New coating process coats particles more evenly and precisely

Ennigerloh/Düsseldorf, May 2014 – With the “Bohle Uni Cone BUC®” process, the Ennigerloh-based special machine builder L.B. Bohle Maschinen + Verfahren GmbH had a new development method for precise coating of particles protected as a utility model in 2013. “We have proven that our new method works much more precisely and evenly than the conventional Wurster process”, said the managing director Lorenz Bohle at the start of the Interpack.

For over 50 years the Wurster process is being applied in the pharmaceutical industry for the coating of small particles, so called pellets.

Most coating systems, which are used today, were based on this method developed by the American pharmacist Dale E. Wurster in 1959. “The major weaknesses are hardly calculable setting parameters and the spray nozzles in the base plate”, explained Lorenz Bohle. The setting parameters must be re-tested in lengthy tests for each product. “This approach is based on experience rather than on verifiable data”, Bohle describes the scientific dilemma. This results in losses in production and major fluctuations in the coating uniformity. The spray nozzles at the bottom of the containers may cause interruption of the entire process in case of failure.

“We have developed two major modifications that solve both problems of the Wurster process”, says Lorenz Bohle. A sloping floor and a conical tip in the centre provide a uniform swirl of the product. Simultaneously, the coating substance is sprayed through lateral nozzles. “We thus achieve an unrivalled coating uniformity. With this process, the customers can also apply active substances on their products with highest precision”, says the CEO. Even in very complex processes, the losses are below one percent”.

The lateral nozzles also ensure a significantly enhanced handling. If a nozzle is blocked, it can be exchanged or cleaned in aqueous operation during the running process.

BUC® protected as European brand

“Due to these tremendous benefits, we have obtained a utility patent protection for the process and have had the Bohle Uni Cone BUC® protected as European brand”, explained Lorenz Bohle.

(Utility patent protection: 20 2012 102 157.9 – Fluid Bed System with a conical fluid bottom; Brand: 011659067)