Principle of Yingtai Thermal Sealing

The principle of thermal sealing (or heat sealing) involves fusing the surfaces of two materials together through heating and pressure, creating a strong bond. This method is commonly used for sealing plastic bags, packaging materials, and some composite materials. Below is the basic principle of thermal sealing:

Principle of Thermal Sealing

1. Heating:

   - The first step in the thermal sealing process is heating. Typically, heating is achieved using electric heaters, heating bars, or lasers to bring the surface of the materials to their melting point or close to it. The temperature and duration of heating must be precisely controlled based on the material's properties to ensure it reaches the correct molten state.

2. Applying Pressure:

   - Simultaneously with or after heating, pressure is applied to press the molten surfaces of the two materials together. This pressure helps the molten material to flow and fill the contact surfaces, forming a tight connection. The amount of pressure and the duration of its application also need to be precisely controlled to ensure the strength and integrity of the bond.

3. Cooling:

   - After the thermal sealing is complete, the materials need to be cooled to solidify the molten bonding area. The cooling process causes the molten material to solidify, forming a strong seam. The cooling time and rate can also affect the quality of the final bond.

Common Methods of Thermal Sealing

1. Pulse Heat Sealing:

   - Involves heating and applying pressure for a short duration, causing the material to melt and cool quickly. This method is suitable for thinner materials.

2. Constant Temperature Heat Sealing:

   - Uses a constant temperature and pressure to seal the materials, typically for thicker materials. The heating and pressure application times are longer to ensure complete melting and bonding of the material.

3. Ultrasonic Heat Sealing:

   - Utilizes ultrasonic vibrations to generate heat for melting the material and making the connection. This method is suitable for some special plastic materials and thin laminated structures.

4. Hot Air Heat Sealing:

   - Uses hot air to heat the surface of the material, melting it before making the connection. This method is commonly used for large areas of material.

Factors Influencing Thermal Sealing

- Material Type: Different materials have varying requirements for temperature and pressure, such as polyethylene and polypropylene.

- Material Thickness: Thicker materials require higher temperatures and pressures.

- Contact Time: The duration of heating and pressure application affects the quality of the seal.

- Pressure Distribution: Pressure needs to be evenly distributed to avoid leaks or weak points.