Neuhaus, Thorsten: Investigation and Optimisation of the Presster : A Linear Compaction Simulator for Rotary Tablet Presses. - Bonn, 2007. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc:
author = {{Thorsten Neuhaus}},
title = {Investigation and Optimisation of the Presster : A Linear Compaction Simulator for Rotary Tablet Presses},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2007,
note = {Tablets are currently the most frequently used pharmaceutical dosage form. Development of new tablet formulations is performed on both eccentric and lab scale rotary tablet presses.
Differences in the working principle of both eccentric and rotary tablet presses, varying process parameters between lab scale and production size rotary tablet presses as well as missing or imprecise instrumentations of those presses frequently impede accurate and reliable characterisation of both materials and formulations during development.
Compression simulators, as e.g. the linear compaction simulator Presster (Metropolitan Computing Corporation, New Jersey, USA), promise reliable characterisations of materials and formulations, such as compressibility and compactibility studies, already in early stages of development by using only small amounts of powder.
Goals of this thesis were the investigation and, if necessary and realisable, the optimisation of the Presster (model 2002, serial number 107), in detail its data acquisition system, force and displacement measurement systems as well as general aspects, potentially affecting tablet properties, as well as the verification of improvements, carried out by precise, accurate and reliable force and displacement measurements, simulating a Fette P1200 (Fette, Schwarzenbek, Germany) rotary tablet press.
The original data acquisition system of the Presster has been found to be totally insufficient to monitor any compaction cycle related signal except of rather slow compaction force signals, e.g. due to its too small sample rate. Therefore, the independent data acquisition system DAQ4 (Hucke Software, Solingen, Germany), providing a sample rate up to 1.25 MHz, has been installed, enabling reliable monitoring of even high frequency signals.
Wrong calibrated compression force measurement systems of the Presster have been revealed by dynamic recalibration of those systems. After that the compactibility data of both the Presster and the Fette P1200 rotary tablet press matched closely.
The original ejection force and take-off force measurement systems of the Presster have not been suitable for precise measurements, e.g. due to their too small Eigen-frequency.
The predominant quality of the newly constructed ejection force and take-off force measurement systems, each equipped by optimised instrumentations, has been proved.
Due to insufficient guidance of cores of displacement sensors, missing consideration of both punch deformation and punch tilting as well as the interference of machine vibrations with the punch displacement signal, the quality and precision of vertical punch displacement measurements, monitored by the original punch displacement measurement system of the Presster, has been insufficient with respect to material characterisation purposes, e.g. in terms of Heckel-plots.
By the development and implementation of an optimised, vibration-resistant punch displacement measurement system, consistent of 2 displacement sensors per punch, vertical punch displacements have been determinable with considerably improved precision.
Therefore, distinctions between different material deformation characteristics have been feasible within the investigated range of tableting speed.
The investigation of punch tilting, which has been found to be smaller than 4.4µm for the two tilting axes investigated, has been feasible using the revised punch displacement measurement system. Beside the mentioned measurement systems of the Presster, general aspects of the tableting process have been investigated with respect to a most precise simulation of rotary tablet presses. In comparison to the tableting process of rotary tablet presses, partly unchangeable differences in the tableting process of the Presster, limiting the accuracy of the simulation of rotary tablet presses, have been observed.
The modifications of the Presster carried out within the scope of this thesis verifiably improved the quality and reliability of force and displacement measurements while simulating a rotary tablet press.
Therefore, this modified Presster can be used for precise and accurate investigations in the scope of material and formulation characterisation and is therefore a valuable tool for research and development as well as trouble shooting purposes.},

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