How a Beverage Can Is Made
The modern two-piece beverage can starts as a coil of sheet typically 0.25 to 0.30 mm thick. A circular blank is drawn and ironed in a press to form a seamless body, then the open end is necked and flanged. The can body must deep-draw without tearing, thin out evenly through the ironing rings, and keep enough strength in the sidewall to resist internal carbonation pressure of around 500 to 600 kPa. The lid and tab are stamped from a different, stronger alloy because they must survive the riveting and opening forces.
Alloy 3004 and 3104 for the Can Body
3004 contains about 1 percent manganese and 1 percent magnesium, giving higher strength than 3003 while retaining the ductility needed for deep drawing. 3104 is a refined version of 3004 with closely controlled levels of iron, silicon and copper, developed specifically for drawn and ironed can bodies. Over the decades, gauge reductions from about 0.42 mm in the 1970s to 0.254 mm or less today have cut the weight of each can while maintaining burst and buckle strength, thanks to tighter composition control and improved mill practice.
Alloy 5182 for the Can End and Tab
5182 is an Al-Mg alloy with roughly 4.5 percent magnesium, giving the higher strength needed for the lid, the scored opening panel and the tab. The end must resist deformation from internal pressure and from stacking loads in the warehouse, yet still open cleanly along the score line. 5182 in the H19 or similar hard temper provides that combination of strength and controlled fracture behaviour. The end is typically supplied as pre-coated coil, with the lacquer applied before stamping.
Surface, Coating and Can-Making Requirements
Can stock must be extremely clean and flat because the drawing and ironing process magnifies any surface defect, oil residue or gauge variation. Coils are supplied with controlled surface finish for lacquer adhesion, and the interior of the can is coated to prevent the beverage from contacting the metal. Buyers specify coil width, gauge, temper, lubricant type, and the coating system used by the can line. Tolerances on gauge and flatness are much tighter than for general building sheet.
Recycling and Sustainability
Aluminum beverage cans are among the most recycled packaging formats, and the alloys in can body and end stock are fully recyclable without loss of quality. A used can returns to the melt and can be re-rolled into new can stock, which is why the industry describes the can as a permanent material. Recycled content in can stock reduces energy consumption dramatically compared with primary metal. Buyers sourcing can coil should confirm the recycled content declaration and the consistency of alloy chemistry, because contaminants upset the delicate balance of the body and end alloys.
FAQ
Why are the can body and the lid made from different alloys?
The body needs maximum formability for drawing and ironing, so 3004 or 3104 is used. The lid must be stronger to resist pressure and to open cleanly, so higher-strength 5182 is used.
How thin can a can body wall be made?
Modern two-piece can walls are drawn down to roughly 0.08 to 0.10 mm in the sidewall while the base keeps more thickness for strength. This is possible because of the controlled composition of 3104 and the ironing process.
Is beverage can stock recyclable indefinitely?
Yes. Aluminum does not degrade during recycling, and the body and end alloys can be remelted and returned to can stock production, provided the scrap is sorted and processed correctly.
What temper is can stock supplied in?
Can body stock is typically supplied in a cold-rolled, controlled temper such as H19, with precisely managed mechanical properties for the drawing and ironing operation. Final properties are confirmed by mill testing.
Does the coating go on before or after forming?
For the can end, lacquer is applied to the coil before stamping. For the body, interior coating is applied after forming so the coating covers the formed surface without cracking at the sharp corners.
Frequently Asked Questions
Q: Which alloy grades does this article cover? The article covers 3004, 3104, 5182 in aluminum coil form, and it compares how the different alloying systems affect strength, corrosion resistance and formability.
Q: What thickness or gauge range is available? Typical gauges mentioned in the article range from 0.30 mm, 0.42 mm, 0.254 mm, which covers the common sheet, plate and foil requirements for this grade.
Q: What surface finishes can be supplied? Surface options covered in the article include coated, which suit everything from plain mill products to decorative and protective coatings.
Q: What are the main applications of this product? The article highlights its use in packaging, building, where the combination of light weight, corrosion resistance and formability provides the main benefit.
Q: What should buyers specify when ordering aluminum coil? Buyers should confirm the alloy grade, temper, thickness, width, surface finish, quantity and delivery terms, and state the standard the material must meet.