„Sticking“ in Tablets: Causes and Solutions

Sticking in tablet production can be very challenging and can have significant implications for the quality of a tablet.

What Does „Sticking“ Mean Exactly?

Sticking occurs when powder adheres to the punches and dies of the tablet press during the compression process. This not only affects the tablet’s appearance but can also influence its function and efficacy.

Primary Causes of Sticking

– Formulation Issues: Some ingredients have a stronger sticking tendency than others. The type of lubricant and its concentration needs to match the formulation.

– Residues on Tooling: Insufficient cleaning can provoke adhesions especially when dealing with indentations like letters.

– Too large concavity of the punches: the density distribution within the tablet results in weak areas in the cup which tend to stick to the punches.

– Layer building of the API: some substances melt during compression especially, when the tablet press heats up during production. By this melting a layer on the punch surfaces is formed and can cause sticking.

– Moisture Problems: Excessive moisture can promote sticking.

 How Can „Sticking“ Be Avoided?

– Formulation Optimization: The right composition is crucial.

– Proper Lubrication: A well-lubricated system prevents adhesions.

– Regular Maintenance: Clean tools are a prerequisite.

– Change tooling: Indentations, concavity and punch material can be optimized.

– Moisture Control: Optimal moisture content should be maintained.

– External lubrication: Is a standard add-on for modern rotary tablet presses.

– Monitor ejection force: increasing ejections forces indicate sticking.

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