A tablet press is a mechanical device that compresses powder into tablets of uniform size and weight. A tablet press can be used to manufacture tablets of a wide variety of materials, including pharmaceuticals, Nutraceuticals, cleaning products, industrial pellets, and cosmetics.
To form a tablet, the granulated powder material must be metered into a cavity formed by two punches and a die, and then the punches must be pressed together with great force to fuse the material together.
There are 2 types of tablet presses: Single station tablet press & Multi-station tablet press.
Different parts with the mechanism of the Compression Machine are given below :
- Tablet Compression machine Hopper
- Feeder System
- Tablet Compression Punches system
- Tablet Compression Dies system
- Tablet Compression Turret
- Tablet Compression Cam tracks
- Tablet Compression
- Filling station and weight control
- Tablet Compression Rollers
- Tablet Compression Ejection Cam
- Take off Blade and Discharge Chute
Tablet Compression Machine Hopper :
The tablet compression process starts from here and the blend or powder has to be put in the hopper which is compressed into tablets.
Depending on the design of a tablet compression machine, we can fill the powder manually or using other automated systems.
The design of the feeder system should be such that it allows an accurate and consistent amount of powder or Blend to flow to the punch and die system.
Tablet Compression Punches:
Punches and Dies
In any tablet press machine, we have
Upper punch system :
The upper punches are on the upper section of the rotary system and they move vertically, in and out of the die bore.
Lower punch system :
The lower punches are on the lower section of the rotary system of the tablet press machine and during the tablet compression process, the lower punches remain within the die bore throughout the entire cycle.
Tablet Compression Die System:
The movement of tablet press machine punches takes place within the die bore or cavity.
It is in the die cavity that the powder is compressed into desired tablets of definite thickness and size and the die cavity determines both the thickness and size of a tablet.
Therefore, the punch and die must be machined together to ensure compatibility.
The turrets are the heart of tablet press tooling.
The rotating turrets have holes that host the die system and they are precisely machined to ensure both die pockets and punch guided are fully aligned for tablet making
Every bore on its surface ensures the die and punch are fully aligned for the optimal tablet-making process.
A segmented rotary turret design increases production while minimizing possible downtime during the manufacturing process and it determines the number of stations.
Tablet Compression Machine Cam Tracks:
Cam tracks are other critical tablet compression machine parts that play an integral role in ensuring a smooth tableting process. The main work of the cam tracks is to guide the upper and lower punches in different stages in the tablet compression process.
As the turret rotates, it is the cam tracks that move the punches in an up and down motion that helps to control the filling, compression, and ejection of already processed tablets.
For example, as the upper cam withdraws top punches from the die, the powder flows in filling the cavity.
On the other hand, the lower cam track pushes the bottom punches upwards within the die cavity. This makes the die to be overfilled by material, allowing for accurate adjustment of the die content.
Again, to achieve a maximum compression force, the upper cam track drives the top punch and the lower cam adjusts the bottom punch.
It is a simple process that must be precisely controlled to achieve the desired tablet size and weight.
Tablet Compression Filling Station & Weight Control:
By controlling the depth fill, the tableting machine can easily regulate the content within its die cavity. Normally, with the help of a lower cam track, the bottom punch moves upwards to a predetermined height.
This ensures the die cavity is filled to a required depth before any compression process begins.
At times, as the bottom punch moves up, the excess powder may overflow. Therefore, to avoid wastages, the excess powder automatically moves to the next to die cavity, which is just about to be filled.
Compression Rollers :
Here is to ensure only powder is compressed to the desired shape and size. However, at times you may find air within the powder particles.
To achieve this, tablet compression machines feature a series of rollers that exert a sufficient amount of force to compress the powder and they expel air first before the compression process begins.
These are the very first rollers in a rotary tablet press. Basically, these rollers apply a small amount of force on the upper and lower punches.
This gives the initial compression force. The aim of this process is to remove air that could be in the die or powder particles.
Main compression rollers
Main compression rollers exert a predetermined amount of force (final compression force) for the formation of tablets. The compression force at this stage is higher than the pre-compression force.
It is important that the rollers remain stable with no vibration during the entire process. This is to ensure consistency of the tablets’ thickness and size.
Tablet Compression Ejection Cam:
The ejection cam is located just after the main compression rollers and like the other cam tracks, ejection cams are also critical aspects of tablet compression machine parts.
Remember, after compression, the tablet is always fixed within the die systems (space between lower and upper punches).
The ejection cams steadily and slowly push the bottom punch upwards. At the same time, the top cams move up and so are the top punches.
As a result, the fully compressed tablets leave the die cavity, i.e. the compressed tablet remains just at the top of the die.
Take –off blade and Discharge Chute:
The take –off blades are fitted just above the feeder housing. Their main role is to deflect the fully compressed tablets into the discharge chute.
The discharge chute, then directs the tablets to a collection bin.