Can Seam Dictionary

Base Plate Spring Pressure
The force of the base plate which holds the can body and end component against the chuck during the double seaming operation and helps form the body hook.

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
That portion of the can body flange that is folded down for the formation of the double seam.

Body Hook Butting
The length of the body hook relative to the length of the double seam. The relationship between body hook and the cover hook radius. 100% body hook butting is undesirable.

Customer End
Packers end, cover, lid, canners end. The end component seamed onto a can body in a cannery.

Customer Seam
Double seam formed by the can and end user or processor.

Can Manufacturer’s End
Bottom end component.

Can Manufacturer’s Double Seam
Bottom seam or factory double seam.

Chuck
Part of a double seamer or closing machine which supports the chuck wall of the end component during seaming.

Closing Machine (Seamer)
A machine which double seams the cover or end onto can bodies which may also incorporate canners requirements such as vacuum, steam flow, and under cover gassing conditions.

Cocked Body
Cylinder improperly aligned (out of square).

Compound
A pliable sealing material consisting of a water or solvent based latex or synthetic material placed in the curl of the end. It fills the voids in the double seam during the seaming operation by assisting 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
That part of the double seam formed from the curl of the end component. Also referred to as end hook.

Curl
The extreme edge of an end component which is turned inward after the end is formed. The curl forms the cover hook in double seaming.

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, where the first and/or second operation 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 occurs when product or foreign material is trapped in the double seam while seaming.

False Seam
A critical defect where the cover hook and body hook do not interlock around the circumference of the container.

First Operation
The first of two operations in double seaming. In this 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 the container.

Juncture
The part of the double seam at the side seam which is also referred to as cross—over.

Knocked-Down Flange
A condition similar to false seam in that the cover hook and body hook do not interlock. This is sometimes recognized when the body hook is observed below the bottom of the seam. A knocked-down flange is typically 1”-2” in length.

Lid
See Customer End.

Mushroomed Flange
A flange this is over formed.

Necked-In-Can
A can that has an end diameter smaller than the main body diameter. This may be at one or both ends of the can.

Overlap
The amount that the body hook and 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. This is measured at the high point of the first operation seam formation.

Pleats
A pleat is 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 downward 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. Typically, reverse wrinkles will be two-dimensional exhibiting depth and width, but will lack amplitude.

Seaming Chuck
See Chuck.

Seam Height
The maximum dimension of a seam measured parallel to the axis of the can which is also referred to as Seam Length or Width.

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 by 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. Sometimes even the best double seam will not have an appreciable impression due to types of materials and tooling used.

Seam Thickness
The maximum dimension of a seam measured at right angles to the seaming chuck wall. Seam thickness represents five thicknesses of material plus compound.

Second Operation
The final operation in double seam formation. The seam components formed int he 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 3 piece can joining 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 which is usually accompanied by a pleat or a vee in the cover hook.

Tightness Rating
The compressive tightness of the double seam measured by rating the extent of normal looseness wrinkle on the face of the cover hook.

Wrinkle
Irregularities or waves observed on the face of the cover hook, further defined as:
1. Normal Looseness: Wavy appearance to cover hook exhibiting depth, width, and amplitude (typically three dimensional).
2. Reverse Wrinkle: Wavy appearance to cover hook exhibiting depth and width, without amplitude (typically two dimensional).
3. Compound Wrinkle: Wavy appearance to cover hook due to compound impression to cover hook, exhibiting width without depth and amplitude.

Vee
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, and may be associated with a pin lip or spur projecting below the bottom of the double seam.