Duty cycle is the number that matters

Duty cycle is the proportion of a ten-minute period a machine can weld at a stated current before thermal cut-out. It must always be quoted as a pair: a percentage AND the amperage it applies to.

Reading it honestly

Sixty percent at 150A means six minutes of arc time in every ten at 150 amps. The same machine might manage only twenty percent at its 200A maximum — two minutes in ten. A specification that says 200A and 60 percent without linking them is telling you two unrelated facts.

Ambient temperature

Duty cycle is rated at a standard ambient, usually 40C. On a hot day in a closed workshop, or with a blocked air path, the real figure is lower. Leave the vents clear and do not stand the machine in its own exhaust.

What to buy

Work out the current you actually weld at, then buy a machine whose duty cycle at that current suits your work. For production fabrication, aim for one hundred percent at your working amperage. For maintenance and site work, sixty percent is usually ample — the arc is off more than it is on while you reposition.

Written for Arcline Welding Supplies — a demonstration store. See the AgenticEcom Suite.