Types & Classification of Tablet Press: Which Tableting Machine Should You Buy?

Are you planning to buy a new tablet press?

Well, it is important you consider all the available types of tablet press machines.

Frankly, when you go shopping for this accessory, there are hundreds tablet punching machines in the market.

Take for instance, at SaintyCo we have over 6 different series with that come in many designs and configurations – both standard and custom options.

There are over a 100 options available.

I know this can be overwhelming and it is likely to confuse you.

Today, I am going to focus on different types and classification of tablet press machines.

These are the key factors I will focus on in this article:

• Explain the working principle of the tableting machine
• List all key components of each type of tablet machine
• Discuss all advantages of each tableting machine
• Quick summary on how to choose a suitable tablet press equipment

With this information, I am sure you’ll choose a suitable tablet press that meets your production needs.

Let’s go straight to our subject of today:

Types of Tablet Press Machines

Broadly, we there are two main types of tableting machines:

• Single station tablet press
• Multi-station tablet press

Now, in the next chapters, I am going to explore all these compression machines in details.

Single Station Tablet Press

A single station tablet press machine is the simplest tableting equipment.

At times, you may also call it a single punch or eccentric press.

Depending on its design, you can operate the machine manually or incorporate an electric motor.

Normally, this machine features a single tooling station with a die, pairs of lower and upper punches.

Therefore, the compression force of the machine is due to the upper punch only. During this period, the lower punch remains stationary.

This implies that the working process tends to be similar to that of hammering motion. It is for this reason that you may refer to is as a single punch press.

You’ll get to know more about this machine as I discuss the working principle of single station tableting machine.

First, let’s explore the different parts of this tablet making machine.

Parts of a Single Punch Tableting Machine

Obviously, the number of parts will depend on the complexity of the machine. In this section, I will focus on the basic components of an eccentric press.

Here are some of the most important parts of a single station tablet making machine:

Hopper: This is the section you’ll put all material to be compressed into a tablet.

Depending on the design, you can fill the hopper manually or using other mechanical means.

Die cavity: It is the die cavity that determines both size and shape of a tablet.

Depending on the type of tablets you intend to produce some of the most common options available include:

• Round shaped die set; they are common in the pharmaceutical industry. You can use it to compress normal concave, concave with flat or bevel edges, deep concave with flat faced and shallow concave with ball shape.
• Oval shaped die set; with this stool set, you can make flat faced tablets with bevel edges or concave tablets with a deep and bevel edges.
• Capsule dye set; from this die set, you’ll make concave tablets with flat faced or bevel edges.
• Other geometrical shapes; depending on your unique tablet designs and geometrical shapes, you can make triangular, benzene, rectangular of rhombus tables

I want you to realize that, choosing a unique or complex die design is essential, especially when you intend to reduce the level of counterfeits.

Punches: These machines have upper and lower punches that press material within the die cavity into a desired tablet.

Cam trucks: They guide the movement of compression machine punches.

Tablet adjuster: It helps to control the size and weight of the tablet by regulating the amount of powder you intend to compress.

Ejection adjuster: It makes it easy to eject the tablet from the die cavity of a tableting machine.

Now, how does a single press tableting machine work?

Well, I am going to summarize the process in the next section.

The Working Principle of Single Station Tableting Machine

I am going to explain this process in three main stages and they include:

• Filling process
• Compression process
• Ejection process

Now, let’s discuss each of these processes in details:

Filling Process

At this stage, withdraw the upper punch from the die using the upper cam.

As you lower the bottom punch, the powder will flow into the hopper thereby filling die cavity.

As the bottom punch moves upwards, any excess powder is swept from the table.

Compression Process

The upper cam forces upper punch into the die cavity.

A predetermined magnitude of force is then applied on the punches to compress powder into a desired tablet.

Ejection Process

Upper cam withdraws the upper punch.

At the same time, the lower punch moves upwards, expelling compressed tablets.

In most machines, it’s the surface plate that removes compressed tablets from the system.

This is a continuous process that you should monitor to ensure consistency and accuracy of the tablet compressing process.

With all these in mind, it is now time to find out why we need this tablet machine.

Advantages of Single Punch Tablet Making Machine

In most cases, you can use this machine to make chewable and effervescent tablets.

During this process, the machine will offer the following key advantages:

• Easy to operate, hence, no need for advanced training
• Robust structure and space saving
• You can manufacture tablets with odd shapes
• Suitable for small batch production more so in R&D
• Reduces weight variations since it uses high pressure
• Operates with low noise levels
• Easy to control material loading process

I know evaluating this machine at times can be a difficult process.

This is why at SaintyCo we are always ready to help.

Normally, I recommend this equipment for laboratories or R&D institutions.

When you invest in this tablet press, chances of profiting from your tableting business are always high.

Apart from the single station tablet making machine, another machine that is popular is the multi station tablet press.

I’ll explore its features shortly.

Multi-station Tablet Press

A multi-station press tablet manufacturing machine, also called a rotary press is one of the most popular equipment in the pharmaceutical industry.

This is due to its high production capacity and cost saving benefits.

Like the single punch tableting machine, rotary presses have upper punches, dies and lower punches.

The name rotatory tablet press is due to the rotating tableting assembly.

It is this assembly that holds dies, upper and lower punches.

As you can see from the section of multi-station tablet press below, this equipment has several tooling stations.

In these compression machines for tablets, it is the rotation speed of the turret and the number of stations that determine the production capacity.

Later in this section, I’ll explore the working principle of multi-station tablet press.

For now, let’s focus on the various parts of this machine.

Parts of a Rotary Press

A rotary tablet press has a complex design when you compare it to as single station press.

Still, it shares the same parts, with the single station press.

Therefore, in this section, I will focus on parts that are unique to multi-station tablet making machine.

