Aluminum die casting defects and prevention
one. Adhesive traces
Appearance inspection: small flakes and metal or non-metallic and metal base parts are welded, and the small flakes are peeled off under the action of external force. After the peeling, the surface of the casting is bright and some are dark gray.
The reasons are as follows:
(1) There are metallic or non-metallic residues on the surface of the die-casting cavity;
(2) When pouring, the impurities are first brought in and attached to the surface of the cavity.
The solutions and prevention methods are:
(1) Before die-casting, the cavity pressure chamber and gating system should be cleaned up to remove metal or non-metal adherents;
(2) Clean up the cast alloy;
(3) Choose a suitable paint, and the coating should be even.
two. Layering (skinning and peeling)
Visual inspection or damage inspection: There are obvious layers of metal in the casting part.
The reasons are as follows:
(1) The mold is not rigid enough. During the molten metal filling process, the template shakes;
(2) The punch appears to crawl during the injection process;
(3) Improper design of runner system.
The solutions and prevention methods are:
(1) Strengthen the rigidity of the mold and tighten the mold parts to make them stable;
(2) Adjust the cooperation of the injection punch and the pressure chamber to eliminate the crawling phenomenon;
(3) Reasonably design the inner runner.
three. Friction ablation
Visual inspection: The surface of the die-casting part has rough surfaces in some positions.
The reasons are as follows:
(1) Improper position, direction and shape of the inner runner caused by the die-casting mold (mold);
(2) Insufficient cooling of the parts where molten metal is scoured severely at the inner runner caused by the casting conditions.
The solutions and prevention methods are:
(1) Improving the location and direction of the inner runner where it is not good at pouring;
(2) Improve the cooling conditions, especially the areas where the molten metal is violently scoured;
(3) Add paint to the ablated part;
(4) Adjust the flow rate of the alloy liquid to prevent cavitation
(5) Eliminate the alloy adherents on the mold (mold).
Four. Erosion
Visual inspection: There are pitting or embossing in the local position of the die casting.
The reasons are as follows:
(1) Improper location of the inner runner;
(2) Poor cooling conditions.
The solutions and prevention methods are:
(1) The thickness of the inner runner should be appropriate;
(2) Modify the position, direction and setting method of the inner runner;
(3) Strengthen the cooling of the eroded parts.
five. Crack
Visual inspection: Put the casting in alkaline solution, the cracks are dark gray. The destruction and cracking of the metal matrix is straight or wavy, with narrow and long lines, which tend to develop under the action of external forces.