The so-called three-piece can consists of a single body, with a top lid and a bottom lid each being a separate piece. This chapter primarily focuses on the manufacturing of the can body, while the lid manufacturing process will be discussed in Part 4.

The process for manufacturing the can body is as follows:
Shearing and welding→Seam patching→Slitting→Necking (expanding or forming the can) →Beading→Flanging→Seaming (capping) →Leak testing→Full coating→Drying→Packaging
Printing Technology for Tinplate

The material used for three-piece cans made of tinplate is tin-plated iron, while the can lid can be made of either tin-plated iron or chrome-plated iron. Both tin-plated iron and chrome-plated iron are susceptible to rust in humid environments. Therefore, external rust protection is required for the can. Modern and exquisite external can printing reflects the personalized demands and brand charm. Additionally, different foods contain various corrosive factors, with aluminum, tin-plated iron, and chrome-plated iron being more susceptible to corrosion than water. The use of coatings can isolate the metal materials from the external environment, preventing abrasion of the metal substrate and inhibiting the corrosive effects of foodborne factors on the substrate.