Insider Q&A: Questions Answered About Water-Cooled Robotic MIG Guns

Choosing between an air-cooled or water-cooled robotic MIG welding gun comes down to an analysis of two things. One, how a company plans to use the gun, and two, how well the investment can pay off over time. Keeping a robotic MIG gun cool is critical because it protects the components from damage due to radiant heat from the arc and resistive heat from the electrical components in the welding circuit.

Although an air-cooled robotic MIG welding gun may seem more cost-effective upfront, it may overheat faster than a water-cooled robotic MIG gun in a similar application, causing costly downtime or repairs. In other words, a water-cooled robotic MIG welding gun may ultimately prove to be the better long-term investment because it can provide significantly longer consumable life and increased productivity. That is particularly true when it’s used on jobs that would otherwise cause an air-cooled gun to quickly overheat and fail.

When is a water-cooled gun the best choice for an application?
Water-cooled robotic MIG guns are often the only choice for some heavy-duty applications, such as for jobs that require more than 400 amps. In general, water-cooled robotic MIG guns are also better for high-amperage applications and jobs that require long periods of operation. Since water-cooled MIG guns typically have higher duty cycles and amperage, they can run for longer stretches of time without stopping or overheating. For this reason, these guns are ideal for multi-pass and longer welds, which generate more heat due to the long arc-on time needed to produce them. They are also better for welding heavy materials, which can generate substantial radiant heat. As a general rule of thumb, most fabricators welding materials thicker than 3/8 in can benefit from the use of a water-cooled robotic MIG gun.

https://youtu.be/rCYdP0tWKaU

How does a water-cooled gun operate, and how does that compare to an air-cooled robotic MIG gun?
An air-cooled robotic MIG gun relies solely on the ambient air and shielding gas to dissipate heat that builds up along the length of the welding circuit, whereas a traditional water-cooled robotic MIG gun circulates a coolant from a radiator unit through cooling hoses inside the power cable, and into the gun neck and body. The coolant then returns to the radiator, where its baffling system releases the heat absorbed by the coolant. Air-cooled robotic MIG guns use much thicker copper cables and inner neck tubes, while water-cooled robotic MIG guns use much less copper in the power cables and thinner wall sections in the necks, as their cooling systems carry away the resistive heat before it builds up.

What should a company look for in a water-cooled gun?
Number One is safety. Since water-cooled robotic MIG guns use high water pressure to cool the gun’s parts — and water and electronics are a hazardous combination — it’s very important to have a gun that automatically shuts off the water supply during a neck change. Having a gun with a neck that can be changed from a safe zone outside of the weld cell is also beneficial.

Number Two is performance. How well can the water-cooled gun deal with the heat of welding? Given that the primary reason a fabricator would choose a water-cooled gun over an air-cooled one is to upgrade or improve duty cycle — the amount of time during a 10-minute cycle that the gun can operate at its rated capacity without overheating — it’s important to select a water-cooled robotic MIG gun with a duty cycle capacity that matches the application for which it’s needed.

Number Three is the ability to handle high thermal stress. Choosing a gun with high-quality components that can be exposed to extremely high temperatures can help ensure greater durability. The components of the gun —from the valves and washers to the seals — must all be made of materials that can withstand high heat. Since these components help seal not only the water but also welding gas, it’s imperative they are made of reliable, high-quality materials.

Always look for water-cooled robotic MIG guns that have both excellent water and gas sealing, as well as perfect “feedability” for feeding the wire through the neck. A neck design with the proper geometry — which accesses the joint with the appropriate travel and work angles — can prevent poor weld quality and/or the need to re-tool expensive fixtures, which could add downtime.

Are water-cooled robotic MIG guns more expensive to operate than air-cooled models?
Yes, water-cooled robotic guns are more expensive to operate. They require more parts than an air-cooled model and have less durable necks that are damaged more easily in the event of a collision. Replaceable parts for water-cooled torches are more expensive as well. Water-cooled robotic MIG guns also require more maintenance than air-cooled models, since the presence of the water circuit introduces more potential issues and replaceable parts.

What are the benefits of water-cooled robotic MIG guns and the available options?
Water-cooled robotic MIG guns offer longer arc-on times and more efficient cooling. Cooler guns also mean cooler front-end consumables, which makes it possible to greatly extend the life of the contact tip and nozzle. Water-cooled robotic MIG guns are typically available in 300 and 600 amp models, and guns on the market come in two styles: conventional and through-arm. In conventional robotic MIG guns, the cable assembly is dressed externally, the arm is exposed and a mechanical safety clutch might need to be added, depending on the manufacturer. In through-arm robotic MIG guns, the cable assembly is carried through the arm of the robot and the clutch is always integrated into the design.

As a result, water-cooled robotic MIG guns on through-arm robots can offer greater protection since the arm of the robot shields the power cable from abrasive wear and minimizes cable whipping during air moves. It’s important to know whether the robotic arm is a conventional or through-arm style so that the gun and associated mounting bracket can be chosen to match. Knowing the robot model is also important for proper mounting hardware and insulation of the gun from the robot wrist.

What maintenance considerations are necessary with water-cooled guns?
It’s smart to do preventive maintenance each day or before the start of each shift, and to inspect water-cooled robotic MIG guns to ensure all consumables and connections are tight and working properly. Welding operators or maintenance personnel should also inspect the water lines often to ensure they are tight and have no leaks, and replace the O-rings when necessary (e.g., when cracks appear).

What benefit is there to using a nozzle cleaning station in conjunction with a water-cooled gun?
Using an automatic reamer or nozzle cleaning station can lead to better quality welds and add significant benefits to the preventive maintenance of water-cooled robotic MIG guns. A reamer eliminates the need to manually clean out the front-end consumables and can, with the addition of an automated sprayer, add anti-spatter compound to help extend consumable life further. This feature adds to the overall cost of the equipment, but it also helps to increase uptime for production and decrease manual intervention.