Causes and Solutions of Bubbles in Zinc Alloy Die Castings

Causes and Solutions of Bubbles in Zinc Alloy Die Castings

Causes and solutions of bubbles in zinc alloy die castings. Zinc alloy die castings are widely used in various industries. Therefore, the appearance and quality requirements of zinc alloy die castings are generally relatively high. In the production process of zinc alloy die castings, a common defect is zinc alloy die castings. Bubbles are prone to appear on the surface. This problem will be found after the completion of die-casting or during further processing. The main reasons for its production are:

1. When the gas in the cavity, the gas volatilized from the paint, and the gas precipitated by the solidification of the alloy are left in the zinc alloy die casting when the mold is poorly exhausted, the pores are formed.


2. In the process of filling and solidification of zinc alloy die castings, the surface of the die castings produces bubbles due to gas intrusion.


3. The intrusion of gas from paint.


4. The zinc alloy liquid contains too much gas and precipitates during solidification.

Solution to bubbles:

1. For hot cracks: do not change the thickness of the die-casting parts sharply to reduce stress; adjust the relevant die-casting process parameters; reduce the mold temperature.


2. Control the generation of pores: The key is to reduce the amount of gas mixed into the casting. The ideal metal flow should continue to accelerate from the nozzle through the split cone and runner into the cavity to form a smooth and consistent metal flow, using a cone. Runner design, that is, the pouring should be gradually reduced from the nozzle to the gate at an accelerating rate, which can achieve this goal. In the filling system, the mixed gas forms pores due to the mixing of turbulent flow and the liquid phase of the metal. From the study of the simulated die-casting process in which the molten metal enters the cavity from the casting system, it is obvious that the sharp transition position and the incremental casting in the runner The cross-sectional area of ​​the channel will cause the molten metal flow to appear turbulent and entrain gas, and the stable molten metal is conducive to the gas entering the overflow groove and exhaust groove from the runner and cavity, and is discharged out of the mold.


3. For water pattern and cold partition pattern: increase the mold temperature, increase the gate speed, or increase the overflow groove in the cold partition area to reduce the appearance of cold partition pattern.


4. For shrinkage cavity: make all parts of the die casting solidification process as much heat as possible at the same time, and solidify at the same time. Reasonable nozzle design, inner gate thickness and position, mold design, mold temperature control and cooling can be used to avoid shrinkage. https://lasercutting-service.comFor the phenomenon of intergranular corrosion: mainly to control the content of harmful impurities in the alloy raw materials, especially lead <0.003%. Pay attention to the impurity elements brought by the waste.

Why do zinc alloy die castings produce bubbles? Now that we understand, we have to correct them to solve the bubble problem.