19 The welding voltage
has little effect on the amount of welding wire deposited; this is determined
mainly by the welding current. The voltage
principally determines the shape of the fusion zone and reinforcement.
High welding voltage produces a wider, flatter, less deeply
penetrated weld than low welding voltage. c.
Welding Speed With any combination
of welding current and voltage, the effects of changing the welding speed conform
to a general pattern: If
the welding speed is increased- a.
Power or heat input per unit length of weld is decreased. b.
Less welding wire is applied per unit length of weld. c.
Consequently, there is less weld reinforcement. If
the welding speed is decreased- a.
Power or heat input per length of weld is increased. b.
More welding wire is applied per unit length of weld. c.
Consequently, there is more weld reinforcement. In
addition to this pattern, welding speed may have another effect on the finished
weld. Normally, only welding current affects
the penetration of the weld. However, if the welding speed is decreased beyond
a certain point, the penetration will also
decrease. This is because a good portion of the molten weld puddle
will be beneath the welding wire and the penetrating
force of the arc will be cushioned by the puddle. Conversely,
if the speed is increased beyond a certain point, the penetration will increase
since the welding wire will precede the
weld puddle. Continued on next page...
