Steels_ Metallurgy and Applications, Third Edition

100 Steels: Metallurgy and Applications

Cu

1. Ironing die


2. Ironing die


3. Ironing die

Punch

can

Bottom end ~[~

tool

Figure 1.101 Wall-ironing with three ironing dies (After Morgan l~~

to the inside. DWI cans are used for beer and soft drinks, for pet foods and some
human foods. Aluminium is a major competitor to tinplate in DWI cans for these
products, although tinplate enjoys a larger share of the UK market at this time.
In the draw and redraw (DRD) process, the initially drawn cup is redrawn
to one of smaller diameter and greater height in one or two re&awing
operations. Like the DWI process, it eliminates the side seam but the maximum
height/diameter ratio that can be produced by multiple drawing is less than that
achievable by DWI. However, DRD has a major advantage over DWI in that
pre-lacquered tinplate can be used, thus eliminating the costly cleaning and spray-
lacquering operations at the end of the process 15~ DRD cans are used for pet
foods and some human foods, including baby foods.
Canmaking via DWI and DRD takes place at high speed and involves severe
plastic strain. The steel, therefore, needs to be of the highest quality and a very
low level of non-metallic inclusions is essential to the efficient operation of these
processes. Gauge control is also important. The DRD process requires higher
values so that extensive drawing can take place. However, care must be taken
to avoid an excessively large ferdte grain size which can give rise to an orange
peel effect and a poor surface for lacquering.

Joining methods

One of the advantages of strip steel, as mentioned previously, is that it has the
ability to be formed into components economically with relatively complicated