Tabletting Technology basics

Dear Friends,

This is an attempt to explain in simple terms what is a  Tablet Rotary and what
Is the tabletting technology is all about, and the basic principle based on which a tabletting machine is designed to accomplish the desired results of making a tablet from the granules.

However,The modern tabletting machine
Employ complex mechanism but still it is nothing but an improvisation of the basic model with more auto control parameters
Using suitable transducers at various points of the machine and inter changeable turrets.

Now coming to the topic let us see

What is Tabletting ?
Tableting is the process of converting pre formulated granules into a unit solid dosage form by compaction of the granules inside the die cavities with the aid of upper and lower punches.

The size and shape of the tablets are the resultant of the shape of punches and dies
Used.
Dosating :
The weight of the tablet to be compressed is achieved by fixing the die volume by altering the height of the lower punches inside the die cavities
The powder is made to flow from the hopper to the feed frame.
The feed frames fill the powder inside the die cavities  from its multiple compartments .
The scrapper plate arrangement at the end of the feed frame remove the excess powder over the die surface.The exact fill weight the powder to be compressed as a tablet is achieved by fixing the height of lower punch inside the die cavities by the dosator unit in the lower cam track.

2.. Compression:
This stage involves bringing together the upper and lower punches under pressure within the die cavities to form the tablet. As the punches comes to the compressing stage, the upper and lower punches are made to move between two large wheels called pressure rollers. These pressure rolls push the punches together inside the die cavity to form the tablet.
The distance between the upper and lower punches determines the thickness and the hardness of the tablet. When the punches are close together, a thin and hard tablet is created. When the punches are farther apart, the tablet made is softer and thicker. The proper balance of thickness and hardness determines the optimum roll distance for any specific product. These adjustments are made while keeping the tablet weight constant.
3. Ejection:
 The ejection stage of the tablet compressing process involves removal of the tablet from the lower punch-die station. In this stage, the upper punch retracts from the die cavity and rises above the turret table. Then the lower punch rises in the die, which in turn pushes the tablet upward to the top surface of the die table and out of the die cavity. A scraper (also called takeoff scraper or tablet rake-off) then pushes the tablet off the die table away from the compressing machine into the collection container through the chute.

Video Graphical representation of tabletting processes

Various control parameters available with the tabletting machine
1.Speed of the Rotary
2. AVG.weight fixing
3. Hardness of the tablet compressed
4. Pressure ton settings
5. Upper punch penetration
6. Pre- compression settings.

1.Speed of the Rotary :  The speed of the tablet rotary is achieved by means of using a variable pulley that facilitate reducing or increasing the speed of the rotary.
Normally speed adjustment is intended to get the desired out , but at times speed adjustments are carried out to overcome issues in tablet making.

Issues &  Remedies
1 Low hardness and Capping
a  Lower the rotary speed and increase dwell time of punches in the dies
b. Lower the hardness settings within the prescribed limits of product parameters specifications.

C. Reposition the punch penetration and select the new area of tablet compression.

D.Check pre compression settings if available .

2 Sticking of powder to the punches Increase the Rotary speed and decrease the punch contact time to the powder
Lower the hardness setting within the prescribed limits of product parameter specification

Secret for your skin care
3 Breakage of punches tip or quick wearing of punches and dies
Adjust the pressure ton lever of the machine according type of tooling and punch and dies size.
Contd..
Dear friends in the next part let us see about
Different Tablet tooling and it's specifications and its usage
And need of importance of pressure ton adjustment in getting good quality tablet and above all to prevent punch tip breakage and dies wearing
Till then
Cheers,
Srikanth Santhanaraman
all the above inputs have been practically adopted in my shop floor experience and hence shared.
P.S.
However simple be this article still it requires the readers to have basic exposure to the industry environment and exposure to tabletting section.
Readers. Of this article can share their inputs based on the experience in the comments section.