What Is Wire Rope MFL Inspection?
Wire rope Magnetic Flux Leakage (MFL) inspection uses the LRM-NDE diagnostic system — a
magnetic rope tester based on the Magnetic Rope Testing (MRT) principle — to assess the
internal and external condition of steel wire ropes in service.
The MRT head contains permanent magnets that magnetically saturate the rope under test.
Sensors within the head detect two categories of signals simultaneously:
LMA — Loss of Metallic Area: A continuous measurement of the total metallic cross-sectional
area along the rope length. LMA decreases as wires corrode, wear, or break — a progressive,
cumulative signal indicating overall rope condition trend and the point at which the rope has
degraded to the discard criterion (typically defined as a defined % LMA reduction).
LF — Local Flaw: Detection of local disruptions in the magnetic flux — indicative of individual
broken wires, severe localised corrosion, kinks, and mechanical damage at specific positions
along the rope. LF signals are discrete, position-specific events that identify areas requiring close
visual examination or immediate rope withdrawal.
Wire rope deterioration mechanisms detectable by MFL:
- Internal and external wire breaks (fatigue fracture, tensile overload)
- Internal and external corrosion — including core corrosion not visible from outside
- Loss of metallic cross-section from abrasion and wear
- Structural damage — kinking, birdcaging, core protrusion, mechanical damage
- Fretting and interstrand wear