Analysis of the causes of hard chrome plating pinholes in die-Dongguan Fenggang Mingzhi Hard Chrome Electroplating Factory

**Reasons for the Formation of Hard Chrome Plated Pinholes in Molds** Hard chrome plating is widely used in molds due to its high hardness, wear resistance, and corrosion resistance. However, one common issue during the plating process is the formation of pinholes—tiny holes that extend from the surface of the coating down to the base metal. These pinholes can significantly affect the quality and performance of the final product. The primary cause of pinholes is the presence of gas, particularly hydrogen, which becomes trapped on the surface of the workpiece during electroplating. This gas prevents the even deposition of chromium, leading to small voids or holes in the coating. In addition, pinholes can also result from imperfections in the base material, such as pits or cracks, which may not be properly covered by the chrome layer. There are several key factors that contribute to the formation of pinholes: 1. **Non-uniform Metallographic Structure or Residual Stress**: If the base material has an uneven microstructure or residual internal stresses, it may not allow proper chromium adhesion. As a result, some areas remain uncoated, forming pinholes. These defects often appear as irregularly distributed cracks or gaps in the coating. 2. **Oil or Contaminants on the Surface**: Any oil or grease left on the surface of the part before plating can interfere with the electrical conductivity. Areas with poor conductivity prevent the deposition of chromium, allowing gas bubbles to accumulate and form pinholes. These pinholes tend to be clustered and irregular in shape. 3. **Rust on the Base Material**: Especially in humid conditions like summer, rust can develop on the surface of the plated parts. Rust is non-conductive and can create localized areas where chromium cannot deposit, leading to pinholes. It is essential to thoroughly clean and prepare the surface before plating. 4. **High Sulfate Content in the Electrolyte**: Excessive sulfate in the plating solution can increase the concentration of trivalent chromium, which promotes the formation of basic chromate on the cathode. This leads to a deterioration of the plating quality, increasing the likelihood of pinholes. 5. **Surface Roughness or Scratches**: A rough or damaged surface can lead to hydrogen evolution during plating. When hydrogen accumulates as bubbles on the cathode, it creates an insulating layer that prevents metal ions from being deposited in those areas. If the bubbles remain trapped, they result in pinholes in the finished coating. 6. **Impurities in the Plating Solution**: The presence of particulate impurities, iron contamination, or excessive oil in the electrolyte can reduce the quality of the plating. High viscosity and poor fluidity of the solution make it difficult for gases to escape, increasing the risk of pinhole formation. In conclusion, the formation of pinholes in hard chrome plating is a complex issue influenced by multiple factors, including the condition of the base material, surface preparation, and the composition of the plating solution. Proper maintenance, cleaning, and control of the plating process are essential to minimize these defects and ensure a high-quality finish. **Information Sources:** Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn

Solenoid Coil Hole Diameter 9mm

The category of solenoid coil which hole diameter is around 9mm. Possible applications are solenoid valves like Dust Collector Pulse Valve, refrigeration valve, Pneumatic Valve, hydraulic valve, LPG CNG valve, automobile valve, injector rail, home appliance Solenoid Valve, and so on.

9mm Hole Solenoid Coil, Solenoid Coil DC24V, Solenoid Coil AC220V, Solenoid Coil AC110V

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