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 mold manufacturing to improve surface hardness and wear resistance. However, pinholes—tiny defects that penetrate from the coating surface to the underlying metal—can occur during the process. These pinholes are often caused by trapped gases, particularly hydrogen, which remain on the surface of the part being plated. In addition to gas entrapment, pinholes can also result from imperfections in the base material, such as pits or irregularities, making the root cause more complex and multifaceted. 1. **Non-uniform Metallographic Structure or Residual Internal Stress** If the base material has an uneven microstructure or unrelieved internal stress, it may not be properly coated with chromium. This leads to areas where the coating cracks or fails, resulting in irregularly distributed pinholes. These issues often appear after the plating process and can significantly affect the quality of the finished product. 2. **Improper Surface Cleaning** Oil or grease left on the surface of the part before plating can prevent proper conductivity. At these contaminated areas, the electroplating process is disrupted, allowing gas to accumulate and form pinholes. The pinholes created this way tend to be localized and irregular in pattern. 3. **Rust on the Base Material** If the part is already rusted before plating, especially in humid conditions like summer, the rust can act as an insulator. This prevents proper deposition of chromium, leading to pinholes. Rust removal is critical to ensure a smooth and defect-free plating layer. 4. **High Sulfate Content in the Electrolyte** Excessive sulfate in the plating solution can increase the concentration of trivalent chromium, promoting the formation of basic chromate on the cathode. This reduces the quality of the chrome layer and increases the likelihood of pinholes forming. 5. **Hydrogen Evolution on Rough Surfaces** When the surface is rough or scratched, hydrogen tends to evolve more easily during plating. Once deposited, hydrogen forms bubbles on the electrode surface, creating insulation that prevents metal ions from depositing in those areas. If the bubbles remain trapped, they lead to pinholes in the final coating. 6. **Contamination in the Plating Solution** Particulate impurities, iron contamination, or excessive oil content in the plating bath can interfere with the plating process. Poor fluidity and high viscosity of the solution make it difficult for gases to escape, increasing the risk of pinhole formation. Additionally, suspended particles can adhere to the part’s surface, further contributing to defects. To minimize pinholes, it's essential to maintain clean surfaces, control the plating solution composition, and ensure proper pre-treatment of the base material. Regular inspection and maintenance of the plating system can also help reduce the occurrence of such defects. **Information Sources:** Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn

Solenoid Coil Hole Diameter 8mm Below

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