Selecting the Right Gun for MIG Welding Is Key to Achieving the Best Results

The MIG welding process offers many benefits for various applications and industries, including fabrication, manufacturing and general maintenance. It’s one of the easiest welding processes to learn and offers good control on thin metals. Because MIG welding uses a spool to constantly feed a wire through a welding gun, it doesn’t require frequent stopping as with stick welding. This feature makes it an efficient process that offers faster travel speeds and productivity benefits.

The versatility and speed of MIG welding also make it a good option for all-position welding on various metals, including mild and stainless steels and aluminum, in a range of thicknesses. In addition, it produces a cleaner weld that requires less cleanup than stick or flux-cored welding.

Selecting the right gun for the job is important to achieving good results and realizing all of the benefits MIG welding can provide. The choice of gun can have a significant impact on productivity, downtime, weld quality and operating costs, not to mention welding operator comfort. This article discusses the options to consider in selecting the appropriate MIG gun for the job.

Selecting the right amperage

Amperage and duty cycle rating are both important considerations, but keep in mind that when it comes to amperage, bigger isn’t always better. Selecting a larger amperage gun than necessary for an application can cost money upfront and cause operator discomfort due to the increased weight, which can result in unnecessary downtime. Welding operators are often better off selecting the smallest amperage gun possible for the application, to provide them with a lighter-weight, more flexible gun that can reduce fatigue and associated downtime. Lower amperage guns also typically cost less.

Duty cycle refers to the number of minutes in a 10-minute period that a gun can be operated at its full capacity without overheating. For example, a 60 percent duty cycle means six minutes of arc-on time in a 10-minute span. Because most welding operators don’t weld 100 percent of the time, it is often possible to use a lower amperage gun for a welding procedure that calls for a higher amperage one.

A lower amperage MIG gun should still be capable of operating at the necessary capacity, while also offering the benefit of being easier to maneuver. That improved maneuverability can help improve weld quality and reduce the need for rework.

Choosing between light- and heavy-duty guns

While a lower amperage gun is appropriate for some applications, be sure the gun offers the necessary welding capacity for the job. Overworking a light-duty MIG gun can lead to premature failure. It’s also important to consider if a facility has multiple applications that make it necessary to have a gun that can handle various amperage needs.

A light-duty MIG gun is often the best choice for applications that require short arc-on times, such as tacking parts or welding sheet metal. Light-duty guns typically provide 100 to 300 amps of capacity, and they tend to be smaller and weigh less than higher duty guns. Most light-duty MIG guns have small, compact handles as well, making them more comfortable for the welding operator.

Light-duty MIG guns offer standard features at a lower price but typically need to be replaced more frequently. They also often use light or standard duty consumables (nozzles, contact tips and retaining heads), which have less mass and are less expensive than their heavy-duty counterparts.

The strain relief on light-duty guns is usually composed of a flexible rubber component and in some cases may be absent, causing the opportunity for kinking that may lead to poor wire feeding and gas flow. Also, some unicables on light-duty MIG guns have crimped connections and may not be able to be repaired, requiring replacement of the cable or possibly the entire gun. Welding operators should watch for these potential issues.

At the other end of the spectrum, heavy-duty MIG guns are often the best choice for jobs that require long arc-on times or multiple passes on thick sections of material, including many applications found in heavy equipment manufacturing and other demanding welding jobs.

These guns generally range from 400 to 600 amps and are available in air- and water-cooled models. They often have larger handles to accommodate the larger cables necessary to provide the higher amperages. The guns frequently use heavy-duty front-end consumables that are capable of withstanding high amperages and longer arc-on times. The necks often are longer as well, to put more distance between the welding operator and the high heat output from the arc. 

Cooling options: air vs. water

When using a heavy-duty MIG gun, choosing between a water- or air-cooled model depends largely on the application and amperage requirements, operator preference and cost considerations. Applications that involve welding sheet metal for only a few minutes every hour have little need for the benefits a water-cooled system can provide. Whereas shops with stationary equipment that repeatedly weld at 600 amps likely will need a water-cooled system to handle the heat of the application.

