The Application of Analytical Ferrography and Spectroscopy to Detect Normal and Abnormal Diesel Engine Wear

Analytical ferrography was used as a wear measurement tool while implimenting a procedure to calculate the wear particle generation rate and filter efficiency during laboratory diesel engine testing. The engine testing methodology with quantitative ferrography proved to be a sensitive wear measurement technique in detecting a reduction in the wear particle generation rate for a better anti-wear (API SF/CD) oil from that of a baseline API SD/CD oil.

Ferrography and spectroscopy were useful as diagnostic tools for the detection and correction of the unexpected circulation of copper contaminant in the lubrication system. A journal bearing failure was detected with qualitative ferrography and verified with an engine teardown while spectroscopy did not detect the bearing failure.

Concurrent spectrometric and ferrographic oil analyses were unable to correlate ferrographic Area Under the Curve (AUC) with mass ppm units, because spectroscopy could not see the concentration increase detected by ferrography over a 6 hour test. The background of soluble and submicrometer sized particles and the limited response of AE spectroscopy to the larger wear particles may explain the this poor correlation. With spectroscopy, the relatively small concentration increase between the initial and equilibrium samples experienced during laboratory testing is unresolvable from the background concentration. Alternately, the insensitivity of ferrography to this background provides only the measurement of the increasing concentration of larger particles (greater than 1 micrometer).