Two-Piece Cans
Two-pieces cans are developed in replaced of three-piece cans that cause lead pollution. The two-piece can is a packaging container with the bottom end and the body shaped from one sheet of metal by deep drawing, with a second end seamed to the can to close it and form a complete package for sale. As the whole can is composed of two pieces, it is known as the two-piece can.
Compared with the three-piece can, the two-piece can has the following advantages: (1) The can body has no side seam, and there's no seam between the body and the bottom end, so the can is tightly sealed with less consumption of raw materials; (2) The can body can be fully decorated and printed; (3) The can making process is easy and efficient. However, it also has some disadvantages.For example, it requires excellent performance of the can-making materials and a high investment in equipment. Besides, can-making technologies, equipment and dies must be excellent as well.
Types of two-piece cans:
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); in terms of can body forming, there are drawn and ironed (DI) cans and drawn and redrawn (DRD) cans; in terms of can shapes, there are round cans and irregular cans. The most commonly ones are DI cans and DRD cans.
DRD Cans
The DRD can manufacturing process is composed of cupping, drawing,
redrawing, flanging, further machining, and forming, as shown in
Figure 2.12.
Baosteel's production process for DRD cans is normally divided into five major steps, including, feeding, punching and cupping, deep drawing and flanging, trimming, and product inspection, as shown in Figure 2.13.
DR Cans
The DI can is formed from a metal strip that is 0.2 to 0.4 mm
thick by a combination of punching and drawing by dies of a punch
press. The wall thickness of the can body after forming is 0.07 to
0.14mm. The bottom of the can remains as thick as the original
metal strip. DI cans are mainly used for products such as beer or
carbonated beverages. The drawing and ironing process of the DI
can (330ML) and its thickness profile after forming
The drawing and ironing process is mainly composed of the following steps: shearing ”ścupping ”ś redrawing ”ś drawing and ironing”ś trimming ”ś necking and flanging. Drawing and ironing, necking and flanging
The cupping process is shown as follows. Diagram of the Cupping Process
Tinplate used for DI steel cans is DI tinplate, and the DI can
manufacturing process is composed of uncoiling, cupping, drawing
and ironing, trimming, cleaning and drying, bottom varnishing,
printing, single inside spraying, necking and flanging, inspection
for leaks, double inside spraying, photo taking and testing, and
stacking, as shown in the following figure.
