Interpretation of paste extrusion data

Statistical techniques were used to analyse fluctuations in extrusion pressure signals during the isothermal ram extrusion of alumina-based ceramic pastes and an unscented soap. Regions of significant variation were found to correlate with the presence of inhomogeneities in the paste such as air bubbles and agglomerates resulting from poor mixing. Regular surface and bulk fracture of the pastes could be detected using frequency analysis techniques. There is potential for use of these techniques for on-line feedback control where the effect can be distinguished from the homogeneous process noise.