Mig - volts versus amps

[gkent]

On virtually every mig, the "wire feed" and amps adjustment is one and the same. Turning up the speed increases heat.

So, on machines with adjustable voltages (i.e. Miller 252), what is the effect of increasing voltage only.

Let's say the setting for 3/16 steel is 18.4 volts/265 FPM. What happens if the volts are increased to, say, 18.8?

[Broccoli1]

It changes the Amps.

[gkent]

I was hoping for a little more detail.

[Broccoli1]

http://www.millerwelds.com/pdf/mig_handbook.pdf

Section 2.3


More info

http://www.hobartwelders.com/weldtal...ire-Feed-Speed

[tackit]

Volts is pressure, so increasing voltage I would say creates a deeper weld....

[Meltedmetal]

Extract from "The Procedure Handbook of Arc Welding"- Lincoln Electric 1995.
"Four major variables affect welding performance with flux core electrodes: arc voltage, wire feed speed rate, travel speed and electrical stickout. These variables are interdependent, and. if one is changed, one or more of the other three usually requires adjustment.
Arc voltage variations, with the wire feed speed (current), travel speed, and electrical stickout held constant, produce the following effects:
1. A high arc voltage produces a wider and flatter bead.
2. An excessive arc voltage may produce a porous weld.
3. A low voltage tends to cause a convex , ropey bead.
4. Extremely low voltage may produce a tendency for wire to stub onto the plate.The wire may dive though the molten metal and strike the joint bottom, pushing the gun up.
In most applications, a good bead shape is obtained by using the highest voltage possible without causing porosity. With higher wire feed rates, higher voltages can be used without causing porosity."
Some people seem to want volt meters and ammeters on their mig equipment but I would suggest that they are no more useful than keen observation of the weld bead characteristics and noting the exact positions of the wire feed speed and the voltage control or taps for future reference. Meters are just another reference point and neither volt meters nor ammeters gives a useful reading until you are welding when you can't look at them. Maybe a talking meter would be more useful but really the story is told in the weld bead.
Meltedmetal