(741f) Powder Flow in a Confined Space Caused By External Forces: The Die Filling Process Case
AIChE Annual Meeting
Thursday, November 20, 2014 - 5:00pm to 5:21pm
The die filling process, which happens prior to the compaction step, affects directly the quality of the final product (tablets). The proper understanding of this process can be used to avoid some problems such as high tablet weight variability and non-uniform tablet pressure distribution. Feed frames have different numbers of interconnected compartments and therefore different numbers of paddle wheels, which spread the powder over an area for the dies to be filled. Most feed frames have two or more compartments, which complicate the powder flow and makes it difficult to understand powder phenomena inside feed frames. Therefore, a new feed frame was built in AutoCAD® based on a single paddle wheel (single compartment) to simplify and have a better understanding of particle flow inside feed frames. The EDEM software (DEM solutions) was used to perform the DEM simulations. A factorial design was developed, which involves 3 factors, each at 2 levels. The factors were the paddle wheel rotational speed, the number of paddles and the paddle height. A single material with monosized spherical particles was investigated for the first set of simulations. Three responses were considered: the number of collisions, die weight variability and particle confinement. Particle confinement was determined using the compressive force and total force applied to the particles. In addition, patterns in confinement were developed. Two more simulations were performed with 2 materials with different particle size to validate the relation between segregation and the number of collisions. This work developed a fundamental and practical understanding of the impact of particle properties, device design, and operating conditions, on the effect on powder phenomena that can be applied to real feed frames.