Rotary tablet presses instrumentation

Zeiss, J.C. Beck, B. Patel, K. Development of a monitoring system for an instrumented rotary tablet press. Pharm. Tech. 1986, August, 60-67. 

Mitrevej, A. Augsburger, L.L. Adhesion of tablets in a rotary tablet press. I. instrumentation and preliminary study of variables affecting adhesion. Drug Dev. Ind. Pharm. 1980, 6 (4), 331-337. 

Dwivedi, S.K. Oates, R.J. Mitchell, A.G. Peak offset times as an indication of stress relaxation during tableting on a rotary tablet press. J. Pharm. Pharmacol. 1991,43, 673-678. Muller, F.X. Augsburger, L.L. The role of the displacementtime waveform in the determination of heckel behavior under dynamic conditions in a compaction simulator and a fully instrumented rotary tablet machine. J. Pharm. Pharmacol. 1994, 46, 468 75. 

The first true compaction simulator capable of mimicking the compaction and ejection cycle of a rotary tablet press was reported by Hunter et al. in the 1970s (2), The evolution of such an instrument presented a novel tool for both powder compression research and scale-up of the tableting process. Celek and Marshall report that although compaction simulators are expensive to purchase, they present the following attributes ... 

The details of instrumentation for tablet presses is thoroughly described in several texts and review papers [1,2,9,10] and will not be repeated here. The concepts, however, are important. The first and most important result of the instrumentation results in a plot of force vs. time (see Fig. 1). This shows the maximum force (or pressure) used for compaction of a tablet and such plots become even more important on a rotary press, when this measurement can be made on each tablet produced. 

In 1966, a U.S. patent was granted to Knoechel and co-workers for force measurement on a tablet press. This patent was followed by two seminal articles in Journal of Pharmaceutical Sciences on the practical applications of instrumented rotary tablet machines. A number of other patents related to press instrumentation and control followed from 1973 on ward. ... 

Ilkka, J. Instrumentation of rotary tablet machine by a portable measuring system. In Data Acquisition and Measurement Techniques Munoz-Ruiz, A., Vromans, H., Eds. Interpharm Press Buffalo Grove, IL, 1998. 

Punch displacement measurements are easily done on a single station press by attaching LVDT to the punch. On a rotary press, such measurements can be done by means of slip ring, telemetry, or instrumented punch. Punch displacement profiles may be used in conjunction with compression force to estimate work of compression and work of expansion (measure of elasticity). Because capping tendency increases with the punch penetration depth, it may be desirable to monitor actual punch movement into the die. The shape of a force-displacement curve is an indication of the relative elasticity or plasticity of the material whereas plastic deformation is desirable for stronger tablets, excess plasticity usually results in tablets that tend to cap and laminate. ... 

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