Alternating current field measurement (ACFM®) is an electromagnetic inspection technique that introduces an alternating current into the surface of a component to detect surface-breaking cracks.

The presence of a cracks disturbs the electromagnetic field and the return signal is instantaneously converted by advanced mathematical techniques so that operators are alerted to the presence of defects.

Immediate defect sizing and recording is a major benefit compared to other NDT methods. Results from independent testing shows ACFM matches magnetic particle inspection (MPI) performances when inspecting underwater structural welds. The amount of missed and spurious signals is significantly lower with ACFM compared to MPI and conventional eddy current testing (ECT).

With ACFM’s lower cleaning requirements and fewer false calls, inspections are significantly shorter, saving customers money.

Advantages of ACFM

Features ACFM MPI ECT
User independence

Excellent

Excellent

Excellent

Through-coating detection

Excellent

Excellent

Excellent

No need for chemicals

Acceptable, but limited

Excellent

Not suitable

Duplex and non-ferromagnetic metal detection

Acceptable, but limited

Excellent

Not suitable

Accurate, auditable inspection records

Excellent

Excellent

Excellent

Size crack length and depth without calibration

Excellent

Excellent

Excellent

High PoD and low false call rate

Acceptable, but limited

Excellent

Excellent

 Yes

 Acceptable, but limited

 No