Duty Cycle:
120A @ 35%
60A @ 60%
50A @ 100% MAX 180A OUTPUT.
Duty cycles are measured over a 10 minute period so at 120A you can weld for 3 1/2 minutes then allow 6 1/2 minutes for the welder to cool, at 60A 6 mins welding, 4 mins cooling, at 50A you can weld continuously. The duty cycles are calculated with an ambient temperature of 40 degrees so in reality the quoted figures are quite conservative.
It doesn't mention the duty cycle at 180A but I'm guessing it's somewhere around 10-15% so 1-1.5 min welding, 8.5-9 mins cooling .
Duty cycles only really come into play when doing longer runs at higher voltages, at bodywork type settings you'd never even come close to the machine's limit.