Factors to Consider Before Making Your Purchase of a MIG Gun or TIG Torch
October 1, 2007
Although MIG and TIG are different welding processes, the advantages and disadvantages of using a water- or air-cooled system are the same. For that reason, you need to consider similar factors and examine the following variables before choosing a system: cost, worksite location, amperage requirements, torch weight and operator comfort. This article explores these considerations and discusses how an air or water-cooled system can help you optimize your MIG or TIG welding performance.
Optimize Your Welding Performance With Air- and Water-Cooled Systems
Torch and cable and cooling play an important role in Gas Metal Arc Welding (MIG) or Gas Tungsten Arc Welding (TIG) and there are two cooling methods: air- or water-cooled systems. Cooling prevents the power cable, torch or gun and consumables from overheating and also protects the welding operator from injury. Although MIG and TIG are different welding processes, the advantages and disadvantages of using a water- or air-cooled system are the same. For that reason, you need to consider similar factors and examine the following variables before choosing a system: cost, worksite location, amperage requirements, torch weight and operator comfort. This article explores these considerations and discusses how an air or water-cooled system can help you optimize your MIG or TIG welding performance.
Water-and Air-Cooled Torch Basics
Air-cooled torches use the ambient air and shielding gas to dissipate excess heat. The power cable on an air-cooled torch contains more copper than the cable on a water-cooled torch to help prevent the cable insulation from melting or possibly burning. As a result, air-cooled torch cables are heavier and less flexible compared to water-cooled torches cables. However, air-cooled systems do not require an independent radiator cooling system and extra hoses that are associated with water-cooled systems. The simpler design of air-cooled systems make them easier to operate, assemble, maintain and transport.
Figure 2: The Q-Gun, a MIG gun manufactured by Bernard, is available in 150-, 200-, 300-, 400-, 500- and 600-amp models.
Both air-cooled MIG guns and TIG torches are available in a variety of amperages for a multitude of applications (see Figure 2). Air-cooled TIG torches are popular for applications equal to or less than 200 amps, but you can also find air-cooled TIG torches in 50- and 300- amp models. Air-cooled MIG guns are available in a wide range of amperages, between 150- and 600 amps.
Water-cooled systems require a radiator cooling system which circulates water, the ambient air and shielding gas to dissipate heat from the torch or gun. However, water-cooled torch and gun cables are lighter and more flexible because the cable contains less copper compared to air-cooled systems. Water-cooled MIG guns are typically available in 300- through 600- amp models, while water cooled TIG torches are usually rated between 250- and 500-amps.
Cost is a major factor you should consider when deciding to purchase an air-or water-cooled TIG or MIG torch. Water-cooled torches and guns require a higher initial investment because you need a separate radiator cooling system in addition to the power source. Water-cooled TIG torches and MIG guns also require higher operating and maintenance costs. You must use specially treated coolant solution in the radiator cooling system rather than tap water, which could cause algae growth or scale (mineral buildup) on the internal torch surfaces and cable assembly. In addition, water leaks from hoses and the torch neck or heads may occur, which require immediate repair in order to prevent weld discontinuities.
Depending on your needs, the higher cost of a water-cooled MIG gun or TIG torch may be a viable investment. The flexible cable, lighter weight and smaller size of a water-cooled system provides more operator comfort, compared to the similar amperage air-cooled gun or torch. For example, the average 250-amp water-cooled TIG torch weighs approximately 3 ounces and measures about 6.5-inches in length, while a 150-amp air cooled TIG torch weighs around 6 ounces and measures around 7.75-inches in length (see Figure 3: WP17.jpg/WP20.jpg—side by side comparison). If you are welding for an extended period of time, the greater weight of an air-cooled torch may increase operator fatigue and cause downtime for cooling.
Figure 3: 150-amp WP17 air-cooled TIG torch (left) weighs 6 ounces while a 250-amp WP20 water-cooled TIG torch weighs only 3 ounces (right).
Saving on consumable costs may be another reason to invest in a water-cooled torch. The radiator cooling system allows the tip, nozzle and/or diffusers to run cooler than with an air-cooled torch. Therefore consumables typically last longer on water-cooled MIG guns and TIG torches and help reduce downtime associated with consumable changeovers.
However, an air-cooled MIG gun or TIG torch can provide several advantages. For example, air-cooled torches work well on lower amperage applications and in many cases, can meet the demands of most industrial MIG and TIG applications while still providing the same performance at a fraction of the operating and maintenance costs.
When choosing air- or water-cooled MIG or TIG torches, also consider the location of the work site. Is the application in the shop or in the field? Air-cooled MIG guns and TIG torches are more practical for outdoor worksites because they require fewer parts, which simplifies transport, set up procedures and parts management.
On the other hand, water-cooled MIG guns and TIG torches are better suited to use in the shop. Water-cooled guns and torches are available in higher and lower amp options but require a separate cooling system. The water-cooling system and the extra hoses make these torches and guns less portable.
Duty cycle is also another major consideration in the purchase of an air- or water-cooled torch or gun. Duty cycle is defined as the percentage of time in a 10-minute period that the torch can be operated at a specific output without overloading. For example, to weld 16ga mild steel, you need at least 160-amps with 100-percent CO2 shielding gas. If a given torch is rated at 150-amps and you operate it at a 160-amp output, duty cycle decreases approximately 20-percent. Running a MIG gun or TIG torch beyond its rated output is not necessarily harder on the gun, but it may cause the torch handle and cable assembly to heat up much faster which leads to downtime.
If the application you are working on calls for amperages higher than what the gun or torch is rated, it is recommended to purchase a higher amperage gun or torch that can operate at a higher duty cycle. Both air- and water-cooled MIG guns are available up to 600-amps. On high amperage MIG applications (450- through 600-amps), the decision to use a water- or air-cooled gun depends on operator preference and cost. For TIG applications, use a water-cooled torch for jobs that are 300-amps or greater in the shop. However, for field applications, some manufacturers also offer 300-amp air-cooled TIG torches.
You need to consider cost, worksite location, application needs, torch or gun weight and operator preference when deciding to purchase a water- or air-cooled system. Air-cooled guns and torches are more portable, easier to assemble and are much more inexpensive. Conversely, torches and hoses on water-cooled systems are more flexible for greater operator comfort. Both air- and water-cooled TIG torches and MIG guns perform well and produce similar performance when used correctly. Although MIG and TIG are vastly different welding processes, you will weigh identical variables with your goals to determine which torch can optimize your welding performance.