Metal cans are commonly referred to as easy to pull cans, where the lid and body are produced separately and finally assembled together. There are three main materials used to manufacture cans: aluminum, tinplate, and laminated iron.
Overview and Characteristics
The advantages of this metal can are very obvious. It has excellent sealing and can withstand high internal pressure, making it very suitable for loading carbonated beverages that only require a little pressure, air, and acid resistance.
classification
Metal cans are classified according to their manufacturing methods; There are mainly two types of cans: three piece cans and two piece cans:
(1) Three piece jar
The application history of the three piece can has been nearly 200 years. Although it has been improved multiple times, its basic composition is still made of three metal sheets (mostly tinplate) for the can body, can bottom, and can lid, hence the name "three piece can". The shape, size, and manufacturing method of the bottom and lid of a regular three piece can are exactly the same, collectively referred to as the lid. There are two main sealing forms for the longitudinal seam of the can body: soldering and welding. The former was used earlier, but due to the presence of lead in soldering, it has been phased out; The latter can avoid lead pollution, with low energy consumption and material consumption, but the production equipment is complex.
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 packaged products.
Three piece can production process
Can body: cutting board - feeding - bending into a circle - overlapping positioning - resistance welding - patching - drying - flipping - pressing ribs - necking (beverage cans)
Can lid making: oiling - cutting and dropping - punching lid - round edge - gluing - drying and curing
Finally, seal the can body and lid and conduct quality inspection
(2) Two cans
Two piece cans were introduced in the mid-20th century. The entire packaging can consists of two pieces, namely the can body and the can lid, hence it is called a two-piece can. The body of the two cans is made of thin metal plates, which are stretched and deformed by a punching machine through a stretching mold, connecting the bottom and body of the cans together.
There are various classifications for the body of two cans: shallow flush cans and deep flush cans according to the height of the can body; According to the material used for canning, aluminum cans and iron cans are classified; According to manufacturing technology, it can be divided into thin drawing cans and deep drawing cans. Compared to a three piece can, a two-piece can has the following advantages:
① Good sealing performance. The can body is directly formed by the punching and pulling process, without leakage and eliminating the need for leak detection
② Ensure product quality. Two piece cans do not need to be welded and sealed to avoid lead contamination from solder cans, and are resistant to high temperatures and sterilization, ensuring product hygiene.
③ Beautiful and elegant. The can body is seamless, with a beautiful appearance, and can be continuously decorated and printed for good results.
④ High production efficiency. Two piece cans only have two components, and the manufacturing process of the can body is simple, which greatly benefits the simplification of the process and the improvement of production capacity
⑤ Save raw materials. The body of the two-piece can is subjected to tensile deformation during molding, and the wall thickness is thinner than that of the three piece can; In addition, the body of the two-piece can is integrally formed without longitudinal seams or seams with the bottom of the can, which also saves materials.
However, the requirements for material properties, canning technology, canning equipment, etc. are relatively high for two cans, and there are fewer types of materials to be filled.
Production process of two-piece cans
Cupping and cupping: coil cutting - stamping pre stretching into blanks - multiple stretching thinning - bottom punching forming - trimming - cleaning lubricating oil - drying - coating white enamel - surface printing - coating inner wall - drying - necking and flanging - leak detection
Deep drawing and cupping: cutting - top punching cup - re punching cup (several times) - flanging - bottom punching forming - trimming - surface decoration - leak detection