How to effectively solve porosity and impurities in aluminum alloy die-casting parts?

How to effectively solve porosity and impurities in aluminum alloy die-casting parts? I think this problem can trouble many die casting manufacturers, and even teachers and technicians may not be able to completely solve it. We know that it is difficult to deal with air holes in aluminum alloy die castings after welding, mainly because there are too many impurities. How to deal with air holes and impurities in aluminum alloy die castings? Let's take a look together with Jiawei Metal.

The most effective method for treating air and sand pores in aluminum alloy die-casting parts is to use brand new ceramic filter materials, without the use of secondary nozzle materials, to reduce impurities.

Analysis of the causes of defects

1. The main causes of pore formation are stomata and shrinkage, most of which are circular in shape, while shrinkage is mostly irregular in shape.

2. The reason for the formation of air holes: During the stamping and solidification process of metal liquid, due to gas invasion, circular holes are formed on the surface or inside of the casting; The circular holes generated by the invasion of gas emitted from the coating; If the gas content in the alloy liquid is too high, circular holes will also be formed during solidification.

3. Reasons for shrinkage:

a. During the solidification process of alloys, shrinkage cavities are generated due to volume reduction or the inability of the final solidification site to be supplemented by molten metal.

b. Uneven thickness of castings or local overheating of castings can cause slow solidification in a certain area, resulting in the formation of concave spots on the surface during volume shrinkage.

Due to the presence of pores and shrinkage cavities, surface treatment of die castings is very troublesome. Holes may enter water, and during baking after painting and electroplating, the gas inside the holes expands due to heat, or the water inside the holes becomes steam and expands in volume, resulting in surface blistering of the casting. Therefore, appropriate methods should be used in production to solve the causes of these defects.

How to effectively solve porosity and impurities in aluminum alloy die-casting parts?

1. About pores

two

The key is to reduce the amount of gas mixed into the casting. The ideal metal flow should continuously accelerate from the nozzle through the splitter cone and runner into the mold cavity, forming a smooth and consistent metal flow. The use of a conical runner design means that the runner should gradually reduce from the nozzle to the inner runner, achieving this goal.

In the filling system, the mixed gas forms pores due to the mixing of turbulence and metal liquid. It is evident from the study of the simulated die-casting process of metal liquid entering the mold cavity from the casting system that the sharp transition position and increasing cross-sectional area of the runner will cause turbulence and entrainment of the metal liquid flow. A stable metal liquid is conducive to the gas entering the overflow and exhaust grooves from the runner and mold cavity, and being discharged outside the mold.

Using brand new ceramic filter materials, without using secondary nozzle materials, to reduce impurities.

2. About Shrinkage

To achieve uniform heat dissipation and solidification of various parts during the solidification process of die casting, reasonable nozzle design, inner gate thickness and position, mold design, mold temperature control, and cooling can be used to avoid shrinkage cavities.

For intergranular corrosion phenomenon, it is mainly to control the content of harmful impurities in alloy raw materials, especially lead<0.002%. Pay attention to the impurities brought by waste materials.

The above is the technical sharing on "How to effectively solve the air holes and impurities in aluminum alloy die-casting parts". If you have the above problems during the die-casting process, you can ask us at any time.