Practical MIG Welding: Parts of a MIG Welder

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Parts of a MIG Welder

06.08

00:00	When we look at a typical MIG setup, it's pretty obvious that there are many different parts that make up a complete welder.
00:05	To better understand these parts and how they interact with each other, let's run through them one by one.
00:11	Each part of the MIG welder assembly is vital to its operation, but there's none more important than the welder itself.
00:17	Regardless of brand, the welder will most likely have a steel cover that protects the internal electrical components with the welder's inputs in the back and outputs and controls on the front.
00:28	On the backside you'll find an electrical lead that supplies power from our wall socket to the machine, a gas fitting that will allow the connection of the shielding gas and a master switch to power everything up.
00:39	On the opposite end of the machine we'll find our vital controls and adjustments as well as the connections for our welding torch and our earth clamp.
00:47	It's worth noting that you may hear the MIG torch referred to as a gun instead.
00:52	These terms mean the same thing and can be used interchangeably.
00:55	Moving away from the welder itself we have the inert gas bottle which in this case is filled with a mix of oxygen, carbon dioxide and argon gas.
01:03	This is supplied to the machine by a screw on regulator that controls and adjusts the gas flow.
01:08	The job of a regulator is a simple one, but it's vital to the MIG welding operation and we'll look at this more closely as we get further into the course.
01:17	On the side of the MIG welding machine we find a hinged door that reveals the wire drive mechanism and wire spool or reel as it's commonly known.
01:25	The wire spool slips over the mounting spigot and allows the MIG welder's drive mechanism to feed the wire continuously into the MIG torch lead where it makes its way to the nozzle and finally the workpiece.
01:36	The physical size of the wire spool is defined by its weight and what you can use is dictated by the design of your MIG welder and what it can accept on its mounting spigot and within the enclosure.
01:47	Spools range from 900g for the smaller hobby welders all the way up to 15kg for larger industrial welders.
01:55	These weights are referenced for mild steel wire which is the most common material we'll be welding with, but the weight will vary for different materials such as stainless steel and aluminium, but the spool size will still be the same.
02:08	We also have a few options in the diameter of the filler wire ranging from 0.6mm up to 1.1mm.
02:14	For the purposes of motorsport MIG welding though, we'll be dealing with either 0.8 or 0 .9mm.
02:22	The wire drive mechanism has a pair of rollers that are gear driven to accurately feed the wire at a speed that is set to your requirements.
02:29	To do this, the rollers have been engineered so that they hold the required diameter of wire and grip it just tightly enough so that it won't crush the wire or cause it to slip which will result in inconsistent wire feed.
02:40	This is one of the most important aspects of a MIG welder's construction and having a reliable wire feed mechanism and understanding how to adjust it properly will greatly improve your MIG welding results.
02:52	It's at the front of the machine that the filler wire, inert gas and electrical current all exit into the MIG torch lead.
02:58	This lead runs all the way to the MIG gun which has a finger operated trigger that starts and stops the welding process.
03:06	With the wire now driven through the torch lead and into the gun, it exits through the contact tip and out to the workpiece.
03:13	This contact tip has a very important relationship to the MIG wire.
03:17	It's made from soft copper, screws into the MIG gun and must match the diameter of the wire that we're using.
03:23	This is because the electrical energy or current is transferred to the wire through the contact tip.
03:29	Matching the diameter of the contact tip to the diameter of the filler wire will ensure good electrical conductivity.
03:35	If we don't correctly match these and run 0.8mm wire through a 0.9mm contact tip, we could see an intermittent energy transfer into the wire causing problems with the resulting weld.
03:48	Remember the drive rollers and how important it is to get the right tension on these? This has a relationship with the contact tip as well.
03:55	If we put too much tension on the rollers, we can crush the wire, causing it to drag through the contact tip which will not only affect our wire speed, but it can also affect the contact tip's ability to conduct current reliably into the wire.
04:09	I don't want to get too deep into the specifics just yet, but once we get the machine set up, you'll see that by employing a few tricks of the trade we can quickly and easily set the wire tension without too much hassle.
04:21	Surrounding the contact tip is the gas nozzle which directs the inert gas over the contact tip and onto the workpiece to shield the arc and the weld pool while we're welding.
04:30	To complete the electrical circuit we also need our earth clamp to be plugged into the machine and attached to our workpiece.
04:37	It's important to note here that while different brands of welder may look different to one another, the components will remain mostly the same between brands and these components are designed around readily available consumables that will need to be replaced on a regular basis.
04:51	The key consumable in Amig welders is of course the welding wire, however the contact tip and the gas nozzle may also require semi regular replacement too.
05:00	All these consumables will be available from your local welding supply store.
05:04	Let's summarise what we've covered in this module before finishing up.
05:08	The core of the mig welder's assembly is the welder itself, protected by a steel cover and featuring inputs at the back and controls on the front.
05:17	The backside houses an electrical lead for power supply, a gas fitting for shielding gas and a master switch, while on the other end we've got essential controls, our welding torch connections and an earth clamp.
05:28	The inert gas bottle, regulated by a screw on regulator contains a mix of gases like oxygen, carbon dioxide and argon.
05:37	A side door reveals the wire drive mechanism and wire spool.
05:41	The wire drive mechanism with gear driven rollers ensures precise wire feeding.
05:46	The mig torch lead carries the electrode wire, inert gas and welding current to the hand operated mig gun.
05:53	The contact tip at the gun's end matches the wire's diameter for good electrical conductivity while the earth clamp completes the circuit and the gas nozzle directs shielding gas over the weld pool.