Tinplate Steel Coil

Tinplate Steel Coil

Tinplate is a general term for electrolytically coated low-carbon steel that is used in metal packaging. It has excellent formability, weldability and corrosion resistance.

The tin plate is cold-rolled to the required gauge and annealed. The tin plate is divided into two groups according to the annealing method: CA – continuous annealing, and BA – box annealing.

Corrosion Resistance

Tinplate Steel Coil has a beautiful metallic luster and excellent properties in corrosion resistance, solderability and weldability. It is widely used in making all kinds of cans including food, beverage and artistic cans that are essential to our daily life.

The tinplate production process is divided into several steps: rolling, tempering, surface treatment and tinning. The rolling is done either in a continuous (tandem) or reversible mill. This is followed by cold rolling, a process that reduces the thickness of the sheet to the final desired gauge with lubricants and cooling agents. Finally, the rolled steel is cold annealed. This can be done continuously in CA-type annealers or in bell-type furnaces depending on the type of tinplate to be produced:

The black plate is then degreased and washed. This removes lubricant residue and other contaminants from the steel surface. The degreasing can be performed in liquid or dry form. Afterwards, the plate is pickled to remove any residual iron oxide that remains on the surface of the metal. The tinplate is then plated with a thin layer of tin. This can be done in a horizontal line using alkaline or acidic electroplating baths. The acidic plating uses sodium Tinplate Steel Coil stannate as the electrolyte, and has high current density and production speed, while the alkaline process is performed at lower speeds with sodium sulfate as the electrolyte.

Good Weldability

Tinplate steel is known for its good weldability, a necessary property to make the cans used for food products. The process of welding tinplate involves using a filler metal that has a lower melting point than the parent metal. This allows the parent metal to be melted into and mixed with the filler, but doesn’t melt and dissolve the entire surface of the steel. The result is a strong weld that doesn’t contaminate the food.

Before welding, the tinplate is cleaned by a series of steps: degreasing and pickling. The degreasing step removes lubricant residues, cooling agents, and other elements that might contaminate the weld. The picking operation removes the iron oxide that adhered to the tinplate before it was welded.

After degreasing and picking, the tinplate is wetted and rinsed to remove any remaining chemicals. It is then dried and lubricated with palm oil. Finally, it is rolled to the desired gauge.

The tinplate can be made by rolling the black steel plate on a continuous hot strip mill or at a sheet mill that uses semi-continuous and then continuous processes. The steel can be rolled to a smaller thickness, which increases its formability. The tinplate can be formed into various shapes to accommodate different uses. These can include beverage cans, food containers, and decorative items.

Good Solderability

Tinplate Steel Coil combines strength, corrosive resistance, light weight and malleability to make it ideal for many precision end uses. It is manufactured in a wide range Tinplate Steel Coil / Sheet of gauges, coating weights and tempers. The tin coating acts as a barrier to prevent water and air from corroding the steel substrate. The alloy layer bonds the steel to the free tin. The tin is also non-toxic, which makes it ideal for use in food packaging.

The tin plating process begins with black plate that has been rolled to a specified thickness in hot strip mills. This is then cold rolled to achieve the desired base width, normally on continuous or reversible mills. The resulting tinplate is known as plain or reduced tinplate and is usually pickled, then washed and lubricated with palm oil before cold rolling again.

During the final stage of cold reduction, a thin surface treatment is applied that gives a “skin-pass.” This gives a smooth finish and induces ductility in the material. It can also be used to eliminate poor quality or out-of-spec sections.

The skin-pass can also be used to add corrosion resistance or enhance mechanical properties, depending on the application. For example, a tin-lead coating provides excellent solderability and is often used to manufacture containers for liquids and foods. However, the solderability of tinplate is perishable and can diminish with age. Proper deposit specification, substrate preparation and the correct handling of plated components can extend the solderability of tinplate products.

Good Printability

The tin layer in tinplate protects the steel from corrosion and provides a good base for printing. In addition, tinplate is highly recyclable, which makes it an attractive choice for packaging. It also has excellent formability, making it suitable for various types of cans. It is available with both surfaces painted or unpainted, depending on the type of container contents. The paintability and printability of tinplate ensure that the containers can be decorated with high-quality images.

Tinplate is made of cold reduced mild steel and coated with commercially pure tin on both sides. It combines the strength and formability of steel with the corrosion resistance, weldability, and aesthetics of tin. It is used in metal packaging products such as food and beverage cans, aerosol cans, and paint drums.

Henkel’s portfolio of strong alkaline cleaners help to keep the tin plate in top condition for the tinning process. The cleaners clean the black plate thoroughly and remove any impurities that would affect the quality of the finished tin coating.

The tinplate production process begins with the preparation of black steel strips, which can be done through continuous or reversible rolling mills. These are then cold reduced, either in tandem or single-reduction, to reach an intermediate gauge. This step can be referred to as “skin-pass” as it is carried out without lubricants. The next step is a tempering operation that induces ductility and improves the shape of the steel strip. The final stage is a tinning operation that increases the thickness of the tin layer to meet customer specifications.