Hairpins
Cross Section Double Seam Defects - Cause & Remedy

Hairpins are sometimes called R's or R-ing. A cross section cut away of the seam will reveal a Body Hook that takes the shape of an “R”. Magnification under a scope or projector of the cross section cut will show a definite resemblance to an "R".

Hairpins
Probable Cause Suggested Remedy
Long Body Hooks and Short Cover Hooks Reduce Lower Chuck or Lifter spring pressure to control Body Hook length.
Tight 2nd Operation seams Loosen 2nd Operation Seaming Roll settings which forces Body Hook Material over the cover Hook Cut Edge.
Sealing compound variations Discuss with Cover Manufacturer