Diagnostic Guide to Common Wire Rope Degradation

Diagnostic Guide to Common Wire Rope Degradation
Mode Symptoms Possible Causes
Fatigue Wire break is transverse
— either straight across or Z shape. Broken ends will appear
grainy.
Check for rope bend around
too small a radius; vibration or whipping; damaged sheaves; rollers
too small; reverse bends; bent shafts; tight grooves; corrosion;
small drums & sheaves; incorrect rope construction and size
(too big); improper installation; poor end termindations. (In
the absence of other modes of degradation, all rope will eventually
fail in fatigue).
Tension Wire break reveals a mixture
of cup and cone fracture and shear breaks.
Check for overloads; sticky,
grabby clutches; jerky conditions; loose bearing on drum; fast
starts, fast stops, broken sheave flange; wrong rope size &
grade; poor end terminations. Check for too great a strain on
rope after factors of degradation have weakened it.
Abrasion Wire break mainly displays
outer wires worn smooth to knife edge thinness. Wire broken by
abrasion in combination with another factor will show a combination
break.
Check for change in rope
or sheave size; change in load; overburden change; frozen or
stuck sheaves; soft rollers; sheaves or drums; excessive fleet
angle; misalignment of sheaves; kinks; improperly attached fittings;
gift & sand; objects imbedded in rope; improper grooving.
Abrasion plus
Fatigue
Reduced cross-section is
broken off square thereby producing a chisel shape.
A long term condition normal
to the operating process. Short term: see “Abrasion.”
Cut or Gouged
or Rough Wire
Wire ends cross-section
is necked down as in a cup and cone configuration. Tensile break
produces a chisel shape.
Check on all the above conditions
for mechanical abuse, or either abnormal or accidental forces
during installation.
Torsion of Twisting Wire ends show evidence
of twist and/or cork-screw effect.
Check on all the above conditions
for mechanical abuse, or either abnormal or accidental forces
during installation.
Mashing
or
Crushing
Wires are flattened and
spread at broken ends.
Check on all the above conditions
for mechanical abuse, or either abnormal or accidental forces
during installation. This is a common occurrence on the drum
when the lower layer is installed with less tension than the
layer going on top.
Corrosion Wire surfaces are pitted
with break showing evidence either of fatigue tension or abrasion.
Indicates improper lubrication
or storage, or a corrosive environment.

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