Like any complex topic or activity, welding has its own set of terms that can be hard to understand when you’re starting out. One welding term that you may have encountered is duty cycle welding. In this article, Duty Cycle of a Welder is explained to help you understand the topic fully.
What is Duty Cycle of a Welder?
The welder duty cycle meaning is the percentage of safe operation time for welding within a set time period at a specific amperage. As an example: A welder that has a duty cycle of 200A at 30% would operate at 200A for around 3 minutes in a 10-minute period. In this example, the remaining 7 minutes would be used by the thermal overload to cool the welding machine down.
Every modern welder has or should have a thermal overload protection feature which cuts the power to critical components when certain temperatures are achieved. This is important, as it protects the welding machine against damage and an auto restart should occur when the temperature is safe again.
The duty cycle will vary depending on the amperage, there are two general rules to remember
- At lower amperage the duty cycle increases.
- At higher amperage the welding machine heats up faster and the duty cycle is reduced.
If we return to the previous example, using a 200A welding machine this would vary as follows:
- 200A the duty cycle will be 30%
- 145A the duty cycle will be 60%
- 110A the duty cycle will be 100%
The Three Types of Duty Cycles in Welding
1. Continuous Duty (S1)
This is the first and easiest to understand duty cycle type. Where the welding machine motor runs for an extended period until it reaches the thermal equilibrium. The S1 duty cycle has a significant impact on the welding machine when it reaches the optimal temperature.
2. Short Time Duty (S2)
This is often abbreviated to S2 and it’s typically followed by the number of duty cycle minutes. As an example: S2 30 minutes. The operation is similar to S1, but the S2 duty cycle will usually shut-off before thermal equilibrium is achieved. The S2 duty cycle usually requires a longer cooling period than S1.
3. Periodic Duty (S3-S8)
The periodic duty cycle covers every cycle from S3 up to and including S8 whether they have no breaks or brakes.
This duty cycle category is focused on specific issues, including: load swapping during breaks, start-ups and electric braking. During these duty cycle operations, the welding machine will not reach thermal equilibrium.
Where is Duty Cycle of a Welder Used?
1. MMA or Stick Welding
This is a more manual welding process using alternating aspects such as electrodes and chipping slags. During MMA welding, the duty cycle is less important when compared to MIG welding because the welding times are shorter. For stick welding, a machine with 140A maximum output would be the smallest viable option. At a duty cycle of 100A at 60%, this would be sufficient for 2.6mm electrodes to operate continuously. Even 3.2mm electrodes would work smoothly.
2. MIG Welding
MIG welds require prolonged welding sessions and it’s a more automated process than MMA. The welder can work for longer which is ideal when working on large orders. This can vary depending on the specific application. A prime example could be: a production set-up when jigs are needed to make the most of the welding sessions. Using a welding machine is another way to work for longer periods.
3. TIG Welding
TIG is typically used for detail work and this increases the importance of the duty cycle. Working with thinner materials and smaller parts will ensure that it’s unlikely that the machine would reach the duty cycle limit. A lot of welding at lower amperage settings with a duty cycle of 100% is easily achievable.
During TIG welding, the filler metal is fed by hand which lowers the on and off time ratios. Certain TIG welding applications such as pipe joints may require longer and continuous welding times.
You may be interested in our article-The Ultimate Guide to TIG Welding: Everything You Should Know
Pros and Cons of Duty Cycle
High-Quality Welds: A full understanding of your welding machine will help you to create better welds with fewer defects.
Weld Prioritization: When you understand the duty cycle of your welder it’s easier to prioritize your welding schedule to meet your targets.
Fire Prevention: When the welding machine reaches the maximum duty cycle temperature the automatic thermal overload protection will prevent ignition. This improves productivity and efficiency to create better welds and to maximize the returns.
Interruptions: When you’re working on a tight deadline and critical welds are required the frequent interruptions can cause significant downtime. This is especially true with welding machines that have a lower duty cycle.
Inferior Welds: Certain welding machines can hit their duty cycle limit after a shorter welding time which can degrade the quality.
Accidents: Overheating is a risk, if the thermal overload protection fails the machine can burst into flames and this can cause injuries or fatalities.
FAQ’s about Duty Cycle of a Welder
1/How is Duty Cycle Calculated?
The basic formula is the percentage of time within the testing period, but there are a number of variables that can influence the duty cycle test.
First, the time period is typically 5-10 minutes and at the upper end of this range the demand is more significant. Whether the testing was conducted on a cold or warm machine will vary due to demands on the cooling system. The ambient temperature in the testing area can affect the test because a higher temperature is more demanding.
What is the Best Duty Cycle for a Welding Machine?
There are several factors to consider, the settings, the welding process and the welding machine are all important. As an example: a TIG welding machine has a number of manual processes which MIG welding automates. This makes the duty cycle less of an issue in TIG welding when it’s compared to MIG welding.
Which Factors Affect the Duty Cycle Most?
There are several factors that affect the duty cycle, including: amperage, voltage, temperature and ventilation. Without sufficient airflow, the machine will heat quickly and it will take longer to cool down. This can occur if the welding machine is placed against a wall which can affect the air circulation fan. Working in an area with good ventilation can prevent temperature shifts that can dramatically affect the duty cycle.
What Happens When the Duty Cycle is Exceeded?
The thermal overload protection should be triggered which will shut down the machine until it’s sufficiently cool for another session of welding. Most modern welding machines have a thermocouple to prevent overheating which should limit the possibility of pushing the welder to a complete meltdown.
Will the Duty Cycle be a Problem for Me?
This will depend on how you weld; certain welds will require shorter times. When TIG welding you will take frequent breaks and arc welding requires electrode changes. In these two cases the duty cycle will not be a major factor.
Duty Cycle of a Welder –Conclusion
Every welder wants a durable machine that can leverage their work. But it’s important to understand the importance of duty cycle in welding to prevent loss, breakdowns and accidents. Regular maintenance is also important to identify potential faults before they cause significant downtime.