A water-cooled MIG welding system pumps cooling solution from a radiator unit, usually integrated inside or near the power source, through hoses inside the cable bundle and into the gun handle and neck. The coolant returns to the radiator where a baffling system releases the heat absorbed by the coolant. The ambient air and shielding gas further disperses the heat from the welding arc. Water-cooled guns range from 300 to 600 amps.

An air-cooled system relies on the ambient air and shielding gas to dissipate the heat that builds up along the length of the welding circuit. These systems, which range from 150 to 600 amps, use much thicker copper cabling than water-cooled systems.

Each system has advantages and disadvantages. Water-cooled guns are more expensive up-front and can require more maintenance and operational costs. However, water-cooled guns also are much smaller and lighter than air-cooled guns, so they can provide productivity advantages due to reduced operator fatigue. Because water-cooled guns require more equipment, they can be impractical for applications that require portability.

Options for handles and cable selection

A MIG gun’s handle, neck and power cable design can all impact how long an operator can weld without experiencing fatigue. Handle options include straight or curved — both of which come in vented styles — and the choice often boils down to welding operator preference. A straight handle is the best choice for operators who prefer a trigger on top, since curved handles for the most part do not offer this option. With a straight handle, the neck can be rotated to place the trigger on top or on bottom. In heavy-duty applications, some welding operators drape the power cable over their shoulder, and in those cases a trigger on top is more accessible.

When it comes to cable selection, smaller, shorter and lighter power cables can offer greater flexibility, making it easier to maneuver the equipment and avoid clutter in the workspace. Manufacturers offer cables ranging from 8 to 25 feet long, and shorter cables often contribute to better feedability of the wire. The longer the cable, the more chance it can get coiled around things in the weld cell or looped on the floor and possibly disrupt wire feeding. However, sometimes a longer cable is necessary if the part being welding is very large.

Other options to consider are the addition of a heat shield, which protects the welding operator from the heat output of a high amperage MIG gun and allows for longer arc-on time. Adding a unicable cover can protect the power cable from a harsh environment.

A side note on self-shielded flux-cored guns

Just as with standard MIG welding, self-shielded flux-cored welding (FCAW-SS) can offer high productivity and quality advantages in certain fabrication applications, while also providing easier training and operation.

Many of the considerations for selecting a FCAW-SS gun are similar to those for selecting a standard MIG gun. Amperage and duty cycle ratings and the application requirements remain among the most important elements to consider in selecting either type of gun.

Here are some issues to keep in mind for self-shielded FCAW-SS gun selection:

•    Operators can choose between a fixed liner and a replaceable liner, which (as the name suggests) can be replaced if it becomes clogged or damaged.

•    Guns with fixed liners typically have external trigger leads, while guns with replaceable liners commonly have trigger leads internal to the power cable, which prevents catching on surrounding equipment. This can be a consideration for applications that require welding around hard corners or fixtures.

•    Trigger options include standard or dual-schedule to allow welding operators to increase or decrease wire feed speed at the gun with the flip of a switch.

The value of comfort

Minimizing fatigue, reducing repetitive motion and decreasing overall physical stress are key factors that contribute to a safer, more comfortable and more productive environment. Choosing a MIG gun that offers the best comfort and operates at the coolest temperature allowed by the application can help improve productivity and, ultimately, the profitability of the welding operation by increasing arc-on time.

Gain Comfort, Productivity with the Right Welding Equipment

Taking into account the heat, the repetitive motions and the sometimes cumbersome equipment, gas metal arc welding (GMAW) can sometimes take a toll on welding operators in the form of aches, fatigue, and physical and mental stress. But there are tools and accessories that promote a more comfortable environment and minimize downtime.

A welding gun’s handle, neck and power cable design all can significantly impact the duration of time a welding operator can weld without experiencing fatigue or stress. This article discusses some things to consider that can help optimize comfort and productivity and, ultimately, the profitability of the welding operation by allowing for greater arc-on time.

