4
Slope in a mig system is used during
short arc welding to limit the short circuit current so that spatter is
reduced when short circuits between
the wire electrode and workpiece are cleared. The greater the slope,
the lower the short circuit currents
and within limits, the lower the spatter. The
amount of short circuit current must be high enough (but not too high) to detach
the molten drops from the
wire. When little or no slope is present in the welding circuit, the short circuit
current rises to a very high level,
and a violent, but miniature, reaction takes place. THIS CAUSES SPATTER.
When a short circuit current is limited
to excessively low values by use of too much slope, the wire electrode
can carry the full current and the short
circuit will not clear itself. In that case, the wire either piles up on the
workpiece or may stub to the puddle
occasionally and flash off. This is schematically shown in Figure 3-4.
Figure 3-4 - Effect of Too Much Slope
