OPERATION
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optimum wire feed.
Solid Hard Wire - like Steel, Stainless Steel require a drive roller with a “V” shape groove
for optimum grip and drive capability. Solid wires can have more tension applied to the
wire from the top pressure roller that holds the wire in the groove and the “V” shape
groove is more suited for this. Solid wires are more forgiving to feed due to their higher
cross-sectional column strength, they are stiffer and don’t deflect so easily.
Soft Wire – Such as Aluminum, require a “U” shape groove. Aluminum wire has a lot less
column strength, can bend easily and is therefore more difficult to feed. Soft wires can
easily buckle at the wire feeder where the wire is fed into inlet guide tube of the torch. The
U-shaped roller offers more surface area grip and traction to help feed the softer wire.
Softer wires also require less tension from the top pressure roller to avoid deforming the
shape of the wire, too much tension will push the wire out of shape and cause it to catch
in the contact tip.
Flux Core / Gasless Wire - These wires are made up of a thin metal sheath that has flux
and metal compounds layered onto the surface and then rolled into a cylinder to form the
finished wire. The wire cannot take too much pressure from the top roller as it can be
crushed and deformed if too much pressure is applied. A knurled-V drive roller has been
developed and it has small serrations in the groove, the serrations grip the wire and assist
to drive it without too much pressure from the top roller. The down side to the knurled wire
feed roller on flux cored wire is it will slowly over time bit by bit eat away at the surface of
the welding wire, and these small pieces will eventually go down into the liner. This will
cause clogging in the liner and added friction that will lead to welding wire feed problems.
A U groove wire can also be used for flux core wire without the wire particles coming off
the wire surface. However, it is considered that the knurled roller will give a more
positive feed of flux core wire without any deformation of the wire shape.
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