Which is the Right MIG Gun?

When it comes to welding, no two applications are alike. Just as it’s important to select a power source that is right for the job, it is also essential to select a MIG gun that will deliver the appropriate amperage and cooling capabilities. There are four main MIG gun categories to consider when making the selection: light-duty, heavy-duty, air-cooled and water-cooled. Like any welding equipment, each has its advantages and disadvantages, as well as applications for which it is best suited.

LIGHT- VS. HEAVY-DUTY MIG GUNS
Depending on the amount of arc-on time required for an application and the amperage needed, a light- or heavy-duty MIG gun may be the best choice. The key is to make sure that the gun provides the necessary amperage to avoid overheating and premature failure.

As a general rule, light-duty MIG guns work well for welding on thin materials, like sheet metal, for tacking or for other applications that require short arc-on times. These guns tend to be smaller and lighter than heavy-duty guns, making them more comfortable for the welding operator, and most MIG gun manufacturers offer them in models ranging from 100 amps to 300 amps. Light-duty MIG guns also tend to be less expensive than heavy-duty ones and use light- or standard-duty consumables (nozzles, contact tips and retaining heads) that are also less expensive.

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There are some limitations to consider when using light-duty MIG guns, too. Despite the lower purchase price, these guns may need to be replaced more frequently due to the lighter-duty components. For example, the strain relief on light-duty guns is often made from a flexible rubber component or absent all together, which can sometimes lead to kinking and cause poor wire feeding and/or shielding 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.

Heavy-duty MIG guns are typically the best option for applications requiring multiple passes on thick sections of material or for long durations of welding. They are available in the marketplace in both air- and water-cooled models (discussed below) ranging from 400 amps to 600 amps. The necks on these guns are often longer, which creates more distance between the welding operator and the high heat from the arc, and the handles on these guns are usually larger, too. While the handle size is vital to accommodate the larger cables necessary for higher amperage output, it can make the gun more cumbersome for the welding operator to maneuver. These guns frequently also use heavy-duty front-end consumables that are capable of withstanding high amperages and longer arc-on times, but they are more expensive.

AIR- VS. WATER-COOLED
Choosing between a water- or air-cooled model for high-amperage, heavier-duty applications depends on several factors, including the amperage required, cost and operator preference.

As with the considerations for a light-duty gun, applications that involve welding at lower amperages for less amount of time are best suited to air-cooled MIG guns. These guns rely 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 amps to 600 amps, use much thicker copper cabling than water-cooled systems so the guns are generally larger.

Water-cooled MIG guns are best suited for applications that require long, continuous welds and are typically available in a range from 300 amps to 600 amps. These guns operate via a water-cooled MIG welding system that pumps cooling solution from a radiator unit, usually integrated inside or near the power source. This coolant passes 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.

Each MIG gun has its advantages and disadvantages. Water-cooled MIG 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 by reducing welding operator fatigue. Also, because water-cooled guns require more equipment, they can be impractical for applications that require portability.

The goal when selecting between air- or water-cooled guns, as well as light- or heavy-duty models, is to weigh out pros and cons like these and always make the selection that will provide the capacity to prevent downtime and drive productivity.