One of the most overlooked causes is the use of incorrect wire liners. The wire liner is often thought of as the simplest component in the MIG gun assembly but can often prove to be the most important and has a dramatic effect on welding fabrication downtime.

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So let's talk about your liner size. There is a debate over how large your wire liner's inner diameter should be in relation to your wire size. There is the belief that using a larger wire liner will provide less resistance if you're going to use a smaller wire. So let's say you use a 035 wire and you also use an 052 wire. Well, maybe you would just use a 52, 62 liner so you could fit both those wires through. The smaller wire, like an 035, it has less column strength, so it can wander inside that larger liner. It can buckle under pressure. It also can cause the liner to wear prematurely because it's rubbing excessively against the liner, and it can also lead to some serious maintenance issues like bird nesting and then also even jamming inside the liner. These are both really maintenance intensive things to have happen. It causes a lot of downtime, wastes a lot of wire, especially the jamming. You really don't want something like that to happen and you can generally avoid it by just using the right size liner in relation to your wire. Diligent maintenance on your wire liner is another important consideration that you want to make. It's a really easy process to do. You should do it after every spool change on your welding machine. Just when you take that torch offline to do that spool change, remove the wire, obviously, from the liner. Also, remove the contact tip and the diffuser from the front end. Use a compressed air liner, put it up against the collet, blow that compressed air through the liner, and then you'll extend the service life of the liner as a result. Let's start with steel, which is going to be the most widely used wire liner material you're going to see out there, and for really good reason. Steel has a really good balance of flexibility and rigidity and performance and it's also a very cost effective option. It can, however, pose problems with a stainless steel wire or a chrome alloy, reason being is that kind of wire can produce excessive wear and increased resistance on the wire liner itself. One tip on that now that we're on the subject of resistance is a lot of operators will try to overcome resistance problems on the wire liner by trying to clamp down tighter on the drive rolls on your welding machine. Not a practice that we would recommend, mostly because it can distort the wire and then also, instead of keeping the wire from slipping inside the wire liner, you can actually pierce the wire through the coil and through the cable in the event of a burn back, which can cause a really big safety hazard, so definitely don't want to try to do that. You also have other wire types like aluminum and silicon bronze. Those are also not considered really good fits for a steel wire liner, reason being is because those wires are very soft and they're a little bit more delicate we should say, for lack of a better term. And so, what happens inside of a steel liner is that it'll be a higher level of resistance. They'll also, with those wires, can cause abrasion inside of the liner and then the steel liner can also introduce contaminates into your weld as a result of welding with those kinds of wires, so definitely don't recommend using a steel liner if are going to weld with those sorts of wires. I'd recommend one of the other materials. Another kind of steel liner that you'll see a lot is an insulated steel liner. It looks virtually identical to the standard steel liner with the exception of this little laminate that you see kind of over the coils and the reason for that is because of how the gas is introduced into your MIG gun. So with a steel liner, you're gonna see a dedicated gas port, dedicated gas line, through your MIG gun and it's gonna feed gas all the way to the front end. With an insulated steel liner, gas is actually introduced through your torch cable and around your wire liner so this laminate actually works to protect your liner from having gas permeate through the coils and then purge out the back. Depending on your torch make and how it's made is going to dictate whether you use a standard steel liner or an insulated steel liner so check with your MIG gun OEM, they'll have that answer for you. It's very clear based on how the torch is built. Beyond the steel liners, which are very cost effective and very popular, there's also plastic liner options that you can use as well. They all look very similar but let's go over how each of them are a little bit different. So first one here, we have a polyamide liner.

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