Abstract: A system is disclosed for nondestructive object testing comprising a magnetic probe responsive to an excitation signal for generating a magnetic field and thereby inducing eddy-currents in the object. The probe further provides an output signal indicative of the presence of a flaw in the object. A distance sensor generates an output signal indicative of the spacing of the probe from the object. Circuitry is provided for receiving the distance sensor output signal and is responsive thereto to supply such excitation signal to the probe. The circuitry employs the distance indication in the distance sensor output signal as an exponent in generating the excitation signal.

Abstract: Non-destructive testing apparatus for rollers and the like of magnetic material comprises a pair of rotating spin rails having intermediate sections of magnetic material. Feeding apparatus deposits rollers on the spin rails and moves them successively past the magnetic sections. A magnet produces flux through the magnetic sections and a roller rotating thereon. Variable reluctance sensing apparatus senses changes in the flux. An eddy current test probe is positioned adjacent the magnetic sections. Variable reluctance and eddy current test circuits produce flaw output signals which control apparatus for segregating the rollers. Advantageously the feeding apparatus intermittently deposits successive rollers on the spin rails and intermittently moves the rollers along the rails in end-to-end relationship.

Abstract: In apparatus in which an object moves longitudinally and rotationally with respect to a multi-probe assembly, each probe including a channel-shaped core of magnetic material having spaced sides which are long compared to the thickness thereof and a coil encircling the core, and bipolar signals are developed whose positive and negative excursions correspond to the largest flaw signal of each polarity simultaneously occurring in the probes, the probes of the assembly are arranged in succession along the longitudinal path of travel of the object and skewed with respect to the longitudinal path of travel with an end of one probe adjacent the end of the next probe to yield flaw indications for longitudinal defects which are largely dependent on the depth of the flaw and independent of its length. Accordingly such indications are approximately the same as for short defects of the same depth, thereby yielding indications more nearly corresponding to the severity of the defects.