11 Critical Tablet Compression Machine Parts You Must Know to Optimize Tableting Process

Knowing tablet compression machine parts is critical in the tablet making process. For a fact, there are many tableting machines in the market with hundreds of parts and components.

However, for the scope of this article, I will focus on the main parts that you’ll find in any tablet compression machine.

To know the exact location and specific functions of these parts, you need a clear understanding of the structural design of tablet press machines.

Understanding the structural design of a tablet pressing machine involves a critical analysis of both the 3D and technical drawings of the machine. Let’s have a look at these examples:

As you can see the machine is complex indeed. However, we will not go into those details since the scope of this article will focus on common parts and their specific functions.

1. Tablet Compression Machine Hopper

The tablet compression process starts from here. It is at this point that you’ll put all powder you intend to compress into tablets.

Tablet press hoppers come in a wide range of shapes 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.

Depending on the design of a tablet press machine, you can fill the powder manually or using other automated systems.

As tablet press machine manufacturer, we put every measure in place to ensure there is a consistent flow of powder from the hopper to compression systems.

Here are major concerns that we have addressed so far:

• Hoppers may feature optimal flow angles to facilitate flow, especially where it is nearly impossible to adjust formulation.
• Some hoppers may feature vibratory rods. This is done carefully to enhance product flow and to prevent possible product separation.

At any given point, the design of these tablet compression machine parts aims to eliminate possible feeder starvation.

2. Feeder System

This yet another critical part of the tablet compression process. Remember, at any given time, the design of the system should be such that 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:

• Feeder housing

Material from the hopper will enter the dye system through the housing. The feeding process should be consistent and accurate to produce high quality tablets.

The feeding housing is made of stainless steel 316L 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.

• 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.

3. Tablet Press Punches

This is yet another critical part of the tablet compression machine parts. Normally, you can choose from simple to complex shapes of tablet press punches.

The design and shape of a press punch tool design have a direct impact on the tablet quality. A reason why here at SaintyCo, we design tablet presses with great accuracy and precision.

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.

To produce the desired tablets, punches move within the die, thereby compressing powder into the desired tablets.

In any tablet press machine, we have:

• Upper punch system

Like the name suggests, the tablet press upper punches are on the upper section of the rotary system. They move vertically, in and out of the die bore as you can see in the animation above.

• Lower punch system

The lower punches are on the lower section of the rotary system of the tablet press machine.  During the tablet compression process, the lower punches remain within the die bore throughout the entire cycle.

4. Tablet Press Die System

Normally, whenever we talk about the tablet press punch then the next component that comes in mind is the die system. As I had mentioned earlier, the movement of tablet press machine punches, takes place within the die bore or cavity.

Therefore, the punch and die must be machined together to ensure compatibility.

It is in the die cavity that the powder is compressed into desired tablets of definite thickness and size.

It is the die cavity that determines both the thickness and size of a tablet. Like the punches, a die system should have the following key features:

• Clean impression on every punch
• Prevent chipping or damaging of tablets
• Feature anti-corrosion protection
• Have non-stick treatment

Other critical features we consider whenever we are machining a tablet press die system include:

• Tapering angle; this is a critical aspect since it allows excess air to escape, while minimizing the tablet ejection force and frictional heat.
• Other technical specifications include die height, chamfer, die bore and die diameter.

Again, we cannot wrap up this section without talking about a fundamental component of the tablet press tooling system – turret.

5. Tablet Press 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.

Again, to guarantee efficiency and reliability, there is always need to allow for any necessary adjustments as far as the dynamisms in tablet compression processes are concerned. Therefore, it is for this reason that tablet press manufacturers are shifting from traditional turrets that were basically dies and punches, to segmented turrets that have segmented sections and punches.

A segmented rotary turret design increases production, while minimizing possible downtime during the manufacturing process. Furthermore, this new design allows for increased number of tablet compression stations and fast part changeover.

Remember, it is the tablet press machine turret that determines the number of stations. This helps to determine the production capacity of the machine for every complete rotation of the turret.

Again, with a properly designed tablet tooling system, you can easily incorporate the multi-tip punches. This is common in the high capacity tablet press machines.

Throughout these design processes, the tooling must still conform to either the Tablet Specification Manual (TSM) or the Euro Standard (EU) tooling. Still, you can also opt for custom tablet press tooling systems.

6. Tablet Press Machine Cam Tracks

Cam tracks are other critical tablet compression machine parts that play an integral role in ensuring seamless 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.

That is, as the turret rotates, it is the cam trucks that move the punches in an up and down motion. This 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.

With the tablet compressed to the desired specifications, the upper cam withdraws top punches. On the other hand, the lower punches move upwards to expel the compressed tablets with the help of lower cam.

In short, you can see that upper and lower cam tracks play an integral role at every tablet compression stage in these machines.

It is a simple process that must be precisely controlled to achieve the desired tablet size and weight.

