Single punch tablet press also called eccentric press or single station press is the simplest machine for tablet manufacturing. Single punch tablet as the name implies employ single set of station tooling that is a die and a pair of upper and lower punches.
The compaction force on the fill material is exerted by only the upper punch while the lower punch is static; such action equivalent to hammering motion and as a result, the single punch press is referred to as stamping process. The single punch tablet press produce about 60-85 tablets/min e.g. Manesty F3.
Components/ funtional parts of a single punch tablet press
- Hopper – This is connected to the feed shoe and it is where the granules/powder mixtures are poured into prior to tableting or compression. The hopper can be filled manually or by using mechanical equipment during subsequent tableting.
- Die cavity – The die cavity is where the powder granules are compressed into tablet. The die determines;
- The diameter of the tablet
- The size of the tablet
- To some extent the thickness of the tablet.
- Punches – This comprises upper and lower punch and they compress the powder into tablets of various shapes within the die.
- Cam truck – This guides the position/movement of the punches.
- Tablet adjuster – This is used to adjust the volume of the powder to be compressed and so determines the weight of the tablet.
- Ejection adjuster – This facilities the ejection of the tablet from the die cavity after compression.
In the production of tablets using single punch, the upper punch compresses the powder into tablets while the lower punch ejects the tablet.
The sequence of events involved in the formation of tablet.
The events involved in tablet production can be divided into 3 stages;
- Position 1 – The upper punch is raised and lower punch drops to create a cavity in the die.
- Position 2 – Feed shoe moves over the die cavity and granules fall into the die cavity under the influence of gravity from the hopper.
- Position 3 – Feed shoe moves out of the way and the hopper punch descends to compress the granules/powder mixture into tablets by progressive reduction of the porosity of the die content and forcing of the particles into close contact with one another.
- Position 4 – The upper punch retracts and the lower punch moves upwards too to eject the compressed tablet. The whole events repeat over and over again unit the feed material is exhausted.
Advantages of Single Punch Tablet Press
- The single punch structure is rational and small.
- Easy to operate and it operates at a high utilization ratio.
- It can manufacture odd shaped products with a diameter of up to 20mm.
- It is ideal for development of tablets and small batch production.
- Single punch tablet press utilizes a high amount of pressure to reduce weight variations between tablets while maintaining a low noise level at the same time.
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- Larry, L. A. and Stephen, W. H. (2008), Pharmaceutical Dosage Form: Tablet. Third edtion. CRC Press, Taylor and Francis Group, LLC.