Hard gelatin capsules are one of the most widely used dosage forms in oral solid preparations and can be filled with various materials such as powders, granules, and microtablets. This article will introduce the primary production process and supporting equipment for hard gelatin capsules based on actual manufacturing practices, helping you gain a more comprehensive understanding of their manufacturing process and key control points.
What Are Hard Gelatin Capsules?
Hard gelatin capsules consist of two parts: the capsule body and the capsule cap. The capsule shell is primarily made from pharmaceutical-grade gelatin, formed by immersing gelatin solution into stainless steel molds and cooling it to set. They exhibit excellent sealing properties and mechanical strength and is the most common encapsulation method for powdered or granular medications.
How Are Hard Gelatin Capsules Manufactured?
The production process of hard gelatin capsules primarily consists of three stages: capsule shell preparation, filling with contents, final product inspection and packaging.
Preparation of Capsule Shells
Preparation of Gelatin Solution
First, dissolve gelatin in purified water heated to 55–60°C. After it completes dissolution, add auxiliary materials such as colorants, light-blocking agents, and preservatives according to the formulation ratio to adjust the appearance and stability of the capsules. And then, degas and filter the gelatin solution to prevent subsequent effects on capsule shell formation.
It is important to note that controlling gelatin viscosity is critical at this stage, typically maintained between 500–1000 cP. Excessively high viscosity may cause uneven film thickness, while excessively low viscosity can result in fragile, easily ruptured capsules. It is the preferred choice for you to adopt a gelatin tank system equipped with online viscosity monitoring and automatic temperature control.
Shell Formation
Transfer the processed gelatin solution to the capsule manufacturing machine. And the cleaned molds are immersed into the gelatin storage tank at a preset speed, with its immersion depth automatically adjusted according to capsule specifications. Upon removal, the gelatin forms a uniform film layer on the mold surface, which prepares it for subsequent drying and shaping.
Drying and Setting
The coated molds enter the conditioning tunnel with precise temperature and humidity control and the gelatin film gradually solidifies and sets. It is particularly critical to choose a suitable cooling temperature and this temperature is usually controlled between 15–20°C. Because the cooling temperatures below this range may lead capsule shells to become brittle and fracture, while higher temperatures result in slower drying and increased energy consumption.
It is recommended to select a drying system with automatic temperature control, which effectively enhances drying uniformity and reduces energy consumption for you.
Forming and Trimming
Separate the capsule shells from the mold by using a precision stripping station with pneumatic ejection system (either ejector pins or compressed air blowing). Subsequently, a high-precision cutting machine removes burrs from the demolded shells to keep length consistent with cutting accuracy as high as ±0.1mm.
Printing
Essential dosage markings, batch numbers, or corporate logos are printed on the capsule surface using food-grade ink. This step is convenient for drug identification and also improving your product’s professionalism and brand recognition.
Empty Shell Inspection
The formed empty shells must undergo multiple checks including appearance, weight, and dimensions. Visual recognition systems and automatic weighing devices automatically reject non-compliant capsules. This ensures consistency and quality stability for your capsules entering the filling stage.
Click the link to learn more about key parameters for capsule quality testing.
Filling Contents
Filling
The capsule filling machine precisely fills the capsule shells with pharmaceutical agents like powders, granules, microtablets, and so on.
Depending on material characteristics, you can employ models equipped with vibratory feeding, metering discs, or vacuum suction systems to ensure filling accuracy and batch consistency.
Sealing
The capsule cap is pressed onto the capsule body to form a complete capsule. For certain products prone to oxidation or moisture absorption, some will take gelatin solution to the seams or capsule shells with snap-lock designs which can increase the capsule’s seal integrity and extend the drug’s shelf life.
Final Product Inspection and Packaging
Capsule Testing
After filling, capsules need to pass the testing for weight variation, disintegration time, dissolution rate, and content uniformity to ensure compliance with pharmacopoeia and production standards.
Packaging
Qualified capsules are packaged into blister packs, bottles, or bulk containers via automated equipment. The packaging area must maintain light-protected and moisture-proof conditions to safeguard product quality.
Equipment for Hard Gelatin Capsule Manufacturing
Capsule Shell Forming Equipment
It is constructed from 316L stainless steel and this equipment integrates dipping, cooling, and demolding processes for producing gelatin shells. Premium models are paired with inline viscosity monitoring and automatic temperature control to maintain uniform coating thickness and enhance production stability.
Capsule Shell Trimmer
The capsule shell trimmer removes burrs from both ends of the capsules. Blades are typically made of tungsten steel and can be adapted to different capsule sizes by changing guide slots. To keep cutting precision, it is recommended to regularly inspect and replace the blades.
