Introduction to metal etching pretreatment

Introduction to metal etching pretreatment

Metal surface pretreatment refers to the pre-processing of metal materials before etching.The aim is to provide a reference for the metal material with a consistent surface state on which subsequent processing can be carried out.The quality of pretreatment will directly affect the quality of etching.What is outstanding is the adhesion relationship between the surface of the workpiece and the anti-corrosion layer after pretreatment. Only the workpiece after good pretreatment can produce the anti-corrosion layer to meet the etching requirements.At the same time, pretreatment is also the process of metal etching, only a good beginning will have satisfactory results.

1. Remove oil from surface

Metal workpiece after processing, transportation and inventory, surface stained with different processing oil or antirust oil and so on, thoroughly clean, otherwise when besmear brushs corrosion resistant paint, paint and etching the metal parts of the adhesion is bad, paint film immerse in etching solution will bubble or break, make without etching the surface of the corrosion damage.In addition, if the oil stains on the surface of the parts that need to be etched are not clean, the oil stains will affect the contact between the etching solution and the metal, so that the partial solution of the etching is not evenly dissolved, and the effect and quality of the metal etching will be affected if some parts cannot be dissolved.The method of oil removal can be selected according to the situation of surface oil removal method. 

2. Surface derusting and film removal

Rust and oil are common in the metal surface dirt, this is because the metal surface in the processing, transportation or storage process and air oxygen, sulfur, moisture contact, easy to produce oxide film or rust layer.If the rust or film is not cleaned thoroughly before etching, the etching effect and quality will be affected.The quality of the protective layer that does not need to be etched is not guaranteed, and the surface of the etched part cannot fully contact the etched solution due to the obstruction of oxide film, which affects the speed of metal dissolution and the uniformity of the etched surface.If the metal etching surface has thick rust or thick oxide film, remove by acid etching or lye immersion.Electrolytic method is more thorough derusting, can choose according to the situation.In the case of thin film or rust layer, weak etching or brief electrolytic etching may be considered. 

3. Surface polishing

The finish on the surface of a metal etching etching is larger, the influence of rough surface, without etching part coating corrosion resistant rubber is very difficult to clean, need to etch area due to the rough surface, etching notch is rough, so before etching, metal surface to be polished, can according to the situation and the requirements of the product, the polishing solution and the method to choose. 

4. Apply anti-corrosion protection layer

Etched metal decorative parts are generally etched part and do not need to be etched part.For example, to etch a metal plaque with text, if the text needs to protrude, the glyph of the text should be protected by corrosion protection paint, which can dissolve the part without text.If you want to carve the text on a metal plate, the text is concave.Then the font should be exposed, the non-text parts with corrosion protection layer protection, and then into the etching solution etching.

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