Metal cans are stamped from metal sheets (usually tin-plated plates, chrome-plated plates, cold-rolled steel plates, aluminum plates, etc.) and are used to store food or items. Its emergence is a milestone in food storage and transportation. According to the different composition structures and manufacturing methods of metal cans, they are usually divided into two types: three-piece   cans and two-piece cans.

1. The three-piece can has been around for nearly 200 years. Although it has been improved many times, its basic composition is made of three metal sheets (mostly tinplate): the can body, the bottom and the lid. The bottom and lid of the ordinary three-piece can The shapes, sizes and manufacturing methods are exactly the same and are collectively called can lids. There are two main ways of sealing the longitudinal seams of the can body: soldering and fusion welding. The former was used earlier, but because solder contains lead, it has become obsolete; the latter can avoid lead pollution and has low energy and material consumption. , but the production equipment is complex (three-piece can body manufacturing process: tinplate printing → shearing → welding → seam repair → slitting → necking → rolling → sealing → leakage → spraying → drying → packaging). Three-piece cans have the characteristics of good rigidity, the ability to produce cans of various shapes, high material utilization, easy size change, mature production technology, and a wide variety of packaging products.

2. The two-piece can was born in the United Kingdom in the 1940s. It refers to a metal can consisting of a lid and a body with a bottom, so it is called a two-piece can. Because the can body and bottom are hollow cup-shaped wholes processed by stretching, this forming method is stamping processing, so the two-piece can is also called a stamped can or a drawn can. According to different processes, two-piece cans are divided into: shallow drawn cans (DR), deep drawn cans (DRD) and thinned deep drawn cans (DI). They have good sealing, beautiful appearance, high production efficiency and saving of raw materials. and other advantages; however, two-piece cans have higher requirements on material performance, can-making technology and can-making equipment.
For two-piece cans, since the body of the two- piece can is directly formed by the stamping process, the process is simple, the equipment investment is low, and the production efficiency is high. Since there is no leakage, the leak detection process can be eliminated.