On-line monitoring of ceramic paste extrusion

Fluctuations in pressure signals that are measured at a die during the extrusion of alpha-alumina-based ceramic pastes have been-shown to contain information about the homogeneity of the paste that is fed into the extruder and phenomena that occur during the extrusion process. Standard error and fractal-analysis techniques give quantitative measures that have shown good correlation with agglomerate breakdown and variation in solid-liquid mixing. Gross extrudate surface fracture could be detected via frequency analysis. The potential use of these techniques for the feedback control of extruders is discussed.