Duty Cycle in Welding Defined and Explained

Key Points

- Understanding duty cycles is important for using welding equipment correctly and maintaining sound welding techniques.

- Duty cycle refers to the percentage of time a welding machine can safely operate before overheating and cooling down.

- Duty cycle requirements vary depending on the type of welding machine and the specific workplace procedures.

- Different welding processes, such as SMAW, GMAW, GTAW and FCAW, have different duty cycle requirements.

- Duty cycle testing is important to ensure that welding machines can handle the work required by the welder and prevent overheating and malfunctioning.

Understanding duty cycles is vital to using welding equipment correctly.

In turn, proper use of welding equipment can help welders maintain sound techniques. Accomplishing this can positively impact the final product and help technicians comply with workplace welding standards.

However, to correctly use welding technology, aspiring welders must first understand what properly functioning equipment looks like. That includes learning about what a duty cycle in welding machinery is and how this performance metric can affect daily productivity as a welder.

Interested in learning even more? Then consider enrolling in Universal Technical Institute’s Welding Technology program! This 36-week welding program teaches students four types of welding using an industry-standard curriculum developed with help from Lincoln Electric.¹

Continue reading to learn more about duty cycles. We'll explain what they are, why they’re important and dig deeper into the process of duty cycle testing!

What Is Duty Cycle in Welding Machines?

Duty cycle refers to the percentage of time a welding machine can safely operate before reaching thermal overload (overheating) and cooling down. This process happens at a given amperage within a specific time, usually 10 minutes.

When the arc power is turned off due to thermal overload, the cooling fan continues to run and blows heat away from the parts that are sensitive to thermal energy.

For example, a welding machine may run at 300A for six minutes before switching to thermal overload and cooling down. Therefore, according to the 10-minute testing period standard, the machine ran at a duty cycle of 60%!

Read: What is a Multi-Process Welder?

What Is a Typical Welding Duty Cycle?

It’s important to note that there aren’t any laws dictating duty cycle requirements in welding. Instead, these numbers may depend on each facility’s specific workplace procedures.

In general, welder duty cycle requirements are 20% for lighter-duty welding machines, 40%-60% for medium-duty welding machines and 60%-80% for heavy-duty welding machines. These recommendations may vary according to other aspects of machine performance like amperage settings and thermal load tolerance.

Students in UTI's Welding Technology program are taught four major welding processes (SMAW, GMAW, GTAW and FCAW) through their welding courses and how to use the appropriate machinery to assist them with these methods. Naturally, that means our students also receive detailed instruction on how to properly maintain and operate this technology, including how to adhere to varying duty cycle requirements.

SMAW welding

Shielded metal arc welding (SMAW), also known as stick welding, is a manual welding technique that allows frequent pauses and therefore requires less machine use. For that reason, stick welders rarely need their machines to run for extended periods and can perform their duties with lighter-duty welding machines.

GMAW welding

Gas metal arc welding (GMAW), or metal inert gas welding (MIG) processes are automated and usually require only brief operational pauses. As a result, the method is relatively efficient and calls for machines with longer duty cycles. Still, some GMAW applications, such as metal sheet welding, do not require machines with high duty cycles.

GTAW welding

Because gas tungsten arc welding (GTAW), or tungsten inert gas (TIG) welding applications are so diverse, and because machine types can differ from project to project, their duty cycle requirements may also vary. This is especially true because many GTAW welding machines can switch between high and low amperage output.

Still, many GTAW applications have a distinct need for machines with lower duty cycles, especially when it comes to detailed welding work on smaller and thinner materials.

For these projects, welding technicians must prioritize precision over power. Otherwise, there may be too much pressure, wrecking the final welded product. Pipe welding, on the other hand, is frequently performed using machines with higher duty cycles.

FCAW welding

Flux-cored arc welding (FCAW) is a semi-automatic arc welding process that uses a continuous hollow wire electrode to heat up and join materials. These methods typically require a higher current since FCAW welders frequently weld thicker materials.

Welding students at UTI can learn the technical fundamentals of each of these welding processes while also gaining hands-on training putting them into practice. After graduation, they can learn about opportunities to apply their skills as an industry professional with help from our Career Services team! Alumni of UTI can also continue to use these services even decades after graduation.

Read: Types of MIG Welding Nozzles

What is the Duty Cycle Testing Formula?

D = (PW/T)(100)%

●     Duty cycle (D), this entire formula’s calculated value

●     Pulse width (PW), also called pulse duration

●     Total period (T), total period    

●     Duty factor (d_f), the calculated value of (PW/T)

Remember that the testing time is usually 10 minutes. So, if you're looking for a duty cycle of 40%, the machine should be able to run for four minutes before going into thermal overload.

However, more than this formula is required for welder duty cycle testing. Environmental testing conditions can also have an impact on the resulting value, which can have a significant impact on the final test results.

Through UTI's comprehensive welding program, aspiring welders can learn more about welding machine performance, duty cycles and how to perform duty cycle testing. For now, we'll just go over a few of the many factors technicians need to think about before starting any numerical duty cycle calculations!

Different testing standards

Manufacturers can claim high performance results if they test according to lower-than-usual standards. For example, their machines could be tested within an eight-minute, five-minute or even three-minute period.

If the five-minute period is followed, a welding machine can claim a duty cycle of 80% after only four minutes of operation, despite the fact that its duty cycle would have only been 40% if tested against the 10-minute time period.

Ambient temperature

Welding machines are more likely to overheat when the surrounding environment is particularly warm. They can also perform better in cooler testing environments since they're then less prone to overheating. This explains why welding machines appear to be less efficient in warmer testing conditions and vice versa.

Humidity can also exacerbate heat because air molecules move more slowly in stuffier, damper air, making it more difficult for heat to escape air vents. As a result, humid testing conditions may also yield inaccurately poor duty cycle testing results.

Maintenance

Welding machines, like all technology, perform better when properly maintained. Otherwise, debris, dirt and other pollutants can clog air vents where heat would usually escape and insulate the heat.

Machines are then prone to overheating, resulting in shorter duty cycles. A welder’s duties include taking care of the equipment they use to complete their welds, so it's critical that every welding professional understands how to maintain their welding machines.

Read: Welding Blueprint Symbols: What Are They, and How Do You Read Them?

Why Is Duty Cycle Testing Important?

Duty cycle testing ensures that welding machines can perform the work required by the welder. Otherwise, welders risk exceeding their welding machines' duty cycles, causing thermal overload.

Many welding machines will cool down upon detecting thermal overload, but despite this protective feature, chronic overuse will result in faster malfunctioning, which could mean extensive repairs and maintenance. If it overheats while performing the task, the machine may malfunction, resulting in the weld being performed less safely and efficiently.

Build Welding Skills with Technical Training at UTI!

Maintaining the technology that allows you to do your job properly is essential to your duties as a welder. That includes understanding what a duty cycle in welding technology is and how it might affect your work in the industry!

If you want to pursue a career in the welding industry, our Welding Technology program can help! This 36-week welding program provides hands-on training from experienced instructors to help you develop the skills and knowledge that employers often require.

You can also learn more about duty cycles as part of an in-depth curriculum that will sharpen your understanding of what good welding work looks like.

Request information to learn more. Submit a welding school application whenever you’re ready!