Structural Composition and Functional Analysis of Soft Capsule Equipment

Soft capsule equipment is a key production line device for realizing soft capsule shell forming, content filling, and sealing. Its structural design directly determines the continuity, precision, and stability of production. As a specialized piece of equipment integrating mechanical, thermal, fluid transport, and control technologies, its overall layout is typically modularized around the process flow. It mainly includes a pelleting system, a feeding system, a sealing and cutting mechanism, a control system, and auxiliary devices. These parts work together to ensure capsule forming quality and production efficiency.

The pelleting system is the core structural unit of the soft capsule equipment, mainly consisting of a pair of opposing rotating mold rollers and their drive devices. The mold rollers have precision-milled or EDM-machined capsule cavities that fit each other. The rollers have internal circulating temperature control channels to maintain a constant temperature required for gelatin liquid film formation. During operation, the upper and lower rollers rotate at strictly synchronized linear speeds, spreading the gelatin liquid coated on the roller surface into a uniform film, providing a foundation for subsequent filling and forming. The rollers are primarily made of corrosion-resistant alloy steel with surface hardening treatment to ensure dimensional accuracy and wear resistance during long-term use.

The feeding system consists of two main lines: adhesive supply and content supply. The adhesive supply section includes a melting tank, a filter, a heated circulating pump, and an adhesive coating mechanism. It stably delivers gelatin liquid to the mold rollers within a set temperature and viscosity range, and uses closed-loop control of liquid level and flow rate to prevent interruption or over-supply. The content supply section comprises a storage tank, a metering pump, delivery pipelines, and nozzle assemblies. For different physical properties such as liquids, suspensions, or pastes, it employs plunger pumps, screw pumps, or peristaltic pumps to achieve precise metering and continuous delivery, ensuring uniform filling volume.

The sealing and cutting mechanism follows the pelletizing process. Its function is to thermally fuse the double-layered adhesive film containing the contents within the mold cavity and to cut and separate the capsules. The sealing unit is equipped with an adjustable-temperature heating plate or hot air device, which melts and bonds the edges of the adhesive film under pressure. The cutting unit uses precision cutters or rollers to separate the beaded capsule strings into individual units, which are then fed into the drying or sorting stages via guide channels. This part of the structure must balance heat transfer efficiency with the synchronization of mechanical movements to avoid poor sealing or burrs on the cut edges.

The control system typically uses a programmable logic controller (PLC) as the main control core, coupled with a touchscreen human-machine interface (HMI) for parameter setting, operational status monitoring, and data recording. Key process parameters such as mold roller speed, adhesive temperature, contents flow rate, and sealing pressure can be adjusted and stored in real time, and can interface with a higher-level information management system to meet the quality traceability requirements of pharmaceutical GMP and other standards. Modern equipment can also integrate online weighing, wall thickness detection, and defect rejection devices to improve the finished product yield.

Auxiliary devices include the frame and support structure, lubrication and cooling system, safety guard, and cleaning interface, etc. The frame is welded from stainless steel or high-quality carbon steel, providing sufficient rigidity to suppress operational vibration. A lubrication and cooling system ensures that bearings and transmission components maintain suitable temperatures during prolonged operation. The cleaning interface supports in-place cleaning (CIP) operations, facilitating rapid restoration of hygienic conditions during batch changes or maintenance.

Overall, the soft capsule equipment achieves fully automated production from capsule preparation to finished capsules through the organic integration of structural modules such as capsule making, feeding, sealing and cutting, and intelligent control. Its structural design ensures process precision while also considering maintainability and expandability, providing a solid hardware foundation for the large-scale manufacturing of high-quality soft capsules.