Electro Tinning / Tin Free Steel

The tinning line is the most complex and sophisticated strip processing line, incorporating the following processes in sequence: dip/spray cleaning, electrolytic cleaning, pickling, TFS plating (first and second steps, plus rinse and drag out), tin plating (plus rinse/drag out and flux), tin reflow, chemical treatment, and oiling. Modern lines also include side trimming and tension leveling.

In the most advanced lines, tin plating is performed using insoluble anode technology, where tin dissolution occurs in special plants. Tenova has successfully addressed the high sludge generation issue that afflicted previous lines. With Tenova's tin dissolution technology, sludge generation is comparable to lines using soluble tin anodes.

Tenova has developed a new low-sludge tin dissolution process for insoluble anode technology, minimizing sludge production and tin loss. Other benefits include reduced manpower for anode handling, increased operational safety, improved coating quality, better process control, more flexible campaigns, and the ability to achieve the lowest tin coating thickness on the strip.

Insoluble anodes have a fixed width. To process strips of different widths, edge masks are used to prevent "white border defects." Tenova's edge mask design ensures easy inspection and access to the cell for maintenance and operational activities.

For certain applications, tin plate can be replaced by Tin Free Steel (TFS) or Electrolytic Chromium Coated Steel (ECCS). TFS can be produced either in the same tinning line (with dedicated additional plating tanks) or in a separate line for high production volumes. Tenova supplies both high-technology tinning and TFS lines, either single or combined.

In ETL lines, conventional chemical treatment (ASTM #300 or #311) using hexavalent chromium will soon be prohibited in Europe and worldwide due to occupational health and safety concerns. Tenova provides equipment for alternative Cr-free passivation, having developed its own process know-how (including Tenova EPZ for zirconium precipitation and Henkel Bonderite® coating) to meet the needs of customers requiring Cr-free passivation for revamping existing lines or new lines.

With the proper coater and drying system, both developed internally, Tenova supplies titanium/zirconium Cr-free passivation sections to produce passivated products named 505 and 555 as per the latest revision of EN 10202.