For instance, hopper, die cavity and punches, all perform the same function as in a single station press machine.

Remember, I had discussed some of these parts in the previous paragraphs.

Now, let me focus on features that are unique to this machine:

Feed peddle: This part plays an integral role in high speed rotations where it forces materials into the dies.

Lower cam track: During the filling stage, lower cam track guides the lower punch to ensure the die cavity is overfilled.

This allows for easy adjustment of the system.

Cam tracks: It guides the movement of both the upper and lower punches to ensure precise movement.

Capacity control: During the filling stage, capacity control adjusts the lower punch track. This ensures the quantity of material remains within the allowable range before compression.

Compression: There are two stages here:

• Recompression stage; it gives material the initial compression and this helps to get rid of excess air. At times, air may be trapped within the die cavity.
• Main compression; main rollers apply the final compression force to form tablets.

Ejection cam: To facilitate ejection of tablets from the die cavity, ejection cam guides the lower punch upwards.

Take-off blades: It deflects the tablets to a discharge chute, which then moves to the collection container.

NOTE: Number of parts may vary depending on the tablet punching machine design.

For this reason, always remember to read the entire manual of a tablet compression machine.

It is the only way to learn more about any multi-station tablet press machine.

Statistics show that, nearly 63% of people don’t read machine manuals.

Don’t be part of this group.

You may end up operating the machine inappropriately, which can be costly.

Having said all these, now let’s have a quick overview of how a multi-station press works.

The Working Principle of a Rotary Tablet Press

To make it easy for you to understand, I will summarize the working principle of this machine in three steps.

These include:

• Filling
• Compression
• Ejection

Now, let’s discuss every process:

• Filling Multi-station Tablet Making Machine

You’ll place the material to be compressed in fixed hopper. The material is then fed into several dies simultaneously.

• Compression Process in Rotary Tablet Press

Like in the case of single punch tablet making machine, it is the punches that exert required magnitude of force to transform powder or granules into tablets.

During this process, it is the rollers and cam track that control these punches by guiding their movement as the table rotates.

Next, the lower cam guide pulls a lower punch to the bottom of the dies.

This ensures all dies are overfilled with material.

As the lower punch rises, excess powder is removed by the swipe blade, which then the pushes material to oncoming die.

After this, the lower punch drops, then the upper punch penetrates the die.

It is at this point that the compression process begins.

Depending on the design of the machine, the process may involve pre-compression and main compression.

By the end of this process, you should have a fully formed tablet within the die cavity.

• Ejection of Formed Tablets

After full compression, the automatic tablet press machine will withdraw the upper punch as the lower punch rises.

This brings tablet above the die’s surface.

All fully formed tablets will be swept off the die to a chute container.

The pull-down cam will then return the lower punch to the bottom of the die.

This will mark a complete cycle of a tableting process, after which the process starts again.

This is a continuous process that takes place fast to meet any high production needs in pharmaceutical and drug industries.

These machines are popular in most industrial setups due to the numerous benefits they offer.

Now, we need to explore the main advantages of multiple station tablet press machines.

Advantages of Multiple Station Tablet Press Machines

Rotary tablet presses guarantee the following key advantages:

• Cost efficient than single punch tablet press
• Suitable for continuous operations where bulk production of tablets is required with an output of over 8,000 to 200,000 tablets per hour. This will depend on design and configuration of the tableting machine
• Features an automated system, thus, eliminating most human interventions. This ensures consistency and accurate tableting process.
• Guarantee independent control of both tablet hardness and weight.

Apart from all these factors I have mentioned, you can classify multi-press tableting machines further depending on the type of tooling.

I want to state categorically this is an important pill press machine design feature that affects the characteristics of tablets.

So, in the next sections, I am going to focus on yet another segment of classifying rotary press machines.

Classification of a Rotary Compression Machine

Broadly, all the available multi-station press machines may have either “B” type or “D” type tooling.

Normally, when we refer to a tablet press tooling, it simply implies a set of all dies and punches.

This is not a random process.

It is guided by certain regulations and laws depending on the geographical location.

For instance, there is the Tablet Specification Manual (TSM) that acts as a guideline to tablet press tooling in the U.S.A.

Moreover, the Euro Standard (EU) tooling is widely used in this industry.

Let’s evaluate these types of multi-station tablet compression machines:

“B” Type Multi-station Press

The diameter of the punch barrel is 0.75 inches or 19mm.

In most cases, you can use with two types of dies:

• “B” dies that have a 1.1875 inches (30.16mm) diameter
• “BB” dies with a diameter of 0.945 inches (24mm)

“D” Type Multi-station Tableting Machine

Nominal diameter of this barrel is 1 inch (25.4mm).

You can use it with a die that has a diameter of 1.5 inches (38.10 mm).

Normally, you’ll find that the “B” type tooling can exert 6.5 tons as a maximum compression force.

On the other hand, a “D” type tooling exerts a maximum compression force of 10 tones.

With all this information, I am sure you can choose the best tablet compression machine that meets the specific needs of any application.

Again, if you still find it difficult to choose the right accessory, feel free to contact us.

Conclusion

In short, we have two types of tablet making machines – multi-station machine that is suitable for large scale production and single station press, which is mainly used for R&D.

By knowing your production requirements, it will be easier to choose a suitable tableting machine that will guarantee a reasonable ROI.

Further Reading

• Tablet Press – Source: Wikipedia
• Tablet Press Instrumentation – By M. Levin
• Tablet Press Monitoring System – By AIA
• Multiple Station Tablet Rotary Presses –  Saraswathi.B
• Tablet Press – By Saraswathi.B
• Working of Tablet Punching Machine – By Chetan Signh Bisht
• Drug Dosage Forms – By Vinay Gupta
• Tablet Press – By Calistus Ozioko