Duty Cycle — What It Is and Why It Matters
Duty cycle is the percentage of a 10-minute period that a welding machine can operate at a given amperage before it must cool down to prevent overheating. A machine rated at 200 amps with a 60% duty cycle can weld continuously at 200 amps for 6 minutes out of every 10, then must idle for 4 minutes to cool.
Duty cycle always decreases as amperage increases and increases as amperage decreases. A machine rated 60% at 200 amps might deliver 100% duty cycle at 150 amps — meaning it can run continuously at the lower output. This relationship is important for production environments where sustained welding is required.
Exceeding the duty cycle causes thermal overload protection to trip, shutting the machine down until it cools. While this protects the machine from damage, unexpected shutdowns during critical welds are disruptive. Understanding your machine's duty cycle at your typical working amperage helps plan realistic production workflows and avoid interruptions.
Frequently Asked Questions
What duty cycle do I need?
For hobby welding with intermittent use, 20-30% duty cycle at your working amperage is sufficient — you naturally pause to reposition, change electrodes, and inspect between welds. For production shop work with sustained welding, 60%+ at working amperage is preferred. For all-day high-amperage production, look for machines rated at 100% duty cycle at your typical output.
What happens if I exceed the duty cycle?
The machine's thermal overload protection activates and shuts down the output until the internal temperature drops to a safe level. This is a protection feature, not a failure — the machine is protecting itself from heat damage. Allow it to cool, then resume welding. Chronic overheating shortens component life.