Design and characterisation of a co-extruder to produce trilayer ceramic tubes semi-continuously

A co-extruder with three separate barrels operated by a single ram has been designed to produce trilayer tubes semi-continuously. A vital step in the design was to predict the pressure required to generate a sufficiently high extrudate velocity while being able to retain the extrudate integrity. A physically based model was used to predict the pressure drops in the co-extrusion process at three different extrusion velocities for five pastes with different rheological characteristics. In general, predicted and measured values were in good agreement. Other important aspects in the co-extruder design, such as velocity and pressure matching of different flow streams are also highlighted. Trilayer ceramic tubes were successfully produced from the designed co-extruder.