Wire feed welding is just another name for MIG welding. The basic idea behind wire feed welding is that you use a welding wire that continually feeds through a MIG welding gun when you squeeze the trigger.
This is a continuous welding process. As long as you keep your finger on the trigger and the welding wire touching the base metal you will be able to wire feed weld all day. There are many different types and brands of welding wire that you can use for many different welding applications.
The most commonly used welding wire is more than likely an AWS ER70S-6 classification wire. This particular class of wire is used in virtually all welding and fabrication shops for many different types of welds. I highly recommend using a precision layer wound welding wire as opposed to a random wound wire.
A layer wound spool of wire will be evenly wound onto the spool from left to right with each layer of wire neatly sitting next to the other. This makes it a lot better for wire feed ability as there will be no bends and small kinks in the wire.
Random wound wire will be just random wound onto the spool in any old-fashioned. Because of the way that the wire is randomly wound on the spool, the wire will cross over itself a few times. And as the spool starts to fill up with the wire, every time there is a crossover of the wires it can make a small bend in the wire.
These small bends in the wire can affect your findability which in turn will affect your overall weld quality.
When using a MIG machine or a wire feed welding machine you will also have welding consumables that need replacing regularly. Every MIG welding gun will have a contact tip and a shroud or a nozzle. And then depending on which brand of welding torch you have there will also be a gas diffuser or some kind of insulator. Some brands of wire feed welding guns like the Bernard range will have the gas diffuser built-in with the tip holder.
I guess that most DIY or home welders will use what is called a gasless welding wire. This is also known as a flux-cored wire. Be careful though because there are two different types of flux-cored welding wires. Well actually there are a lot more than two, but for general home, welding makes sure that you get a gasless MIG welding wire that is an E71T-GS.
Now if you do decide to use a gasless MIG welding wire you are going to have to change the wire feed rolls. The reason for this is because it is a flux-cored wire the wire is not solid all way through. So because the flux is on the inside of the wire the wire is very soft.
If you use your standard feed rolls you will see that they are shaped with a vee groove in them which is what you want to use if you are using solid wire. The problem is that if you use the same feed rollers on your softer flux-cored wire you will find that the wire gets squashed and this can lead to all sorts of wire findability issues so to solve this problem you need to use what is called a knurled feed roller. The knurled feed roller has, like, many small teeth in the grove of the feed rollers. These little teeth help to grab the softer wires and give it traction and push it through the whole length of the welding gun.
Finally, you’re going to have to use a slightly larger contact tip for when you use a flux-cored wire.
So if the wire diameter is for argument sake 0.9 mm you want to use a 1.0 mm contact tip. This will greatly help with the smooth feeding of the wire and allow better welding.