Manufacturing of tablets in pharmaceutical industries is done by using a machine which is known as a compression machine.
In the old era, single-punch compression machines were used but nowadays more advanced & sophisticated compression machines are used which are known as rotary compression machines.
In this article, we will discuss the basic principle & workings of compression machines to make it easy for all to understand the exact way in which the compression machines work & compress the tablets.
Principle Of Compression Machine
The tablet compression machine works on the principle of compaction or compression in which powders or granules are filled in a die and after filling & weight adjustment pressure is applied by compression rollers & this pressure from rollers is transmitted to the powders or granules to form a tablet by plastic deformation.
Working Of Compression Machine
To understand the working of compression machines let’s take a practical example. Suppose a pharmacist wants to compress product Z which is manufactured by the wet granulation process. First of all, take line clearance for the compression process & after line clearance, the operator will ensure that the pressure & weight is adjusted to zero value which is gradually increased to achieve the required weight and hardness in the next stages which we are going to discuss.
- Add the granulated product in the hoppers of the compression machine & run the machine manually or on a jog to fill the dies with granules, this is the first stage of the compression process which is known as Die Filling stage of compression.
- In the die-filling stage, the granules from the hopper flow down to the feeder & from the feeder, the granules enter into the dies. In this stage, the lower punch is at its lowest position in the die to allow maximum filling of the die cavity.
- After die filling, the turret rotates and the head of the lower punch passes over a weight adjustment cam to adjust the required weight where the excess powder is removed with the help of tail over die; this stage of compression is known as metering or weight adjustment.
- In the weight adjustment stage, the lower punches play a key role because weight is regulated by changing the position of the weight adjustment cam up or down.
- After weight adjustment as the turret revolves punches pass through the compression rollers & in this stage upper punch is pulled down in the die and head of the upper punch passes below the upper compression roller & lower punch is pushed up in the die as it passes over the lower compression roller & this arrangement results in the formation of tablet in the die as the result of applied pressure, this stage is known as compression stage.
- When the tablet is formed in the die, the next step is to eject or remove the tablet from the die cavity & for this as the turret revolves the upper punch is pulled up & the lower punch passes over an ejection cam & raised in the die to remove the tablet. This stage is known as the ejection stage & tablets after ejection are collected in the drum.
Before starting the compression process ensure that the pressure & weight values are adjusted to zero because if the pressure is too high or the weight knob is at its maximum limit it may result in damage to the compression machine or its tooling due to overloading or overpressure.
Once the dies are filled with powder or granules the weight is increased to adjust it according to requirement & when weight is adjusted then pressure is increased to achieve the required level of tablet hardness.
- Pre Compression Of Tablets
- Advancements in tablet compression machines.
- Calculation of compression machine capacity.
- How to reduce compression machine breakdown.
- How to compress Bilayer tablets?