Analysis of Common Defects in Zinc Alloy Die Castings

1. Patterns and metal flow traces on the surface of zinc alloy die castings Causes:

1. The runner leading to the inlet of the casting is too shallow.

2. The injection specific pressure is too high, resulting in excessively high metal flow velocity and causing splashing of the molten metal.

Adjustment methods:

1. Deepen the gate runner.

2. Reduce the injection specific pressure.　　

2. Fine protrusions on the surface of zinc alloy die castings Causes:

1. Rough surface.

2. Scratches, pits or cracks occur on the inner surface of the cavity.

Adjustment methods:

1. Polish the cavity.

2. Replace the cavity or repair it.　　

3. Ejector pin marks on the casting surface, with uneven and rough surface Causes:

1. The ejector pin (knockout pin) is too long;

2. The cavity surface is rough, or there are impurities.

Adjustment methods:

1. Adjust the length of the ejector pin.

2. Polish the cavity and remove impurities and oil stains.　　

4. Cracks or local deformation on the surface of zinc alloy die castings Causes:

1. Uneven distribution or insufficient number of ejector pins, leading to uneven force:

2. The ejector pin fixing plate is deflected during operation, resulting in greater force on one side and smaller force on the other side, which causes deformation and cracks of the product.

3. The casting wall is too thin, resulting in deformation after shrinkage.

Adjustment methods:

1. Increase the number of ejector pins and adjust their distribution positions to make the ejection force on the casting balanced.

2. Adjust and reinstall the ejector pin fixing plate.