From paper fan to finished cup: The process of combining the bottom paper of the cup with the cup body

Paper cups may seem simple, but the bonding of the bottom paper to the cup body is a crucial process that directly determines the leak-proofness and durability of the cup. Paper cup machines, through precise design, achieve stable bottom bonding.

1. Materials

    In the paper cup manufacturing process, the cup body is formed from printed and laminated paper fan, while the bottom paper is usually slightly thinner than or the same thickness as the cup body, and is then die-cut into a circle. These materials need to be placed in specific positions within the paper cup machine, ready for the next step of processing.

2. Positioning of the Bottom Paper and Cup Body

    The paper cup machine rolls the cup body into a cup shape using a mold, and then rotates it on a turnplate to the position where the bottom paper is fed. This process requires high precision: if the bottom paper is misaligned, the paper cup is prone to leakage or deformation. Paper cup machines typically use technologies such as vacuum adsorption and mechanical positioning to ensure that the bottom paper and cup body are perfectly aligned.

3. Bottom Preheating, Folding, and Knurling Fixing

    The paper cup machine first feeds the bottom paper into the bottom of the cup body and folds the bottom in half. Then, it preheats the bottom of the cup body to melt the bottom coating, making it easier for the bottom paper and cup body to adhere. Finally, knurling creates tiny bumps and grooves on the edge of the bottom paper, tightly interlocking it with the cup body paper, making the paper cup structure stable and leak-proof.

4. Post-forming Inspection

    After the paper cup machine finishes production, the factory will randomly select a certain number of paper cups for a leakage test to check if any liquid is seeping from the bottom. If leakage is found, it indicates that there is an abnormality in the bonding of the bottom of that batch of paper cups, which needs to be investigated and adjusted.

5. Why is the bonding between the bottom paper and the cup body important?

    Leak-proof: The bonding between the bottom paper and the cup body, through a process of bottom sealing, preheating, and knurling, forms a reliable seal, preventing liquid leakage.
    Structural stability: A firm bottom bonding ensures the paper cup is not prone to collapse, maintaining its shape even when filled with hot drinks.
    Production efficiency: The complete bottom bonding process enables the paper cup machine to produce paper cups stably and efficiently, ensuring consistent quality for every cup.