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Published on 2019-11-26

A look at how tin containers are made for packaging.

November 26, 2019

Manufacturers use tin cans for canning a wide variety of products in different industries. These include products in the food and beverage industry and the pharmaceutical industry.

Packagers prefer tin cans over regular metals because regular metals react with acidic products which cause the material to corrode. When this happens, the corroded substances can contaminate the packaged product while damaging the can itself. Contrastingly, tin cans are totally safe for packaging food products, medicines, and cosmetics for longer time periods. This is because they can resist acidic contents.

But have you ever wondered what tin cans are made of and how they are manufactured? If you do, then this article might be able to give you the answer you are looking for. Keep reading if you are interested!

What Are Tin Cans Made Of?

Traditional Tins

Generally speaking, the traditional way of producing cans are through tin-plating. Nowadays, you will see a lot of products packaged in tin-plated cans. These cans usually consist of iron or steel materials coated with tin in a process called tin plating. Because of this, tin-plated cans actually consist of about 1 to 2% tin.

The tin coating on the metal serves as protection from other elements to avoid damages to the can. This is also the main reason why they use tin platings for a wide variety of commercial purposes. Of course, these purposes include tin can wrappings.

The only drawback of traditional cans is that they are much heavier compared to aluminum tins (modern cans). This makes tin-plated cans more expensive and less convenient to transport.

Modern Tins

In the modern-day, the majority of tin containers you will see in the market are now made from different kinds of treat metals. Aluminum materials are the most common ones. But any material can be used so long as you can easily shape it and it is rust and corrosion-resistant.

Both modern and traditional tins are excellent for canning different kinds of products especially that they are recyclable. This means that manufacturers of cans can strip the layer of tin then recycle the steel or iron as scrap metals.

How are Tin Cans Made

There are mainly two types of tin cans used in the packaging industry: 2-piece and 3-piece tin cans.

2-Piece Tin Cans

  • Cup Blanking and Drawing – A press produces cups from coils of steel or aluminum.
  • Ironing and Doming – The cups are then subjected to a sequence of rings. This process irons out the cans to form the bottom domes.
  • Trimming – The cans spin while a cutting device trims the cans to length.
  • Cleaning – The trimmed cans undergo several cleaning processes.
  • Printing and Varnishing – The cans are now rolled against a cylinder for printing and varnishing.
  • Bottom Varnishing – The cans pass an applicator for bottom varnishing.
  • Baking – The varnished cans then wind through a conveying system inside an oven for drying and setting of lithography.
  • Inside Spraying – The application of a compounded protective coating inside the cans follows.
  • Baking – The next baking process comes next to cure the inside coating.
  • Necking – The necks of the cans are reduced so that they will fit the size of the can end.
  • Flanging – Flanges are formed on the cans’ rims for double seaming in the future using a tin can sealing machine.
  • Testing – Each of the produced cans are tested for leakages.

3-Piece Tin Cans

  • Shearing – A shear press cuts a large metal coil into sheets.
  • Coating – A protective coating is applied onto the metal sheets which are cured after.
  • Printing – The manufacturer decorates the sheets according to the customer’s preferences.
  • Varnishing – The decorated sheets undergo varnishing before curing.
  • Slitting – The body sheets are cut into individual blanks which are later formed into tin cans.
  • Scroll Shearing – A device cuts the body blanks into smaller scroll sheets.
  • End Forming – Stamping of ends from the smaller scroll sheets follows. The finished products are packed and delivered to customers and fabricating plants.
  • Body Forming – A bodymaker forms the body blanks into cylinders then joins the side seams through soldering, cementing, or welding.
  • Flanging – The cylinders from the previous process enter a flanger. The flanger rolls the metals on both of the cylinders’ ends to form flanges. Similar to the 2-piece cans, these flanges are created for double seaming purposes.
  • Double Seaming – An end of the can, either the top or the bottom end, depending on the customer’s specifications, is connected to the can through double seaming.
  • Spray Coating – The placement of a final coating on each can’s interior surface follows. This coating serves as the can’s protection from rust and corrosion.
  • Baking – The applied interior coating undergoes baking and curing processes through an oven. This oven is a funnel type one in which the operator must control the time-temperature values carefully.

Conclusion

Though tin cans can be either made from steel/iron materials or treat metals like aluminum ones, they basically undergo the same manufacturing processes. These processes ensure that the cans will not be affected by other elements that can cause rusting and corrosion. Thus, protecting the packaged products from damages and increasing product shelf lives.

By the way, do you have used tin cans at home? Help promote a greener environment by recycling them through these 18 amazing off-grid uses of old tin cans. Have fun!



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