| Summary: | In this work, the failure analysis procedure was carried out on various industrial
mechanical and electrical components, namely gear train components of an overhead
travelling crane and polymer coatings from an induction motor stator winding. The
gear components include a large driven gear in which all its teeth have been lost from
apparent frictional wear, a smaller driving gear with partially broken-off teeth and a
shaft which has broken clean in half. Windings extracted from one slot of a large AC
induction motor stator were made up of 8 strands of copper conductors which have
debonded from each other and both their polymeric enamel and glass fibre coatings
appear to be peeled off.
The main objectives were to investigate the failure mechanisms involved in the final
failure and to finally deduce the most probable main root causes of failure for the
respective components. Various analytical procedures were carried out to achieve the
preceding objectives, such as fractography and metallography using scanning
electron microscopy (SEM) and electron dispersive x-ray spectrometry (EDX) for
metallic samples, and thermal analysis using thermogravimetry (TGA) and
differential scanning calorimetry (DSC) for polymeric samples.
Results indicated that large concentrations of defects were found within two of the
three gear train components provided with lack of fatigue failure features, thus
suggesting failure of the travelling overhead crane due to overloading. Visual
observations of the polymer coatings in its as-received condition strongly indicated
signs of thermal degradation. No solid proof of contamination or corrosion was found in both samples. Suggestions for future work were also put forth in order to
improve the findings which were obtained.
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