Tablet compression cycle

What is tablet compression cycle? How does the tablet shaping take place?

In a very simple language if I have to explain this then it would be: Granules (Powdered form) which are filled in the die cavity where compaction takes place at a defined load which shapes granules into tablet.

There are three stages involved in this cycle:

1.Filling stage

2.Compaction stage(pre-compression and main compression)

3.Ejection stage

To illustrate this cycle lets a have look on the below diagram.

From the above diagram you will understand that the three stages of compression cycle.

Filling stage: At filling stage you have to adjust the lower punch w.r.t to die for which fill depth settingneed to be done in such a way that required powder only gets filled to maintain the tablet weight. So this part becomes very important as far as tablet weight is concerned.

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Pre-compression: In few double rotary presses you will not find this stage of pre-compression. But insingle rotary and Mega presses this stage is must. Now why this stage becomes important is due to the product nature. When there are too many fines in the granules and if Powder is directly compressed in main compression stage tablet may not achieve required hardness or fail in friability test or may have erosion or sticking picking issues and many more other issues unless your granules are free flow in nature,non sticky or moisture sensitive. At pre-compression stage with a slight compaction of defined loads binds these granules and forms a tablet without gaining required hardness ,weight and thickness. Yes, but this stage helps tablets to achieve these parameters in main compression stage.

Tablet compression cycle

Main Compression Stage: The final compression to shape a tablet occurs at this stage. Tablets getcompressed at defined load to achieve the required weight, hardness and thickness. These loads generated by rollers on both upper and lower punches which varies from 2 Tons to 10 Tons. These loads are defined depending on the punch cavity and steel grade so it can bear that load without causing any wear and tear to tip, machine parts and meet the tableting parameters .i.e. weight, thickness and hardness. This the stage where granules shapes to tablet.

Ejection Stage : After forming the tablet shape ,it is equally important to eject them without causing anydamage .For that ejection blade setting becomes very important, mostly in case of shape (caplet, oval, animal and any other special shape)tablets setting should be in such a way that the length of the tablet should comes in contact of ejection blade to avoid jumping of tablet.

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