A Guide to Electric Welders
Tom Vondrasek | 10th May 2024 | 6 minutes to read
Electric welding uses electricity to generate heat to fuse metal together. Besides the electricity, it also requires a donor metal or filler rod to help weld the metal together. Electric welding, unlike gas (oxygen, acetylene) welding concentrates the heat into a small area.
It is very intense, and you can't leave it in the one spot for too long, otherwise it may burn a hole into what you are trying to weld. The other issue is that metal is a good conductor of heat and too much heat may distort the metal. This is one of the main issues with trying to gas weld thin steel sheets.
The best advice when getting a new welder is to get two metal offcuts or something similar to the welding job you want to do and practise. This teaches you the welder and how to set it up.
Most of the new welders, like the Cigweld range, come with presets where you enter the metal thickness and your filler wire diameter, then the welder sorts out the rest for you. While the welder does some of the work here, welding is still a practise makes perfect job, so practising for novices is essential.
The Welders
There are 3 main types of welders that can be used to fuse metal together. Before going into these it is important to understand welding flux and why it is needed as well as some basic electrical theory.
Welding Flux
Welding flux is required to shield the weld from the atmosphere. Not using flux can cause the weld to be weaker and more porous. When welding, metal is turned into a hot liquid pool and if open to the atmosphere it basically gets contaminated. Flux creates a gas bubble or protective shield over the molten pool of liquid to stop this happening.
There are two ways flux is applied when welding:
- Flux coated or cored welding rods or wire. As the rod or wire is melted to fuse with the material being welded the flux provides a protective shield over the weld.
- The welder adds an inert gas which flows over the weld. The inert gas is usually comprised of Argon with a combination of other gases.
Basic Electrical Theory
Electric welders rely on an electrical circuit to work. This is not the power point you use to plug in the welder. It is the welding itself that requires an electrical circuit. You basically have two leads that come from the welder. One has the welding torch, the other has a clamp. The clamp as is known as earth or ground. The power comes from the welding machine, through the torch, in through the job being welded to the earth clamp and then back to the machine to complete the circuit.
Welding is like lightning. The electricity jumps the gap from the torch to the job being welded and this generates the intense light and heat which melts the metal. This is why it is important that the earth clamp has a good connection to the job and is ideally close to the point being welded.
3 Main Welder Types
Stick Welder (Arc Welder)
The earliest form of electric welding. You clamp a flux coated rod into the torch. It looks like a stick and that is where the name comes from. Strike it on the surface to be welded and away you go.
There are different sizes and types of flux coated rods depending on the type of metal (mild steel, stainless steel, cast iron) you are welding and its thickness. Stick is good for welding solid heavy metal parts on trailers, chassis, gates, and farm equipment. It can be used outdoors as its not affected by wind.
Metal Inert Gas (MIG) Welders
A MIG welder works much the same way as a stick welder. The big difference is instead of a stick or welding rod it uses a spool of wire. The spool of wire is held in the body of the welder and the torch has a button on it. When the button is pushed, it feeds the wire onto the job by running through the torch cable and out through the head of the torch. It strikes the arc causing the welding process to begin. Having a spool of wire means you can do a longer continuous weld when compared to a stick.
Gas and Gasless Wire
The difference between gas and gasless wire when used in a MIG is as the name suggests:
Gas means it is a bare metal wire and you need to use an inert gas as a shield when welding. This is normally supplied in a pressurised bottle which connects to the welder. When the torch button is depressed it not only feeds the wire onto the job it also feeds the gas onto the job.
Gasless means the wire is coated in a flux and there is no need to use an inert gas when welding. The flux coating on the wire provides the shielding.
Both wires can run through the same torch. All MIG welders are set up to run the inert gas. The pressurised gas bottle is normally available separately, just like any other welding consumable.
Depending on the wire used, MIG welding can be used on a lot of different metals. Using the gas seems to give greater flexibility in what you can weld. For example, car panel work is best used with gas as the metal wire is thinner which means you use less heat when melting it. Less heat means less panel distortion.
Tungsten Inert Gas (TIG) Welders
A TIG welder works like gas welding. It can fuse two pieces of metal together without the need of a rod or filler wire. It does this by simply heating up the metal, causing it to melt together. Although it can do this, in most cases you will need to use a filler wire when welding.
The TIG welder is different from a MIG as it has no wire feed through the torch. The torch has a tungsten electrode in it that strikes the arc. Note that it will slowly wear out in time.
The person welding feeds a filler wire in with one hand while holding the torch in the other. This is exactly the same as gas (Oxy Acetylene) welding where the gas torch is now replaced by an electric one. The TIG needs to use an inert gas when welding which, like the MIG, flows through the torch. This eliminates the need to have flux on the filler wire.
Like the MIG, the TIG can be used on all sorts of metals, you just need the correct filler wire. The other thing to watch for is whether the TIG is an AC or DC welder or can do both. TIG DC welders are good mild steel and stainless-steel welders, while AC welders are better for aluminium or non-ferrous metals.
