Medicine Bag welding: Analysis of the Key Process for Ensuring Drug Safety

 Core processes and technologies of medicine bag welding

1. Heat sealing welding

Principle: The medicine bag material (such as polypropylene, polyethylene composite film) is melted by a heating plate or pulse heating, and then pressed to form a weld.

Application: Widely used in large-capacity packaging such as infusion bags and powder injection bags.

Advantages: Mature process, low cost, suitable for large-scale production.

Challenges: Temperature and time must be strictly controlled to avoid overheating and deformation of materials or weld defects.

2. Ultrasonic welding

Principle: Use high-frequency vibration (20-40kHz) to generate heat by friction of material molecules, and then combine after partial melting.
Application: Suitable for heat-sensitive packaging such as paper-aluminum composite materials, such as some oral medicine bags.
Advantages: No heat-affected zone, protect the activity of the medicine; short welding time (0.1-1 second), high efficiency.

3. Laser welding

Principle: High-energy laser beam (such as CO₂, Nd:YAG) focuses on the material seam to melt and combine.
Application: Used for high-precision, small-batch medicine bags, such as customized packaging of special medicines.
Advantages: Non-contact processing, narrow weld (0.1-0.5mm), beautiful and high strength.

Key points of quality control for medicine bag welding

1. Material compatibility

Medicine bags are usually made of multi-layer composite films (such as PP/PE/aluminum foil), and it is necessary to ensure that the melting points of the welding layer materials match. For example, the melting point of polypropylene is 160-170℃, and the welding temperature needs to be higher than this value but lower than the decomposition temperature of the outer material.

2. Process parameter optimization

Temperature: If the heat-sealing temperature is too low, it will cause a cold weld, and if it is too high, the material will be carbonized.

Pressure: In ultrasonic welding, insufficient pressure will lead to incomplete fusion, and excessive pressure will penetrate the material. The pressure range (0.1-0.5MPa) needs to be dynamically adjusted according to the material thickness (0.1-0.5mm).