Rotary Tablet Press Machines: Basic Concepts, Types, Components, and Maintenance

Industries like pharmaceuticals face huge demand in today’s world. If you own a business in the industry, you likely need sophisticated, state-of-the-art machinery to stay relevant, meet expectations, and beat your competition. One such advanced machine is a rotary tablet compressing machine. 

In this article, we’ll discuss everything about these machines, including their types, components, operating principles, common problems, and maintenance tips. 

An Introduction to the Rotary Tablet Press Machine.

No matter whether you’re manufacturing fertilizer granules or medicinal tablets, you’ll require a press machine. 

In general, tablet manufacturing involves compressing a powder into a tablet. The process occurs with the help of tooling, punches, and dies; consider the animation below. 

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The rotary tablet manufacturing machine features a rotating core with tooling stations. The machine’s continuous cycling allows you to continuously produce multiple tablets with minimal manual input and required space.   

The Types of Rotary Tablet Manufacturing Machines.

You’ll find the following types available in the market. 

1. Single-Punch Rotary Press Machine.

This is a small-scale production machine that consists of a single punch, which limits its production speed and capacity. However, your rotary press machine may come with different tooling sets to let you vary the size and shape of your product. Due to its small output, it’s mainly used in laboratories or by small businesses. 

2. Multilayer Rotary Press Machine.

This tablet-making machine can produce tablets that are layered with different materials. It has multiple hoppers and feeders that can dispense different ingredients on the tablet bed as it rotates. Each layer is compressed separately on the table. 

This results in a product with multiple films, each often containing a different color or active ingredient.

3. High-Speed Rotary Press Machine.

This machine is designed to move at a very high speed. So, it can typically produce 200-800 tablets per minute! It has automatic feeding and ejection systems that eliminate the need for inconsistent manual input. This is the one to opt for if you want a large-scale tablet manufacturing machine. 

Main Parts of Rotary Tablet Press Machines.

how tablets are manufactured

This tablet manufacturing machine features the following main units.

1. The Hopper.

You load your powdered or granule raw material through this large funnel-like structure of the tablet press machine. 

2. The Feeder.

If you want to adjust the rate at which your raw material is processed, you control the feeder. 

This part essentially consists of channels, funnels, and chutes that transport the raw material to the tablet press’s compressor. The process occurs in a controlled and regulated manner. 

3. Compression Zone.

This part compresses the powder to your required tablet shape. 

The compressor has dies and punches shaped like the tablet; these apply pressure to the raw powder and mold it into your product. The punches are typically made of stainless steel. The dies are made of hardened steel and have a hole in the center that matches the shape and size of the punches.

These punches are mounted on a rotating turret.

4. Turret.

This part is a circular disc that golds the punches in a circular arrangement. It rotates at high speed during the manufacturing process to move the punches from the compression zone to the ejection zone. 

5. The Cam and the Cam Tracks.

In a rotary machine, the cam is a rotating element with a track grooved into its surface. When it rotates with the help of a motor, the groove guides the movement of the upper punches and dies. 

These components work together with the compression rollers to generate the required pressure. The rollers move up and down along the cam track, applying the necessary pressure to press the raw material into the tablet. 

6. The Ejection System.

This system consists of a series of ejector pins that push the tablets out of the dies and onto a conveyor belt or into a collection tray.

7. The Control Panel.

You or your operator will adjust the machine’s settings through the control panel. On the outside, it typically includes a display screen, control buttons, and indicators for speed, pressure, and temperature. Inside the machine, it has sensors, motors, and electronic components that let you adjust such parameters.

8. Safety Features.

Your rotary tablet press machine will come with various safety features, such as interlocks, guards, and emergency stop buttons. These will protect your operator and your machine in cases of accidents. 

How a Rotary Press Machine Operates to Produce Tablets.

How a Rotary Press Machine Operates to Produce Tablets.

Let’s discuss how the machine manufactures its products.

Step I: Feeding.

First, you put your powder or granules into the hopper. The machine’s feeding system takes the raw material as per your set-up speed. 

Step II: Compression.

The feeder passes the powders onto the dies. 

The cam track guides the upper punchers onto the die, and the compression roller moving on top of the cam track applies pressure to the punchers and dies. The compression process happens in two phases:

1. Precompression.

Here, the powders or granules are compacted slightly to form a cohesive layer. This helps keep density uniform and remove air packets that can later result in capping. 

