doubleseamed

Doubleseamed refers to the condition of a container, typically a metal can, whose lid has been sealed with a double seam. The double seam is formed when the edge of the can body (the flange) and the edge of the lid are mechanically joined by two interlocking folds that run around the circumference. This results in an outer and an inner seam that together secure the end to the body.

Manufacturing and structure: A double seaming operation uses specialized equipment with rolls and chucks to shape and interlock the lid and body flanges. The process creates a seam that typically comprises multiple layers of metal at the seam line, usually involving an inner and outer fold. The resulting seal is designed to be hermetic and resistant to handling and transportation.

Materials and applications: Doubleseamed containers are common in food and beverage packaging, especially for steel or aluminum cans. They are used for products ranging from canned vegetables and fruit to carbonated drinks and pet foods. The method is favored for its durability, cost efficiency, and ability to preserve product integrity without adhesives.

Quality and inspection: Seam integrity is critical to safety and shelf life. Quality control includes visual inspection, measurement of seam dimensions (such as seam height and uniformity), and leakage testing (vacuum or pressure tests). Proper alignment and correct seaming pressure are essential; deviations can indicate under- or over-seaming, denting, or material issues.

Defects and causes: Common defects include gaps in the seam, missing or deformed folds, and seam cracks. Causes may include damaged components, incorrect machine settings, improper can dimensions, or poor material quality. Addressing these issues involves equipment adjustment, material checks, and, if necessary, redesign of the seam parameters.

See also: Can, closure, packaging, seam quality.