27 Common Terms in the Can Seaming Industry

When you are new in the packaging industry, you will encounter some terms which might be helpful if you familiarize yourself with them. Double seaming is one of the most common processes you will get into when packaging tin or aluminum cans. And in the can seaming industry, it is crucial that you know what you are dealing with. This is because a reliable seam is important in the packaging process.


So to help newbie packagers like you, we have listed the 27 common terms that can help you get by in the can seaming industry. Without any more chitchats, let us go on with our list.

#1 Cover/Lid/End

Also called Customer End, Canner’s End or Packer’s End, this is the end part that is double seamed into a filled container in a canning factory.

#2 First Operation

This is the initial stage that forms a double seam in which the flange of the cover is subjected to a concave seaming roller. The 1st seaming roller causes the cover’s flange to interlock with the can body’s flange loosely.

#3 Second Operation

This is the last stage that completes a double seam. This stage compresses and flattens the loosely formed seam in the first operation to complete a hermetic seal.

#4 Tightness Rating

A double seam’s compressive tightness measured through rating a cover hook face’s looseness extent.

#5 Body Hook

This is the part of a can’s body that is bent down to form a double seam.

#6 Cover Hook

Also referred to as an end hook, this is a component of the double seam that is created from the cover’s flange.

#7 Countersink Depth

This is the measurement that starts from the seaming panel’s top edge to the chuck wall radius’ bottom part.

#8 Side Seam

It is the seam found on 3-piece cans that joins the two ends of a metal blank. This seam is soldered, welded, or cemented to form the can’s body.

#9 Curl

This is the end component’s extreme edge which is folded inward after forming the edge. It forms a double seam’s cover hook.

#10 Flange

The body’s flared projection around a container’s top.

#11 Juncture

Also called a crossover, this is a double seam component found over a side seam.

#12 Overlap

It is the amount of interlock between the cover’s hook and the can body’s hook.

#13 Pin Height

This is the measurement between the base plate’s highest part and the seaming chuck’s lowest part. 

#14 Seam Height

It is the seam’s maximum dimension measured in parallel to a can’s axis.

#15 Seam Thickness

It is the seam’s maximum dimension measured in perpendicular to the chuck’s wall.

#16 Cutover

This is a critical seam defect in which the can is damaged at the seaming chuck wall’s top portion.

#17 Dead Head

This is also known as a Slipper, Spinner, or Skidder. It is a seam defect in which the  1st and/or 2nd double seam operation is not completely formed around the can’s circumference.

#18 Droop

This is a condition in which a seam’s smooth projection is overhanging in the normal seam. It usually occurs when a foreign material or some product is caught in the seam while the double seaming process is undergoing.

#19 False Seam

This is a critical seam defect in which the body and cover hooks are not interlocking around the can’s circumference.

#20 Knocked Down Flange

This is a condition that looks like a false seam wherein the body and cover hooks do not properly interlock. It has a typical length of 1 to 2 inches.

#21 Mushroomed Flange

An over-formed flange.

#22 Pleats

It is a fold found in the lid hook’s metal that is extending from the lid’s cut edge down towards the cover hook’s radius. Sometimes, a spur or sharp vee is found below the radius.

#23 Pucker

This is a seam defect in which the cut edge of the cover’s hook distorts downwards but does not actually fold.

#24 Sharp Seam

In this condition, the seam will have a sharp and pointed edge which indicates that the seam was forced on the seaming chuck’s top portion.

#25 Spur

This is an irregularity in the can’s seam in which a sharp portion is protruding from the double seam’s bottom. This is typically accompanied by vees or pleats in the cover’s hook.

#26 Vee

This is an irregularity which happens on a cover’s hook. In this condition, the material in the cover’s hook is not formed smoothly. Thus, causing the material to split, forming a V-shape opening found on the cover hook’s face. 

#27 Wrinkle

Waves or irregularities found on the cover hook’s face.


All of the terms mentioned in this article are related to the sealing process which is done using a can seaming machine . You may have noticed that the last terminologies discussed are double seam defects. If you want to know more about these double seam defects, you can read more here. It might also help you understand these terms better if you familiarize yourself with the double seaming process.

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