Manufacturing Process and Specifications of Metal Can Lids
Metal can lids, including those for three-piece and two-piece cans, are crucial for sealing. Despite variations in lid types, such as beverage and food lids, the manufacturing processes remain similar. Here, we focus on the structural features and manufacturing techniques of representative can lids.
Product Process and Specifications
Manufacturing Process of Can Lids
The manufacturing process of can lids involves the following steps: coil cutting/sheet material → blanking and forming → curling → seaming → drying → packaging.
The equipment for lid production mainly includes sheet cutting equipment, punching equipment, curling machines, sealing machines, drying equipment, and packaging equipment.
Product Specifications of Can Lids
- Names of Different Lid Parts: Describes the different parts of the can lid.
- Types and Functions of Expansion Rings: The expansion ring’s main function is to enhance the lid’s strength and ensure the seal structure. During sterilization, the air trapped in the can expands rapidly, increasing the internal pressure. To prevent the lid from deforming due to expansion and ensure that the lid retains its original shape after cooling, an expansion ring is pressed onto the lid. This guarantees sufficient structural strength and elasticity.
From long-term production practice, it’s known that the shape of the expansion ring depends on the type of canned food, the organization of the contents, and the vacuum degree. Generally, canned foods with solid contents and small headspace and low vacuum, such as canned luncheon meat and products with bones, require a stronger expansion ring. On the other hand, canned foods with more soup, larger headspace, and higher vacuum, such as clear vegetable soup, require expansion rings with better rebound performance.
Currently, expansion rings on can lids typically consist of a convex rib and a slope. However, for can lids with an internal diameter of 153mm, three convex ribs are sometimes used, while lids with diameters of 99mm and 83mm may have two or more convex ribs.
