An array system for fast, sensitive eddy current inspections : Hedengren, K.H.; Hurley, D.C.; Kornrumpf, W.P.; Young, J.D.; Sutton, G.H. ASNT 1993 Fall Conference and Quality Testing Show. NDT: A Partner in Engineering Innovation, Long Beach, California (United States), 8–12 Nov. 1993. pp. 51–53. ASNT (1993)

Abstract

A unique eddy current array system for non-destructive testing has been developed by GE. Conformable sensor arrays, multiplexing multichannel data acquisition electronics, hybrid electronic/mechanical scanning for rapid complete surface coverage, and signal/image processing for automatic flaw detection are key features of the system. The development was motivated by stringent new inspection throughput requirements which could not be met using the traditional approach to eddy current testing. The system, which is the first of its kind in the world, has been in use for production inspections of turbine disk dovetail slots at a GE manufacturing plant since September 1992. Key to the system are the novel flexible array sensors that conform to the slot`s curved surfaces and inspect the slot in a single pass. The inspection coverage rate is more than an order of magnitude faster than with the previous single probe process, while maintaining required defect sensitivity. Though the technology was originally developed for detection of surface-breaking cracks in fracture-critical engine components, it can be readily extended for other applications demanding rapid search for near-surface defects. Typical inspection coverage rates of 3--4 square inches per second on large areas indicate significant opportunities for future production and field service applications.