1.Prepare the plastic cosmetic tubes and fillings: Firstly, fill the cosmetic product into the plastic cosmetic tubes, ensuring that the quality and quantity of the filling meet the requirements. This may involve using automated equipment or manual operation.

2.Preheat the plastic cosmetic tubes: Before the sealing process, it is usually necessary to preheat the plastic cosmetic tubes. This can be done by exposing the tubes to the appropriate temperature, typically through hot air or hot water.

3.Seal the tip or nozzle: For plastic cosmetic tubes, the seal is typically applied to the tip or nozzle. This involves exposing the tip or nozzle of the tubes to a heat sealing machine's heating element to soften the plastic.

4.Sealing operation: Once the plastic is softened, the heat sealing machine will heat the tip or nozzle area and apply appropriate pressure to seal the plastic. This creates a sealed area, preventing leakage or contamination of the cosmetic product.

5.Cooling and solidification: After the sealing is completed, the plastic needs to cool and solidify to ensure the stability and integrity of the seal. This typically takes some time, depending on the materials used and the sealing performance.