Production of Tin Plates and Tin Free Steel Oct04

Production of Tin Plates and Tin Free Steel...

Production of Tin Plates and Tin Free Steel  Tin coating is the process of thinly coating sheets of steel with tin (Sn), and the resulting product is known as tinplate. It is most often used to prevent rust. The sheet of steel on which the tin coating is done is known as black plate. When chromium (Cr) and chromium oxides is used for coating in place of tin then the coated sheet is known as tin free steel. Tin free steel is produced by applying electrolytic chromic acid treatment over steel sheets. On tin free steel sometimes polyethylene terephthalate (PET) or polypropylene films are laminated in order to eliminate the painting and cleaning processes when using tin free steel. History The tinplate industry is founded on the invention of the process of preserving sterilized food for long periods of time by Nicolas Appert in 1810. The Appert process was adapted to the preservation of food in tinplate containers by John Hall in 1812 in London. By the 1820s, canned foods were widely sold in UK and France, and by 1839, foods were being canned in the USA. Starting in the 1880s, a series of technical innovations which took place has transformed the tinplate industry. These included the replacement of wrought iron with steel black plate in about 1880, the development of continuous cold reduction in 1927 that eliminated hot pack rolling, the introduction of continuous electro tinning on a small scale in Germany in 1934 and on a commercial scale in the USA in 1937 which replaced the hot dip process, the invention of double cold reduction in 1960, and the invention of tin free steel in the early 1960s in Japan and the USA. Presently there are two processes for the tinning of the black plates namely...

Tin Free Steel

Tin Free Steel Tin free steel (TFS) is an electrolytic chrome plated steel consisting of a thin layer of chromium and a layer of chromium oxide deposited on a cold rolled steel base (black plate steel) which gives it a beautiful, lustrous metallic finish on both sides. It is also known as electrolytic chromium coated steel (ECCS). TFS offers outstanding corrosion resistance, lacquer adhesion as well as printability. It is an economical and high quality replacement for tinplate. It is not suitable for soldering and can only be used for welding after edge cleaning. ECCS must be lacquered on both surfaces. TFS has been developed to meet economic requirements, and excels tinplate in paintability, paint adhesion and economy. It is widely used for making beverage can and 18 litre cans. It is also used for making photographic film cases and as a protective material for optical fiber cables. The cross section of tin free coating on steel sheet is given in Fig 1. Fig 1 Cross section of tin free coating on steel sheet Features of tin free steel  The main features of tin free steel are given below: Paint adhesion – TFS has excellent paint adhesion properties which is far better than those of tinplate. The external surfaces of cans should be painted to prevent corrosion. The internal surfaces should also be painted to prevent corrosion except when the content is motor oil or cooking oil. Heat resistance – High temperature baking (around 400 deg C) causes neither discoloration nor deterioration in material properties in TFS steel. Resistance to black sulphide stain – TFS steel has excellent resistance to black sulphide stain. Due to it TFS is the most suitable material or making fish cans. Appearance – TFS steel provides the unique surface luster characteristic of metallic chromium even...