Don’t overdo the amperage

One of the easiest and most important things welding operators can do to minimize fatigue and stress on the wrists and hands is to scale back on the amperage of the welding gun when possible. A lot of welding operators automatically use a 400 amp welding gun when a 250 or 300 amp model will do just fine for the job. Typically the higher the amperage, the larger the size of the gun handle and the more it weighs. 

MIG gun amperages reflect the temperatures above which the handle or the cable on the gun becomes uncomfortable. Using an underrated MIG gun for a higher amperage application can cause damage.

Look at the application’s duty cycle requirements and how much of the time the welding operator actually spends welding, and consider using a lower-amperage welding gun if the job allows. Duty cycle is defined by the amount of arc-on time in a 10-minute period that the equipment can be operated at maximum capacity. Some welding guns offer 100 percent duty cycle, while others are rated 60 percent or below. In some cases, MIG guns offering 100 percent duty cycle may list a 60 percent duty cycle rating, as well. 

Regardless of the MIG gun manufacturer lists the rating, it is unlikely that a welding operator will be operating the gun at full amperage and full duty cycle at all times. That makes it feasible to use a lower amperage model for many applications. Often, the higher amperage rating is needed only if the welding operator is running the power source continuously. In that case, it is also important to ensure that the gun is capable of running at the higher duty cycle to avoid failures.

In a shop setting, another option to gain greater comfort and productivity is using a water-cooled welding gun for GMAW applications. These guns can offer several benefits in production environments requiring extremely high heat applications. Water-cooled guns are generally smaller, lighter and easier for welding operators to manage for longer periods of time in high heat. However, they do come with more maintenance considerations and a higher price tag.  

Picking the right handle

GMAW gun manufacturers offer multiple handle and trigger options to increase welding operator comfort. Handles typically come in curved and straight designs, one or the other of which may be more comfortable for a given welding operator to hold and control. Some processes also may be more suited to a certain handle type, depending on what the work requires. But the choice between straight handle and curved handle often comes down to welding operator preference, so experiment to determine the preferred design. Usually, a smaller handle is easier for the welding operator to maneuver and many are available in the marketplace.

Some manufacturers offer vented handles, which can be beneficial in that they cool down faster after the welding operator stops welding, so they may be slightly cooler when the gun is picked up again.

Locking triggers are offered on some guns and can help alleviate “trigger finger,” which can occur from repetitive grasping and gripping of the gun trigger. When running a long, continuous weld, a locking trigger eliminates the necessity to squeeze the trigger throughout the whole weld, easing hand fatigue. Welding operators also can look for triggers that don’t have as much pull pressure or pull force required to maintain the arc.

Reduce strain with the right neck

Many GMAW and flux-cored arc welding (FCAW) guns are available with rotatable and flexible necks in various lengths and angles. These options allow the welding operator to select one that best suits the joint access required for an application, and they help minimize unnecessary movement.

If the weld requires a long reach or access at a tight corner, having a longer neck or an angled neck can improve comfort in that welding position. Flexible necks can be easily adjusted to fit different welding angles, and rotatable necks allow welding operators to rotate the neck as needed, making them a good option for welding out of position, including overhead.

Neck couplers are tools that allow welding operators to combine two necks when a longer one is needed. A longer neck also can help the welding operator stay further away from the heat of the welding arc. Many manufacturers make custom necks, as well, but these generally cost much more than a neck coupler and take time for welding gun manufacturers to develop. If a welding operator needs a more immediate and less expensive solution, the neck coupler may be the better option.

Another option to improve operator comfort are smaller, tapered nozzles. These can help the welding operator reach restricted joints, though remember that spatter build-up can be an issue since the opening to the nozzle is smaller and can become more easily clogged.

All of these neck and nozzle features can help minimize a welding operator straining to reach a weld joint, which reduces the opportunity for fatigue or injury.

Another accessory that can help with comfort and heat issues is a neck grip, typically high-temperature silicone rubber sleeves designed to reduce heat exposure and help the welding operator hold the neck in a steady position. They also allow the welding operator to rest the neck on his or her hand or forearm, using it as a pivot point to maneuver the GMAW gun more comfortably.

