During the production process of die-casting parts, there will be many quality problems, which are common quality defects in die-casting parts. Undercasting is one of the defects. What are the reasons for the occurrence of undercasting in die-casting parts? Based on the analysis, the following is a summary:

During the forming process of die-casting parts, incomplete filling in certain areas is called undercasting. When the undercast part is severe, it can be considered as the shape of the casting not meeting the requirements of the drawing. Usually, under casting is not allowed to exist.

The reasons for under casting include:

1) Poor filling conditions and irregular condensed metal in the undercast areas;

When the pressure is insufficient, insufficient, or the metal at the forefront of the movement solidifies too early, it causes undercasting in areas such as corners, deep depressions, thin walls (even thinner than the average wall thickness), and cylindrical hole walls.

The mold temperature is too low;

The pouring temperature of the alloy is too low;

Poor positioning of the sprue creates significant resistance to movement.

2) Gas obstruction, surface lubrication of undercast parts, but irregular shape

Difficult to establish an overflow system in areas where gas accumulates;

During the activity of molten metal, turbulence is intense, enveloping the gas.

3) There are residues in the plastic mold cavity

Improper dosage or spraying method of paint can cause local paint deposition.

The gap between the molded parts is too large, or the sliding cooperation gap is too large. When filling, metal enters, and after the casting is removed, it is not completely carried out and appears as a sheet-like clamp on the gap. When a sheet-like metal (metal sheet, whose thickness is the size of the gap) protrudes more from the surrounding surface, the height of the protrusion is adjusted to the appropriate wall thickness of the casting when the mold is closed, so that future castings will have grooves that penetrate (in terms of wall thickness) at that location. This type of penetrating groove becomes a special form of undercasting. This under casting phenomenon often occurs in deep cavities composed of inlays.

Insufficient pouring material (including thin excess material).

On a vertical die-casting machine, during injection, the downward movement of the lower punch causes insufficient clearance of the nozzle opening, resulting in a series of poor filling conditions.