Press simulator

The Presster is a single-station press that can mimic the load profile of any production press. The IVesster uses mechanical means to achieve geometric similarity with different tablet presses. Kinematic and dynamic similarities are achieved by matching the speed and force of compression. The process parameters for both press simulations are indicated in Table 4. 

Levin, M. (1999), Theory and practice of tablet press simulation for process scale-up, paper presented at the Arden House Conference Harsiman, New York, USA. 

Guntermann, A. (2005), The Presster—A tablet press simulator, paper presented at TabletTech, Brussels. 

Matching the force-time profile of a production tablet press is the primary goal of any tablet press simulation. However, the rate of force application and the shape of the resulting signal are not usually known in advance. 

Ph. Mandin, H. Roustan, R. Wiithrich, J. Hamburger G. Picard, Two-phase electrolysis process modelling from the bubble to the electrochemical cell scale Transactions on Engineering Sciences, 2007 WIT Press, Simulation of Electrochemical Processes II, p73... 

Today, the main thrust in new developments for die presses is in the area of machine data measurement and control. Techniques have become available to accurately measure the parameters during a press cycle which may only last a few hundred milliseconds. Figure 220 is the reproduction of a typical graph obtained on a four-channel oscilloscope showing top and bottom punch press force, top and bottom punch stroke, and ejection force. Based on such information, production machines can be programmed and automatically controlled. Even more sophisticated systems, so-called press simulators, are being developed and introduced. 

Figure 250. (a) Photograph and (b) diagrammatic representation of the NCB/CRE roll press simulator where (b) shows the link and drive mechanism... 

A more detailed study of material motion in the actual compaction zone has been made in the roll press simulator using marker beads, 16 mm cinematographic photography, and stereoanalysis. The flow pattern of particles in the cups of the roller press was recorded which enabled determination of strain distribution. Figure 251 shows examples of bead positions before and after partial compaction. 

Figure 251. Results of roll press simulator tests. (a) Bead pattern before compaction, (b) bead pattern after partial compaction...

Above the final compaction phase, depicted in Fig. 8.124, similar conditions exist as shown in Fig. 8.123 which are modified by the fact that the roller surfaces are not smooth and, therefore, an interlocking effect assists in pulling material into the nip. The feed and compaction zones are less clearly defined, only determined by interparticle friction, and no longer depend on the friction between material and roller surfaces. However, it has been determined in a roll press simulator [B.12b, B.42] that, as a result of insufficient interparticle friction, with certain particulate solids, large portions of material, that was initially contained between one pair of pockets, are squeezed out and move back into the following space. 

The most difficult laboratory evaluation is that of high pressure roller presses. As discussed in Section 8.4.3 the conditions in the nip between the two counter rotating, converging roller surfaces depends on so many parameters, that it is practically impossible to accurately predict press performance. To simulate the process and get an insight into the macroscopic and microscopic events that occur during densification in the nip, a roller press simulator (Fig. 11.24) was designed and extensively used. For details, an earlier book by the author should be consulted [B.12b]. 

One of the disadvantages of this roller press simulator was that it still needed a relatively large amount of material and movement was slow and limited. There is a special need in the pharmaceutical industry to accurately predict the compaction behavior of dry powder formulations in roller presses during the development of... 

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