Tin Can School
Can Seam Dictionary
UN approved – Dangerous goods packaging
(D.G Pail)
UN Code: UN 1A2/Y1.6/100, UN 3A1/Y1.2/100
Beaded Can: A can that is reinforced with
regular ring indentations around the body.
Body : The principle part of a container or
can.
Body Hook: The portion of the can body that
is folded down for the formation of the double seam.
Body Hook Butting: The length of the body
hook in relation to the length of the double seam.
Customer End: Packers end, Cover, Lid,
Canner’s End – the end component that is seamed onto a filled can in a cannery.
Customer Seam: The double seam formed by
the canner or processor.
Can Manufacturers End: Bottom end of the
can. Attached at the can manufacturer.
Can Manufacturers Double Seam: The bottom
seam, or the Factory double seam.
Chuck: That part of a double seamer or
closing machine that supports the chuck wall of the can end during seaming.
Closing Machine: A machine which double
seams the cover or end onto the can bodies.
Compound: A pliable sealing material
consisting of a water or solvent based latex, or a synthetic material placed in
the curl of the can end. It fills voids in the double seam during the seaming
operation, and assists in the formation of a hermetic seal.
Countersink Depth: The measurement from the
top edge of the seaming panel to the bottom of the chuck wall radius.
Cover Hook: The part of a double seam
formed from the curl of the end component. Also known as the end hook.
Curl: The extreme edge of the end component
which is turned inward after the edge is formed. The curl forms the cover hook
in a double seam.
Cutover: A critical defect where the metal
is fractured at the top of the seaming chuck wall.
Dead Head: A seam defect, also called a
Skidder, Spinner or Slipper. It is where the first and/or second operation of
the double seam is not fully formed around the circumference of the can.
Droop: A condition where a smooth
projection of the seam extends below the normal double seam, This condition
normally occurs when product or foreign material is trapped in the double seam
during the seaming process.
False Seam: A critical defect where the
cover hook and the body hook do not interlock around the circumference of the
can.
First Operation: The first of the two
operations in double seaming. In the First operation, the curl of the end
component is tucked under the flange of the can body and the two are rolled
together, interlocking the cover hook and the body hook.
Flange: The flared projection of the body
around the top of a container.
Juncture: The part of a double seam that is
over the side seam. Also referred to as cross-over.
Knocked Down Flange: A condition similar to
False Seam where the cover hook and the body hook do not interlock. Typically
1-2 inches in length.
Lid
Mushroomed Flange: A flange that is
over-formed.
Necked In Can: A can that has an end
diameter that is smaller than the body diameter.
Overlap: The amount that the body hook and
the cover hook interlock with each other.
Pin Height: The distance between the
highest part of the base plate, and the lowest part of the seaming chuck.
Measured at the high point of the first seaming operation.
Pleats: A fold in the cover hook metal that
extends from the cut edge downward toward the cover hook radius and sometimes
below this radius in a sharp vee or spur.
Pressure Ridge: See Seam Impression.
Pucker: A pucker is a condition which is
intermediate between a reverse wrinkle and a pleat, where the cover hook at the
cut edge is locally distorted downwards without actually folding.
Reverse Wrinkle: A non-tightness type of
wrinkle that projects towards the can body wall or the center of the can. A
reverse wrinkle is formed during the first operation seam, and cannot be ironed
out regardless of the tightness rating.
Seaming Chuck: See Chuck.
Seam Height: The maximum dimension of the
seam measured parallel to the axis of the can.
Seam Impression: A ridge formed around the
inside of the can body and contained within the double seam. It is an
impression of the chuck formed by the pressure applied to the seaming rolls
during double seam formation. The degree, or depth of the pressure ridge is
determined by the type of roll profile used and seam tightness.
Seam Thickness: The maximum dimension of a
seam measured at right angles to the seaming chuck wall. Seam thickness
represents five thicknesses of metal, plus compound.
Second Operation: The final operation in
double seam formation. The seam components formed in the first operation are
ironed or flattened, compressing the compound to fill the voids and areas not
occupied by metal.
Sharp Seam: A condition where the seam has
a sharp edge, and/or radius on the upper inside edge of the chuck wall,
indicating it has been forced over the top of the seaming chuck flange.
Side Seam: The seam along the length of a
three piece can joining the two edges of a blank to form a body – welded,
cemented or soldered.
Skidder: See Dead Head.
Spur: A localized irregularity
characterized by a sharp protrusion at the bottom of the double seam, It is
usually accompanied by a pleat or vee in the cover hook.
Tightness Rating: The compressive tightness
of the double seam measured by rating the extend of looseness wrinkle on the
face of the cover hook.
Vee: A irregularity on the cover hook,
where the cover hook material does not form smoothly, and the material splits
causing a “V” shaped opening on the face of the cover hook. It may be
associated with a pin lip or spur projecting below the bottom of the double
seam.
Wrinkle: Irregularities or waves observed
on the face of the cover hook.
Normal Looseness: Wavy appearance to cover
hook exhibiting depth and width, and amplitude (Typically Three dimensional)
Reverse.
Wrinkle: Wavy appearance to the cover hook
exhibiting depth and width, without amplitude. (Typically Two dimensional).
Compound wrinkle: Wavy appearance to cover
hook due to compound impression on cover hook. Exhibits width, without depth or
amplitude.
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