The FAQs about MIG gun nozzles and contact tips

The MIG gun nozzle is arguably the most visible of the consumables; the nozzle guides the shielding gas to the weld puddle and protects internal components from spatter.

The MIG gun nozzle is arguably the most visible of the consumables. The nozzle plays multiple roles in the MIG welding process. It guides the shielding gas to the weld puddle and protects internal components from spatter.

One of those internal components is the contact tip, which guides the welding wire accurately and repeatedly to the weld joint. The contact tip is where the actual energy transfer happens between the gun and the wire.

Andy Monk, product manager for Bernard, and Ryan Lizotte, technical service manager for Tregaskiss, break down the relationship of these two important MIG gun components and discuss what to consider regarding materials, types, shapes and sizes, and user tips (no pun intended).

TW: What material are MIG nozzles most commonly made from?

Andy Monk: I would say brass and copper are the most popular. On lower-amperage applications, most people want brass nozzles to help eliminate spatter adhesion. When you get up to higher amperages, maybe 300 amps and above, you see people generally migrate to copper because of heat. Higher amperage equals higher heat, and copper generally stands up to that heat better. If you heat up brass enough, it’ll begin melting and distributing itself into the puddle, which you definitely don’t want to do.

TW: What are the pros and cons of using a brass nozzle or a copper nozzle?

Ryan Lizotte: You’ve got to pick the nozzle for the application, that’s generally the dividing line. Copper for heat, brass for spatter. You’ll know very quickly if you picked the wrong one. The nozzle will be caked in spatter or start to soften up and melt into the puddle.

TW: What about the types of MIG gun nozzles? Welders have multiple options at their disposal.

RL: I think there’s a lot to this one. You can say that thread-on and slip-on are the major nozzle styles. Generally, it boils down to the user’s preference. Sometimes the feeling is if I thread it on, I know it’s seated all the way; I may feel it’s a stronger connection and it’s an extra step to do. A slip-on is very convenient; if you’re pulling your nozzle on and off a lot, a slip-on is much more convenient than a thread-on.

And then we get into nozzle shapes and lengths and bore sizes and outside diameter [OD]. There’s a lot of categories you can filter through to pick your nozzle. The vast majority of them will ultimately come down to user preference, outside of material selection.

MIG gun nozzles and contact tips are two consumables that play important roles in the MIG welding process. Two Rivers Marketing for Bernard/Tregaskiss

AM: Some of that preference is driven by application. Sometimes you’ll use a tapered nozzle—a smaller-bore nozzle to reach a joint you need to weld as opposed to a larger nozzle. Or, if you are dealing with high heat, a really wide joint, or really high deposition rates, you might use a bigger nozzle to make sure the larger weld puddle is adequately covered by shielding gas.

TW: Let’s now talk contact tips. What are they made from? Which ones are the most widely used?

RL: There is some user preference involved here, but when it comes to contact tip solutions, I think we’d need to give more guidance based on the application. We have certain solutions that we know are best suited for welding with solid wire, solutions that may be better for cored wire, better for CV welding versus pulse welding.

The general materials that are offered for a contact tip are a copper tip or a chrome-zirconium tip, which is a hardened version of a copper tip. There’s also another tip made out of a different material that’s designed specifically for pulse welding and automation applications. Depending on the application or wire size, you might get different contact tips.

AM: Access and application can play a role too. You’re always going to want a contact tip that’s compatible with the consumable family you’re using. In terms of access, if you’re using a tapered nozzle to reach something tight, use a tapered tip.

TW: Is it better to go bigger or smaller with contact tip sizes?

RL: We do have different OD contact tips, you just have a larger cross section of material. Generally, those are mostly used in very-high-amperage situations—you know, 500 to 600-plus amps, sometimes water-cooled. The more mass at the front end helps deal with all the heat that’s being generated and keep everything cool.

With wire size, the size of the tip is driven by the type and size of wire you’re going to use.

AM: You’re hearing us say application-dependent a lot, but that’s kind of how the consumables game works. When you get into that commercial realm, you’ll see tips of smaller outside diameter—less copper, less current-carrying capacity—because they just don’t need to be as big. Sometimes it’ll cost a little bit less.

