Microdynamic analysis of particle flow in a confined space using DEM: The feed frame case

Abstract The effect of feed frame and paddle wheel design and operating conditions on particle flow is not fully understood. Performance optimization of the tablet press feed frames is an issue of great significance in the pharmaceutical industry. Inadequate die filling and the amount of shear-strain applied in the tablet compressing stage can result in losses of the finished product because of poor quality. Most feed frames have two or more compartments, which complicate the powder flow dynamics. Therefore, a feed frame was built based on a single paddle wheel to have a better understanding of the particle flow and the force exerted over the particles using discrete element method simulations. A factorial design was developed, which involves the paddle wheel speed, the number of paddles and the paddle height. Results showed that the faster the paddle wheel speed, the lower the relative standard deviation of the die weight. The number of paddles was also demonstrated to be an important factor on decreasing the die weight variability and affects the force exerted over the particles. These findings can lead to changes in feed frame design to avoid high die weight variability, reducing the undesired attrition and segregation effect improving tablet quality.

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