| Pr�ftechnik NDT GmbH, Germany, has developed a compact and ergonomic rotating system, model RS35 HS, for precision eddy-current testing during high-speed production of ferrous, non-ferrous and austenitic bar and wire. In these applications, longitudinal defects (cracks, seams, laps, etc.) in the material surface are of major concern. Due to its high-resolution and transverse movement across the crack (rather than along it), the rotating system is the most reliable detection method for finding longitudinal defects. Eddy-current probes rotate around the test piece, scanning it in a helical pattern. Every time a probe crosses a crack, it generates a defect signal. Thus, the rotating system generates a great number of consecutive signals that reliably identify the flaw as a crack of some length.
A major advantage of the new RS35 HS is the easy changeover to other material diameters. The probe diameter is quickly adjusted using an external lever and hand-wheel. The guidance system can be assembled in advance for different materials or diameters and the appropriate system simply screwed into place when needed. The type of probe is selected according to throughput and surface condition. An LCD display shows the diameter setting and rotational speed. The RS35 HS rotating system is suitable for test piece diameters ranging from 2 to 35mm and is used for testing during continuous production with or without cut-off (e.g. drawing line), and testing of cut pieces (off-line). It runs at rotational speeds of up to 12,000rpm and provides 100% testing for a minimum detectable notch depth of 30�m (depending on surface quality) at high line speeds.
The new Pr�ftechnik rotating system incorporates innovative lift-off compensation electronics that compensate for the varying signal amplitudes caused by test pieces that are not centred or not absolutely round.
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