet of weld metal. Standard MIG/MAG welding is performed using a stable voltage power source that supplies a built-in and constant self-adjusting arc.
Advantages of MIG / MAG Welding?
- They can both be operated in different ways, including automatic, semi-automatic, even robotically.
- MIG / MAG allows for the swift production of high-grade welds.
- Due to low flux usage, there is not a chance the slag will get stuck in the weld metal.
- MIG / MAG is a versatile process that makes it possible to be used in fusing different metals and alloys.
- MAG welding can be carried out in different positions; hence, it is one of the most universally used welding processes.
Disadvantages of MIG / MAG Welding?
- Short circuit transfer is mandatory for vertical or upward welding. As, without quick freezing flux, there is nothing to keep the fluid weld pool in place.
- It is difficult to perform welding outdoors in the absence of enclosures because the welding gas requires protection from the wind.
- Availability of limited deoxidants during the process warrants that all rust must be taken out of the workpiece before welding begins
- Flux-cored arc welding (MAG welding with flux-cored wires) could be more adaptable for situational welding and outdoor usage. All arc operations require adequate protection, especially when it comes to the eyes
