Knowledge from the Tools: ARC FORCE
ARC FORCE is an common feature found in modern MMA-stick inverter welders that increases welding amperage (heat) as the arc voltage decreases, thereby stabilizing the arc.
ARC VOLTAGE is the voltage that exists between the electrode and the earth (work lead) during the welding process. Arc voltage is proportional to the arc length, i.e. As the arc length decreases the arc voltage also decreases.
The Arc Force setting is the maximum percentage of the set amperage the actual welding amperage may increase by. E.g. 100 Amps @ 20% Arc Force may increase to 120 Amps maximum.
For the welding of new/clean mild steel and vertical up welding, I use an Arc Force of around 20% percent.
Otherwise, painted and/or rusty steel and sometimes for corner fillets or 'back penetration', I'll use an A/F of 50%.