7. Tablet Press Filling Station & Weight Control

With the help of different movements of the cam systems, material will flow into the die cavity depending on the position of the punches. In most cases, tablet press machine manufacturers use servo motors to control movement of the cam track for accurate dosing.

This is due to their high precision and ease of integration to other computerized systems of other machine parts.

A critical procedure in this section of tablet compression process in the:

• 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 wastages, the excess powder automatically moves to the next die cavity, which is just about to be filled.

To achieve these, all the other components must coordinate smoothly for a seamless tableting process.

8. Compression Rollers

The idea 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. That is, they expel air first before the compression process begins.

Most machines have two sets of rollers:

• Pre-compression rollers

These are the very first rollers in 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.

Any air within the die cavity or powder particles will obviously result in low quality tables. This process is necessary for the reason that, any powder in the machine’s hopper may have air between its 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.

9. Tablet Press Ejection Cam

Again, the ejection cam is located just after the main compression rollers. Like the other cam tracks, ejection cams are also critical aspects of tablet compression machine parts.

Without them, there is no way you’ll access the already processed tablets.

Remember, after compression, the tablet is always fixed within the die systems (space between lower and upper punches).

So, what’s the exact role of the ejection cams?

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.

10. 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.

I hope this information has been useful, especially if you want to know the various parts of these machines and how they work.

As you might have realized, all the 10 tablet compression machine parts I have mentioned above mainly focus on the processing section. That is, feeding, compression and discharging stages.

However, there are other components that also help to achieve this process.

So, in the next section, I am going to discuss other tablet compression machine parts that play an integral role in tableting process.

11. Other Tablet Compression Machine Parts

As you’ve seen in the 3D and technical drawings at the beginning of this article, a tablet press machine is basically an assembly of different parts. It is an electromechanical machine whose parts coordinate to perform a desired function – compress tablets.

In this section, I will give a general overview of additional parts of tableting machines. They include:

· Touch Screen Control Panel

It is from the touchscreen HMI system that the machine operators can control every aspect of the tablet making process. This HMI can either be attached to the main machine or exist separately.

Quite a number of tablet compression machines that are available in the market use SIEMENS or Allen-Bradley PLC systems. However, here at SaintyCo, we mainly use SIEMENS PLC.

Therefore, the control panel forms an integral part of these integrated computerized system that monitor every aspect of the tableting process.

· Sealing System

The sealing system provides advanced dust handling capability. This isolation reduces need to clean the machine regularly and possible cross contamination.

· Electric Motors, Gears and Belts

The compression rollers, punches, dies, turret, etc. are all moving parts. This implies that the machine uses a prime mover (s).

In this case, depending on the kind of motion we intend to create, we can opt for a servo motor or an induction motor.

For example, a servo motor is a perfect choice for the filing system. This is because it is easy to control servo-motors to meet the highest degree of precisions such as 0.01mm.

However, for the pre-compression and compression stages, synchronous motors offer a better speed and control.

Furthermore, to transmit this motion to other sections, we may use a combination of both gears and belts.

Every tablet press machine design is such that it can accurately compensate any load variations. Even the motor can accurately start this machine, whether under maximum load or with no load.

In short, to achieve a desired motion, we need to incorporate mechanical, hydraulic and electrical systems. Frankly, we may not go into intricate details about these systems since they are available in the technical manual of the tablet press machine.

· Lubrications Systems

Moving parts form integral sections of tablet compression machine parts. Therefore, to avoid wear and tear due to friction, we need to lubricate moving parts.

Quite a number of tablet press machines feature a central lubrication system. The machines automatically lubricate moving components.

· Hydraulic Pump Unit

An efficient hydraulic pump unit will help maintain consistent pre-pressure and main pressure. This guarantees smooth and accurate tableting process.

Again, to avoid possible damage that may occur on the tablet press tooling system, these machines are equipped with an overloading protective unit. This automatically stops the machine in case of overload.

Other parts of the machine include robust structure, rubber wheels (depending on the size of a machine), switches, LED light indicators, lockable polycarbonate cabinet and cooling system, among other small parts.

Normally, I do insist that you request for the brochure since it is the only document that has all the tablet compression machines parts for specific models.

Conclusion

As you can see, there are quite a number of tablet compression machine parts and their designs vary depending on the type of machine. For instance, a high capacity pharmaceutical tablet press machine has more parts than tableting machines designed for clinical trials or R&D.

At SaintyCo, we have a range of modern tablet press machines that we can configure to meet unique specifications.

For any inquiries or questions, feel free to contact our technical team.

Further Reading

• Tablet Press Machines – Source: SaintyCo
• Multiple Station Tablet Rotary Press – By Saraswathi.B
• Tablet Press – Source: Wiipedia
• Types & Classification of Tablet Press – Source: SaintyCo
• Case Study on the Upgraded SaintyCo Tableting Machines – Source: SaintyCo
• Multiple Station Tablet Rotary Press – Source: Pharmainfo
• Tablet Press Instrumentation – Source: MCC-Online
• Working and Principle of Tablet Compression Machine – By Ankur Choudhray