Sprung Seam
Cross Section Double Seam Defects - Cause & Remedy

Sprung Seams have developed as a result of the welded side seams on can bodies in lieu of a soldered side seam. Usually the Cover Hook Radius is separated from the can body wall within an approximate one inch area anywhere around the can seam perifery. The first good sign of a Sprung Seam is a variance in the Seam Thickness by .004 of an inch or more when checking seam dimensions.

Sprung Seam
Probable Cause Suggested Remedy
Long Body Hooks ranging above .085 of an inch. Reduce Lower Chuck or Lifter spring pressure to bring Body Hook dimensions within specifications.
Overtight seams forcing compound to compress beyond its purpose. Loosen 2nd Operation seam thickness to equal the compiled thickness of can body and cover layers plus allowance for the compound. Allow compound to act as the filler and sealer initially intended in the Double Seam.
Tight 1st Operation seams. Loosen 1st Operation seam thickness following guidelines as to what a good 1st Operation seam should be. See 1st Operation Seams outlined at the beginning of this Trouble Shooting Guide.