Tablet Press Instrumentation

In 1952–1954 Higuchi and his group have instrumented upper and lower compression, ejection, and punch displacement on an eccentric tablet press, and pioneered the modern study of compaction process. This work was followed by Nelson who was the member of the original group. In 1966, a U.S. patent was granted to Knoechel and coworkers 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. – 15] Despite the availability of published designs for instrumenting rotary presses, much of the early work on compaction properties of materials was done on instrumented single punch eccentric presses primarily, due to the relative ease of sensor installation, as well as availability of punch displacement measurement. – 18] In mid-1980s, custom-made press monitoring systems were described, and the first commercial instrumentation packages became available, including both the systems for product development and press control. The first personal computer-based tablet press monitor was sold in 1987, and the first Microsoft Windows-based press instrumentation package in 1995. A new era of compaction research has begun with the introduction of an instrumented compaction simulator in 1976, while a compaction simulator patent was issued as recently as 1996. A new generation of “compaction simulators” was born when a mechanical press replicator was patented in the year 2000. A good exposé of the early stages of press instrumentation and resulting research is presented in review articles by Schwartz, Marshall, and Jones. A comprehensive review can be found in a relatively recent paper by Çelik and Ruegger. For other historical information on the press instrumentation, the reader is encouraged to peruse Ridgeway Watt’s volume. There have been a number of papers published on various disparate instrumentation topics, and in a recent volume by Muños-Ruiz and Vromans, there are two good articles on the subject—but, unfortunately, they deal with marginal issues of single station press and instrumented punch only.