How cans are made

I was interested in finding out how cans are printed after a session looking at the design of the can really close up. It turns out that the cans are printed as the cans are created.
My information on this post has come from the Can Makers website: www.canmakers.co.uk
This is exactly how the can is made and includes the printing as well.

 The first step is to obtain a big reel of aluminium or steel strip that will be used to make the can.

 The strip is lubricated with a thin laer of oil and then a cupping press blanks out thousands of shallow cups of the metal every minute.

 Each shallow cup is then pushed through a series of rings which raises the walls of the can, thins out the metal and irons it out into its final can shape.

 Trimmers are then used to cut off the spare, uneven metal and the offcuts go elsewhere to be recycled.

 The can is then passed through a washer and then dried which works to take out any excess oil from the previous steps.

 The clean cans are then coated with a clear base coat or a coloured base coat depending on the later steps. This helps make a good surface fro printing the design on to.

 The cans then pass through another dryer to dry the base coat properly.

The next step involves the printing which uses a rotary printing process. It is most likely to be flexography based on the metal being used. The printers apply the design in up to 6 colours plus a varnish.

 Varnish is also coated around the base of the cans using a rim-coater.

 The cans go through another drier which dries the inks and the varnish thoroughly.

 The inside of the cans are sprayed with a special coat of protective lacquer. This is done to protect the contents of the can and avoid any erosion.

 The cans go through another oven to dry the inside.

 The cans go through a 'Necker' which pushes in the can walls just above the top and causes the top to flare out. This makes it ready to hold the lid in a later stage.

 Cans are tested in a light tester which can see if there are any holes or cracks in the cans. Any bad cans get automatically rejected.

The finished can bodies are sent to a warehouse and packaged to be sent to a filling plant.





The next steps involve the can lid:

 The end of the cans are made from the same aluminium material as the bodies. 

 The sheet is fed through a machine which stamps out the ends. It can do thousands in a minute. 

 While they are being stamped the machine also curls the edges up into a rim. 

 The end are passed through a machine which then lines the inside of the curl with a compound sealant which will make it water tight. 

 An inspection system uses video feeds to check each can lid properly. 

 Elsewhere the tabs are made from a thinner width of aluminium coil. The can ends are sent through a system of cutters which score them and attach the tabs on top. 

 The final product emerges. 

 The lids are packaged in sleeves and sent out to the filling factory where they will be attached to the bodies aftr filling. 

It is actually quite a complex process which is not really thought about much when drinking a can. Considering the hundreds of millions of cans that are made in each batch it is quite an impressively cheap exercise considering the complexity of the manufacture and the retail price of a single can. 

One thing that stuck out from the process is that it utilizes the same rotary print machinery that I have researched before this. It is also interesting that it uses a hexachrome printing machine and when examining the can in the session I saw that it had 6 colours so this makes sense.