In the process of cold stamping, although different molds or other tools are used in the can end blanking and flanging, the same production equipment and machines can be used, and the micro crimping is also suitable for steel and aluminum. The two-piece can is shaped and processed. Regardless of the type and size of the metal packaging container, micro-beading technology can bring cost-saving benefits. If calculated according to the reduction of multiple dimensions of the container, the average material and processing cost can be saved by 10~20%.
This new technology related to micro-crimping was first proposed at the 5th International Meeting of Tinplates in 1995. The meeting also presented a pilot project for evaluating micro-bedding technology. The results of several tests show that this technology is fully applicable to metal packaging containers for various foods, including food packaging that requires heat treatment. The initial practical situation in the past decade shows that the micro-beading technology has outstanding advantages in various products of metal containers. For metal can manufacturers, the size of the can body blanking and the length of the edge trim are significantly reduced, and the amount of sealant at the can end is reduced. In the can production line, the productivity is significantly improved. At the same time, the consumption of the electrode, the paint on the inner and outer walls and the color strips are reduced, which in turn reduces the cost of packaging and transportation. As a packaging company for metal container users, it will also benefit from a variety of features that reduce pollution, reduce inventory space, reduce transportation, reduce canning costs, and high quality double hemming structures. In addition, the streamlined structure of the micro-bead is more aesthetically pleasing and makes it easier to crush and easier to handle than conventional metal cans. From the perspective of economic prospects, by analyzing and comparing the structural size and type of several two-piece cans and three-piece cans, it can be estimated that the cost savings are considerable. Of course, the more the number of purchases, the more the final cost reduction will be.

Second, the commercialization of new technologies
The Packaging Technology Research Center, a technology research institute in Brazil, is very interested in this miniature crimping structure. After a series of vibration, impact and vertical loading tests on the micro crimping, they found that the structure is very good. Dynamic mechanical properties. Therefore, they believe that the metal can micro-beading technology can replace the conventional hemming process, and these good properties can be obtained even with ultra-light metal sheets. The first user of this miniature crimped metal can was CICA, a Brazilian food company owned by a group company in the United States. The food company transformed two tomato food processing lines with this new micro-bending technology. From 1993 to 1996, the company shared more than 100 million new types of crimped metal cans.
Through several years of use by CICA Foods, it has been shown that the various metal cans of the micro-beading structure have almost the same defect rate as the standard conventional double-edged metal containers due to various reasons. At the same time, the company's quality record with miniature crimped metal cans shows that its quality is more consistent than standard double crimping. Therefore, the company is now more inclined to adopt micro-crimping technology. In addition to South America, this new technology has been used for many years in North America and Central America, for example, in many practical applications for food, vegetables and certain metal cans. Due to good trial results in beans and cereals, CICA Foods decided to shift its production line to this new crimping technology.
The US Department of Agriculture has stated that this micro-beading process technology is permitted for food packaging such as canned meat and poultry, as it provides similar performance to conventional double crimping processes. The FDA (Food and Drug Administration) also issued the same opinion based on the test results and the samples provided. The US CMI (Metal Can Manufacturing Association) has issued a technical manual on the micro-bead manufacturing process and its operating instructions.

