Measurement of abrasive wear on wire ropes using non-destructive electro-magnetic inspection

This paper discusses the problems associated with the non-destructive inspection of wire ropes which have been subject to abrasive wear. Wear is a common form of degradation on wire ropes, which is difficult to quantify by visual inspection since, although it has the advantage that it is on the surface of the rope, very small changes in wear scar size can be associated with a relatively large volume of material lost. Electromagnetic inspection is accepted as the most effective technology for locating rope degradation but debate continues as to the interpretation of quantitative measurements. For darnage such as abrasive wear the assessments are made by reference to the loss of metallic area signal (LMA), however measured. Possible variation between sets of equipment raises the questions of calibration and interpretation of the signals from the apparatus. The authors report upon experiments to assess the accuracy of three proprietary magnetic non-destructive test heads on a variety of rope constructions with artificial (and hence quantifiable) abrasive wear. The results obtained show a surprising consistency for distributed wear, and confirm that LMA measurements give a "snap-shot" of cross sectional area, not the critical effective area loss.

 Author(s): Chaplin, C.R., Ridge, I.M.L., Tytko, A.