Characteristics and solutions of slag hole defects in Die casting

Defect characteristics:
During the Die casting and casting process, the slag or impurities in the alloy liquid are wrapped by the flow of the alloy liquid and participate in the cavity together with the Die casting and filling process. After cooling and solidification, holes (sometimes slag, sometimes debris) are formed in the casting, leaving holes or foreign matter on the machined surface after processing. Because it is caused by slag and oxide scale, it is irregular, the surface is not only irregular, but all or part of the hole is filled with slag and the like.
Discovery method:
Visual inspection after processing or x-ray inspection.
Cause Analysis:
(1) In the alloy smelting process, slag or foreign matter is mixed into the alloy liquid.
(2) Excessive impurities and impurities in the alloy material.
(3) In the process of alloy smelting, refining and degassing and slag removal (slag removal and slag removal) are incomplete and cannot play an effective role. Or the refining agent itself is not pure.
(4) During the alloy refining process, the refining temperature is too high, and the viscosity of the alloy is too high, so that the slag does not easily float from the surface of the liquid, so the removal effect cannot be achieved. Alternatively, the alloy liquid has low temperature and low fluidity. Too low a casting temperature results in a free state of silicon in the aluminum-silicon alloy.
5] During the alloy refining process, the agitation is too strong and the slag is related to the alloy liquid.
[6] When the alloy is refined, the standing time is short and the slag cannot float.
(7) The overflow tank on the mold is not set correctly, and the overflow tank cannot collect the slag.
(8) Splash during the filling process to form oxide inclusions in the alloy during the filling process.
(9) There is dirt in the material tube, the pressure on the soup head is dirty, and the cavity is dirty. Excessive black lead oil enters the mold cavity during the filling process.
(10) The recycling cost includes a large amount of water or oil.
(1) The choice of materials should be made of relatively pure alloy ingots. All charges placed in the furnace must not be mixed with greasy dirt, water, debris and other substances that may produce slag and matter.
(2) Refine and remove slag according to the operation requirements. The slag must be dried first and of high purity.
(3) Appropriately increase the charging temperature to facilitate the dregs.
(4) Completely eliminate any foreign matter that may come into contact with the alloy liquid.
5] Try to use less black lead oil while keeping the soup head running normally.
[6] Clean the melting furnace (parts) and its melting tools in a timely manner.
(7) During the long-term heat preservation process, do not intentionally or unintentionally damage the alloy liquid on the surface of the alumina protective film to prevent the strengthening oxidation of the alloy.
(8) Magnesium-containing aluminum alloys are prone to oxidized slag.

(9) Aluminum alloys with high copper and iron content are prone to free silicon.

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