Capsule Printing Machine
Capsule printing machine can print dosage markings, batch numbers, logos, and other information onto capsule surfaces, supporting multi-color printing. This meets FDA, EMA, and GMP requirements for product labeling, serialization as well as traceability and it also enhances brand recognition and product identification.
Capsule Sorting Machine
The capsule sorting machine automatically sorts empty shells, filled capsules, and skewed or abnormal capsules, supporting sizes from 000 to size 5. Through sorting, you can ensure consistent capsule quality entering the filling or packaging stages.
Capsule Filling Machine
This filling machine precisely fills powder, granules, or pellets into capsule bodies using metering pins or compacting pins, then seals the capsules by pressing the capsules together to form complete capsules.The filling machine offers metering accuracy controlled within ±1% and can fill over 2,000 capsules per hour, significantly boosting your production efficiency.
Click the link to learn more about capsule filling machine components, operating principles, and applications.
Capsule Polishing Machine
The capsule polishing machine smooths and even capsule surfaces through rotating brush or roller polishing. This is suitable for various sizes and shapes to maintain consistent product appearance quality.
Capsule Inspection Machine
The capsule inspection machine scans capsules to check the capsules’ defects such as cracks, deformation, discoloration, filling volume, or residue. Using this equipment allows you to promptly remove non-compliant capsules during production in time and achieve a defect detection rate exceeding 99.5% to guarantee batch consistency. Common types include X-ray inspection machines, laser-based inspection machines, vision-based inspection machines, and capsule weight checking machines.
Capsule Counting Machine
Capsule counting machines have the ability to rapidly and accurately tally thousands of capsules, which can save your time and reduce error rates. Its counting precision adjusts to capsule size and packaging methods to meet diverse production needs.
Capsule Sealing Machine
The machine achieves uniform sealing through binding applied by nozzles, brushes, or dip-coating units. This sealing machine realizes rapid, consistent sealing for your products and it can enhance barriers against air, moisture, and contaminants to extend shelf life.
Capsule Coating Machines
The capsule coating machine applies a coating to capsules. The capsule coating masks the odor of the medication, improves swallowability, and enables controlled-release or enhanced stability by adjusting the coating thickness, thereby adding value to your product.
Conclusion
The production of hard gelatin capsules involves critical stages such as capsule shell preparation, filling with contents, and final product inspection and packaging. The entire process requires specialized equipment for molding, cutting, printing, sorting, filling, sealing, polishing, and inspection. When selecting equipment, please consider the production efficiency, automation level, material adaptability, and quality control capabilities.
If you have any further questions about hard gelatin capsule production or require assistance with equipment selection, please contact us.
FAQ
1.What are the benefits of hard gelatin capsules?
- Easy to Fill: The hard gelatin capsules can handle different material forms including powders, granules, and microtablets.
- Excellent Dissolution Performance: The capsule shell rapidly swells and ruptures upon contact with gastric fluid which means the drug to achieve rapid onset of action without undergoing a disintegration process.
- High Storage Stability: Compared to soft gel capsules, hard gelatin capsules are less prone to oxidation or leakage.
- Longer Shelf Life: Proper packaging and environmental control can significantly extend product shelf life.
2.How to select hard capsule size and specifications？
Hard capsules typically range in capacity from 0.13 to 1.37 milliliters (corresponding to fill weights of approximately 65mg to over 1g) and this can satisfy most dosage form filling requirements. Sizes are designated by model numbers, ranging from the largest size 000 to the smallest size 5.
Model selection is primarily determined by your formulation. You must comprehensively consider factors such as the active ingredient dosage, powder bulk density, and compressibility to ensure smooth filling and accurate dosing.
3.What is the difference between hard gelatin capsules and soft gelatin capsules?
Hard gelatin capsules are primarily used for solid medications such as powders, granules, pellets, etc.. It features a sturdy structure and flexible filling capabilities.
The soft gelatin capsules are more suitable for oily substances or highly active drugs, offering excellent sealing properties and absorption efficiency.
You may select the more appropriate capsule type based on the physicochemical properties of the drug, production process, and storage requirements.
For further details on the differences between soft and hard capsules in manufacturing processes and applications, click the link to view more information.
4.What is the shelf life of hard gelatin capsules?
Under storage conditions compliant with pharmacopoeia standards—namely at room temperature, protected from light and moisture—hard gelatin capsules typically maintain their integrity for 2–3 years.
In fact, the specific shelf life may vary depending on gelatin formulation, manufacturing processes, and packaging methods like foil blister packs, bottles. We recommend confirming details based on your specific packaging solution.
