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What is the cause of the yellowing of the coating of precision automobile stamping parts?

The residual potion and additives in the precision stamping parts are spit out, and the tin layer attached by electroplating is easily corroded by these substances. Causes surface oxidation, resulting in yellowing of the coating.

Inadequate treatment and unbaked workpieces can also lead to yellowing of the coating.

The adhesion of tetravalent tin, excessive additives, zinc impurity contamination in the plating bath (less likely), insufficient coating thickness, iron impurity contamination (phenomenon is not easy to find during electroplating), storage environment. These are all causes of yellowing of precision metal stamping parts.

Die is an indispensable process equipment in stamping fabrication, which plays an important role in product quality, prolonging product life and production efficiency. Due to the frequent wear and tear of the mold during the production process, the working size is lost, and it is difficult to meet the production demand. Therefore, it is very important to improve the durability of the mold.

The surface treatment of automobile stamping parts refers to the process of forming a covering layer on the surface of the workpiece by a certain method. The main purpose is to make the surface of the workpiece beautiful, anti-corrosion effect, etc. The surface treatment methods are as follows.

Electroplating: The part to be electroplated is immersed in an aqueous solution containing the metal compound to be deposited, and an electric current is passed through the plating solution to precipitate and deposit the electroplated metal on the part. General electroplating has galvanized, copper, nickel, chromium, copper-nickel alloy and so on.

Oxidation treatment: It can be divided into chemical oxidation and anodic oxidation.

Passivation treatment: pure iron and pure aluminum react in concentrated sulfuric acid or concentrated nitric acid, and the atoms on the surface react with the acid to produce a dense oxide film, which prevents the internal substances from continuing to react with the concentrated acid to achieve a protective effect.

Electrophoresis: Paint is plated on the surface of the material under the action of an external current. It is characterized by rich colors, but poor adhesion, and it is difficult to control the uniform color.

Mechanical plating: The particles of the coated metal impact the surface of the product, and the coating is cold welded to the surface of the precision stamping part.

The methods to improve the durability of the mold generally include the following:

Improve the design of the stamping die, correctly select the stamping die material, reasonably carry out the forging and heat treatment of the stamping die parts, reasonably arrange the stamping die manufacturing process and ensure the machining accuracy, correctly select the press, and reasonably use and maintain the stamping die.

The above are a few tips commonly used to improve the wear resistance of precision stamping dies. The improvement of wear resistance can not only prolong the service life of the mold, but also reduce the production cost of the mold, and also ensure the quality of the manufactured products and improve the production efficiency.

Automotive Sheet Metal Fabrication

Pintejin Sheet Metal shop offers a cost-effective solution for a wide range of industries with our custom metal stamping and custom sheet metal fabrication capabilities. Our stampnig operations include a variety of sheet-metal forming manufacturing processes, such as punching, blanking, embossing, bending, flanging, and coining. Our professional, experienced and well-trained engineers can execute the complex metal stamping operations with precision and accuracy.

No matter what your metal fabrication needs are, Pintejin can offer the right solution: from single sheet metal part or sub-assembly of stamped metal parts to turnkey solutions for mechanical and electrical assemblies. We have the technology, equipment and the experience to fabricate customised metal products from aluminium sheet metal fabrication, steel, zinc plated steel, stainless steel sheet metal fabrication, brass and copper. Designs that require CNC machining of surfaces or components can be accommodated. We can supply polished, galvanized, zinc coated or powder coated finishes for any sheet metal work or stamped metal components. Coupled with our accurate and reliable metal fabricating equipment, we guarantee precision and repeatability in custom sheet metal work. You’ll be taking advantage of the best sheet metal fabrication china can produce.


With Pintejin automated and highly streamlined sheet metal fabrication service, you can expect a sheet metal fabrication quote within 12 hours and lead times as quickly as three days.Our rapid prototyping offering also includes a solid and reliable manufacturing capability (led by our expert team with 15+ years of experience) and technical and quality assurance, including SGS and RoHS material certifications, in-process quality reports, and First Article Inspection.



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