Due to the customization requirements of non-standard metal stamping parts, the corrosion resistance of their surface treatment directly impacts product lifespan and reliability. Different materials require specific processes to form a stable protective layer that isolates them from corrosive media. For example, ferrous metal stamping parts (such as steel and cast iron) are often treated with galvanizing. This electrolytically deposits a zinc layer on the surface. The active nature of zinc causes it to oxidize preferentially, thus protecting the base material from rust. Aluminum alloy stamping parts, on the other hand, rely on anodizing technology to form a dense oxide film in an electrolyte, significantly improving corrosion resistance, wear resistance, and insulation properties. This makes them particularly suitable for applications with high environmental adaptability requirements, such as electronic device casings.
The corrosion resistance of non-standard stainless steel stamping parts primarily depends on the stability of the passivation film. Surface treatment processes such as passivation or chromium electroplating create a dense oxide film on the surface through chemical or electrochemical methods, effectively isolating corrosive media such as water, oxygen, and acids and alkalis. If the passivation film is locally damaged, the exposed metal and the intact film will form a corrosion cell, accelerating localized corrosion. Therefore, the process must ensure uniform film adhesion and strong adhesion. For example, after passivation treatment, 304 stainless steel stamping parts form a stable oxide film on their surface, maintaining a low corrosion rate even in humid environments. However, 201 stainless steel stamping parts require sandblasting or brushing to remove surface defects and increase oxide film coverage to enhance corrosion resistance.
Surface treatment also improves the corrosion resistance of non-standard metal stamping parts by improving surface finish and flatness. Sandblasting uses high-speed abrasive jets to remove burrs and protrusions on the stamped part, creating a matte finish and increasing surface roughness, providing a good base for subsequent anodizing or painting. Polishing mechanically or chemically reduces surface roughness, eliminating microcracks and defects, and reducing points of adhesion for corrosive media. For example, aluminum alloy stampings that are sandblasted and then anodized produce an oxide film with uniform thickness and color, significantly improving corrosion resistance compared to untreated parts. High-precision mechanical parts, on the other hand, can be polished and then chrome-plated to achieve a mirror-like finish, effectively resisting environmental corrosion such as salt spray and humidity.
The blackening process is suitable for non-standard steel stampings that do not require high wear resistance, such as equipment gears and sprockets. This process uses chemical or electrochemical methods to create a black oxide film on the surface. It is low-cost, simple, and does not affect the dimensional accuracy of the part. The oxide film formed by this process isolates air and moisture, delaying the onset of rust while also enhancing the appearance and quality. For example, non-standard steel stampings used in agricultural machinery can remain rust-free for years in the humid environment of the field after blackening, significantly reducing maintenance costs.
While knurling and brushing processes do not directly form a protective layer, they indirectly improve corrosion resistance by modifying the surface morphology. Knurling creates a pattern on the surface of the stamped part, increasing the friction coefficient and preventing slippage during operation. It also reduces surface flatness and reduces the adhesion of corrosive media. The brushing process removes fine surface scratches through mechanical friction, creating a non-mirror metallic luster that conceals imperfections that develop during use and maintains a clean appearance. For example, brushed stainless steel tool handles are less likely to show surface scratches, and less corrosive media remain during cleaning, resulting in improved long-term corrosion resistance.
The surface treatment process for non-standard metal stamping parts must be carefully selected based on the material, usage environment, and performance requirements. Processes such as electroplating, anodizing, and passivation directly enhance corrosion resistance by forming a protective layer; sandblasting and polishing indirectly enhance corrosion resistance by improving surface quality; and processes such as blackening, knurling, and brushing meet specific application requirements through cost optimization and functional adaptation. Appropriate application of these processes can significantly extend the service life of non-standard metal stamping parts, reduce the risk of failure due to corrosion, and ensure stable equipment operation.
