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Heat distribution and airflow channelling in the coater
New solution improves process and tablet quality in film coating
With the aim of improving process and tablet quality in film coating Lödige Process Technology has introduced a new technical solution by which the air and thus heat energy is evenly distributed over the entire tablet bed.
In contrast to conventional coating systems, with the “airflow around the coating drum” process the air flows in via a distributor pipe and circulates around the drum of the coater. The air thereby enters the drum over an enlarged area, ensuring a very even, almost turbulence-free airflow inside the coater especially in the nozzle zone to guarantee optimum coating results. Thermal imaging cameras were systematically used in the development of the process – the first time in this area of application.
In tablet coating the airflow has a decisive influence on the coating process. Turbulence in the nozzle zone will cause fouling on the inside of the coater, on the nozzles and the spray arm. This may reduce operation life time in campaign production or – when the encrustation becomes detached – lead to a deterioration in product surface quality. Furthermore, an uneven airflow results in unbalanced temperature distribution in the drum. In the “cold zones” the freshly sprinkled tablets dry poorly with the risk of twin formation. On the other hand, tablets will be overheated in hot spots which will lead to rough surfaces.
Turbulences must, in any case, be prevented, particularly in the use of organic solvents such as acetone or ethanol, as spray drying and consequential defects in the film-coated tablets may otherwise occur.
All these faults will be reliably prevented with the “airflow around the coating drum”.