Tablets are complex systems and the behaviour of disordered particulates under pressure is still far from being well understood, especially with high-speed compression cycles similar to presses used in industry. Manufacturing problems are usually discovered towards the end of the development process when high speed compression runs are studied for the first time. The use of a compaction simulator in the early stage of development is a significant benefit for the product development process. Since tablets are particulate materials, their physical aspects have much in common with the problems, which are studied by other engineering sciences and reflect the interdisciplinary character of the research field.
In the pharmaceutical process of tablet production, wet granulation is commonly applied to powder mixtures in order to improve powder characteristics, such as flow and compressibility. The desired granulate properties are controlled by a combination of formulation design (choosing the starting material and liquid according to its properties) and process design (choosing the type of granulator and the operating parameters). Changing the formulation and/or the process is followed by a high number of experiments based on the “trial and error principle”.

The compaction simulator allows simulating mechanically a multi station rotary tablet press, on the basis of the dwell time, of the material to be compressed. A tablet formulation is usually developed using slow (large dwell time) single station tablet presses and is afterwards transferred to a high speed tableting machine with a small dwell time of the material to be compressed. In fact, up to now scale-up of the tableting process is still an empirical process. Furthermore, the tablet presses are running with increasing capacities (e.g., one million tablets per hour) and not every tablet formulation is capable for high speed tabletting. The key is to search for mathematical models, which are able to predict the performance of a tablet formulation.

Special focus will be spent on excipients exhibiting different polymorphic modifications and recently obtained results confirm the importance of particle shape and surface of the particulate system during tablet formation. Many problems are discovered during high-speed tableting, such as adhesion and insufficient tablet strength due to the decreasing dwell time. These critical steps will be analyzed and the formulations will be optimized by the application of percolation theory. Further research work is aimed to follow this direction.