How a Pill Press Machine Design Affects the Tablet Performance Characteristics

I’ll explain every concept in detail to make it easy for you to understand.

1. Tooling Design of Pill Press Machine

Do you know that compaction is a critical process in tableting technique?

Well, it is a process that determines both the physical and chemical properties of a tablet.

Therefore, to produce the required tablet size and shape, you need to have the right tooling design.

As professional tableting press manufacturers, we invest heavily in understanding the basics of tablet compression process.

That is, from analyzing tool design to assessing quality of the final tablets.

You can learn more about these machines in one of my previous blog posts: What is a Pharmaceutical Tablet Press Machine (An Ultimate Guide for Beginners & Professionals).

Whenever you’re choosing a tablet press tooling with an aim of improving the performance characteristics of the final product, you need to focus on the following:

Standardization of the Tablet Compression Tooling

Why is standardization an important aspect?

Adopting the European or American tablet specifications offer great procedural and economic advantages.

This is from the fact that, interchanging tablet press components will be easy and simple.

It is for this reason that manufacturers strictly follow the Tablet Specification Manual (TSM) and Euro Standard (EU) requirements for tablet tooling.

They outline specifications for different types of tooling as you can see in the table below:

When you adopt these standards, part modifications will be minimal, hence, reducing cost of operating the machine.

This is also possible with a number of innovative technologies in the tablet press industry.

At any given time, we have to consider shape, size, unique identification markings, esthetic appearance, production efficiency and uniformity, among other factors.

Tablet Punches

This is a critical tool that determines the efficiency of the tablet compression process.

As tablet press manufacturers, we strive to improve on tablet punches consistently to produce durable and efficient tooling.

That is, with our in-house tooling, we can modify the head radius (HR) and head flat (HF), for unique tablet pressing specifications.

You should note that modifying the configuration of the punch head will affect essential parameters of the tablet press process such as:

• Compression profile
• Contact time
• Dwell time

You can see this in the diagram below:

All these involve R&D, alongside experiments to establish suitable configurations for any tablet punching machine.

In case you find it difficult to choose the right pill press machine tooling, feel free to contact us.

2. Key Considerations when Designing a Tablet

I know every pharmaceutical company wishes to have the best tablet design.

However, you can’t talk about a tablet design without mentioning the tooling process.

Normally, a good tablet design will determine the overall production cost, tooling strength, premature tooling failures, etc.

A good tablet should be one with a desirable shape and profile, which can range from simple to complex.

That is, you may choose a round or non-round profile.

It is the tablet profile that will determine the complexity and shape of the tableting equipment.

Again, as you decide on the tablet design, it is important to consider:

• Possible embossing requirements
• Packaging
• Company’s branding
• Nature and type of granule

Moreover, the ability to swallow a tablet will depend on its profile and design.

Remember, this is an important performance characteristic of a tablet.

It is quite annoying to produce tablets that are difficult to swallow.

Even with the complex shapes and designs, this still remains a critical aspect that you must solve when choosing a tooling system.

For example, in case you intend to have heavily embossed tablets, it is important to avoid profiles with deep cuts.

This is because the tablets with deep cuts may have softer cores and these can lead to erosion or sticking.

Features such as coating or break lines are other performance features you may consider.

For instance, coating tablets may be for aesthetic purposes while breakline make it easy to divide a tablet.

In short, a good pill press machine should allow for incorporating appropriate design features.

This should include a good shape, breakline, coating and profile, among other factors.

3. Consider the Dwell Time of Pill Press Machine

I have mentioned this in the initial stages of this article.

However, it is important to explore how optimizing dwell time can help improve the performance characteristics of a tablet.

Remember, at any stage, we strive to have a fast, efficient, accurate, predictable and fault free tablet manufacturing process.

The good news is that you can achieve this by knowing the dwell time of your tablet pressing machine.

When you have a proper control of the pill press machine, it is possible to avoid these possible scenarios:

• Exerting too much compression force that can damage the press or cause tool failure
• Using too little compressive force that does not press granules or powder effectively

To achieve this, you need to analyze and understand the dwell time of your machine.

That is, the time a tableting machine’s individual punch head flat (HF) is in direct contact with the compression roller in the rotary tablet press machines.

Therefore, to attain a suitable amount of dwell time of tablet press machines, you need to analyze the following:

• Size of the punch head flat (HF)
• Shape of the punching head
• A pre-compression system may be necessary (see the exact location of pre-compression unit in the diagram above)

The truth is that a slight change in dwell time will adversely affect the tableting process.

Therefore, you can only leverage on this with machines whose head flat diameters are precisely machined to meet the right specifications.

4. Choosing the Right Components of Tablet Press Machine

You cannot talk of a high-quality tablet with suitable performance features without evaluating the various components of a pill press machine.

That is, you need to evaluate all parts that:

• Compress; a process that reduces the bulk volume of powder or granules thus displacing air. Depending on the type of material, some of the processes here may include elastic deformation, plastic deformation or brittle fracture.
• Consolidate powder; consolidation will affect the final properties of the tablet since it involves bonding. You can explain this process in terms of mechanical, intermolecular force or liquid-surface theory.
• Decompress; this is the rate at which the machine removes the compression force.
• Eject; you need a force to break the compressed tablet from the die wall. Normally, ejection force may vary from 200N to 800N, depending on the situation and the type of material you’re processing.
• Scrape off the fully processed tablet

In short, with the help of our technical team, we can take you through a comprehensive process of evaluating every tablet press machine.

Remember, a thorough grasp and specification of pill press machines will obviously guarantee an optimal performance and high quality tablets.

For instance, knowing the type of cam to use will solve nearly all tableting difficulties.

You can learn more about this in our study about tablet press machines: What is a Pharmaceutical Tablet Press Machine (An Ultimate Guide for Beginners & Professionals)

5. A Flexible Design Allowing for Adjusting Operating Parameters/Conditions

Well, this is a broad subject that requires you to know how to troubleshoot tableting machines.

Again, we have a complete guide on how to troubleshoot this equipment.

It will help you reduce possible downtime, hence, seamless production.

For example, you may need to do the following to ensure an optimal tablet pressing process:

• Adjust material flow problems/flow issues; if you don’t control it properly, there is a high chance that your machine may experience feeder starvation or overfilling of the feeder.
• Wrong feeder paddle configuration will result in tablet inconsistency
• Automated human machine interface (HMI) allows for easy and precise operation of the machine. Such systems eliminate possibility of human intervention that is prone to errors.
• Adjusting rotation speed; tablet harnessing depends on a proper choice of turret RMP
• Aligning all mating surfaces to reduce possible compression issues

Apart from these, adopting proper maintenance procedures is a sure way of ensuring a tablet press machine operates optimally.

That is, you need to do a routine inspection and maintenance of all components of the machine.

The procedure may include tightening loose sections, lubricating moving parts, replacing worn out sections, etc.

Conclusion

I know it is the desire of every business to manufacture tablets with the right performance characteristics.

The truth is that you can only achieve this if you acquire a pill press machine with appropriate design features.

This will range from choosing the right tool design, considering tablet requirements and analyzing machine specifications.

For more information on tablet press machines, feel free to contact us.

Further Reading

• A Design of Experiments for Tablet Compression – By Mathew N. Bahr
• Fundamentals of Tablet Compression – By Armin H. Gerhardt
• Tablet Press – By Calistus Ozioko
• Multiple Station Tablet Rotary Press – By Saraswathi. B