Alternating Current Field Measurement (ACFM) is a non-destructive testing (NDT) technique that uses electromagnetic fields to detect and measure surface-breaking cracks in metals:

How it works

An ACFM probe induces electric currents on the surface of a metal, and measures the electromagnetic field that results. Any disturbances in the field indicate the presence of a defect, and the magnitude of the disturbance can be used to estimate the size of the defect.

Benefits

ACFM has several advantages over other NDT techniques, including:

Surface coatings: ACFM can be used without removing non-conductive protective coatings, such as paint, rust, or zinc-based coatings.

Speed: ACFM is faster than traditional methods like Eddy Current Testing (ET).

Accuracy: ACFM can accurately and repeatably size surface-breaking cracks.

Environmental impact: ACFM is more environmentally sustainable than other NDT techniques because it doesn’t use chemicals.

Uses

ACFM is used in a variety of industries, including offshore oil and gas, machine building, civil engineering, and shipbuilding.