Large-scale fluid bed coating operations using Wurster coaters are common in the pharmaceutical industry. Experimental measurements of the coating thickness are usually analyzed for just few particles. To better predict the coating uniformity of the entire batch, computational techniques can be applied for process understanding of the key process parameters that influence the quality attributes. Recent advances in computational hardware, such as graphics processing unit, have enabled simulations of large industrial-scale systems. In this work, we perform coupled computational fluid dynamics-discrete element method simulations of a large-scale coater that model the actual particle sizes. The influence of process parameters, inlet air flow rate, atomizing air flow rate, bead size distribution, and Wurster gap height is studied. The focus of this study is to characterize the flow inside the coater; eventually, this information will be used to predict the coating uniformity of the beads. We report the residence time distribution of the beads inside the Wurster column, that is, the active coating zone, which serves as a proxy for the amount of coating received by the beads per pass. The residence time provides qualitative and quantitative measurements of the particle-coating uniformity. We find that inlet air flow rate has the largest impact on the flow behavior and, hence, the coating uniformity.

GEA developed a semi-continuous tablet coater which can be integrated into a continuous tableting line, accelerating the switch from traditional batch production to the continuous mode of operation. Process understanding is the key element for process control and is important for continuous manufacturing. Computational tools can improve the fundamental understanding and process performance, especially those related to new processes, such as continuous tablet coating where process mechanics remain unclear. In the last years, Computational Fluid Dynamics and the Discrete Element Method have increasingly been applied in the pharmaceutical industry. The goal of this work was to develop and validate a high-fidelity CFD-DEM simulation model of the tablet coating process in the GEA ConsiGma® coater. Simulation results for the tablet movement, coating quality, and heat and mass transfer during the coating process were validated and compared to the experimental outcomes. The experimental and simulation results agreed well on all accounts measured.

No abstract

Aluminum coatings reinforced with either Al2O3 or SiC particles were deposited onto aluminum substrates and subjected to various tests. The coatings were made with mechanically alloyed powders via atmospheric plasma spraying (APS). Both types of coatings had uniformly distributed hard particles, porosities in the range of 4 to 5%, and bond strengths of around 20 MPa. The wear resistance of the SiC-reinforced coatings, however, was almost 35% higher than the coatings containing Al2O3. X-ray examination (XRD) showed that the Al2O3 particles undergo partial phase transformation during spraying, making them more prone to wear.