Low-carbon strip steels 99

oo,,

___

4------ Wall Ironing --...--.---

Redrawn , .... cup - Phase , , ....... I ,, Phase , ,, II , Phase , ,,, ,, , III ,, Bottom -- _ forming

I

L~,Trlmmlng O,egreasln..g(~ .... l ~ -...----,--

Necking Flanging

Decorating .... Curing .... , ......

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Inside spraying Palletizlng

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O

Scrolled sheet Initial cup

Figure 1.100 Drawing and wall-ironing operation sequence (After Morgan tS~

the need for a welding operation and relies solely on presswork. Morgan cites
the following advantages for DWI over three-piece cans:

1. More effective double seaming of the top end to body, because of the absence
   of the sensitive side seam junction (particularly valuable for processed foods
   and carbonated beverages).


2. Significantly lower metal usage and cost.


3. More attractive appearance due to the absence of a side seam.

Following the initial drawing operation, the cup is redrawn to final can diameter.
During wall-ironing, the can may pass through a series of dies which produce
a substantial reduction in wall thickness and a complementary increase in body
height. The principle of wall-ironing is shown in Figure 1.101. Following trim-
ruing, the can is degreased prior to applying decoration to the outside and lacquer