There are many types of welders available. In this section, we cover the three most popular ones: MIG, Arc and TIG welders, and explain what inverter and MMA welders are. 

Each type of welder uses a slightly different welding process. As a result, they require different skill levels and vary in speed, control and the types of materials they can be used to weld.

MIG welders explained

MIG is an acronym for Metal Inert Gas. MIG welders work using an arc welding process with a continuous solid wire electrode that’s fed automatically through the welding gun at a constant pre-set speed. The electrode melts with the metal workpiece to create a weld pool that’s used as a filler metal to form the joint. 

There are two ways that a MIG welder can produce a shielding gas to protect the weld pool and metal from reacting with airborne contaminants. First, the welding gun can feed gas from a canister alongside the electrode. Or a flux-cored wire electrode containing a shielding gas releasing material can be used.

MIG welders are perfect for beginners because they are easy to use. They produce a neat and clean weld with no slag (waste material), so there's less post-weld cleaning required. They deposit the weld pool at a higher rate than other types of welders, so welding tasks can be completed in less time. And the continuously fed wire electrode means less time is wasted compared to welders, where you must frequently stop to change the electrode. In addition, the flux-cored electrode option works well on dirty or rusty materials, but the continuous wire electrode method requires the base metals to be clean before welding. 

There are also a few disadvantages. Such as, the initial set-up and maintenance costs are high. They can only be used in non-draughty conditions (so they can’t be used outside). And they are less efficient if you need to use them for long periods due to their low duty cycle (i.e., the amount of downtime they need to cool down between uses).

MIG welders are best used for joining steel, stainless steel and aluminium in a wide variety of thicknesses.

What gas is needed for a MIG welder? 

Argon is the best gas for MIG welding. It can be used on its own or mixed with one or two other gases such as helium and carbon dioxide to allow deeper penetration into the metal.

Are MIG welders AC or DC?

MIG welders use a DC current for welding, providing a smooth welding output, less spatter (metal particles thrown out as it welds), and a more stable arc. 

MIG welding diagram
A MIG welder is made up of the following features and functions:

• Welding machine: this plugs into an electricity supply and feeds the electrical current into the base metal and electrode.
  Ground clamp: this is attached to the base metal and is connected to the welding machine by a cable.

• Welding gun: this is connected to the welding machine via a cable.

• Gas nozzle: this runs through the welding gun to supply the shielding gas. It’s connected to a gas canister.

• Contact tube: this copper tube runs through the welding gun and supplies the electrode with an electrical current.

• Consumable electrode: this runs through the contact tube.
  Arc: the electrical current that jumps between the electrode and the base metal to create extreme heat.

• Welding pool: the molten pool of metal created by the electrode used to form the joint.

• Gas shield: the protective layer of gas surrounding the welding pool.

Parent and weld metal: the two pieces of metal which are being joined together.

Arc welders are also known as stick welders. They use an arc welding process with a metal stick or rod electrode as a filler metal. The sticks are covered in a flux material that releases a shielding gas as it's melted to protect the molten weld pool from contamination. The sticks are available in different diameters and lengths, and it's essential to use the correct type for your application.

Arc welders are simple to use and easy to learn, so they are ideal for anyone with little welding experience. The arc is not affected by wind, so it can be used outdoors and inside. And they also work well on dirty or rusty metals, meaning no cleaning is required before welding. Another advantage is that the absence of an inert gas supply makes them cheaper to use and easily portable. And the sticks are quick and easy to change, so they're ideal when frequently switching between different welding tasks.

There are a few disadvantages of an arc welder. For example, this type of welding deposits slag (waste material) onto the joint which must be chipped or scraped away as you work. And while the filler stick is easy to replace, it has to be replaced every few minutes. So, constantly stopping work to clean the slag and replace the stick makes working with these welders relatively slow. Arc welders also create more spatter (metal particles thrown out as it welds) than a MIG welder. 

Arc welders are best used for joining steel, stainless steel and iron and are designed for jobs such as repairing pipework or equipment or fabricating metal shapes. However, they aren’t suitable for welding metals thinner than 1/8”.  

TIG welders explained

TIG is an acronym for Tungsten Inert Gas. It’s similar to a MIG welder, except, instead of using a consumable solid wire electrode as a filler metal, it uses long non-consumable tungsten electrodes to directly fuse two metals together. TIG welding can use both a DC current and an AC current.

TIG welding gives the welder greater control over the process to create a very high-quality weld. However, it's a more complex and difficult process to master than other types of welding and is significantly slower. And, because there's no filler metal, it can only join thin metals. The process doesn't produce any slag to clean away after welding, but the base metals must be very clean and well prepared before the welding starts, as any type of foreign matter will contaminate the weld.

TIG welding can be used for metals such as steel, stainless steel and iron, but it’s best suited to non-ferrous metals such as titanium, aluminium, magnesium and copper alloys.

Inverter welders explained

An inverter welding machine is a type of MIG or arc welder. Traditional welders use a transformer to power their engine, whereas modern welders use an inverter. Inverter welders are used to efficiently convert electrical current from AC to a usable DC, more suited to welding. The old transformer power units are cheaper and less complex than an inverter, but they are heavy and overheat more quickly.

The benefits of an inverter welder are that they are smaller and lighter in size and have a higher duty cycle, meaning they can weld for longer periods before needing time to cool down. They are also more efficient to run, and their power can be adjusted to suit different types of welds. 
The only downside of an inverter welder is its complex circuit board, so if it fails, the whole board must be replaced.

What is an MMA welder? 

MMA is an acronym for Manual Metal Arc. An MMA welder works similarly to a MIG or arc welder. But, instead of using an automatically fed wire electrode as a filler metal, it requires the operator to manually apply a filler metal as they weld.