Choosing the right MIG gun is as much a personal choice as it is about performance
by Nestor Gula
Welders always remember their first MIG guns and it forms their preferences for future MIG guns. “Generally, most of the operators that go through any formal training will weld during their training with a certain type of gun,” says Jeff Henderson, global business manager, torches and exothermic cutting systems for ESAB. “So, they’re kind of hooked on that gun because they don’t know any difference.”
The personal preference of a certain type of welding gun does have a great impact on work efficiency and performance. A weld operator will not be as efficient with a tool that he is not comfortable with–after all, it’s the operator that will be holding the gun for six to eight hours a day, producing quality welds. “There are some personal preferences that come into account. For example, the handle shape can have a significant impact on a welder’s comfort. Some welders prefer the ergonomic, or curved handle shapes, which are designed to fit more comfortably in the hand,” says Nicole Corbin, associate product manager, guns and torches from Lincoln Electric. “Others prefer the barrel, or straight handle style, which allow for the gun to be held in multiple positions.”
A weld operator’s personal preference is only one of the deciding factors when selecting a new welding gun. “Welding operators may have a specific handle type they like–curved or straight–and may prefer consumables that screw into the front end of the gun or they may like tool-less parts that slide or drop into position. It’s also important to understand the environment in which a welding operator is welding,” says Jerome Parker, product line manager for Bernard. “Performance may differ between welding guns, but the key is to have a product that is appropriate for the work that needs to be done. For instance, you can’t weld 1/8-in. plate with a 200-amp gun. It will overheat. So, make sure the performance of the gun fits the application first. Preference is secondary.” It is important that you understand the material being welded and the amperage that will be used to successfully complete the welds. “Then, look at features that ensure the welding operator is comfortable and can perform the task at hand. MIG gun weight, as well as the ability to access weld joints and gain proper visibility to the weld joint, are all considerations,” he says.
All MIG guns are rated by the amperages that they can be used with and a duty cycle. “There are some that are rated as low as 20 per cent,” says Henderson. “Normally you’re looking at 40, 60 and 80 per cent duty cycles. You don’t want a gun if it’s been in an application that has a fairly high duty cycle and amperage. They can overheat if the design or the manufacturer didn’t include enough of the copper material to run cool.”
Properly selecting the right amperage for the application is critical–choosing a higher amperage rating than needed might not be a good decision. “If you select a gun with too high of an amperage rating, it can be heavier than necessary. Your gun rating does not have to match your machine, just the specific application you are working on,” explains Corbin.
Another important feature of the MIG gun is its robustness. “A MIG gun is used, and unfortunately, abused, more frequently than many other tools, and it is important that the gun is designed to be up to the task,” says Corbin. “Look for a durable plastic handle and internal bolted connections, which tend to last longer than crimped connections and are easier to repair.”
Another thing to consider are the consumables–nozzles, contact tips, and diffusers. “They should be durable and high performing. A simple contact tip can change weld performance drastically, so it is important the expendables that are compatible with the chosen MIG gun are proven to have lower resistance and higher wear qualities,” says Corbin.
When welding at very high amperages, a water-cooled MIG gun may be a good choice. “Water-cooled guns are good for welding at very high amperages on thick base material where longer arc-on time is required. These guns are available in 400 amps or more and are good for long, continuous welds,” says Parker. “If a company is exceeding the standard for arc-on time, which is nine and a half minutes in a 10-minute duty cycle, a water-cooled MIG gun would be a fit. When companies make the switch to a water-cooled MIG gun, it’s important that the welding operator who uses it is properly trained in procedures for turning the water cooler on before activating the welding gun’s trigger, otherwise premature failure of the gun is inevitable.”
Water cooled MIG guns come with their own set of complications, however. “The biggest apprehension most people have with purchasing a water-cooled MIG gun is that you are introducing more connections into your welding system, which means that there is a higher chance that something could leak,” says Corbin. “The last thing anyone wants in their fabrication shop is water running everywhere. Additionally, water coolers require routine maintenance to assure that bio-growth does not clog up the system.”
On a health and safety front, MIG welding guns that have a fume extraction system incorporated in it are a viable option.
MIG welding aluminum presents its own issues for MIG guns. “Aluminum wires don’t have the columnar strength of other wires, making them more difficult to feed with a standard MIG gun,” says Parker. “Spool guns are generally used for aluminum welding with smaller wire sizes.” Spool guns generally have small, one pound, spools of wire mounted on the gun. “If someone was frequently switching between multiple types of materials, then a spool gun may be a good solution as the wire is very easy to change out,” says Corbin. “However, spool guns can be more cumbersome than a traditional MIG gun. Another option would be investing in a dual drive feeder, which would allow you to set up two guns off the same feeder and would not require any effort to switch from one to the other.” Push-pull guns are also utilized for aluminum welding. “A push-pull gun can aid in feeding any wire, but it is primarily used for aluminum welding with smaller wire sizes,” says Parker. “Most welding operators would not want to use these guns unnecessarily because they are heavier than a standard MIG gun.” A push-pull MIG gun can have uses when the gun wire is very long to assist in feeding the wire. “It would be helpful to that motor to assist the feeder that’s 50 feet away to get that consistent wire feed to the weld pool,” says Henderson.
Companies and welders typically upgrade their MIG guns because they need a gun in a different amperage range or duty cycle than the one they currently have.
“Manufacturing shops may be interested in seeking out MIG guns with premium expendable performance. This decreases the amount of time welders take to change over contact tips and nozzles, and in turn, increases productivity,” says Corbin.
There are a lot of gun solutions to choose from since most manufacturers can make MIG guns for use with any brand of feeder, “provided the gun has the proper trigger control wire and power pin interface,” explains Parker. “The exception would be a MIG gun that is system specific, such as one paired with a welding information management system that is designed to provide data feedback about arc-on time or quality metrics.”
Taking care of your MIG gun is a fairly simple. The weakest link is the cable itself.
“As the wire is fed through what we call the conduit liner, it’s bringing in flaked particles of that liner, and
it can clog and even chip it,” says Henderson. “It can get so bad that it can affect the feed through the liner itself. So proper maintenance to ensure everything’s clean is important.”
Making sure the connections are all tight will prevent the gun from overheating. “Check that the connections are tight throughout the gun to reduce the opportunity for electrical resistance,” says Parker. “Keep the MIG gun and cable as straight as possible during welding to avoid kinking that could lead to tears in the outside of the cable.”
Adds Lincoln Electric’s Corbin, “while welding environments are typically not pristine, and sparks and spatter are unavoidable, it is important to utilize all equipment as it was intended. Be aware of how often you are dragging your gun cable across sharp metallic edges, as this will wear the cable over time.” SMT