The
"X-Chart" Abrasion Resistance Vs. Bending Fatigue Resistance
While there is a possibility, there is little likelihood
that an application can be found for which there is a precisely suitable wire rope - one
that can satisfy every indicated requirement.
As with all engineering design problems, feasible
solutions demand compromise to some degree. At times, it becomes necessary to settle for
less than optimum resistance to abrasion in order to obtain maximum flexibility; the
latter being a more important requirement for the given job. A typical example of this
kind of trade- off would be in selecting a highly flexible rope on an overhead crane.
Conversely, in a haulage installation, a rope with greater resistance to abrasion would be
chosen despite the fact that such ropes are markedly less flexible.
Two compelling factors that govern most decisions as to
the selection of a wire rope are abrasion resistance and resistance to bending fatigue.
Striking a proper balance with respect to these two important characteristics demands
judgment of a very high order. A graphic presentation of just such comparison of qualities
between the most widely used rope constructions and others is given by means of an
X-chart.
Referring to this chart when selecting a rope, the
midpoint (at the X) comes closest to an even balance between abrasion resistance and
resistance to bending fatigue. Reading up or down along either leg of the X, the inverse
relationship becomes more apparent as one quality increases and the other decreases.