DETERMINATION OF CASE DEPTH IN SMALL SINTERED PARTS USING ULTRASONIC WAVES.

Abstract

The development of a technique for nondestructively monitoring the case depth of small sintered parts is studied for the particular example of a hammer from an impact lineprinter. The technique is based on measuring the resonant frequencies of flexural waves in the part and has been implemented in a manner which can easily be applied to measurements in a manufacturing environment. To use this technique, a theoretical model was developed to predict the effect that different case depths would have on the experimentally measured resonant frequencies. A high resolution modal analysis study of the print hammer was also performed to measure the vibrational modes associated with the various resonant frequencies, to help understand the results of the acoustic test, and to test certain aspects of the theoretical model. A good correlation was found between the measured resonant frequencies and the case depth as predicted by the theoretical model, although the results possess an interesting frequency dependence which is not predicted by the model.