NDLI: Non-contact eddy current hole eccentricity and diameter measurement

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Non-contact eddy current hole eccentricity and diameter measurement

Content Provider	NASA Technical Reports Server (NTRS)
Author	Chern Sr., E. James
Copyright Year	1998
Description	Precision holes are among the most critical features of a mechanical component. Deviations from permissible tolerances can impede operation and result in unexpected failure. We have developed an automated non-contact eddy current hole diameter and eccentricity measuring system. The operating principle is based on the eddy current lift-off effect, which is the coil impedance as a function of the distance between the coil and the test object. An absolute eddy current probe rotates in the hole. The impedance of each angular position is acquired and input to the computer for integration and analysis. The eccentricity of the hole is the profile of the impedance as a function of angular position as compared to a straight line, an ideal hole. The diameter of the hole is the sum of the diameter of the probe and twice the distance-calibrated impedance. An eddy current image is generated by integrating angular scans for a plurality of depths between the top and bottom to display the eccentricity profile. This system can also detect and image defects in the hole. The method for non-contact eddy current hole diameter and eccentricity measurement has been granted a patent by the U.S. Patent and Trademark Office.
File Size	375872
Page Count	7
File Format	PDF
Alternate Webpage(s)	http://archive.org/details/NASA_NTRS_Archive_19980237753
Archival Resource Key	ark:/13960/t4km47d05
Language	English
Publisher Date	1998-01-01
Access Restriction	Open
Subject Keyword	Mechanical Engineering Eccentricity Calibrating Scanners Impedance Eddy Currents Holes Mechanics Defects Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science
Content Type	Text
Resource Type	Article

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