Determine actual welding machine operating load from arc-on time, operating time and repetitive weld cycles, then compare it with the machine's rated duty cycle.
Actual welding duty cycle is the percentage of a defined period during which the welding arc is active.
For example, 6 minutes of arc-on time during a 10-minute period gives a 60% actual duty cycle.
The reference period must be clearly defined when comparing actual workload with a machine rating.
| Term | Meaning |
|---|---|
| Actual duty cycle | Percentage of the selected operating period when the arc is active. |
| Rated duty cycle | Manufacturer's specified operating capability at stated output and test conditions. |
| Arc-on time | Time the welding arc is actually operating. |
| Idle time | Time spent fitting, positioning, inspecting, changing consumables or otherwise not welding. |
For repetitive welding, the duty cycle can be calculated directly from the weld portion and total cycle.
A 45-second weld inside a 75-second cycle therefore gives a 60% cycle duty cycle.
Welding machines commonly have different duty-cycle ratings at different output currents. This calculator therefore also compares the entered welding current with the machine's rated current.
This is only a comparison indicator. It must not be used to calculate a new duty-cycle rating for a machine at a current not covered by the manufacturer's specifications.
Welding power sources generate heat while delivering welding output. A high actual duty cycle means the equipment spends more time under load and has less time between welding operations for heat dissipation.
Actual duty cycle is useful for production planning, machine selection and understanding equipment utilization.
A machine may have a relatively low actual duty cycle during normal fabrication because the operator spends significant time positioning parts, changing consumables and inspecting welds.
The portion of the reference period when the arc is not active is the non-welding portion of the cycle.
This does not mean that the machine's internal components instantly return to ambient temperature. Actual cooling depends on the machine design, fan operation, ambient temperature, ventilation and accumulated thermal load.
The duty-cycle rating is a manufacturer's specification, not simply a mathematical percentage that can be exceeded whenever the calculated job duty cycle appears acceptable.
How do I calculate welding duty cycle? Divide arc-on welding time by the selected reference period and multiply by 100.
What does a 60% duty cycle mean? It means the arc is active for 60% of the defined reference period. For a 10-minute period, that equals 6 minutes of arc-on time.
Is actual duty cycle the same as rated duty cycle? No. Actual duty cycle describes the job's workload, while rated duty cycle describes the machine's specified capability under defined conditions.
Does welding current affect duty cycle? The machine's rated duty cycle can change with output current. Use the manufacturer's rating for the required current.
Can duty cycle be calculated from repetitive weld cycles? Yes. Divide weld time per cycle by total cycle time and multiply by 100.
Does idle time reduce duty cycle? Yes. Idle time increases the reference period without increasing arc-on time, reducing the actual duty-cycle percentage.
Can this calculator tell me if my welder will overheat? No. It calculates operating load but does not model the machine's internal thermal behavior.
Why can two welders have different actual duty cycles? Differences in weld length, positioning, fitting, travel speed, consumable changes and production workflow can produce different arc-on percentages.
Should I use this calculator instead of the machine manual? No. Use it to estimate the job's actual load, then compare that result with the manufacturer's published specifications.