How to select Tablet Press Machine

Equipment is critical to producing quality and efficient products in the pharma manufacturing process. Above all, their ability to create products of desired therapeutic effects largely depends on their suitability with the product's physical and chemical characteristics.

Equipment not selected according to the desired product characteristics can damage the reputation and impact of well-researched and formulary-developed drugs.

Before purchasing equipment for your process or application, you must know your requirements and determine what functions you want in your specific equipment. It helps narrow choices and selects an optimum machine from the pool of available machines.

In this article, we will discuss how to select a tablet press machine, but first, what is a tablet press machine?

Introduction to tablet press machine

The tablet press machine is utilized in the Oral Solid department to produce tablets from powder. It compresses the powder in the tablet shape of the desired physical characteristics and ejects it from the machine's output section.

The main machine parts consist of Turret, Compression Rollers, Dies and Punches. Additional components are also present to facilitate the machine's functioning.

A turret is a large circular structure that rotates in a circular direction during machine operation. It houses dies & pairs of punches in the upper and lower positions.  Dies are small-shaped metallic components that rest in the rotating turret, and powder (being compressed) is filled in them. The number of dies depends on the machine configuration.  Two pouches are installed for each die - upper and lower punch. Punches are long metallic structures that compress powder from above and below. 

The compression roller presses the punches from above and below to exert force on the punches; then, the cumulative function of dies, punches, and compression roller determines the physical characteristics of the tablet. 

Like every pharma product machine, they are designed and configured to suit individual product requirements, achieved by implementing specialized functions. This selection depends on the product requirements for which a tablet press machine is being purchased.

Importance of correctly selecting tablet press machine

Let's discuss why it is necessary to choose the appropriate tablet press machine for your applications.

Fail to achieve proper product characteristics

The table's physical characteristics are vital to a tablet's correct functioning and therapeutic effect. Its size, shape and hardness determine the efficacy of a pharma tablet product, which in turn is dependent on the machine's performance and how well the machine can produce tables of desired characteristics.

If the correct tablet press machine is not selected, the machine will fail to incorporate the desired physical characteristics into the tablets. Examples include shape and weight, which are vital to the success of a tablet drug product.

The, the overall result of machine mismatch will be the inability of a tablet to deliver the required therapeutic effects. The tablet's properties will fail to provide the label claim, and as a result, the drug product will become useless, making it a loss for the pharma drug manufacturer.

Inefficient utilization of machine resources

Selecting out of specification tablet press machine makes it over or under operation. It can either waste precious resources to run the machine, or the machine will produce a product well below the required quality and product characteristics. 

Tablet press machines require a handful of resources to operate. The volume of these resources is fixed and cannot be altered. If the machine selected is above the actual product requirement, the cost of utilities and different resources will exceed the total productivity of the machine, making it a non-profit option.

On the other hand, if the tablet press selected is far below various requirements, it will fail to produce tablets of the required quality and quantity, causing an overall loss for the organization. 

Guidelines for selecting a tablet press machine for your pharma applications

Let's discuss some factors to consider when selecting a tablet press machine.

Commercial scale or Lab scale

One critical factor to consider when selecting a tablet press machine is commercial scale or lab scale. Commercial scale is used to manufacture routine production  batches, while lab scale is used to manufacture batches intended for R&D purposes.

The commercial model is manufactured considering a pharma organization's commercial & market requirements and can produce tablets that have been developed and formulation finalized. Their output capacity is much higher than the lab scale model because it has more tooling station as compared to lab scale. These machines also have advanced features to improve product quality and enhance machine operation. 

On the other hand, lab scales are built by considering developmental or R&D requirements. They contain less advanced features and typically only have one station or set of tooling that produce only one tablet per revolution, significantly decreasing the total productivity. The lab scale machine is also small and has fewer automated components - only relevant components to operate the machine.

What are your product requirements?

Knowing your tablet's requirements is necessary, like every other pharma processing equipment. Although a tablet press machine can produce a range of products, there are still limitations in creating the type of product. 

Tablet products typically differ in physical characteristics such as shape, size, and hardness. A major line of difference is a specific tooling type, such as D-type and B-type tooling that can be incorporated in a machine.

Tablet press machines are manufactured to operate with particular tooling types. Some of the latest machines can also utilize more than one tooling which comes at a higher cost. 

Another tablet standard in the pharma industry is a double-layer tablet type, which is produced by a special machine, called double tablet press machine. In it, two tablets are combined in a single tablet, and this machine requires more complex components and operations than standard machines. 

Gravity vs Force Feeder

The feeder in the tablet press machine is used to fill the die before being compressed. The working and mechanism of the feeder affect the amount of powder being filled into the die, which in turn affects the tablet's physical and therapeutic characteristics. There are two types of feeders: gravity feeders and force feeders. 

A gravity feeder is used when the powder has excellent flowability and does not offer resistance on its way into the die. It has no internal parts and a channel designed according to the powder characteristics which guides the powder into the die through a channel. A gravity feeder is more suitable for low-speed operations and excellent flowability powder.

A force feeder forces the powder from input to output into the die. It can increase the rate and speed of powder feeding into the die, which is specifically helpful for high-speed machines and powder having low flowability. It consists of motors' pedals, which are rotated by a Variable Frequency Drive - VFD. The speed of the force feeder can be increased or decreased depending on the product requirements. 

Automatic weight control

The weight of every tablet in the pharma industry is a critical formulation and quality factor that must be maintained throughout production. Otherwise, the tablet will fail to deliver the required therapeutic effects, and the quality department will ultimately reject the product and production process.

During the tabletting process, the weight is continuously verified. If it goes above or below the standard value, the operator adjusts the weight by adjusting mechanical parts during the machine operation or stopping it. After adjustment, the operator again checks the weight and continues the tabletting operation. 

Nowadays, automatic weight control is also being developed to check the weight automatically and, if necessary, adjust the machine's mechanical part, automatically. It consists of pressure sensors installed at appropriate parts, mainly below the compression rollers. The sensor values depend on the power quantity in the die. Suppose a pressure sensor value changes due to the variation in powder quantity in the die. In that case, the central controller automatically adjusts the relevant mechanical part to compensate for the weight variation until correct sensor values are sensed at the central controller. 

Commonly, the automatic weight controller does not come as a standard machine part. Instead, it has to be specially added by paying an additional cost.

Compression Force

The compression force is exerted by the compression rollers on the punches that exert force on the powder in the die. The compression force is responsible for giving the tablets its relevant physical characteristics. 

Every table press machine has limitations in applying the compression force, which must be considered before purchasing a tablet press machine. A compression force must align with your product and process requirements. 

Echahangebale Turret

The turret is the central part of the tablet compression machine, which houses the main components, such as punches and dies. It is circular-shaped and driven by the main motor. During operation, it rotates at high speed, and at the same time, the powder is pressed to produce tablets, which are collected at the appropriate channel.

A single turret can only handle specific tablet types. To produce another kind, one has to change the machine. Nowadays, manufacturers also provide the option of changing the turret, achieved by using specialized additional parts in the tablet compression machine. 

The exchangeable turret can offer additional advantages compared to the non-exchangeable turret, which also comes at an extra cost.

About the Author:

Muhammad Asim Niazi

Muhammad Asim Niazi has a vast experience of about 11 years in a Pharmaceutical company. During his tenure he worked in their different departments and had been part of many initiatives within the company. He now uses his experience and skill to write interested content for audiences at PharmaSources.com.