What is TFS and Its Uses
What is TFS (ECCS)
The development of tin free steel is due to decreasing tin resource and the upward price trend for this material. The steel has a electrolytic coating of chromium and oils which are applied in the rolling mill.
The chrome layer acts as corrosion barrier. The oxide layer recues chrome surface oxidation and covers discontinuities in the surface. The Chromium coating process was developed in Japan and one version, known as Hi-Top was made in the United Kingdom.
The cost of tin-free steel is lower than of tinplate, but is increased by the necessity for lacquer coating.
It may be noted that the substrate used for TFS (ECCS) is the same as Tinplate. The steel types can be MR, L, SPCC and the tempers can be ordered similar to Tinplate. The mechanical properties of ordered TFS match that of equivalent tinplates, it is just the coating that is different from Tinplate. However, unlike tinplate where differential tin coating can be ordered for the top and the bottom surface, the chromium coating is equal on both sides in TFS (ECCS)
Redbull TFS can
TFS (ECCS) is the most common alternative to tinplate for food contact applications is ECCS (electrolytic chromium/chromium oxide coated steel The function of a chromium coating not only prevent atmospheric oxidation or but also prevents Sulphur staining of the steel by foodstuffs.
Chromium coating also improve lacquer adhesion. TFS (ECCS) must be lacquered on both surfaces because it shows poorer resistant to corrosion in acidic medium. ECCS is always used with an additional organic coating (i.e. can coating
The surface of TFS ( ECCS) is thin, hard and sensitive to scratches. ECCS without protective coating cannot be used for food cans as hydrogen swell occur after 3 months storage. For toxicological reasons, the US Food and Drug Administration require that the inside of TFS-CCO be lacquered.
The adhesion of lacquer to TFS-CCO is very good compared to tin-plate steel. It is said to be 10 times better, however, TFS is not compatible with soldering. Although TFS can be welded when the metallic coating layers are removed, its weldability is inferior to Tinplate.
Usage of TFS (ECCS)
Tin free steel is used mainly for those applications where tin is not required as a sacrificial element. It has the following applications