There are many quality problems encountered in the production of aluminum alloy die-casting. The reasons are also multi-faceted. In production, it is necessary to make a correct judgment on the quality problems produced, to find out the real reasons, and to propose practical improvement measures, so as to continuously improve The quality of aluminum alloy die-casting parts does not affect the normal use of castings, meets production needs, and reduces enterprise costs.
In the position where the core and the wall thickness of the die-casting mold change greatly, the fluidity of the aluminum liquid is unstable, and the pores are easily generated, which is also the reason for the large number of pores around the bolt hole of the die-casting aluminum parts. The air hole around the bolt hole is small, less than 1/3 of the thread length, and is not in the threaded area. It has no effect on the torque and will not affect its performance. It may not solve the problem of the air hole at this point.
2, shrinkage hole
The method of eliminating the shrinkage cavity can be achieved by reducing the wall thickness of the region where the shrinkage cavity is located, enabling rapid and uniform solidification, or by optimizing the casting and mold structure. Under the premise of preserving the original structure of the water pump casing and the cylinder block, after comprehensive consideration, the cooling water channel is added to the mold in the area to enhance the cooling, accelerate the solidification speed of the aluminum liquid, reduce the volume of the shrinkage hole, and shrink the volume. The hole is controlled in the center area to prevent the shrinkage hole from leaking too close to the waterway or oil path. After this measure, the shrinkage cavities near the aluminum pump casing were significantly improved. Porosity and shrinkage are two common quality defects in die casting production. In severe cases, the scrapping of die castings will occur, and attention should be paid to and improved in production.
Correctly control the alloy composition. In some cases, a pure aluminum ingot may be added to the alloy to reduce the magnesium content in the alloy or the aluminum-silicon intermediate alloy in the aluminum alloy to increase the silicon content; change the structure of the aluminum alloy die-casting part, increase the rounded corner, Change the draft angle and reduce the wall thickness difference; change or increase the ejection position to make the ejection force uniform; shorten the mold opening and core pulling time; control the mold temperature and maintain the mold heat balance.
4, under casting
Increase the wall thickness of the third main bearing block of the cylinder from 4mm to 5mm, thereby increasing the flow area of the aluminum liquid and accelerating the filling speed; increasing the height and thickness of the ribs in the lower part of the pump area, equivalent to adding one to the water pump Sprue. After taking measures, the problem of under-cast quality in the third main bearing housing and the pump area was improved.
In order to prevent the occurrence of defects, as long as the conditions of the die-casting process, the process parameters during die-casting, the die-casting aluminum floor drain and die structure, the die-casting equipment and the production operation procedures and management specifications are met, and the causes and analysis are based on the defects of the die-casting parts. Regularity, accumulating and summarizing experience in practice, can take targeted measures to effectively eliminate quality defects and improve the quality and production efficiency of die-cast parts.