The most effective method of using aluminum alloy die casting parts for steam holes and sand holes is to use a new ceramic filter material without using secondary nozzles to reduce impurities.
Cause Analysis:
1. Analysis of hole causes: mainly caused by pores and shrinkage, pores are round, and most of the shrinkage is irregular.
2. The cause of the stomata:
A) In the process of punching and solidification of molten metal, due to gas intrusion, round holes are created on or in the casting.
B) The volatilized gas from the coating invades the resulting round hole.
C) The gas content of the alloy liquid is too high, and it will produce round holes when it solidifies.
2. Shrinkage causes:
A) In the solidification process of the molten metal, shrinkage occurs due to the shrinkage of the volume or the lack of liquid metal in the final solidified part.
B) Partial overheating of castings or castings with uneven thickness results in slower solidification in one part and recesses in the surface when volume shrinks.
Because of the presence of pores and shrinkage holes, the die castings are troublesome for surface treatment. The holes may enter water. When baking is performed after painting and electroplating, the gas in the pores expands by heat, or the water in the pores may become vaporized. Swelling, which results in blistering on the surface of the casting, must be appropriately addressed in production to address the causes of these defects.
Solution:
1, on the pores:
The key is to reduce the amount of gas mixed into the casting. The ideal metal flow should be accelerated from the nozzle through the splitter cone and runner into the cavity to form a smooth and consistent metal flow. Conical flow channel design is used. That is, the pouring should be gradually reduced from the nozzle to the inward gate, which can achieve this goal. In the filling system, the mixed gas is formed by mixing the turbulent flow with the metal liquid phase to form pores. 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 transitional points and the incremental pouring in the runner are evident. The cross-sectional area will cause turbulence and gas flow in the metal liquid flow. The smooth metal liquid will help the gas to enter the overflow trough and exhaust trough from the runner and cavity and exit the die.
Uses new ceramic filter material, no secondary outlet material, reducing impurities
2, on the shrink hole:
To make the die casting solidification process at the same time as far as possible uniform heat dissipation, while solidification. The use of reasonable nozzle design, thickness and position of the inner gate, mold design, mold temperature control and cooling, to avoid shrinkage. For the phenomenon of intergranular corrosion: The main content is to control the content of harmful impurities in the alloy raw materials, especially lead <0.002%. Pay attention to the impurity elements brought about by the waste.