Figure 7-48.Wearfacing bulldozer end bits.
Figure 7-49.Wearfacing shovel teeth.
Figure 7-50.Waffle or crosshatching.
(locked-in) stresses. Without checking, the combination
of residual stresses and service stresses may exceed
tensile strength and cause deep cracks or spalling (fig.
7-47). Be sure to induce checking if it does not occur
naturally or if it is unlikely to occur, as in large parts
where heat builds up. You can bring on checking by
sponging the deposit with a wet cloth or by spraying it
with a fine mist of water. Also you can speed up check-
ing by occasionally striking it with a hammer while it is
cooling. When a check-free deposit is required, use a
softer alloy and adjust preheating and postheating re-
Bulldozer blades are wear-faced by placing the end
bits in the flat position and welding beads across the
outer corners and along the edges. Be sure to preheat the
high-carbon blades before wearfacing. On worn end
bits, weld new corners and then wear-face (fig. 7-48).
Wear-face shovel teeth when they are new and
before being placed into service. The weld bead pattern
used in wearfacing can have a marked effect on the
service life of the teeth. Wear-face shovel teeth that work
mainly in rock with beads running the length of each
tooth (fig. 7-49). This allows the rock to ride on the hard
metal beads. Teeth that are primarily used to work in
dirt, clay, or sand should be wear-faced with beads
running across the width of each tooth, perpendicular to
the direction of the material that flows past the teeth.
(See fig. 7-49.) This allows the material to fill the spaces
between the beads and provide more protection to the
base metal. Another effective pattern is the waffle or
crosshatch (fig. 7-50). The wearfacing is laid on the top
and sides of each tooth, 2 inches from its point. Stringer
beads behind a solid deposit reduce wash (fig. 7-51).
Figure 7-51.Comparison of wearfacing patterns for shovel teeth.