Unimig VIPER 182 Mk II, Operating Manual

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Drive Roller Selection
The importance of smooth, consistent wire feeding during MIG welding cannot be emphasised enough. The
smoother the wire feed, the better the welding will be. Feed rollers or drive rollers are used to feed the wire
mechanically along the length of the welding gun.
Feed rollers are designed to be used for certain types of welding wire, and they have different types of
grooves machined in them to accommodate the different types of wire. The wire is held in the groove by the
top roller of the wire drive unit and is referred to as the pressure roller; pressure is applied by a tension arm
that can be adjusted to increase or decrease the pressure as required. The type of wire will determine how
much pressure can be applied and what type of drive roller is best suited to obtain optimum wire feed.
Solid Hard Wire (V Groove)
Steel or 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 bend so easily.
Aluminium (U Groove)
Aluminium requires a U shape groove. Aluminium 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 (Knurled/F Groove)
These wires are made up of a thin metal sheath that has fluxing, and metal compounds layered onto it 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/F Groove drive roller has been
developed, and it has small serrations in the groove, the serrations grip the wire and assist in driving it without
too much pressure from the top roller. The downside 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.
Roller Diameter: 30/22
V Groove Roller (Steel Wire)
SKU Description
0.6-0.8V30/22 Drive Roll V Groove 0.6-0.8mm
0.8-1.0V30/22 Drive Roll V Groove 0.8-1.0mm
0.9-1.2V30/22 Drive Roll V Groove 0.9-1.2mm
1.0-1.2V30/22 Drive Roll V Groove 1.0-1.2mm
Knurled/F Groove (Flux-Cored Wire)
SKU Description
0.8-0.9F30/22 Drive Roll Knurled 0.8-0.9mm
0.9-1.2F30/22 Drive Roll Knurled 0.9-1.2mm
U Groove Roller (Aluminium Wire)
SKU Description
0.8-1.0U30/22 Drive Roll U Groove 1.0-1.2mm
0.9-1.0U30/22 Drive Roll U Groove 0.9-1.0mm
0.9-1.2U30/22 Drive Roll U Groove 0.9-1.2mm
1.0-1.2U30/22 Drive Roll U Groove 1.0-1.2mm
TOP PRESSURE ROLLER
V GROOVE
TOP PRESSURE ROLLER
U GROOVE
TOP PRESSURE ROLLER
F(Knurled) GROOVE
MIG DRIVE ROLLERS
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