Working and Principle of Tablet Compression Machine

Working and Principle of Tablet Compression Machine

Tablet compression machine makes the tablets by pressing the granules in die with lower and upper punch. 

Tablets are being formed by compressing the granules using the compression machines.

Different innovations to tablet compression machines are being done to improve the production rates and now it is possible to produce more than 500,000 tablets per hour. A tablet formation takes place by the combined pressing action of two punches and a die.

Principle of Tablet Compression Machine:

The basic principle behind the tablet compression machine is hydraulic pressure. This pressure is transmitted unreduced through the static fluid. Any externally applied pressure is transmitted via static fluid to all the directions in same proportion. It also makes it possible to multiply the force as needed.

Different Stages of Compression Process:

The tablet compression procedure that is used in different pharmaceutical companies is divided into four distinct stages. These are named as filling, metering, compression and ejection. These all four steps are explained below:

1. Filling: This procedure of the tablet compression machine involves transfer of the granules into position for tablet compression. The ultimate product is then blended for homogeneous blend. Then the mixture flows to the compressing tool punch-die cavity. The punch-die cavity is made of punch-die and lower punch. Then the position of lower punch in the die is responsible for the volume of the cavity. This volume must be appropriately adjusted for weight of granules to be compressed to make the tablets.

Related: Lubricant Concentration in Pharmaceutical Products

2. Metering: The metering procedure for the tablet compression procedure involves removal of excess granules from the compression machine. At this stage the required weight (volume) of granules to be compressed into tablets is controlled by the height of the lower punch in the die and the height of the lower punch is controlled by the metering cam. The lower punch is raised to the required level in the die to get the required weight of granules in the punch-die cavity. The excess granules are scraped from the surface of the die table. The metering method is similar to the process used to determine the weight of flour during the making of a cake.

3. Compression: During compression stage the top and bottom punches come together by pressure within the die to form the tablet. As the punches enter into the compression stage, the top and bottom punches move between two large wheels called compression rolls. These compression rolls push the punches to words the die to form the product. So, distance between the top and bottom punches determines the thickness and the hardness of the tablets. When the punches are so close together, a thin and hard tablet is created. Today AWC (auto weight control) machine is used for better result.

4. Ejection: The ejection procedure for the tablet compression 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. Then by a scrapper tablets are collected in the container.
There are different types of compression machines are available for tablet manufacturing and these have their identification on the basis of the number of tablet compression stations as 25 station, 35 stations, 55 stations etc.