Welding Guns: Gas Cooled vs. Water Cooled

It is hard to imagine, but the patents for what would become gas metal arc welding (GMAW) were issued nearly 100 years ago, introducing the first concepts of a GMAW gun. Since then, the gun has evolved and remains a workhorse of the arc welding industry.

The development and application of GMAW guns in industry revolve around two primary design types: gas cooled (often referred to as air cooled) and water cooled. Water-cooled guns typically use a mixture of water and coolant that offers freeze protection and helps stabilize the interaction of metals — such as copper, brass, and aluminum — in the cables and hardware. This cooling design is handled much like modern automotive systems.

Gas-cooled guns rely on a shielding gas mixture flowing through the power cable, gun body, and nozzle to help dissipate heat generated by the arc and amperage carried through the gun. The gas mixture itself is key to the performance and duty cycle. In typical gun designs, using 100% CO for applications like flux cored arc welding can positively impact the duty cycle and amperage capability of the gun. The opposite is true when the shielding gas is either 100% argon or with only small amounts of CO₂, as found in aluminum or stainless steel applications.

Gas Cooled vs. Water Cooled

Gas-cooled guns have long been considered the simplest and lowest-cost option because they have fewer parts, require no coolant circulator, and need less maintenance. However, this perception is shifting as companies look at the total value of a GMAW system. While the price of the gun itself is often similar between gas- and water-cooled designs, a water-cooled system requires a cooler or circulator, which adds to the overall upfront cost. Despite this, water-cooled guns can reduce long-term costs through hardware advantages. Their copper coaxial cables are nearly three times smaller while providing a higher duty cycle than an equivalent gas-cooled cable.

Consumable Life

Manual welding consumable life varies with many factors, but in general, an adequately sized water-cooled gun can ex-tend the life of wear parts, such as contact tips and nozzles, by two to five times compared to a gas-cooled gun. Designs that move coolant as close as possible to the heat source keep these consumables much cooler than gas-cooled designs. In some cases, the nozzle can be safely touched just 90 seconds after high-amperage welding (500 A).

A gun with a water-cooled nozzle design can provide high-amperage use in the 700+ A range for large-wire applications, extending the duty cycle and improving operator comfort for the most demanding applications.

Onboard Electronics

The focus on welder efficiency, reduced fatigue, and quality brings electronics and onboard controls into the discussion. Features such as digital wire feed speed control, job selection, and process feedback on the gun add to design requirements. For gas-cooled guns, the heat must be considered along with the system’s duty cycle, especially if it has onboard electronics that can be affected by heat. This often requires a larger handle or longer gooseneck and may reduce the gun’s duty cycle and amperage capability. In water-cooled designs, size and internal heat are no longer limiting factors, allowing guns to remain compact while offering excellent amperage and duty cycle capabilities along with remote process control. The onboard controls enable welders to use the exact parameters needed, make adjustments on the fly, recall set programs, and, in some cases, use a built-in LED inspection light.

Safety and Operator Comfort

Like many other skilled trades, the welding industry continuously works hard to attract new professionals, and the need for manual welders remains critical. Manufacturers relying on manual welding should consider the comfort and safety benefits that water-cooled guns provide. Suppose a manufacturer requires a welding fume solution and uses a gun with fume extraction capability. In that case, the advantages of using a water-cooled solution can amplify the benefits of a gas-cooled solution. Typically, fume extraction guns are used in applications like welding stainless steel filler metals, and high-argon content shielding gas can reduce the duty cycle and increase the heat that the wear parts are subjected to.

The benefits of water-cooled guns include the following:

• Reduced heat and fatigue
• Smaller, lighter-weight gun handles
• Onboard controls for efficiency
• Improved performance on fume extraction guns
• Water Coolers Get Smarter

Another feature of water-cooled gun systems is the coolant circulator. New equipment platforms offer coolers that are controlled and optimized by the welding power source. The cooler pumps have a design life exceeding 20,000 hours and use brushless direct current motors. The system can automatically start and stop the pump and detect flow and coolant temperature, offering energy and maintenance advantages. Advances in the cooler components also allow a 24-month interval for coolant changes on single-shift manual welding systems.

Conclusion

The cost of purchasing a manual GMAW system with water-cooled features can be higher. But if you consider the actual cost of ownership and look deeper into the wear parts costs, performance, and comfort of your employees, it is well worth a second consideration.

This article was written by Wesley Doneth (regional strategic product manager, Perfect Welding, Fronius USA) for the American Welding Society.