Welders who have bought inexpensive hobby TIG welding machines to use at home may have noticed that while these machines start strong, they struggle to put out heat after an hour or so of work. When this happens, welding will be distinctly harder, requiring slow travel speeds and long dwell times to obtain sidewall fusion. The issue will grow worse as the welder keeps operating the machine, and, if the welder continues, eventually the machine will stop working until it has been allowed to cool.
The cause of these difficulties is the TIG welding duty cycle. Every arc welding machine generates heat not just at the arc, but also inside the power supply. When internal heat reaches a certain level, thermal protections will be initiated to protect the welding machine. Duty cycles are universal across welding power supplies, but they are more noticeable in home hobby welders, as these often need to be operated at maximum amperage to create acceptable welds and therefore hit their threshold quickly.
In professional/industrial TIG welding machines, weld duty cycles tend to be higher. However, they still exist, and a low duty cycle can bottleneck productivity. Switching to a machine with a higher TIG welding duty cycle may improve overall welding productivity for a shop or project.
Understanding TIG Welding Duty Cycles
A welding duty cycle is the percentage of a set amount of time that a machine can be safely operated at a certain amperage. If a home TIG machine is rated for a welding duty cycle of 50 percent at 145 amps, that means that it can be run for five out of ten minutes at that amperage. The higher the amperage that the machine is run at—the hotter the machine—the less time it can be run before thermal protections activate. Conversely, the lower the amperage, the longer the machine can weld without encountering any issues.
In most professional GTAW welding machines, the hundred percent TIG welding duty cycle is sufficient for the majority of operation the welding machine will do.
It is relatively rare for a TIG welding machine to give a complete list of its duty cycles anywhere except in the manual. Looking through a specification sheet on a sales or review site, a welder is likely to see a single number, such as 60, listed as the duty cycle. This number translates to the welding duty cycle at the maximum setting for the machine. The majority of GTAW machines, however, also have a lower amperage setting at which the welding duty cycle is a hundred percent. At this amperage setting, there is no risk of heat building up to the point that it could damage the machine.
In most professional GTAW welding machines, the hundred percent TIG welding duty cycle is sufficient for the majority of operation the welding machine will do. As a result, most welders only ever run into problems with TIG welding duty cycles when they purchase a bargain price hobby welder. However, it is possible to exceed a duty cycle professionally when using a welding machine for welding operations that are outside of the norm for TIG welding.
Understanding Professional TIG Machine Duty Cycles
One important addition to understanding professional TIG welding duty cycles, as opposed to those in hobby welders, is understanding how pulse welding affects the duty cycle. Pulse welding is a TIG welding setting that is found on most professional machines that isn’t always available on home TIG welding machines, especially those at the budget end of the market.
Pulse welding causes the amperage to fluctuate during welding between a low background amperage and a higher primary amperage. This allows for better penetration while helping to keep the heat of the weld within acceptable tolerances. It is frequently used in welding thin metal or trickier metals like stainless steel or aluminum to avoid burn-through or heat distortion. In pulse welding, it is the average weld current between the high primary amps and lower background amps that will determine the duty cycle and whether a welding power supply is capable of handling the job.
The Importance of Welding Duty Cycles in Orbital TIG
It is no secret that TIG welding is time-consuming. However, it is still rare for a welding operation to exceed a TIG welding machine’s welding duty cycle as TIG welding is very tiring and the welder is likely to need a break before they exceed the time limit even at the machine’s maximum amperage. The lengthy setup and prep of the workpiece between welds also give the machine plenty of time to cool off between welds. However, there is one notable exception in TIG welding where welding duty cycles become a concern: Automated TIG welding, including orbital TIG welding.
Orbital TIG welding is a mechanized welding process in which the movement of the tungsten electrode and the feeding of fill material is done via a weld head and wire feeder. The process has some important advantages, but has its drawbacks as well.
Orbital TIG Welding Benefits
One of the biggest advantages of orbital welding is that large-scale welding can be done with the neatness and precisions of TIG. High-purity pipe welding processes, for instance, can be applied to very large, thick-walled pipes. An automated orbital weld head and wire feeder also make it possible to use TIG welding in welding projects where the size of the workpiece material would usually preclude the use of time-consuming manual TIG welding. For example, orbital welding makes it possible to perform big bore pipe welds using the TIG process. Orbital TIG also allows for the rapid welding of thin-walled tube. Many welding operations can be completed quickly using orbital welding, enabling an increase in productivity.
Orbital TIG Welding Drawbacks
Two disadvantages of orbital TIG welding are that large-scale pipe welding tends to require high amperage settings and takes time. Welding substantial amounts of pipe and pausing only to move the weld head can cause heat to build up in the power supply. As a result, the TIG welding duty cycle of a machine does matter in orbital welding.
In order to maintain high productivity for orbital pipe or tube welding, a welder will need an orbital welding machine with a duty cycle of nearly 100 percent, indicating that it is capable of running at the maximum setting without damaging the machine or the weld head. Fortunately, high-quality orbital welding power supplies with 100-percent TIG welding duty cycles are available from some manufacturers.
Arc Machines, Inc. is proud to offer orbital welding power supplies and weld heads with a 100-percent TIG welding duty cycle for maximum productivity through every shift. For product inquiries, contact sales@arcmachines.com, and for service contact service@arcmachines.com. To develop a custom solution, contact us to arrange a meeting.
