1、 Flow marks and patterns

　　Appearance inspection: There are stripes on the surface of the aluminum plate casting that are consistent with the flow direction of the molten metal, and there are clearly visible non directional patterns that are different in color from the metal substrate, with no development trend.

　　The reasons for the formation of flow marks are as follows:

　　(1) The mold temperature is too low.

　　(2) Poor design of the sprue and poor positioning of the sprue.

　　(3) The material temperature is too low.

　　(4) Low filling speed and short filling time.

　　(5) The pouring system is unreasonable.

　　(6) Poor exhaust.

　　(7) The spray is unreasonable.

　　2. The reason for the formation of patterns is due to excessive coating or poor coating quality inside the mold cavity. The solutions and prevention methods are as follows:

　　(1) Adjust the cross-sectional area or position of the internal pouring channel.

　　(2) Raise the mold temperature.

　　(3) Adjust the speed and pressure of the internal pouring channel.

　　(4) Appropriate selection of coatings and adjustment of dosage.

　　2、 Mesh like hairy wings (turtle cracks)

　　Appearance inspection: There are network like protrusions or indentations on the surface of aluminum die-casting parts, which continuously expand and extend with the increase of die-casting times.

　　The reasons for this are as follows:

　　(1) There are cracks on the surface of the die-casting mold cavity.

　　(2) Uneven preheating of die-casting molds.

　　The solutions and prevention methods are:

　　(1) The die-casting mold should be annealed regularly or after a certain number of die-casting cycles to eliminate stress in the mold cavity.

　　(2) If there are cracks on the surface of the mold cavity, the formed surface should be polished to remove the crack layer.

　　(3) The preheating of the mold should be uniform.

　　3、 Cold insulation

　　Appearance inspection: The surface of the aluminum plate die-casting parts has obvious, irregular, and sunken linear patterns (with both penetrating and non penetrating types) with small and narrow shapes. Sometimes the junction edges are smooth, and there is a possibility of breakage under external force.

　　The reasons for this are as follows:

　　(1) Two metal flows are connected to each other, but they are not completely fused and there are no inclusions between them, and the bonding force between the two metal flows is very weak; (2) The pouring temperature or die-casting mold temperature is too low;

　　(3) The pouring position is incorrect or the flow path is too long;

　　(4) Low filling speed.

　　The solutions and prevention methods are:

　　(1) Appropriately increase the pouring temperature;

　　(2) Improve the injection ratio, shorten the filling time, and increase the injection speed.

　　(3) Improve exhaust and filling conditions.

　　4、 Shrinkage (dent)

　　Appearance inspection: There are smooth indentations (resembling discs) on the surface of the thick majority of the aluminum plate die-casting parts.

　　The reasons for this are as follows:

　　(1) Caused by contraction

　　1.1 Improper design of die-casting parts with large wall thickness differences;

　　1.2 Improper pouring position;

　　1.3 Low injection ratio and short holding time;

　　1.4 The local temperature of the die-casting mold is too high.

　　(2) Unreasonable design of cooling system;

　　(3) Premature mold opening;

　　(4) The pouring temperature is too high.

　　The solutions and prevention methods are:

　　(1) The wall thickness should be uniform;

　　(2) The transition between thickness and thinness should be eased;

　　(3) Correctly select the location for introducing alloy liquid and increase the cross-sectional area of the inner runner; (4) Increase injection pressure and prolong holding time;

　　(5) Reduce the pouring temperature and die-casting mold temperature appropriately;

　　(6) Local high temperatures require local cooling;

　　(7) Improve overflow conditions;

　　5、 Imprint

　　Appearance inspection: The traces left by the contact between the surface of the aluminum plate casting and the surface of the die-casting model cavity or the appearance of step marks on the surface of the casting.

　　The reasons for this are as follows:

　　1. Caused by the ejection component

　　(1) The end face of the top rod is worn;

　　(2) The length of the top pole adjustment is inconsistent;

　　(3) The joint part of the die-casting model cavity does not match well with other parts; 2. Caused by splicing or moving parts

　　(1) Loose inlay parts;

　　(2) Loose or worn activity parts;

　　(3) The side wall surface of the casting is formed by inserts interspersed between the moving and fixed molds.

　　The solutions and prevention methods are:

　　(1) The length of the top pole should be adjusted to an appropriate position;

　　(2) Secure inserts or other movable parts

　　(3) Eliminate sharp corners during design and adjust gaps accordingly;

　　(4) Improve the casting structure to eliminate the interlaced inlay form in the die-casting mold and improve the die-casting mold structure; 6、 Adhesive traces

　　Appearance inspection: Small pieces of metal or non-metal are welded to the metal substrate, and under external force, the small pieces are peeled off. After peeling, the surface of the casting may be shiny or dark gray.

　　The reasons for this are as follows:

　　(1) There are metal or non-metal residues on the surface of the aluminum plate die-casting model cavity; (2) During pouring, impurities are first introduced and attached to the surface of the mold cavity.

　　The solutions and prevention methods are:

　　(1) Before die-casting, the mold cavity, pressure chamber, and pouring system should be cleaned thoroughly to remove metal or non-metal adhesives; (2) The poured alloy should also be cleaned thoroughly;

　　(3) Choose the appropriate coating, the coating should be uniform.