Looking for help when selecting a MIG gun?
By Ross Fleischmann, Senior Brand Manager, ESAB
There's plenty to consider when selecting a MIG gun for your application. From operating cost and conventional versus advanced consumables design, to ergonomics and durability, choosing the right MIG gun impacts weld quality, operator comfort and system productivity. Here are 10 key questions you need to ask in your search for the MIG gun that's best for you.
Q: What is the operating cost of the MIG gun?
A: More than any other factor, consumables life — especially that of the contact tip — dictates operating costs. Some fabricators may be tempted to save a few pennies on cheap tips imported from Asia, but they can cost more in the long run not just because of their shorter life, but also because of downtime associated with tip changes and more frequent burnbacks.
Today, the longest lasting tips available — Velocity™ consumables from Tweco®, an ESAB brand — feature gas ports that enable shielding gas to flow through and over the contact tip and keep it 30% cooler. Keeping the copper cooler means it stays harder and more wear resistant. In higher amperage applications, long-lasting contact tips extend life by 500% or more.
Q: Does the gun use conventional or an advanced consumables design?
A: Conventional consumables deliver conventional results, which may or may not include more frequent contact tip changes and burnbacks, increased downtime, an erratic arc and higher operating costs.
Velocity MIG consumables address many of these problems. Their advanced design includes fewer parts, fewer threaded connections, an all-copper conductive path without threaded connections, contact tips without threads ("drop-in" style contact tips) and contact tips with shielding gas ports that eliminate the need for a diffuser. All these factors combine to extend contact tip life by up to 5x or more, delivering the lowest operating cost possible. It's not uncommon for fabricators to report a single tip lasting for five, eight and even 12 44-lb. rolls of wire before needing to be replaced. Other benefits include a more stable arc, fewer burnbacks, the ability to remove a burnback without tools and lower inventory costs.
Q: Do you need an ergonomic handle, and what constitutes "ergonomic" in a particular application?
A: For applications that call for laying weld beads with a weaving motion of the MIG gun, a paddle-shaped MIG gun handle that fits naturally into the palm of the welder's hand will help reduce hand fatigue. For these applications, a gun such as the Tweco Classic is considered ergonomic. In other applications, such as in all-position welding and reaching into corners and tight spaces, guns with a lighter, smaller circumference would be easier to use and maneuver around tight corners and such MIG guns — like the Tweco Spray Master™ are ergonomic for those applications. In any given facility, using several different gun styles might be the most appropriate approach.
Q: How durable is the MIG gun?
A: In high arc-on time, high-heat industrial applications, some MIG gun designs only last six months, where others can last 18 months or longer. Asking other fabricators about their experience with a particular gun model is one good way to get the real story on gun durability.
Leading brands such as Tweco provide guns with premium construction and components. For example, their gun handles feature a single molded tubular construction with few or no fasteners, and the handles are made from glass-filled nylon plus impact modifiers that make the gun tougher or more flexible so that it better resists cracking. Cheap knockoffs use weaker designs and less-durable materials, which is why they don't last as long. Considering the cost of downtime, brand name guns always make better financial sense in the long run.
Q: What's the number one cause of MIG gun failure?
A: Frequently, the gun cable fails first. Hot parts and sharp edges (especially those from laser-cut parts) can damage the cable, and fork trucks may run over cables causing damage to the Cablehoz. To preserve your investment, use some sort of cable wrap or covering in harsh environments.
Secondly, gun liners (conduit liners) also get worn or damaged. In turn, this hinders smooth wire feed performance and will manifest itself as an erratic arc. To simplify liner maintenance and lower inventory costs, use a Tweco "universal" conduit liner, which will work in any brand of MIG gun.
Q: Can I repair the MIG gun myself?
A: That depends on the specific gun model, with some being specifically designed for easy field maintenance without specialized tools. If you're a small fabricator in a remote location, or if you're a large fabricator with a sophisticated maintenance team, you might prefer a gun that permits easy maintenance and installation of replacement parts. The Tweco number series – now the Tweco Classic - became the world's best-known MIG gun design for this reason. Other gun designs have varying degrees of complexity and are not as suited for field repair; notably, guns like the Tweco Spray Master require a specialized tool for crimping electrical connections.
Q: Should I choose an air-cooled or a water-cooled gun?
A: Each type of gun has its pros and cons. Air-cooled guns are simpler and cost less, but the gun and cable will weigh more because of the heavy-duty construction required to dissipate the heat. Water-cooled guns weigh less and use a lighter cable, but the cooling system adds significant cost, requires ongoing maintenance and makes the system impractical for mobile applications.
Q: Should the gun rating match the power source rating?
A:Not necessarily. When configuring a welding system, keep the application in mind. Generally, operators want the lightest gun they can get away with. For example, a gun rated at 350 amps might work perfectly well for welding at higher amperages but at a lower duty cycle.
Q: Do you want dual-schedule capabilities?
A: If you want to be able to switch between two sets of welding parameters, such as for welding in the flat and vertical up positions, consider a gun with a dual-schedule trigger.
Q: Can I use a standard MIG gun for welding aluminum?
A: Yes, with several caveats. First, don't use the same MIG gun you use for welding carbon steel. Rather, use a gun with nylon- or PTFE-coated conduit liner. The coated liners have much lower friction and hence improve feeding performance, and the coating prevents carbon steel particles from rubbing off and contaminating the aluminum.
Second, to prevent the wire from buckling inside the gun liner or bird nesting at the drive rolls, use the shortest gun length possible (10' or less), and keep the cable as straight as possible when welding. Pushing 3/64ths aluminum wire 8' to 10' typically results in smooth feeding adequate for most applications. Often the use of a boom or scaffolding will allow for placing the power supply in close proximity to the work-piece, this also keeps the power supply controls close to the welder. Repositioning the power supply is often the best way to facilitate aluminum wire feed issues and is often much more cost efficient.Third, use 5356 wire if it's compatible with your application, as it has stronger columnar strength and feeds better than the softer 4043. Lastly, for optimum wire feeding performance with minimal downtime, recognize that your application may simply demand a spool gun or push-pull gun for feeding aluminum.
Welder/fitter Jeremy Holloway prefers paddle-shaped gun handles like the Tweco Classic, saying, "Skinny handles you have to squeeze a lot more - it puts a lot of stress on your hand. This gun is nice because you barely have to move your finger to pull the trigger."
Conventional consumables (top) have three sets of threaded connections in the conductor path: the contact tip, gas diffuser and end of the conductor tube. The new Velocity consumable design (bottom) eliminates all threads from the conductor path, improving thermal and electrical conductivity.
Velocity MIG gun consumables feature gas-ported contact tips, which extend consumables life up to 5x or more, minimize gun downtime and lower operating cost.