Working and Principle of Tablet Compression Machine

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, Neutraceuticals, cleaning products, industrial pellets and cosmetics.
In the tablet compression machine main principle is compressing of the upper and lower punch in a die hole, the hydraulic pressure plays a key role. This pressure is transmitted unreduced through the static fluid. Any externally applied pressure is transmitted via static fluid to all the direction in same proportion.

There are 2 types of tablet presses: 

  1. Single station tablet press.
  2. Multi-station tablet press.

Different parts with mechanism of Compression Machine are given below :
  1. Tablet Compression machine Hopper
  2. Feeder System
  3. Tablet Compression Punches system
  4. Tablet Compression Dies system
  5. Tablet Compression Turret
  6. Tablet Compression Cam tracks
  7. Tablet Compression Filling station and weight control
  8. Tablet Compression Rollers
  9. Tablet Compression Ejection Cam
  10. Take off Blade and Discharge Chute

Tablet Compression Machine Hopper:
  • Tablet compression process starts from here. we have to put all powder or granules intend to compress into tablets.
  • Hoppers come in a wide range of shapes, sizes and designs. Whatever the shape, it should be such that the material can flow seamlessly into the tablet compression chamber.
  • Again, since it is one section that is in direct contact with the material, it is made of stainless steel.

Feeder System:

  • It allows an accurate and consistent amount of powder to flow to the punch and die system.
  • Tablet press machine feeder system is made up two critical components.

1.   Feeder housing 
  • Material from the hopper will enter the die system through the housing. The feeding housing is made of stainless steel, since it is in contact with the product. Also, the product must not stick on the feeder housing as it will cause inconsistencies during the feeding process.

2.   Feed peddles 
  • Quite a number of high speed rotary tablet press machines have a feed peddles. The feed peddles ensures consistent and accurate material feeding into the die systems.
  • Without a feed peddle, especially if the machine is operating at a high speed, there could be chances of some dies being filled half way. This may result in tablets with varying thickness or the degree of compaction.

Tablet Compression Punches:
  • This is another critical part of the tablet compression machine parts. Normally, we can choose from simple to complex shapes of tablet press punches.
  • The design and shape of a compression punch tool design have a direct impact on the tablet quality. 
  • Under normal circumstances, these tablet compression parts are subjected to abrasive environments and exposed to extremely high pressure. Therefore, they require high quality material and if possible with a special coating to prevent sticking or wear.

In tablet compression machine, there are two types of punch system.

1.   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.

2.   Lower punch system:
  • The lower punches are on the lower section of the rotary system of the tablet compression machine and during the tablet compression process, the lower punches remain within the die bore throughout the entire cycle.

Tablet Compression Die System (see in the above image with punch) :
  • The movement of tablet compression 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 die cavity determines both the thickness and size of a tablet.
  • Therefore, the punch and die must be machined together to ensure compatibility.

Tablet Compression Turret:

  • There have been a lot of developments in the recent past as far as designing these tablet compression machine parts is concerned. As a matter of fact, turrets are the heart of tablet press tooling.
  • The rotating turrets have holes that host the die system of a tablet making machine. They are precisely machined to the required rotational tolerances and dimensions. Every bore on its surface ensures the die and punch are fully aligned for optimal tablet making process.
  • 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 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 (See in the animation Above):
  • Cam tracks are other critical tablet compression machine parts that play an integral role in ensuring 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 which helps to control filling, compression and ejection of already processed tablets.
  • For example, as the upper cam withdraws top punches from the die, 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 (See in the animation Above):
Weight control
  • By controlling the depth fill, tableting machine can easily regulate the content within its die cavity. Normally, with the help of 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 wastage, the excess powder automatically moves to the next die cavity, which is just about to be filled.

Compression Rollers (See in the animation Above):
  • 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.

Pre-compression rollers:
  • These are the very first rollers in rotary tablet press. 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 (See in the animation Above):
  • 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. 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.

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