The analytical ferrograph - Some factors affecting deposit formation

Wear debris examination is widely practiced as one of the possible indications of the condition of operating machinery. A ferrograph has been designed to support this technique by magnetically separating and displaying wear particles on a glass substrate according to size. Experiments have demonstrated that the pattern of wear particle deposition is dependent on the rate of flow of the sample along the substrate, the oil viscosity, the substrate angle and barrier width, and the sample delivery angle. These parameters have been optimized to provide particle separation needed for morphological examination of samples used in the experiments, but for other oil types, trial and error methods may be necessary to achieve optimum results. Preliminary experiments with quantitative ferrography showed that it was possible to improve repeatability of measurements by modification of the standard preparation methods; however, sample contamination by insoluble organic material was difficult to control and adversely affected the measurement of wear.