Two-piece can

There are in essence distinct types of cans and ends (or lids). The lids are always attached after filling the can with foodstuffs; thus, the packers and fillers purchase empty cans and lids and seam the lids onto the cans.

Two basic styles of cans: three-piece cans, which consist of a body and two ends, and two-piece cans, which consist of an integral bottom-and-body, with only one end. Three-piece cans are nearly all made of tinplate.

Two-piece cans are usually made of aluminum or of tin-free steel, though they can be made of tinplate. In terms of can body height, there are shallow drawn cans and deep drawn cans; in terms of raw materials, there are two-piece aluminum cans and two-piece steel cans (tinplate cans).

Most of the drawn cans find usage in the beverage as well as the food industry. Drawn cans are also widely used for packing sweets, and these are usually closed with a slip lid. Both steel and aluminum substrates can be used.

There are two main methods used commercially to make two-piece cans:

*Drawn and ironed (D&I) process which can be adapted to produce a can for pressure packs (including carbonated beverages) and for food containers. This is a variation on beer and beverage cans.

*Drawn and redrawn (DRD) process which is a multistage operation and produces a can mainly suitable for food products. For taller cans, such as large salmon cans, two or three operations – draw and redraw (DRD) or multiple redraw are used.
Two-piece can

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Three-Piece Can

A three piece can consist of three parts:
•Cylindrical shell (body)
•Top end
•Bottom end

Three-piece cans are mainly used for food, but may be used for some non-carbonated beverages, particularly fruit juices. Three-piece cans to be filled with dry food, e.g., milk powder, instant baby food, sweets or roasted nuts.

Three-piece welded food cans are only constructed from steel, as aluminum is not suitable for welding by this particular process. Tin-free steel is electrocoated with a layer of metallic chromium covered by a layer of chromium oxide.

Before the bodies are formed, coatings are usually applied to the interior and exterior surfaces with a roller onto the flat sheet.

Exterior coatings are applied for decoration, to protect the can from corrosion, to protect the printed designs from marring or abrasion, or to reduce friction on the bottom of the can to facilitate handling.

The wall of the can is rolled to form a cylinder and the seam (joint) is welded. In some types of three-piece cans, the side seam is crimped rather than welded or soldered.

For both food and drink cans, one end is then mechanically seamed on to the bottom of the can body. This end is commonly referred to as the maker’s end (ME). Where easy-open ends are fitted to three-piece cans, it is common practice for this end to be fitted at this point, leaving the plain end (non-easy-open) to be fitted after filling.

After the can is filled with the product mix the can is sealed with a tight mechanical structure - the so-called double seam. The double seam, in its final form and shape, consists of three layers of lid and two layers of body material.
Three-Piece Can

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