For canned food distributors and food packers, it’s essential to consider the quality of the metal cans used for canning foods. This is to ensure that the food is secured and safe for consumption. The food also has to last for a long time and has to endure the long process of transportation and mass distribution. All these factors come down to the quality of the metal cans for canning foods.
Everything You Need to Know About Metal Cans for Canning Foods
Metal packaging innovations maximise its use as a different material. For example, advances in can forming and metal deposition onto packaging materials enable greater material efficiency and unique antimicrobial and microwave susceptibility properties.
Cans, which are made of steel or aluminium, are the most commonly used metal packaging. Electrolytic tinplate or electrolytic chromium/chromium oxide-coated steel, also known as tin-free steel, is used to make steel-containing cans. Although metal cans are widely used in the food canning industry, tin cans are a much better alternative.
The Process of Making a Metal Can
The process of making a metal can for canning foods depends entirely on what type of food will be stored in the can. A different process is done for cans for beverages and cans for preserved food.
Metal cans are divided into two types based on their manufacturing method: two-piece or three-piece.
Two-piece cans are drawn and ironed from a blank metal sheet to make a successively same-diameter taller can, or they are drawn and redrawn to make a smaller diameter.
Three-piece cans are created by coating the steel first and then rolling the can wall into a cylindrical shape. The seams are welded, and the base is secured to the cylinder by double folding the cylinder and end lip and crimping—a technique that is known as double seaming.
Making a Two-piece can:
- Cup blanking and Drawing – a press produces hundreds of cans per minute from massive coils of aluminium or steel.
- Ironing and Doming – the cans are forced through a series of rings to lengthen cans and form the bottom dome.
- Trimming – the cans are put on a spinning tool and cut into the desired shape.
- Cleaning – all the cans are cleaned in a cycle through multiple cleaning stations.
- Printing and Varnishing – The cans are rolled through a printing roller to print labels and brand logos on all cans.
- Bottom Varnishing – The cans go through an applicator that coats the bottom in varnish.
- Baking – the cans are put in an oven to dry, and set the printing and lithography.
- Inside Spraying – all the inside of the cans is sprayed with a protective layer to prevent corrosion.
- Baking – the cans go through an oven to bake and cure the protective coating.
- Necking In – the necks are narrowed through a machine to fit the designated end size.
- Flanging and Testing – The can rim is flanged to allow for future double seaming of the ends. Each can is then mechanically tested for leakage. Finally, cans are stacked in cartons or pallets for shipment.
Making a Three-piece can:
- Shearing – At 150 sheets per minute, the large coil of metal is cut into pre-scrolled sheets. The irregular ends of the sheets are intended to maximise the number of ends per sheet.
- Coating – The inside of the pre-scroll sheets is coated with a protective coating and cured.
- Printing – The sheets are pre-printed with labels and desired logos, and a varnish overcoat is placed over the printed labels.
- Second Coating – A second coating of the internal protective layer. The sheets are then cured after coating.
- Slitting – Whole body sheets are slit into individual sheets to be moulded into individual cans.
- Scroll Shearing – The individual sheets are then cut into scroll sheets that will go through the end-making process.
- End Forming – The ends of the scroll sheets are stamped and will be packed into tubes for distribution to fabricating plants and clients.
- Body Forming – The body blanks are moulded into cylinders through a body maker and then joined at the side seams with cement or weld.
- Flanging – From the body maker to the flanger, the formed cylinder travels. The metal is rolled on both ends to form a flange on each end of the can. This flange will eventually go through a double seaming process.
- Double Seaming – The end of the can (either top or bottom as per client preference) is sealed in a double seam.
- Spray Coating – The interior surface of the can is finished with a final coating. This is a protective coating that has been specially formulated for the finishing.
- Baking – The final interior coating is baked and cured in a time-temperature-controlled funnel-style oven.
- Testing – All the end products go through a quality control inspection for any defects on every can.
- Packing – The cans are packed for distribution and transport to clients.
Steel is used in most canned food cans around the world today. Although there is a thin layer of tin on the surface, only 5 to 6 pounds of tin are used per ton of steel. Most people in the industry refer to this type of packaging as “tin cans”.
Tin cans are most commonly used in packing food preserves and beverages. Other materials used in making metal cans for canning foods include aluminium, tinplate, and modern tin.
MC Packaging: Global Manufacturer of High-Quality Tin Cans
MC Packaging has been in the business of manufacturing quality tin cans for a global clientele for over 50 years. In those years, MC Packaging has been delivering premium quality tin cans to established brands in the food packing industry.