Benefits of shorter power cables

When selecting power cables, choose the smallest and shortest power cable possible that can still meet the needs of an application. Smaller and shorter power cables are lighter and more flexible, making it easier to maneuver these components without excess stress on the wrists or hands. They also can minimize clutter in the workspace, prevent excessive coiling and reduce tripping hazards. Less clutter and coiling also cuts down on the chance of poor wire feeding that could cause downtime and hinder productivity. Another advantage: Smaller and shorter cables tend to be less expensive.

Other helpful tips

Selecting standard-weight consumables can potentially ease forearm strain if the job does not call for heavy-duty consumables, as these are heavier. If the application calls for higher amperages, however, the welding operator may have to use the latter, as heavy-duty consumables dissipate more heat to prevent consumable damage and they can increase comfort in that manner — that is, by reducing heat stress.

Weld position is another way to maximize comfort on the job. Place the workpiece flat and move it into the most comfortable position whenever possible. Maintaining a clean working environment is important. In some cases, a fume extraction gun paired with the proper portable fume extraction system can be a viable option to replace wearing a powered air purifying respirator, for example, and lessen the amount of equipment the welding operator has to wear. To maintain compliance and safety, it’s always a good idea to consult an industrial hygienist to be certain that’s an appropriate step.

Parting thoughts

Having equipment that is easy to operate during the welding process is a good step in achieving a comfortable, safe work environment. Lightweight welding guns with appropriate handle and neck designs for the job and for the welding operator can help achieve safe and productive results. The reduction of heat stress, wrist and neck fatigue and repetitive motions can also help decrease overall physical and mental stress for welding operators.

Premier Boat Fabricator Improves Productivity 25 Percent with New MIG Guns and Consumables

When 90 percent of your business focuses on boat fabrication and repairs that require you to meet specific deadlines and codes, having the right welding equipment to manage the job isn’t just ideal, it’s essential. The welding operators and supervisors at Hike Metal Products Ltd. are no strangers to this fact. They know that the equipment they use needs to produce quality results, and it has to be easy to maintain. Downtime for weld repairs or MIG gun and consumable replacements simply isn’t an option.

“We’re pretty well-known worldwide in the boat building industry for the quality of the vessels we build,” explains Frank Baptista, plant manager, Hike Metal Products. “We can relate that back to the equipment we use to make our boats.”

The boats to which Baptista refers include those for the Canadian Coast Guard, the popular Maid of the Mist at Niagara Falls and police boats throughout Abu Dhabi. They have also fabricated boats for areas ranging from Florida to California and Venezuela, and recently finished an $8.5 million fireboat for the Chicago Fire Department. 

Hike Metal Products also tackles tough fabrication and repairs for other non-marine applications ranging from water treatment plants and oil recovery to agriculture.

For the last several years, Hike Metal Products has relied on Bernard T-Gun™ Semi-Automatic Air-Cooled MIG Guns (formerly Tregaskiss TOUGH GUN™ Semi-Automatic Air-Cooled MIG Guns) and TOUGH LOCK™ Consumables to meet the quality and productivity goals on its marine applications in particular. Local welding distributor, Ron Latrielle of Praxair in Chatham, Ontario introduced the products to the company. Praxair has worked with Hike Metal Products for the last 20 years, providing their welding supervisors and operators with new solutions to help them improve their welding performance and keep their competitive edge. Also involved with Hike Metal Products and their equipment is Kevin Cole, a representative from Bernard sister company, Miller Electric Mfg. Co. Along with Latrielle, Cole introduced the company to Miller XMT® 350 Multi-Process Inverters and Suitcase RC wire feeders that they have paired with their T-Gun MIG Guns to gain greater remote access to projects.

Gaining greater productivity

Hike Metal Products, located in Wheatley, Ontario, Canada, has been serving the boat industry since 1958, designing and fabricating ferries, research vessels and patrol boats, as well as hovercrafts and icebreakers. The commission for the recent Chicago Fire Department fireboat arose, in part, from the company’s successful completion of a similar boat for the city of Baltimore, along with the company’s industry-wide reputation for quality and punctuality.

