Double Seam Defects

Double Seam Defects

There are a number of double seam defects that can arise during the food and beverage canning process. To aid in the can seam inspection process, we’ve comprised a list of the most common double seam defects that are detected by food and beverage canners. We have several can seam analysis products that inspect double seams and provide easy-to-use information to ensure double seam quality.

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A more reliable indication of proper seaming pressure is obtained from inspecting the Cover Hook Wrinkling. Because of the difference in radius, as the various parts of the seam are pressed together, wrinkles will naturally occur in the inside radius of the cover hook. Measuring the depth, type and quantity of these wrinkles will help you to determine that the correct pressure is being applied, and ensure your seamer is operating properly.

A Cut Over is a critical defect where the metal is fractured at the top of the seaming chuck wall.

Cut Over

Dead Head is a condition where the first and/or second operation seam is not completely formed around the circumference of the can.

Dead Head

Droop is a condition where a smooth projection of the seam extends below the normal seam.

Droop

A False Seam is a critical defect which occurs when the cover and body hooks do not interlock around the can seam’s circumference.

False Seam

Knocked Down Flange is a critical defect. It occurs when the cover and body hooks do not interlock in a localized area of the double seam. Typically 1-2 inches in length. 

Knocked Down Flange

A Long Body Hook is a condition where the body hook length approaches or exceeds the specification. 

Long Body Hook

A Long Cover Hook is a condition where the cover hook length approaches or exceeds the specification. 

Long Cover Hook

A Loose First Operation Seam may not allow sufficient tuck up of cover curl to form a sufficient amount of cover hook and overlap.

Loose First Operation Seam

A Pleat is a fold in the cover hook that extends from the cut edge downward toward the cover hook radius and sometimes below this radius is a sharp Vee or Spur.

A Seam Bump is a short area of the double seam where the seam thickness suddenly increases by .004″ or more.

Seam Bump

As the rollers push the cover and body hook materials together, and against the seaming chuck, an impression is left on the inside of the can body. Too much pressure can cause this impression to damage the can liner.

Seam Impression drawing

A Sharp Seam is a condition where the seam has a sharp edge or radius on the upper inside edge of the countersink wall. 

Sharp Seam

A Short Body Hook is a condition where the body hook does not meet the minimum specification. 

Short body hook

A Short Cover Hook is a condition where the cover hook does not meet the minimum specification.

Short Cover Hook

A Sprung Seam is a condition were the seam is pulled away from the body wall. In some extreme cases, the seam is pulled away from the body wall the entire way around the can. 

Sprung Seam

A Tight First Operation Seam can create flatness on the bottom of the first operation seam throughout its length. The cover hook may also be turned back into the body hook.

Tight First Operation

A Vee is an irregularity on the cover hook when the cover does not form smoothly. The material splits causing a V-shaped opening in the face o the cover hook.

Vee

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