On-line monitoring of ceramic paste extrusion

Fluctuations in pressure signals that are measured at a die during the extr usion of alpha-alumina-based ceramic pastes have been-shown to contain info rmation about the homogeneity of the paste that is fed into the extruder an d phenomena that occur during the extrusion process. Standard error and fra ctal-analysis techniques give quantitative measures that have shown good co rrelation 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.