Fusing two metal workpieces using heat is at the heart of welding. Different methods, materials and equipment have led to 4 major types of welding currently practised today. This includes MIG, TIG, Stick and Flux Core Welding, and each gets different results and is used for different applications.
Most beginners start with either stick or MIG welding and graduate onto the intricacies of TIG welding where extreme precision and the cleanest welds are needed.
What is MIG Welding?
MIG or Metal Inert Gas welding is an arc welding process that uses a continuous solid wire electrode that is heated and fed into the weld pool from the welding torch. This also feeds a shielding gas supplied from a separate gas tank to protect the weld from airborne contaminants. MIG welding gained in popularity from the 1950s onwards with abundant availability of shielding gases, most notably Helium, Argon and CO2. Today it is widely used in welding thinner sheets of mild and stainless steel, aluminium and its alloys, titanium, copper and other non-ferrous metals. Particular usage is in the automotive, aviation, construction, manufacturing and oil and gas industries where the process covers general maintenance and repair tasks. It can also prove handy in smaller household repairs.
How it Works
MIG welding relies on an electrical current to melt and fuse metal workpieces. The current is supplied from a mains supply, modified to the specific requirements of the workpiece from the welding machine, with the simultaneous use of shielding gas and electrode fed from the welding torch. The aim is to reduce oxidation from the surrounding air to produce a weld that is strong, durable and aesthetically pleasing. Welders have control over the current and heat levels from the MIG welder and the rate at which the wire electrode is fed into the weld pool.
Equipment Used in MIG Welding
To start welding you’ll need a MIG welding machine, an inert shielding gas supplied from a gas cylinder, the right electrode wire for the metal workpiece, magnets and clamps to set the workpieces to the correct position, a welding helmet and basic PPE gear, as well as tools like angle grinders and metal brushes in cleaning the weld once it’s cooled. Undoubtedly the MIG welder is the most important piece of gear, and there are MIG welders readily supplied with torch guns (and additions for feeding different types of wire), connecting hoses and connections, Combination welders also allow for stick welding, and those higher up the price range, basic TIG welding as well.
MIG Welders – What to Look for
With MIG welders differing significantly in price, welding novices need to take into account several criteria in selecting what’s right:
Cheap welders start at around $300-ish and can go deep into four figures. Being a cheapo means the welder won’t last in anything more demanding and the welds will speak for themselves. Spending a little more does get you the basics and you’ll have a machine to hone your skills and still get decent results. More expensive welders are intended for heavy-duty everyday use, often combining TIG welding as an option. Price points often determine what you’re trying to do. For basic repairs to smaller trailers or the backyard fence where the welds just need to hold can be done with inexpensive household welders, and as the name implies, these won’t find much use in industrial applications. In addition, welding metals in thicker gauges will be a challenge, particularly aluminium pieces that require separate spool guns feed wire specifically for that metal.
Amps -The More the Merrier
The amount of heat the MIG weld machine can generate is down to the intensity of the electric arc. Amps are the deciding factor here, and bigger numbers mean the welder can get hotter to make the workflow smoother, more precise and quicker. This is a must in thicker non-ferrous metals like aluminium. Gasless welders (and those using flux-cored wire) can produce 120 Amps for shorter periods (or duty cycles), whereas industrial welders produce on average 250 Amps and this widens the scope of their use. This is the rated max amp output, but you’ll find dials and settings to vary the output needed for each job.
Amps are also directly related to the input voltage. Most welders are single-phase, meaning they run on 240V and use inverters to change to stable DC output. Three-phase welders, on the other hand, are large powerful welders running on 415V and are limited to large industrial applications due to their cost.
This is the amount of time the welder can produce a stable electric arc at a rated amperage before it overheats. Again, high amperage is necessary for heat generation, and lower-end welders can struggle here, meaning more downtime. This is fine for simple welding jobs where time isn’t an issue, but when you rely on welding to pay the bills, welders with higher duty cycles make more sense.
Most MIG welders are fine with mild steel, but step up to stainless steel, aluminium or titanium and you need a more powerful welder to get decent-looking welds. The thicker the metals also mean the harder the work. Mid-range welders are good in automotive repair jobs, and light industrial tasks for shorter periods, but still do a good job. If you also need a stick or TIG welding capability, then choose a combination welder for a slight premium.
Spool Guns, Gas Regulators, Hoses, Cabling, Torches and More
Spool guns are attachments with wire necessary for welding aluminium and even the most basic MIG welders are spool compatible and with dedicated switches. Standard torches used in ferrous metals come in three types – Binzel, Tweco or Bernard style and are connected with cabling to the output in the welder. The majority of welders are also both the gas and gasless type, meaning some applications can be done with fluxed electrode wire only. Where inert gases come into play, there are gas regulators on the welder to control the amount of inert gas reaching the torch and weld pool and supplied from separate cylinders via gas hoses. Basic welders include shorter hoses (2m in length) and power leads, as well as torch and stick hoses (in combination welders) limiting portability. Spending a little more get you a more powerful MIG welder, with better additions, more choice and range in different tasks, and what’s most important – tough, durable and good-looking welds.