Huxley Bertram White Paper: Testing strain rate during tablet decompression

The latest technical bulletin from high performance powder compaction specialist Huxley Bertram (HB), discusses the pharma industry need to simulate  punch movement in a production press accurately to predict tableting quality.

In particular, this technical bulletin highlights how strain rate during tablet decompression becomes increasingly significant as production press speed increases.

Temperature testing  

Authored by Compaction Simulator specialist Martin Bennett, the article includes findings from testing carried out on an HB100 tablet research press equipped with a Temperature Instrumented Punch. These demonstrate the direct connection between strain rate, that is a function of press speed and elasticity, and the internal temperature generated within the tablet.

The article discusses how press speed and load govern the heat generated, the amount of air that escapes, the residual stresses following elastic recovery, the friction heating during ejection, and the speed of stress changes during exit from the die. The critical ‘decompression event’ is where residual air and residual die wall pressure can combine to cause tablet fractures.

Strain rate and tablet stability

The bulletin, based on knowledge gained over many years of building compaction simulators for leading pharma companies, notes that more experienced manufacturers pay greater attention to accurate strain rate simulation over a wide range of production speeds to build a superior knowledge space for the operational manufacturing process.

This means that the ability to control high strain rates during temperature controlled tests is a key factor in ensuring product quality, and to identify any material transformations during tableting that should be examined in early stage formulation testing.