11/10/2022 0 Comments Soda cans![]() ![]() Therefore aluminum grades are identified based on the alloying element and heat treatment, using a four digit representation, from 1XXX to 8XXX. ![]() The strength of aluminum can be increased by alloying it with manganese, silicon, copper, magnesium, zinc, etc. With additional electro-coating, either anodic or cathodic, greater protection can be achieved in applications where the metal comes in direct contact with a corrosive environment. It does not oxidize progressively because a hard, microscopic oxide coating forms on the surface and protects the metal from corrosive environments. Aluminum also has high thermal and electrical conductivity, emissivity, strength-to-weight ratio, fracture toughness, energy absorption capacity, cryogenic toughness, fatigue strength, etc. This wide range of applications is possible due to properties such as superior corrosion resistance, natural and chemical inertness, recyclability and the ease with which a variety of parts can be produced. Aluminum alloys are widely used in day-to-day life as thin foils in food packages and beverage cans, as structural members in public transport systems, aircraft parts, etc. Īluminum is available in abundance on the Earth’s crust, largely in the form of cryolite or bauxite. In water-borne spray coatings, solvent contents lower than 10–15% are being sought. Such a procedure avoids the need to apply in two coats, and is potentially capable of giving defect-free coatings resistant to the contents of the can at lower dry film weights. There continues to be commercial interest in the electrodeposition of water-based lacquers in beer and beverage cans. Most successful systems are based on epoxy-acrylic copolymers with amino or phenolic crosslinkers. Water-based coatings have reduced overall costs and lowered the amount of solvent that has to be disposed of by after-burners to avoid pollution. The majority of these coatings have been successfully converted to water-borne colloidally dispersed or emulsion polymer systems, especially on the easier substrate to protect, aluminium. Beer is a less aggressive filling for the can, but its flavour may be spoilt so easily by iron pick-up from the can or by trace materials extracted from the lacquer, that it also requires similar high-quality interior lacquers. ![]() Resistance to corrosion by such products is provided by coatings such as epoxy-amino resin or epoxy-phenolic resin systems. The shape is relatively simple, but interiors are cured by convected hot air, in schedules around 3 min at 200 ☌.Ĭarbonated soft drinks are acidic. Coating viscosities must be very low, and solids about 25–30%. The can is held in a chuck and rotated rapidly during spraying to obtain the most uniform coating possible. The lance may be static or may be inserted into the can and then removed. The rapid application is achieved by short bursts of airless spray from a lance positioned opposite the centre of the open end of the horizontal can. Bodies for beer and beverage cans are lacquered after being made and degreased. Some 800–1000 cans a minute will be produced from one coating line, with bodies and ends coated separately. So a lacquer with excellent protective properties is required, to be used at minimum coat weight (6–12 µm, dependent on metal type).Ĭan-making is economical only if the cans can be made very quickly. Modern beer and beverage tinplate has a low tin content at the surface, the main functions of the tin being cosmetic and lubricating (in the drawing process). In Europe, tinplate is often cheaper, and many cans are made of this. In the USA, where aluminium is cheaper, most beer and beverage cans are made from that metal. Between 19, beer and beverage containers became 25% lighter. Spin-necking saves metal by reducing the diameter of the neck. This method of construction allows much thinner metal to be used and the can has maximum strength only when filled with a carbonated beverage and sealed. The body is produced from one piece of metal by a process known as drawing and wall ironing. Now most beer and beverage cans are two-piece cans. Once the can was made in three pieces: the body (from a flat sheet) and two ends. Can-makers are constantly seeking ways of making the package cheaper. The beer and beverage can is a form of food packaging, and must not add excessively to the cost of its contents. Turner, in Paint and Surface Coatings (Second Edition), 1999 12.4.5 Interiors of two-piece beer and beverage cans ![]()
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