Product Introduction
Tin Free Steel Food Packaging means Tin Free Steel products are used for food packaging. The raw material food grade Tin Free Steel is one type of Tin Free Steel Coil for Packaging. Food grade Tin Free Steel (TFS) is produced by applying electrolytic chromic acid treatment over steel sheets. Tin Free Steel (TFS) product was developed to meet economic requirements, and excels tinplate in paintability, paint adhesion, and economy. It is widely used in replacement of electrolytic tinplate (ETP) in market segments not requiring welding, such as for food packaging: metal closures and ends, DRD cans and cemented seam cans.
Product Feature and Application
①Excellent paint adhesion: Tin Free Steel (TFS) has excellent paint adhesion properties that far surpass those of ETP, and the corrosion resistance of coated TFS is almost the same as that of ETP;
②Excellent heat resistance: High-temperature baking of Tin Free Steel (TFS) causes neither discoloration nor deterioration in material properties.
③Excellent resistance to sulphur blackening: The metallic chromium in Tin Free Steel (TFS) has excellent sulphide resistance when canning protein-rich foodstuff, whereas ETP requires expensive sulphur resistant lacquer;
④Excellent filiform rust resistance: Tin Free Steel (TFS) has excellent under film corrosion resistance, which is superior to that of ETP;
⑤Excellent alkali resistance: The chromium coating in Tin Free Steel (TFS) is not amphoteric, making TFS a preferred choice for packing alkaline products such as detergents and pigment dispersants.
Product Details
Any product manufactured using food-grade Tin Free Steel for Food Packaging purposes falls under the category of Tin Free Steel Food Packaging. For example: raw material -- Food Grade Tin Free Steel; Finished Products -- DRD Cans, Twist-off Caps, Can Lids.
As one type of TFS Food Packaging, food grade Tin Free Steel (TFS) is composed of four layers, including steel base, metallic chromium layer, chromium oxide layer and oil film, as shown below.
Function of Each Layer of TFS
①The role of steel base is similar to that of ETP, which ensures the formability of TFS usage and machining and provides strength of finished products;
②Metallic chromium layer has strong passivation capability and good corrosion resistance, but as it is cathodic coating, it can only provide mechanical protection for steel base. Besides, due to strong passivation capability of metallic chromium, an extremely thin layer of passivation film is easy to produce (chromium oxide);
③Chromium oxide layer has relatively high chemical stability, and the electrode potential of the film is more positive than that of iron. When surrounded by ordinary corrosive media, it is cathodic coating, requiring coating to protect the contents. As an amorphous layer, the layer can close pores of the metallic chromium layer and provide excellent coating adhesion;
④The role of the oil film is similar to that of ETP, and its lubrication is better than that of ETP, for tin itself is of lubricity.
Deliver, Shipping and Serving
①Offers coils and sheets, coil packed in a vertical form or a horizontal.
②A label that indicates the manufacturing history is affixed to the outside of the packaging. In addition, a service card is contained inside.
③With regard to types of packing and markings, please consult us.
FAQ
Q: What are electrolytic tinplate and Tin Free Steel's parameters inspected?
A: Mechanical Properties - Hardness (temper grade).
Dimensional Accuracy - Thickness, Width and Cut-length.
Lubrication - Oil film.
Corrosion Resistant Property - Tin coating (for Tinplate), Metallic chromium and chromium in Cr-oxide (for TFS), Passivization film weight, Alloy-tin Couple (for required), Iron solution value (for required), Tin grain size (for required), Corrosion resistance SO2 test (for required), Porosity Test (for required), Pickling lag value (for required).
Q: What are different features between Tin Free Steel and Electrolytic Tinplate?
A: Appearance - Even when the same surface finish as electrolytic tinplate is applied to the substrate steel sheet, it provides the unique surface luster characteristic of metallic chromium.
Corrosion resistance - As it has excellent corrosion resistance after painting, it is generally used with both surfaces painted. It can also be used with the internal surface unpainted, depending on the contents.
Solder-ability - Tin Free Steel is not compatible with soldering.
Weld-ability - Although Tin Free Steel can be welded when the metallic coating layers are removed, its weld-ability is inferior to electrolytic tinplate.
Coating weights - Unlike the multiplicity of coating weights with tin, only one standardized chromium-coated product is manufactured.
Q: What is available surface finishes of Electrolytic Tinplate and Tin Free Steel?
A: Bright surface (B) - Glazed surface obtained after melting treatment of electro tinned smooth raw material strip with extremely fine stone figures by processing.
Stone surface (R) - Glazed surface obtained after melting treatment of electro-tinned raw material strip featuring certain oriented stone figures.
Stone rough surface (R2) - Glazed surface obtained after melting treatment of electro-tinned raw material strip featuring certain oriented stone figures, roughness higher than "R".
Silver surface (S) - Glazed surface obtained after melting treatment of electro-tinned raw material strip with rough matt surface.
Silver rough surface (S2) - Glazed surface obtained after melting treatment of electro-tinned raw material strip with rough matt surface, roughness higher than "S".
Matte surface (M) - Matt surface of general matt raw material strip without reflowing treatment.
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Product Manufactured Process
Tin Free Steel Food Packaging's raw material - food grade TFS line adopts the two-step process, the major steps of which include:
Uncoiling → Alkaline cleaning → Straightening → Pickling → Metallic chromium plating → Chromium oxide plating → Oiling → Side cutting → Quality inspection → Coiling
