Tinplate Coil

Tinplate coil is a thin metal strip that can be decorated in various ways. It has a high corrosion resistance and can be printed with logos or other information.

Before being coated with tin, the steel undergoes several processes. This includes degreasing and washing to remove residues of lubricants and cooling agents. The coils are then annealed, either continuously or in bell-type furnaces.

Processes

Once the steel is melted it must be rolled into slabs, which will then be turned into plate or strip. This is done in continuous tinplate coil (tandems) or reversible rolling mills. The thickness of the tinplate can be varied by selecting different cold rolling passes, or alternatively the material can be hot rolled to reduce its gauge.

Before the cold rolling process, the strip must be cleaned or “degreased” and pickled. This is done in a series of chemical baths, using water or steam jets. Degreasing removes any residual elements from the belt surface, such as lubricant residues and cooling agents. Pickling removes iron oxide adhering to both sides of the strip. The degreasing and pickling process are followed by a cooling stage, which ensures the metal is at the desired temperature before the cold reduction takes place.

The material is then cooled and tempered to form a harder, tougher metal. In this phase, the sulphur content is reduced as much as possible, since it reduces ductility and increases corrosion resistance. Silicon, however, must not be removed as it hardens and increases the risk of acid corrosion. Manganese, on the other hand, counteracts these effects and is therefore present in tinplate, although it must also be kept to a minimum, as it influences ductility and surface quality. Finally, phosphorus is added, which prevents the formation of rust in tinplate, but must also be limited as it has an effect on ductility and on the mechanical properties of the metal.

Properties

A tinplate coil is a steel strip that is coated with commercial pure tin on both sides. It combines the strength and formability of steel with the corrosion resistance, weldability and aesthetics of tin. It also prevents rust and oxidation. It can be made on acid or alkaline electrolytic lines. The main difference between the two is that acid lines have a non-corrosive electrolyte and a simpler and cheaper preparatory section. However, they have a lower current density for tin plating.

The black sheet coil passes through several operations on the tinplate line, which prepare it for tinning. These include degreasing, washing and pickling to remove the iron oxide adhered to the metal. The next step is the electrolytic tin depositing process, followed by a hot dip coating and passivation treatment. The tinplate is then ready for packaging.

The tinplate coil is then rolled to reduce its thickness and make it more uniform. Rolling can be done either continuously or in batches, and it can cause a recrystallization of the metal. This is called annealing. It can take place in continuous annealing furnaces or in base (or bell) annealing furnaces. The former produces fine equiaxed grains and isotropic material, which leads to better mechanical properties such as a higher elastic limit.

The last stage is temper rolling, which makes the steel tough and allows it to be bent without tearing. This operation is optional. It can be replaced by a second gauge reduction, known as skin-passing. This step is used to eliminate poor quality or pin hole sheets from the tinplate.

Applications

Tinplate coil has a wide range of applications, from food packaging to musical instruments. It is also used in electronics because it has excellent malleability and ductility. In addition, tinplate is extremely durable and resists corrosion and temperature change. Its high resistance to corrosion and abrasion make it ideal for creating the outer shell of battery cases.

During the electrolytic tinplate process, black sheet coil passes through tanks containing tin anodes and an electrolyte. As electric current flows between the anodes, tin dissolves from the anode and deposits on the strip. The amount of tin depositied is controlled by the strength of the current and the current setting. This allows for the tin plate to be coated with different amounts of tin.

Once the steel substrate is coated with tin, it undergoes temper rolling. This process tempers the tinplate by rolling it hot to create a smooth surface that is easy to fabricate and has good mechanical properties. The tinplate can be tempered either continuously or in bell-type furnaces.

The tinplate is then ready for cold-reduction. It is rolled to a thinner thickness using either continuous or reversible mills. It is then annealed in a protective atmosphere to ensure it can be used for metal packaging applications. The tinplate can be annealed in two ways: CA-continuous annealing, or BA-box annealing.

Packaging

Tinplate has a unique position in the market as a packaging material. This is because of its ductility and aesthetics. It is also non-toxic and corrosion resistant. Moreover, it can be easily shaped and printed to meet specific packaging requirements.

Tin plate is made up of thin-gauge flat carbon steels, with tin or chromium coated on both sides. This particular combination gives tinplate its properties: strength and stiffness, formability, welding ability, lacquer ability and printability, good cosmetic appearance and corrosion resistance.

Typically, tinplate is passivated to stabilize its surface and prevent the growth of tin oxides. This helps improve the quality of finished products and the performance of the tin coating, Hardened & Tempered Steel Strip Supplier particularly in terms of corrosion resistance. Our range of tinplate passivation chemicals includes both chrome-based and chrome-free formulations, from single-component liquid cleaners to sophisticated systems where surfactants are dosed separately to boost cleaning efficiency on demand.

Henkel’s solutions are also used to remove residues such as oil and iron, which may interfere with the tin plating process. We offer a wide range of strong alkaline cleaners for this purpose, which are suitable for use in both hot and cold rolling mills. Our portfolio also includes products to enhance the performance of tinplate in applications such as aerosol and paint drums. Our range of anti-corrosion additives is ideal for use in the tinplate industry.