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.

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

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

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

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. 

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

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

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

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.

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.

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

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

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

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. 

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.

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.