Capsule Filling Machine Working Principle Explained

The capsule filling machine’s working process is multistage. It comprises various distinct steps. Here, we take you through those stages step by step. We will also explore different filling methods based on the capsule type and dosing mechanism, among other things.

How Do Capsule Filling Machines Work?

They take in empty capsules and fill them with the required substance. These steps seem straightforward. Well, they are when using manual fillers. However, they turn to complex when it comes to automatic types.

Automatic filling machines rely on complex technologies like computer programs, sensors, and various drive systems. The drives are either electrical or pneumatic.

The filler may also be a linear or rotary device. Operation modes include intermittent and continuous filling, among other variations. In the following section, we take you through the working principle of a capsule filling machine.

Capsule Filling Process

The process follows a series of steps. These include receiving the capsules, rectifying them, injecting the material, and ejection. As you’ll learn below, a few other steps occur outside the device.

Capsule Orientation and Rectification

The machine receives the capsules from the hopper. These face different directions, which can make filling them challenging. The rectification and orientation unit makes them face one direction. It also places them the right way up, usually with the body ending down.

Cap and Body Separation

Another system separates the caps from the bodies. This action prepares the capsules for injection with the product. It typically uses vacuum pressure to do so, preventing damage. After separation, the pieces move to the filling station.

Filling Capsules

A mechanism delivers the required substance into the empty bodies. The material can be powder, granules, pellets, or tablets. Mechanisms vary widely depending on the machine’s design and components.

Popular ways include the vibratory plate, the auger method, and the dosator principle. Another technique uses tamping pins to compress the material. We will explore these later when discussing the process’s mechanisms.

Cap Replacement and Sealing

Another mechanism replaces the cap. This action occurs with the help of plates and pins or pneumatic force to avoid causing damage.

Sealing locks the capsules to protect their contents. The machine may heat-weld the two pieces together. Alternatively, it may coat the inner surface with liquid gelatin.

Ejection and Separation

It’s now time to eject the capsules. In intermittent motion fillers, this action prepares the station for another cycle. Correctly filled capsules and damaged capsules go separate ways.

Error-free pieces move to the sorting and inspection section. After that, the cleaning and polishing unit removes excess powder and other material. It also gives them the desired shine. Finished capsules undergo a labeling process before packaging.

Capsule Filling Methods

The process can take many forms. It mainly depends on the automation level, with manual and automatic fillers using differing mechanisms. The most popular types of capsule filling include:

Manual Method

The operator inserts capsules in the loading tray (cap up and body down) and places it on the capsule bed. Lifting the upper plate removes the caps, leaving the bodies open.

The next step involves using the powder tray to fill the bodies. After that, the operator positions the pin plate to compact the powder. Finally, they replace the capsule caps.

Vibratory Plate Method

This method utilizes a flat plate drilled with holes to hold the capsule bodies. Spreading powder on its surface fills the bodies. A vibratory mechanism helps ensure uniform spreading and other actions like descending.

Auger Method

A screw-like rod, auger, rotates to dispense powder. The auger sits in a hopper with an agitator to fill the space around it with material. The auger’s rotation forces powder the hopper outlet to fill empty capsules.

The material the auger dispenses depends on how long the bodies stay underneath the hopper outlet. Increasing the speed reduces the amount/weight and vice versa.

Dosator Principle

In this method, a dosing tube equipped with a spring-loaded piston moves down a powdered bed. This action fills the space between its tip and the plunger with powder or other substance.

The plunger then forces the powder into the capsule body after doctoring (scraping off) excess filled powder and dispensing it into the open body. Adjusting the plunger controls the material amount and weight.

Tamping Finger Method

A series of projections, usually five, take turns descending and compressing powder inside a space in the powder bed. They do so through a series of holes drilled on a dosing disc.

The last action injects the compressed powder into the open bodies. Using discs with varying thickness alters the size of the plug, regulating its size.

Manual vs. Automatic Filling

A manual capsule filling machine requires you to apply pressure using your hand. On the other hand, semi-automatic filling employs augers and vibratory powder plates.

Fully automatic capsule filling machines utilize tamping pins and dosator mechanisms. Dosator-filling is the most popular method. It also has higher speed levels, producing thousands of capsules per hour.

Hard Gel vs. Soft Gel Filling

The filling process of hard gelatin capsules also differs from soft gel encapsulation. Hard-gelatin types enter the filler already manufactured. Softgel fillers produce the encapsulation ribbon inline.

Hard-gel filling uses the earlier discussed methods, such as auger, dosator, and tamping pins. In soft gel filling, a gelatin film flows into a tooling system with rolling dies to seal it.

Critical Parameters of Capsule Filling Machine

Various requirements govern the capsule filling machine working to ensure its proper operation. They include capsule type and size, settings, and surrounding conditions.

Capsule Type and Size

You can only use the filler to produce capsules of a specific size. As such, the manufacturer usually indicates compatibility on the device’s specs sheet.

Popular sizes in the pharmaceutical industry and other sectors include 000, 00, 0, 1, 2, 3, 4, and 5. Most are gelatin and usually hard-gel or soft-gel.

Machine Settings

Users can set the machine’s operation to achieve desired functions. Examples include machine speed and material dispensing rate. You can also set the tamping force or vacuum pressure for cap separation and other tasks. Automatic machines offer more control features.

Environmental Control

The operator must ensure conditions are right for the manufacturing process. Some, like excessive heat, dust, or humidity, may affect the capsule material. That, in turn, would negatively impact your capsule products, reducing their quality.

Best practices include keeping heat and humidity levels within limits and constant. On the other hand, employing air filtration helps ensure dust-free machine surroundings. Other hazards include chemicals and other materials.

Conclusion

The capsule machine process includes simple and complex procedures. Mechanisms also differ based on the machine type and its specifications. Understanding how these devices work can help you get the most out of them. You’ll know how to correctly use them while ensuring various situations do not affect their operation.