Can Seam Dictionary

can seam dictionary

Bearded can

A can that is reinforced with regular ring indentations around the 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

Packer’s 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 manufacturer’s end

Bottom end of the can; attached at the can manufacturer

can manufacturer’s double seam

The bottom seam, or the Factory double seam


That part of a double seamer or closing machine that supports the wall of the can end during seaming

closing machine

A machine which double seams the cover or end onto the can bodies


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


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.


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.


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.


The flared projection of the body around the top of a container


The part of a double seam that is over the side seam; also known as the 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


The top of the can, see also Customer End

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


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.


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


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 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


See Dead Head


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 extent of looseness wrinkle on the face of the cover hook


An 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.


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 exhibiting width, without depth or amplitude