Solutions and Preventive Measures for Aluminum Die Casting Defects

Die casting is a metal manufacturing process, especially suitable for manufacturing a large number of small and medium-sized castings. So die casting is the most widely used one of various casting processes. However, non-standard operations and parameters can also produce many defects. The following is an introduction to the defect solutions and preventive measures on aluminum die casting.

1. Flow marks and patterns

Appearance inspection: There are stripes on the surface of aluminium die casting that are consistent with the flow direction of the molten metal. Moreover, there are obviously non-directional lines that are different from the metal matrix in color without the development trend.

The causes of flow marks are as follows:

1) The mold temperature is too low

2) Poor runner design and poor position of inner gate

3) The material temperature is too low

4) Low filling speed and short filling time

5) Unreasonable gating system

6) Inadequate exhaust

7) Unreasonable spray

The reason for the pattern: too much paint in the cavity or poor paint quality.

The solutions and preventive measures are as follows:

1) Adjust the cross-sectional area or position of the inner runner

2) Increase mold temperature

3) Adjust the speed and pressure of the inner runner

4) Appropriate selection of paint and adjustment of dosage

2.Mesh hairy wings (cracked turtle)

Appearance inspection: The surface of aluminum die-casting parts has raised or recessed traces like mesh-like hair, which will expand and extend with the increase of die casting times.

The reasons are as follows:

1) There are cracks on the surface of the die-casting cavity

2) Uneven preheating of die casting mold

The solutions and prevention methods are:

1) The die-casting mold should be annealed regularly or after a certain number of die-casting to eliminate the stress in the cavity

2) If a tortoise crack has appeared on the surface of the cavity, the molding surface should be polished to remove the crack layer

3) Preheat the mold evenly

3. Cold shut

Appearance inspection: The surface of aluminum pressure die castings has obvious, irregular, and sinking linear lines (both penetrating and non-penetrating). The shape is small and narrow. Sometimes the junction edge is smooth, and it may be broken under the action of external force.

The reasons are as follows:

1) The two metal streams are connected to each other, but they are not completely fused and there are no inclusions in between. And the bonding force of the two metal streams is very weak.

2) Pouring temperature or die casting mold temperature is too low

3) The runner position is wrong or the flow path is too long

4) Low filling speed

The solutions and prevention methods are as follows:

1) Increase pouring temperature appropriately

2) Improve the injection ratio, compress the filling time, and increase the injection speed

3) Improve exhaust and filling conditions