How a two-piece drawn and wall-ironed food can is made
Two-piece metal cupping manufacturing
1. Aluminium or steel strip arrives at the can manufacturing plant in large coils.
Aluminium or steel plates are shipped to cannery in large rolls
2. The strip is lubricated with a thin film of liquid and then fed continuously through a cupping press, which blanks and draws thousands of shallow cups every minute.
The metal plate is lubricated by a thin liquid film and then enters the continuous punching machine, punching out thousands of metal shallow cups per minute.
3. Each cup is rammed through a series of tungstenether rings. This is the drawing and ironing process which redraws the cup to a smaller diameter and thins the walls, whilst increasing the height.
Each cup is then stamped with a series of tungsten carbide rings. This is the process of stretching and flattening the wall of the cup to create a finer diameter, a thinner wall and an increased height of the jar
4. Trimmers remove the surplus irregular edge and cut each can to a specified specified height. The surplus material is recycled.
The finishing machine removes excess flash and cuts the cup exactly to the required height. The excess material is recycled
5. The trimmed can bodies are transferred through highly efficient washers and then dried. This removes all traces of lubricant in preparation for coating internally and externally.
Finished cans pass through a high-speed cleaner and dry. This step is to remove the lubricating fluid residue to prepare for the inner and outer coating
6. The cans are coated externally by passing them under a waterfall of clear lacquer which protects the surface against corrosion.
The cans are coated with a waterfall-like varnish spray for rust protection
7. Lacquered external surfaces are dried in an oven
The paint film outside the can is dried by oven
8. The cans are passed through a flanger, where the tops of the cans are flanged outwards to accept the ends after the cans have been filled.
The cans are formed with a squeegee to form the top flap so that they can be sealed with the bottom of the can after canning
9. The cans are passed through a beader, where the walls of the cans have ethnic beads formed in them to give added strength.
The jar is reinforced on the tank wall by a crimper to reinforce the strength of the tank
10. Every can is tested at each stage of manufacture. At the final stage they pass through a light tester which automatically rejects any cans with pinholes or fractures.
Each jar is manufactured to a high degree of detection. Finally, the jar can automatically eliminate pinholes or burst jars with an optical detector
11. The inside of each can is sprayed with lacquer.
This special lacquer is to protect the can itself from corrosion and from any possibility of interaction between the contents and the metal.
The interior of each jar is sprayed with a varnish. This special coating is for rust prevention and to prevent the corrosion of the metal material
12. Lacquered internal surfaces are dried in an oven.
The inner paint film dries through a drying tunnel
13. The finished can bodiesare then transferred to the warehouse to be automatically palletised before despatch to the filling plant.
The completed cans are transported to the warehouse and automatically palletized and wait for filling