Continuous Powder Feeding: Equipment Design and Material Considerations

The continuous feeding of raw materials is a fundamental initial step in the continuous production of solid dosage forms. The continuous feeding process is considered critical as deviations or disturbances in individual feeders may produce compositional variability in the following mixing steps. This variability may then impact downstream unit operations and result in a detrimental change to the quality attributes of the final product. To design a robust feeding process and optimise the feeding performance, it is essential to understand feeder design and the underlying relationships between the material properties, feeder tooling configuration and feeding process parameters. In this chapter a brief overview of continuous feeding equipment and feeder operation modes is provided. The chapter describes the equipment and process considerations for the design of a continuous feeding process, with a primary focus on loss-in-weight (LIW), twin-screw feeders, primarily employed during the continuous production of pharmaceutical solid dosage forms. The chapter finishes with a description of modelling approaches employed to investigate feeder performance and the integration of the feeding process to the subsequent steps of the overall continuous manufacturing process.