RL: If you’ve got a tip that’s not properly matched to the application, you’re going to be burning through tips from either mechanical wear or overheating. It’s just not up to the task.

MIG guns and their components, like the nozzles and contact tips, require routine maintenance, whether it is for hand-held or automated welding operations.

TW: What is the proper contact tip recess or stick-out in relation to the nozzle?

RL: If we’re going to use broad strokes here, I would say a recess is generally used in semiautomatic or hand-held welding, and a stick-out is generally used in automated welding. The reason for that is when someone is holding a gun and the tip is sticking out of that nozzle, if you touch the tip to the workpiece while the trigger is pulled, you’re going to short it right to the weldment or table. Because of that human element where I can control how close or far away from the puddle I am, it is a little riskier to have that electrode exposed and able to touch the workpiece. A nozzle with a tip recess can prevent you from touching the tip to the workpiece. Whereas in an automated application, because it’s highly repeatable using a robot or some type of equipment in a repeatable fashion, I’m not so worried about accidentally touching that tip to the workpiece. It allows me better access with the tip being stuck out of the nozzle, and I’m not worried about those accidental shorts happening with my contact tip.

TW: You both have discussed hand-held and automated welding. Have you noticed a shift in how a robotic MIG gun goes through these consumables?

RL: How tips are used in different applications is something we’re aware of. It’s what has led us to some of the contact tip development. [Tregaskiss’ HDP contact tips] were developed because we had customers saying, “Hey, now that we’re using pulsed waveforms in 90 to 100% of our applications, our tip wear has gone through the roof.” Tips are failing more because pulsed welding is much harsher on consumables. The same type of failure happens in a hand-held operation; the operator isn’t going to notice that because they can compensate for the wear.

There are still significant things that a robot cannot do that a person can. It causes a huge pain in the automotive world when a weld is off-position over and over again. Because of minor wear on different components, a robot can produce welds off-position, whereas if a person is welding those parts, they are never going to be complaining about the minor wear.

TW: How can nozzle and contact tip selection ultimately impact the bottom line?

AM: If the nozzles or contact tips you’re using require shutdown for maintenance at a greater rate than other available nozzles or contact tips, then obviously you’re not getting as many parts out the door.

TW: What advice do you have to properly maintain contact tips and nozzles to make them last?

RL: A very basic one for me is that you leave your consumables in the packaging until you’re ready to use them. We go to a lot of places where people have pockets full of contact tips and they’re just everywhere. You get debris inside of them, they start to oxidize once you take them out of the packaging. There are all these things that can happen that may contribute to poor consumable performance—and it’s just because you tore the bag open as soon as you got them.

AM: From a hand-held perspective, I would say this: A MIG gun should not be used as a hammer. Using it as a hammer or banging a hot nozzle on another hard surface to remove spatter buildup will deform the nozzle and it’s just not going to perform as well.

I would also suggest cleaning your parts every now and then. Routine maintenance goes a long way. A lot of times, [maintenance] is built into a program in automated welding. It can also benefit hand-held applications. Every now and then, remove the nozzle, clean off the spatter that's built up on it, the gas diffuser, and the contact tip. That’ll go a long way to increasing the life of your parts.

RL: Grounding is another one that we deal with all the time. People will have erratic welding, create a lot of spatter. A lot of times, it’s related to grounding. You put all those consumables on the front end and they’re all really tight. You’re passing a lot of power across these parts, and if you don’t have good solid electrical connections from one part to the next, it’s going to create resistance, which creates heat. It will overheat those parts, performance will suffer, and consumables life is going to suffer as a result.

AM: While not replaced as often as nozzles and contact tips, liners are also an important replacement part.

RL: I think [nozzles, contact tips, and liners] go hand-in-hand. The liners are often more forgotten about than the tip or nozzle.

AM: There are a number of different types of liners. Two critical things to know: Make sure you have a liner that’s compatible with the wire size you’re using. No. 2, make sure it’s trimmed correctly. Trimming it incorrectly may result in the liner not being optimally positioned behind the contact tip, which can create a lot of weld issues, from wire chatter to excessive burnback and spatter.

RL: Trim it to the right length, make sure it’s the right size. Don’t forget about it. It’s not supposed to be there forever, it is a consumable.