Progress in eddy current testing

Multifrequency eddy current testing is being increasingly used for 100% inspection of heat treated parts. Although spot checks and statistical process control methods can detect slow changes in a process, unpredictable defects occurring for only a short time are likely to go undetected. Only a method like multifrequency eddy current inspection can guarantee that all defective parts will be found. The computer-based nondestructive testing (NDT) instruments use 8 to 32 test frequencies to check hardness, case depth, and heat treat pattern; to detect material mixes and grinding abuse; and to determine whether parts have the required microstructure. Among the method`s many applications are forgings, bearing balls and rings, fasteners, and a variety of automobile components, such as brake disks and parts for seat belts, transmissions, and steering systems.