Third, the micro-hem structure characteristics

In addition to the commonly used two-piece cans and three-piece cans, the metal cans with a capacity of 900 ml are very popular in South America and Central America. It is only necessary to use 150 million vegetable oil metal cans per month in Brazil. Obviously, this outstanding consumer market will have great potential for production, both for steel plants and metal cans. In particular, with the introduction of new micro-crimping technology, vegetable oil companies using metal cans can reach more than 6% of the total price in terms of cost reduction. At this time, people will inquire about the mechanical properties of the micro-beaded metal containers after they are subjected to the external load during the process of transportation and processing, and whether they can ensure the structural integrity of the packaging container. In order to evaluate the micro-hem structure and compare it with the standard crimping structure, the Packaging Technology Center of the Brazilian Institute of Science and Technology has conducted a series of comparative tests on these two crimping structures.
1. Normative impact test
During this test, a standard impact load was arbitrarily applied to the two types of crimping structures of the above metal cans in two angular directions of 45° and 67°. This impact load is specifically determined according to the standard double crimping structure test, and the impact energy applied in the two angular directions is 0.95 and 2.25 joules, respectively. Since the metal can loses its seal and undergoes large deformation, it is easy to contact with bacteria in the external environment to cause a fat can. Therefore, the reduction of the internal vacuum of the container and the change of the center line of the tank will be used as an evaluation (parameter) index of the structural integrity of the container after the impact.
After testing and evaluating the analysis, it has been found that the mechanical properties of the micro-beads can be comparable to conventional crimped structures in the 45° impact direction and better than conventional crimped structures in the 67° impact direction. The good mechanical properties of the micro-bead structure are believed to be due to its better plasticity. That is to say, it is more resistant to deformation when subjected to a certain impact force, and has a relatively uniform deformation pattern. In addition, it has a more compact structure and is one of the important reasons. Therefore, from the standpoint of sealing, the micro bead will have a better effect after being subjected to an impact force.
2. Test according to ASTM standards
To further evaluate the performance of both the micro-bevel and the traditional crimping, comparative tests were conducted in accordance with ASTM (American Society for Testing and Materials). The test piece is made of 0.16 mm thick tinplate, including the can body of the container and its two ends. The test content includes vibration test, drop impact test and vertical load capacity test of two types of rolled metal cans. Among them, the vibration test standard is ASTM-D999/75, and the drop test standard is ASTM-D775. According to the vibration test, the mechanical properties of the micro-beaded metal can are basically the same as those of the conventional double-edged metal can. However, the performance of the micro-crimped metal can is better when the metal cans are dropped separately and placed in a carton and dropped in two test conditions. During transportation and storage, it was also found that the ability of the miniature crimped metal can to resist vertical compressive loads was always strong.

Fourth, the development of micro crimping
In South America, all metal cans are processed using the same gauge thickness of 0.16 mm, as steel mills in the region do not produce steels less than 0.16 mm thick. However, some steel companies in Europe can produce 0.14mm, 0.12mm? and 0.08mm steel sheets, which provides great potential for processing micro-beaded metal cans. A metal container factory in Brazil uses the above-mentioned 0.14mm? and 0.12mm tinplate to process different types of metal cans of micro-beading structure, mainly used for canned tomatoes and meat products. On these factory production lines, after filling the tomatoes in metal cans, the micro-hems are processed at 95° and pasteurized. These process programs can run on the same device. In another production plant, the meat metal cans are automatically filled and then crimped on a semi-automatic crimping machine and placed in a stable digester at 121° for 60 minutes, while the cooling process is negative. Completed under pressure.
Production over the past few years has shown that the dimensional check and visual inspection results of the micro-bead structure are satisfactory. In all metal cans processed with 0.14mm? and 0.12mm steel plates, the formed can lid hooks are very slippery, and there is no structural instability or rise on either of the micro-beads of the two products or on their materials. Wrinkle phenomenon. These metal can products have the same good structural integrity and are also very tightly sealed. If compared to conventional double-edged metal cans, the overall weight of these cans can be reduced by approximately 35%.
In summary, the test results obtained in the miniature crimped metal container and the practical reaction are very successful. It also shows that this miniature crimping structure has the potential to further reduce the amount of material used. The optimization of reducing the weight of the steel sheet and reducing the size of the crimping structure will make the micro-crimped metal can reach a truly ultra-lightweight. Undoubtedly, the cost-effectiveness of this new micro-beading process and new technology is very significant, which will make the industrial sector more competitive in the market and obtain a new economy under a lower investment environment. growth point.
(Author / Song Baofeng Zhuzhou Institute of Technology School of Packaging and Printing)