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 REBUILDING AND HARD-FACING CRUSHER
ROLL SHELLS (Continued)
Welding Techniques
the crusher face 1-2 in. apart to provide gripping
action (Figure 2-67).
To assure efficient crushing, the hard metal overlay
must not only be wear-resistant, it must also supply the
Another hard-facing procedure particularly effective in
necessary gripping action to sustain an adequate flow
crushing 3/4 in. or larger material incorporates the use
of material through the rolls. Maximum wear
of weave beads spaced 1/2 in. apart. Steps 1 through 4
protection from any high-alloy, hard-facing overlay is
(Figure 2-68) show method of application. Use the
provided by a two-layer deposit. DO NOT USE
skip-weld process to stripe the center two-thirds of the
MORE THAN TWO LAYERS. Stacking layer upon
roll face, first on wide spacing of about 6 in. apart,
layer will result in cracking and eventual spalling.
then gradually filling in areas between until the beads
are no more than 1/2 in. apart.
The best gripping and crushing action is determined by
the arrangement of striping ribs on the roll face. The
Repeat the same procedure and skip-weld weave beads
pattern used is determined by the type of material
across the face of the shell directly over the first
being crushed, the desired aggregate size, and the
beads. Remember to start and stop welding short of
severity of abrasion.
the roll ends. This method of application deposits a
double layer of hard metal on the center two-thirds of
One of the more popular methods of hard-facing is to
the roll shell, the area subjected to the most severe
cover the entire surface of the rebuilt roll shell with a
wear. It also results in a more uniform wear pattern
single layer of hard metal, using the skip-weld
across the entire roll shell surface.
procedure. After applying the first layer of hard metal,
weld transverse beads of the same material across
2-73
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