A Sharp Seam is a typical defect when the edge of the seam appears sharp. Beyond potential harm to the user of the can, who can cut themselves on the edge, there are additional concerns about the metal “edge” created by the sharp seam, which is more fragile and can break relatively easily, compared to a proper round seam edge.
The possible causes of Sharp Seam:
- In many cases, incorrect setup of the first or second operation roll causes the chuck to touch one of those toolings and become damaged. When the chuck lip is eroded, the first and second operation rolls actually cause the seam to become sharp.
- Incorrect setup of the roll to check distances (particularly the height of the roll) can create a large cap between the roll and chuck, causing the metal to bend and fold sharply in that area.
It is highly recommended to use a clearance gauge system to set up a seamer to prevent a sharp seam.