de Forest, A. V.
Chairman of Board of Directors, Magnaflux Corp., Chicago, Ill.
Betz, C. E.
Vice President, Magnaflux Corp., Chicago, Ill.
Pages: 17 Published: Jan 1945
Magnetic particle inspection has now had a full fifteen years of development and has won an important place in many fields as a standard inspection method. Its nondestructive nature, the ease with which it can be applied, and the fact that in general it requires no elaborate and costly installation has made it particularly attractive. The development of the method as it is in use today actually dates from 1929. Before that time the general principle had been described by Major William E. Hoke in a patent issued to him in 1922 following work which he had done in connection with the Hoke gage blocks. In 1929 two radical improvements were made. These consisted of the introduction of circular magnetization, and the use of magnetic particles specifically designed for inspection; and useful applications date from these improvements. First applied for locating quench and grinding cracks and later to finding fatigue cracks at overhaul, the method gradually spread to locating nonmetallic stringers and seams in bar stock and spring wire and to welding, forging and casting defects, in many cases supplementing or supplanting X-ray inspection in heavy sections.
Paper ID: STP47861S