How to improve the adhesion during electroplating of aluminum alloy die-cast parts?
To improve the performance of aluminum alloy die-cast parts, it’s essential to address surface roughness. The methods used should target the factors that affect the roughness of the cast surface. So how can surface roughness issues in aluminum alloy die-cast parts be effectively handled?
1. Use fine-grain refractory sand with high refractoriness
Select high-quality sand that can withstand high temperatures and contributes to a smoother surface finish.
2. When using reclaimed sand, remove overly fine particles, burnt clay, ash, metal oxides, scrap metal, iron-coated sand, and other harmful impurities
This helps improve the quality of the recycled sand. Regularly add a proper amount of new sand to maintain consistency.
3. Strictly control the moisture content in green sand
Water is a strong oxidizing agent. Add appropriate amounts of carbonaceous materials such as coal powder, asphalt, or hydrocarbons to create a reducing atmosphere in the mold. However, when using high-pressure molding, the amount of carbonaceous material should be reduced to limit gas generation.
4. Reduce pouring temperature, pouring speed, and pouring height appropriately
Also reduce the height of the cope (upper mold) and the pouring cup to minimize dynamic and static pressure as well as thermal shock on the mold.
5. Enhance the refining of high-melting-point alloys like cast steel
Purify the molten metal to reduce oxidation and gas absorption. Lower the content of elements that form low-melting phases (e.g., sulfur and phosphorus in cast steel or cast iron, phosphorus and lead in bronze). Control elements that lower surface tension and increase vapor pressure of the melt (e.g., manganese and silicon in cast iron and cast steel, lead in bronze).
6. For large and thick-walled aluminum die-cast parts, open the mold earlier
This speeds up cooling and helps prevent solid-state sand adhesion.
7. Use patterns and core boxes with smooth surfaces
This directly improves the surface finish of the final cast.
Surface roughness greatly affects the usability of aluminum alloy die-cast parts. Therefore, it’s crucial to promptly address the influencing factors during the casting process to ensure both the quality and performance of the final product.