Extended head flats increase dwell time

A variety of options are available for punches and dies to help compress difficult drug products

One commonly overlooked punch modification, the extended head flat, increases the diameter of the flat area atop the punch head.

Typically, this option does not require any modifications to the press and you can use it with cam tracks that meet Tableting Specification Manual (TSM) or European Union (Eu) standards.

The extended head flat offers multiple benefits, including a longer dwell time — the time the head flat spends in contact with the pressure roll — at a given press speed to better compact poorly compressible products.

The longer dwell time may even reduce the amount of force required to attain a specific tablet hardness.

Although, extending the head flat is beneficial in many situations it is important to note that extended head flats and the resulting extended dwell time is not always the ideal way to mitigate common tableting issues such as capping for all products.

Recent studies, sponsored by Natoli Engineering, have shown that for some products reducing the head flat or even eliminating the head flat entirely (thus reducing or eliminating the dwell time) can be beneficial in some circumstances.

In some cases, the reduced or eliminated head flats have been shown to reduce ejection forces and can be beneficial in solving capping issues.

Studies on these relatively new head profiles are currently being finished at the Natoli Institute at Long Island University and the data and study results will be available soon.

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Natoli Engineering Company (more information, website)