Completing such a massive project, however, was no easy task. Nor was it a leisurely one. Hike Metal Products completed the job — from the day they received the raw materials for the project until they delivered the final product — in 16 months. It’s an impressive feat when you consider the fireboat is 90 feet long and capable of pumping 14,000 gallons of water a minute. It’s among the largest boats the company has fabricated and delivered in recent years. It also has a special name: the Christopher Wheatley, named in honor of a Chicago firefighter who died in the line of duty in 2010. 

As with most of the company’s projects, this one required welding thick portions of mild steel (up to 3/4 inch) using flux-cored wire and relatively high amperages (up to 400 amps) — often for long periods of time. The company used 1/16-inch welding wire and completed all welds to code according to the Canadian Welding Bureau (CWB).

According to Latrielle, such applications very often require a water-cooled MIG gun in order to withstand the heat; however, he was able to outfit Hike Metal Products with 400-amp air-cooled models of the T-Gun MIG Gun instead — with no problems of overheating. That’s important considering that welding operators at Hike Metal Products can weld up to 60 feet of welds in a single day.

“We were really pleased that we could get away with not using a water-cooled system, which just has more parts and more things to go wrong with it,” explains Latrielle. “The air-cooled T-Gun MIG Guns have been able to handle the amperage that they are pushing and get the job done.”

Baptista adds that the previous MIG guns he and his team used couldn’t boast the same durability.

“Because of the heat we weld with, the triggers on our old guns just wouldn’t last. We had to change them every other week,” he says. “Now if something goes wrong with our T-Gun MIG Guns, it’s almost time to change the entire gun anyway.”                               

In addition to their durable triggers, the T-Gun MIG Guns feature a sturdy cable strain relief on the front and back ends to prevent kinking and abrasion. This feature also helps minimize the time and cost for cable replacement. The guns have the Double-Life MIG Gun System, as well: identical connections on the front and back ends. When the front end or cable becomes worn, welding operators at Hike Metal Products can double the life of their gun by removing the trigger switch and gooseneck and flip-flopping them to the back end. The guns also feature a Lifetime Warranty on handles and switches. If either component breaks, Bernard will replace them for free.

“The features on the 400-amp gun are just so durable that the guns just go and go and go,” says Baptista. “That’s good, because if you’re not fixing the gun, you’re welding, right?”

Hike Metal Products Quality Manager Dave Hewstone, along with Latrielle, like too that the guns have simplified the process of searching for welding equipment and maintaining inventory.

The guys (welding operators) like them and they do such a good job, I don’t have to be out there looking for another product to meet the challenges of our projects all the time. What I like is that the guns perform for my customers. They do the job. We don’t hear a lot of complaints

Dave Hewstone, Quality Manager, Hike Metal Products

Adding to their arsenal of welding equipment is the TOUGH LOCK Consumable System that Latrielle introduced along with the Bernard T-Gun MIG Gun. This consumable system consists of TOUGH LOCK Contact Tips and Retaining Heads with Dual Taper Technology, a second rear taper between the gooseneck and the contact tip that helps improve electrical conductivity and extend the life of the TOUGH LOCK consumables. It’s a benefit that Baptista has noticed firsthand.

“With our previous consumables, we changed out our contact tips anywhere from three to four times a day,” he says. “Now, in the morning, we just get rid of the old tip and put in a new one.”     

These contact tips also feature a dual-lead thread design that allows the tips to be rotated 180 degrees to create a new wear position and extend the tip life even further.

The Results

According to Hewstone, Hike Metal Products has enjoyed a 25 percent increase in its productivity since converting to the Bernard T-Gun MIG Gun and TOUGH LOCK Consumable System. That productivity increase has resulted from the company reducing downtime for MIG gun maintenance and consumable changeover. And, jokes Hewstone, the productivity also comes from the company’s top-secret planning and fabrication.

“No, really, there are no real top secrets to our success,” Hewstone says. “Just hard work, to be honest with you.”