A rotary tablet press machine is one of the most popular types of tablet compression machines.

Normally, we use this machine for high production of tablets such as pharmaceutical industries.

Even though there are different series of tableting machines, the working principle still remains the same.

In this article, I am going to focus on the working principle of the rotary tablet press machine.

However, even before I do that, it is important to know the various parts of tablet presses.

Smart S with a control panel/tablet compression machine

A rotary tablet press machine with a separate control panel.

Parts of Rotary Tablet Press Machine

In this section, I will not focus on the detailed aspect of tablet press machines.

This is because I have an article that explores all parts of this machine: 11 Critical Tablet Compression Machine Parts You Must Know to Optimize Tableting Process

So, before I move to the next section, I will list all important parts here:

  • Hopper; holds powder you intend to press
  • Die cavity; it determines the size, type and texture of tablets
  • Feed paddle; directs material into the die cavity
  • Punches & dies; they help to compress powder into tablets
  • Cam tracks; they guide the upper and lower punches.
  • Capacity controls; it ensures proper filling of the die cavity
  • Compressors; they may include pre-compression and main compression systems. This compresses the powder into a desired tablet.
  • Ejection cam; this helps to remove tablets from the die cavity
  • Take-off blade; deflects tablets into discharge chute
  • Control system; controls and coordinates most functions of the machine
Smart S-tablet press dimensions

A technical drawing showing different parts of tablet press machine.

You should note that, apart from these parts of the rotary tablet press machine, there are other parts such as lubrication systems, motors, electrical and hydraulic systems.

Again, the number of parts will depend on the complexity of a machine.

Having said that, now let’s focus on the subject of this article:

How a Rotary Tablet Press Machine Works

Here, I am going to review every stage on how a rotary compression machine works:

· Powder Filling Stage

At this stage, you’ll feed the tablet press machine with powder.

That is, place your powder in the hopper from where it will flow to the tooling system of the machine ready for compression.

Hopper

A section of rotary tablet press hopper

Due to the geometrical shape of all hoppers, this powder will flow to the tablet press tooling system.

· Powder Metering Process

Tableting process involves precise filling and compression of powder in the die cavity.

Therefore, the machine should move excess powder that may be the source of any form of inconsistencies.

At this stage, your rotary tablet press machine should ensure the accurate filling of the die cavities.

This should include the desired volume and weight of powder that should be compressed into tablets.

Tablet making process

Four critical steps in tablet making process

During this process, the lower cam of the turret moves upwards to a predetermined level.

This results in excess powder that is scraped from the die surface.

· Tablet Compression Process

Basically, this machine derives its name “rotary tablet press” from the fact that it has a rotating turret.

It is this turret that holds the tablet tooling system.

A rotary tablet press machine turret

A rotary tablet press machine turret

Normally, the production capacity depends on the size of rotary tablet press machine’s turret.

In most cases, you may divide turret into the following key sections:

  • Upper turret; section that holds upper punches
  • Lower turret; part that holds lower punches
  • Die table; a section that holds dies

With the powder filled in the dies to the right depth, the upper and lower punches begin to compress the powder.

This is how the process goes:

This is a tablet press machine tooling system

An animation of tablet making process.

Normally, the upper and lower punches exert a predetermined amount of pressure that compresses tablets to the right size and depth.

The pre-compression process removes any traces of air that might be within the powder particles.

From the pre-compression stage, it then moves to the main compression.

The main compressor exerts significant amount of force that compacts powder to a desired thickness and hardness.

This is due to the pressure that is exerted on the punches by a series of pressure rolls.

Remember, this is a continuous process where the turret moves the in a rotary manner.

Normally, a complete revolution should produce the exact number of tablets as the number of dies on the turret.

· Tablet Discharge

At this stage, the upper cams will pull the top punches back to their initial position.

On the other hand, the lower punches are lifted up.

As a result, the lower punch pushes the already processed tablets out of the die cavity.

The scraper will then remove the tablet from the compression machine to the discharge chute.

Basically, this will mark the end of one complete cycle of the tablet compression machine (i.e. the turret has gone through one complete revolution).

As I mentioned earlier, this process remains the same irrespective of whether you have chosen any of the following rotary tablet press machines:

  • Single rotary tablet press machine
  • High speed rotary tablet compression machine
  • Single sided rotary tablet press machine

At times, we may also refer to these machines as multi-station tablet press machines.

You can see this clearly from the animation above.

Of course, this is basically from the fact that it has several tooling stations.

Tablet press machine tooling system

A section of the tooling system of tablet press machine

Now, that you’ve learned how a rotary tablet press machine works, I think it will be fair to discuss two main advantages of these machines in any tablet compression industry.

Advantages of Rotary Tablet Press Machines

Some of the main advantages, why you should go for this machine include the following:

· High Production

A rotary tablet making machine has many tool stations therefore, it is suitable for large scale tablet production.

That is, a single machine can have an output of 5,000 to over 430,000 tablets per hour.

This makes it a perfect choice for most large scale productions like in the pharmaceutical industries.

· Fully/Partially Automated Systems

Basically, this eliminates any possible human interventions that may lead to many errors during the tablet making process.

Therefore, you can control both weight and hardness of the tablets independently.

Furthermore, the machine automatically manages the cavity.

Apart from these two, other advantages such as robust design, cost saving features, efficiency and reliability depend on the specific design of the machine.

Conclusion

In short, the working principle of any rotary tablet press machine involves powder filling, compression and tablet discharge.

As you can see, the tablet making process using these machines is simple and straight forward.

At SaintyCo, we have a range of rotary tablet presses that vary in design, technology and production capacity.

For more information about SaintyCo tablet press machines, feel free to contact our team.

Further Reading