2. Compression.

Here, the machine exerts a higher pressure on the loosely compressed tablets to shape them properly. This results in tablets. 

Step III: Rotation and Ejection.

The rotating turret leads the manufactured tablet away, and the ejection system moves it to the discharge chute. The punches and the dies reset their position, and the cycle continues. 

Removing Excess Powder From the Tablets.

As tablets are prepared by pressing powders, their surface can have some loose particles. This is where a tablet dedusting machine comes in. 

You can incorporate a deduster in your assembly line and feed it the prepared tablets. It will either use a brush or use an air system to clean dust and debris off. This ensures the tablets are high-quality and free of contaminants. 

How to Deal With Common Rotary Tablet Press Machine Problems?

These tablet-pressing machines have to handle large and sensitive work at high-speed. Whereas reliable pharmaceutical equipment manufacturers will give you the best machines, you can face some complications periodically. Here are some common problems along with their solutions.

1. Non-Uniform Tablet Weight. 

Many manufacturers face problems with varying tablet weights, and the cause can lie anywhere from the machine to the raw material. 

Your powder or granules should be uniform and have decent flow properties for consistent results. Invest in quality equipment, like fluid bed processors, to ensure your formula is appropriately dried and processed. 

If you’re sure the fault is not within your raw material, the feeder is inconsistent, or the machine’s compression system is not working correctly. In this case, it’s best to consult the machine’s manual and call a professional if you can not troubleshoot the problem.

2. Tablet Capping or Lamination.

Rotary-Tablet-Press-Machine-dimensions

This defect occurs when the tablet’s upper or lower face sheds its surface, creating a cap-like structure. 

Improperly cleaned punches, over-compression, improper machine lubrication, and formulation issues can lead to this chipping. 

If your raw materials are not at fault, try adjusting your compressors. Ensure that the pre-compressing force is not too low and the main compressing force is not too high. Some formulations also require low turret speeds. 

It’s always best to make sure all surfaces are adequately cleaned and lubricated. 

3. Tablet Sticking.

This happens mainly because of high friction, so clean your punches and dies thoroughly and lubricate them. The machine’s tooling or punches and dies may also be worn out. In that case, you’ll have to replace them. 

4. Tablet Hardness Problems.

In some cases, you may notice your products are prone to cracking or powdering. Here, you must make sure your powders or granules are drying properly before you feed them to the compressor. Otherwise, their flow properties can be affected. If you are sure your formulations are correct, then you’ll have to check your compressors for the fault. 

How to Maintain Your Rotary Tablet Press Machine?

Machines need maintenance and cleaning if they are to last long.

Maintenance. 

The importance of maintaining your rotary press machine can not be understated – it directly affects the sensitive pharmaceutical formulations you’re making. Consider the following essential tasks:

1. Regular Lubrication.

You must lubricate your machine’s moving parts to minimize wear and tear. The type and frequency of lubrication will be specific to your machine. Make sure the lubricant that will directly interact with your granules or powders is compatible with the formula and does not affect the medicine’s active ingredient. 

2. Component Adjustment and Calibration.

You need to periodically ensure that your machine is calibrated properly to adjust parameters like temperature and pressure as expected. Also, make sure the die and the punch are always aligned. 

Make checking these things a part of your monthly maintenance routine.   

3. Replacement of Damaged Parts.

Worn-out and damaged parts will affect the quality of your tablets. They may even lead to problems like overheating and affect other machine components. So, it’s best to keep an eye out and schedule regular inspections. 

Deep-Cleaning.

Although cleaning your machine after every run is essential, you must cleanse it properly occasionally. 

  1. Disassemble your machine. You can only ensure there is no corrosion once you separate all components. 
  2. Use a vacuum cleaner or compressed air to dust off all residual powders and granules. These can interfere with the motion of your tablet press machine’s components and cause wear and tear. 
  3. After it’s dusted, use a suitable solvent to clean the surface. Make sure you follow the manufacturer’s guidelines and consult with them before changes. 
  4. Dry every component properly before reassembling it. Otherwise, you risk corrosion. Left-over solvent can even interfere with your tablets, rendering them unsafe. 
  5. Reassemble the machine and make sure you do not leave parts loose. 

Endnote

Rotary tablet press machines can allow you to upscale your production and manufacture hundreds of tablets per minute. However, you must ensure you choose the right type of machine and maintain it well. 

Your investment in a tablet press will only serve you well if you purchase from reputed manufacturers. You can contact us today for a quote!

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