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Modelling of dosator filling and discharge

Modelling of dosator filling and discharge

Angulo Pinzon, Oscar Andres (2012) Modelling of dosator filling and discharge. PhD thesis, University of Greenwich.

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Dosators (and other machines operating on generally similar principles) are widely used in the pharmaceutical industry for dosing products that are delivered to the customer in powder form (i.e. capsules and dry inhaled powder applications). However a significant problem for this technology is the ability to predict how accurately and reliably, new formulations can be dosed from these machines prior to scale-up for manufacture.

Dosator filling machines have been on the market for over forty years, and their mechanisms have been refined over the time; in parallel with development work of formulation scientists. Despite the work that has progressed in both of these important fields, there has been only a limited improvement in the understanding of how the formulations behave when introduced into production line equipment. Typical problems include variation in potency and manufacturing dose weight – both being issues that can be difficult to predict and counter (especially where mainly the manufacturing process is undertaken on a batch basis).

Many manufacturing problems can be traced back to an inadequate understanding of the bulk properties of the powders at the formulation stage. Common issues encountered during full scale production include extended commissioning; high levels of out of specification materials (specifically through dose weight variation).

The project aims to provide a predictive tool to industry, the use of which can improve manufacturing efficiency, minimise costs and risk when launching new products. The approach proposed focuses on the development of an analytical model for the pick up and discharge of powder into and out of dosators, based upon established particle/powder characterisation techniques combined with an improved understanding of dosator machine factors, constitutive models and geometry of the machine.

The model will be used to predict fill dose weights and filling/discharge behaviour of new products in dosator fillings systems; likewise, to investigate what changes in powder flow properties mean to dosator operation. Recommendations for the practical use of flow property measurement techniques in conjunction with the model are also outputs from this project.

To simulate the process and (very importantly) validate the model, a dosator single shot testrig was engineered at The Wolfson Centre to measure forces acting on the dosator during the filling stage, the force required to eject the dose and the dose weight. In addition other important aids, such as a dosator demonstrator and an ultimate bearing application of soil mechanics, are key in the understanding of the process and estimate the stress distribution occurring in the stages of the operation.

In addition, the development of this research provides a better understanding of the compaction phenomena in dosator operation, and more importantly, critical flow properties and machine settings factors compromising the uniformity of the fill dose weight in production lines using dosator filling machines not mentioned in the literature yet. Although this project has focussed on dosators, the general concept could be applicable to other volumetric powder filling systems.

Item Type: Thesis (PhD)
Additional Information: This research was carried out at The Wolfson Centre for Bulk Solids Handling Technology in collaboration with GlaxoSmithKline.
Uncontrolled Keywords: dosators, dosator filling machines, manufactures, computer modelling,
Subjects: T Technology > TP Chemical technology
T Technology > TS Manufactures
Pre-2014 Departments: School of Engineering
School of Engineering > Department of Engineering Systems
Last Modified: 14 Oct 2016 09:24

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