There are numerous non-destructive testing methods for wire ropes, including commonly used techniques such as ultrasonic testing, radiographic testing, acoustic emission testing, eddy current testing, electromagnetic testing, and mechanical, acoustic, electrical current, optical, and vibration testing methods. Until recently, electromagnetic testing has been the predominant method for non-destructive wire rope testing, with other non-destructive testing technologies still largely confined to laboratory research stages.

Steel wire ropes are the "lifeline" for lifting and transporting equipment. Due to the lack of scientific and effective detection methods, the danger of rope breakage caused by strength loss has always been潜伏. The long-standing major hazard source remains unresolved due to the emphasis on the issue but the lack of technical means.

Current manual inspection method for wire ropes: inspect with the eyes and measure with calipers. Due to the unique structure of wire ropes and random factors, as well as influences from personnel quality, working environment, and harsh operating conditions, manual inspection cannot ensure the normal operation of wire ropes.

Wire rope defects are categorized into two main types: Local Fracture (LF) and Loss of Metal Area (LMA). The Local Fracture (LF) type primarily refers to discontinuities within the wire rope, such as broken wires, wire corrosion pits, deep wire wear, or other local physical degradation of the wire rope. The Loss of Metal Area (LMA) type refers to damage that reduces the total metal cross-sectional area of the wire rope, detectable by instruments and measured by comparing the detection points to reference points symbolizing the metal cross-sectional area on the wire rope.

For the local damage LF-type defects, the principle of magnetic flux leakage detection is to detect defects in the wire rope by the leaked magnetic field at the breakage point of the wire. For the metal cross-sectional area loss LMA-type defects, the principle of the main magnetic detection method is to detect the change in the metal cross-sectional area of the wire rope by measuring the magnetic flux passing through the interior of the wire rope.

Based on the different working principles of electromagnetic detection methods, the magnetization methods are categorized into AC magnetization, DC magnetization, and permanent magnet magnetization. The permanent magnet magnetization method is used in magnetic detection.

The working principle of the permanent magnet magnetization detection LMA type for defect identification is: By magnetizing a section of steel wire rope (the test area) along its axial direction through a sensor head (magnetic circuit) to saturation; with a constant magnetic induction intensity, the magnetic flux in the cross-section of the wire rope is proportional to its area. The axial main magnetic flux is measured through an inductive coil, a Hall element, or other devices capable of effectively determining the change in magnetic or steady magnetic fields, thereby quantitatively detecting the cross-sectional loss of the test area.

The working principle of the permanent magnet magnetization inspection LF-type for detecting defects is as follows: When the magnetic field passes through discontinuities in the steel wire rope (such as broken wires, rust, or localized shape abnormalities), it undergoes a change, forming magnetic leakage. Electric signals are detected through Hall element sensors, induction coils, or other appropriate devices, and the localized loss of the steel wire rope is determined by recording the output electric signals.

Currently,无损 detection instruments for wire rope defects in service are predominantly utilizing permanent magnet magnetization stimulation and Hall element sensors on the market.