The packaging gluing process (particularly for corrugated cardboard boxes) is a crucial stage of production that determines the strength and aesthetics of the finished box. It is typically carried out using specialized machines known as automatic folder-gluers.
The process involves several key stages:
- Blank preparation Before the cardboard sheet is glued, it must be cut, shaped, and creased along the fold lines (creating what is known as a “blank”). The machine picks up individual flat sheets from a feeder and introduces them into the forming section.
- Adhesive application This is the most critical moment of the entire process. Depending on the packaging’s intended use and technical requirements, various gluing methods are employed:
- Dispersion adhesive (cold glue): The most common method for standard boxes. The adhesive is applied via nozzles or glue wheels onto the glue flap (the side edge of the blank).
- Hot-melt adhesive: Applied hot, it bonds almost instantly upon cooling. It is used where immediate bond strength is required or when gluing challenging surfaces (e.g., varnished ones).
- Folding and pressing (forming) After adhesive application, the machine’s mechanisms (conveyor belts and guides) precisely fold the packaging along the designated fold lines, joining the edges to be glued. The folded box then passes through a compression section (long belts applying pressure), allowing the adhesive to set properly and preventing the product from coming apart due to material tension.
- Quality control and packaging The glued packages are automatically counted, aligned into bundles, and banded (or stretch-wrapped). At this stage, modern production lines can use optical sensors to reject defective units (e.g., those with unglued sections or glue stains). Once prepared in this way, the bundles are palletized and ready for shipment to the end customer.