Air-Cooled vs. Water-Cooled MIG Gun: Which is Right for You?

For some companies, choosing between an air-cooled or a water-cooled MIG welding system is pretty cut and dry. Mobile fabrication and repair companies that weld sheet metal for only a few minutes every hour will have little need for the benefits provided by a water-cooled system. Likewise, shops with stationary equipment that repeatedly weld at 800 amps probably won’t be able to find an air-cooled system that can handle the heat of the application.

But for many companies, however, it’s not such an easy decision. Each type of cooling system has advantages and disadvantages, and deciding which is right for your company requires a careful analysis of the following factors:

• Amperage requirements
• Duty cycle
• Torch weight and operator comfort
• Work site location
• Cost

First Things First

Keeping MIG welding equipment cool is necessary to protect the power cable, gun and consumables from damage due to the radiant heat from the arc and the resistive heat from the electrical components in the welding circuit. It also protects the operator from heat-related injuries and provides more comfortable working conditions.

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

An air-cooled MIG welding system relies solely on the ambient air and shielding gas to dissipate heat that builds up along the length of the welding circuit. Air-cooled systems use much thicker copper cabling than water-cooled systems, which allows the cable to transfer the electricity to the gun without building up excessive heat from electrical resistance. By contrast, water-cooled systems use relatively little copper in their power cables because the cooling solution carries away the resistive heat before it builds up and damages the equipment.

Amperage Requirements

The welding amperage will be an important factor to weigh when deciding between an air- or water-cooled system. In general, air-cooled systems are better for low amperages and water-cooled systems are better for high-amperage applications.

Air-cooled guns are available with ratings from 150 – 600 amps, and water-cooled guns range from 300 – 600 amps. These ratings represent the current loads under which the guns become so warm that they are uncomfortable for the average operator to hold. Because guns are rarely used to the limits of their duty cycle, it’s often a good idea to purchase a gun that’s rated to a lower amperage than the maximum to which it will be exposed. For example, a 300-amp gun can handle more than 400 amps and it is substantially lighter and more maneuverable than a 400-amp gun.

Duty Cycle

Closely related to a gun’s amperage capacity is its duty cycle — the amount of time during a 10-minute cycle that the gun can operate at its rated capacity without becoming uncomfortably hot. Exceeding a gun’s duty cycle can lead to operator pain and will also reduce weld quality and decrease the service life of the gun and consumables.

There is no industry standard for establishing amperage ratings based on duty cycle, so two guns both rated to 400 amps could have significantly different duty cycles. This makes it important for the customer to consider a gun’s amperage rating and duty cycle together in order to form an accurate assessment of the MIG gun’s capabilities.

Gun Weight and Operator Comfort

Welding all day long in an industrial or construction environment can take a significant toll on the hands, arms, shoulders and back (not to mention most other body parts) of a welding operator. A heavy, bulky and difficult-to-maneuver gun only exacerbates these aches and pains, and it accelerates the time they take to set in.

One of the benefits of water-cooled guns is their size and weight. Because water is more efficient than air at carrying away heat that builds up from the heat of the arc and electrical resistance, water-cooled guns use less wire for their cables and smaller gun components, resulting in reduced operator fatigue.

Although air-cooled guns are generally heavier and more difficult to maneuver than water-cooled guns, significant differences in gun design between manufacturers can also have a big impact on how quickly the gun contributes to fatigue. It’s a good idea to physically hold a gun to determine its comfort level prior to making a purchase.

Worksite Location

Because water-cooled guns require more equipment than air-cooled systems, they can be impractical for applications that require portability. Transporting the cooling system and coolant hoses of a water-cooled MIG gun can reduce productivity and cause unnecessary downtime. Water-cooled systems are most practical in applications where they will be stationary or moved very little. By contrast, air-cooled MIG guns are easily carried and moved from site to site within a shop or out in the field.

Cost

Finally, companies must evaluate the cost of the two systems before making a purchasing decision. Doing so, however, is not as simple as looking at their respective price tags. In addition to the sticker price of the systems, companies need to consider maintenance costs as well as productivity and downtime costs associated with operator fatigue and equipment longevity.

A water-cooled system requires the purchase of a coolant flow system (including radiator, pump, hose lines, etc.), which leads to a higher up-front cost than an air-cooled system. Because water-cooled systems require a special coolant solution in order to avoid mineral or algae build-up in the coolant lines and radiator, they involve more extensive maintenance and higher operational costs than an air-cooled system. Furthermore, coolant leaks can lead to equipment damage and weld discontinuities that add to the cost of owning a water-cooled system.

In addition to being less expensive up-front, an air-cooled system also offers the advantage of being better suited to low amperage applications. Thus, for example, a company that needs to weld at 150 amps and 600 amps in the same weld cell can keep its costs down by purchasing a single air-cooled system rather than a water-cooled system for the high-amperage applications and an air-cooled system for the low-amperage applications.

That doesn’t mean, however, that a water-cooled system is more expensive than an air-cooled system. As mentioned earlier, a water-cooled MIG gun is much smaller and more lightweight than an air-cooled MIG gun, which can help decrease operator fatigue and increase productivity over the course of a day.

When set up properly, a water-cooled MIG gun can provide significant long-term cost savings compared to an air-cooled gun. The coolant in a water-cooled system also extends the service life of the consumables by drawing away the heat absorbed from the arc. Longer consumable life means less downtime for changeovers and lower consumables inventory.

Conclusion

Unfortunately, there is no one-size-fits-all formula for choosing between an air-cooled and a water-cooled MIG welding system. Each company must analyze their welding operations and determine which type of system offers the benefits most important to them. Considering these factors — cost, worksite location, gun weight and operator comfort, duty cycle and amperage requirements — will provide a good start toward making a wise decision.

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