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What are Two-Piece cans?
Manufacturing Process of Two-Piece Cans
Two-piece cans typically use tinplate (electrolytic tin-coated steel) or aluminum. The main processes include:
Deep Drawing – A flat metal sheet is stretched into a cylindrical shape using a punch and die, forming the can's bottom and sidewalls as a single unit.
Drawing and Ironing (DWI) – Used mainly for beverage cans, where the metal is drawn and then thinned (ironed) to achieve uniform wall thickness while maintaining strength.
Trimming & Flanging – The top edge of the can is trimmed to ensure a precise height, and a slight flange is created to facilitate lid sealing.
Internal Coating & Printing – A protective coating is applied inside to prevent metal corrosion and food contamination, while the exterior is printed with branding and product details.
Filling & Seaming – The can is filled with its contents, and the can end (lid) is sealed using a high-pressure seaming process.
Main Uses:
- Beverage packaging: such as beer, carbonated drinks, and so on. Due to the good sealing and high strength of tinplate two-piece cans, they can withstand the pressure of beverages and have strong shading, which can effectively protect the quality of beverages.
- Food packaging: like fish, meat cans, and so on. Its good barrier properties can prevent food spoilage, prolong the shelf life.
- Chemical product packaging: Some chemical raw materials, refrigerants, and other high-pressure gases or liquids will also be packaged in tinplate two-piece cans, because of their high-pressure resistance and good safety performance.
Raw material requirements:
- Tinplate: Tin-plated tinplate is generally used, the thickness is usually around 0.23mm - 0.30mm. Tinplate is required to have good corrosion resistance, ductility, and strength to ensure that the cans can be shaped smoothly and can withstand the pressure of the contents and the influence of the external environment in the process of use.
- Coating: The inner coating should be non-toxic and harmless, can be well combined with tinplate, and can resist the erosion of the contents to ensure the safety and hygiene of food or other goods; the outer coating is required to have good adhesion, abrasion resistance and decorative properties to improve the aesthetics and durability of the can body.
Prone to defects:
- Uneven wall thickness: due to mould wear, process adjustment, and other reasons, resulting in inconsistent wall thickness of the can body, easy to deform when in use.
- Broken elbow wire: the elbow of the easy-open ring is the key part; if there is a break here, the can will not be able to open normally.
- Welding point air leakage: If the welding is not in place, there will be air leakage at the seal of the can, which will affect the sealing performance of the product.
- Printing blur: poor printing quality, pattern, or text blur will reduce the aesthetics of the product and market competitiveness.
- Metallic foreign matter: impurities in raw materials or metal shavings generated by equipment wear and tear may be mixed into the cans, posing a potential safety hazard.
New technology for two-piece cans in China:
-Lightweight technology: By improving material properties and design, the car body's strength and performance are ensured. Tinplate is reduced to achieve lightweight and reduce the cost of raw materials and transport.
- High-speed automated production technology: Develop high-speed can-making equipment and automated production lines to improve production efficiency and reduce labour costs, while ensuring product quality stability.
- New coating technology: develop inner and outer coating materials and coating processes with better performance, such as high corrosion resistance, high adhesion, environmentally friendly coatings to meet the packaging needs of different products, and more in line with environmental requirements.
- Can innovation technology: design a variety of novel cans, such as shaped cans, cans with special functional structure, to increase product differentiation and market attractiveness.
-Intelligent inspection technology: Use machine vision, sensors, and other technologies to carry out online inspection of cans, detect and eliminate defective products on time, and improve product quality and production efficiency.
Would you like a comparison between two-piece and three-piece cans, or want to know the Differences Between Two-Piece Cans And Three-Piece Cans?
