Stanley MBF5 User Manual page 25

Look for surface cracks, galling or gouge marks. Breaks
that start as surface damage have a "sea shell" pattern,
with the damaged spot at the center. A large "sea shell"
indicates a slow growing break; a small one indicates a
break that has been compounded by side stress.
Stress failures start small, and spread into the center
of the steel. In a stress failure, the coarser the grain,
the greater the stress was, and the more rapid was the
failure.
• Failures in this area are usually the result
• Failures in this area are usually the result
• Failures in this area are usually the
• Failures in this area are usually the result
PROPER CARE OF TOOL BITS
of blank firing, worn bushings, worn
retainer pins or the lack of lubrication.
of worn retainer pins or blank firing.
result of prying, metal-to-metal contact or
corrosion. Prying failures often exhibit a
shell-like formation near the edge of the
steel diameter where the break began, and
a "tail" opposite that where the remaining
steel bent and tore.
of heat build-up, mushrooming or improper
contact with the work.
MBF5 User Manual ◄ 25