In view of the 10 defects that often appear in aluminum die casting, Zhejiang Taixing Electromechanical Technology Co., LTD. (specializing in aluminum die casting motor housing [vertical electrical housing/horizontal electrical housing/stretching electrical housing], aluminum die casting mold, etc.) summarizes the solutions as follows

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The first. Flow marks and patterns

Appearance inspection: there are stripes on the surface of the casting which are consistent with the flow direction of the metal liquid, non-directional stripes which are obviously visible and different from the color of the metal substrate, and there is no development trend.

1. The causes of flow marks are as follows:

(1) Die temperature is too low.

(2) Poor design of runner and poor position of inner gate.

(3) Material temperature is too low.

(4) Low filling speed and short filling time.

(5) Unreasonable casting system.

(6) Poor exhaust.

(7) Unreasonable spray.

2. The cause of the pattern is too much spraying or poor quality of the paint in the cavity. The solution and prevention methods are as follows:

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

(2) Increase the mold temperature.

(3) Adjust the speed and pressure of the inner runner.

(4) Appropriate selection of paint and adjust the dosage.

In the second. Reticulated hairy wing (Turtle crack)

Appearance inspection: there are raised or sunken marks on the surface of die casting like netted hair, which will expand and extend with the increase of times of die casting.

The reasons are as follows:

(1) Cavity surface of die casting mold has cracks.

(2) Uneven preheating of die casting die.

Solutions and prevention methods are as follows:

(1) Die casting mold to be regular or die casting a certain number of times, should be annealed, to eliminate the stress in the cavity.

(2) If turtle cracks have appeared on the cavity surface, the molding surface should be polished to remove the crack layer.

(3) Preheat the mold evenly.

In the third. Cold insulation

Appearance inspection: the surface of the die casting has obvious, irregular and sunken linear pattern (with or without penetration) with small and narrow shape, sometimes with smooth edges, which may break under the action of external force.

The reasons are as follows:

(1) Two metal flows butt joint, but not completely fused and there is no inclusion between the two, the two metal binding force is very weak;

(2) The casting temperature or die casting mold temperature is too low;

(3) The runner is not in the right position or the flow is long;

(4) Low filling speed.

Solutions and prevention methods are as follows:

(1) Properly raise the casting temperature;

(2) To improve the short filling time of injection molding than compression, and to improve the injection molding speed.

(3) Improve the exhaust and filling conditions.

In the fourth. To make (a dent).

Appearance inspection: there are smooth indentations on most of the thick surface of the die casting.

The reasons are as follows:

(1) Caused by contraction

1.1 The wall thickness difference of the die casting is too great if the design is improper;

1.2 Improper runner location;

1.3 The injection ratio is low and the holding time is short;

1.4 Local temperature of die casting die is too high.

(2) Unreasonable cooling system design;

(3) Die opening early;

(4) Excessive casting temperature.

Solutions and prevention methods are as follows:

(1) The wall thickness should be uniform;

(2) The thickness transition should be relaxed;

(3) Correctly select the leading position of the alloy solution and increase the cross-sectional area of the inner runner;

(4) Increase the injection pressure and extend the holding time;

(5) Properly reduce the casting temperature and the temperature of the die casting mold;

(6) Local cooling to local high temperature;

(7) Improving discharge and overflow conditions;

The fifth. mark

Appearance inspection: marks left by contact between casting surface and cavity surface of die casting model or step marks on casting surface.

The reasons are as follows:

1. Caused by ejector element

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

(2) The adjustment length of the ejector bar is inconsistent;

(3) The cavity splicing part of the die-casting model does not fit well with other parts;

2. Caused by splicing or active parts

(1) The insert part is loose;

(2) The movable part becomes loose or worn;

(3) The side wall surface of the casting is formed by the inserts that move and fixed molds interpenetrate each other.

Solutions and prevention methods are as follows:

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

(2) Tighten the insert or other moving parts

(3) Eliminate the sharp Angle in the design and adjust the clearance to fit;

(4) Improve the casting structure so that the die casting die eliminates the insertion form of penetration and improves the die casting die structure;

6. Adhesive trace

Appearance inspection: the flaky parts and metal or non-metal parts fused with the metal base part, and the flaked parts were peeled off under the action of external force. Some of the flaked parts were shiny and some were dark gray.

The reasons are as follows:

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

Solutions and prevention methods are as follows:

(1) Clean the mold cavity pressure chamber and casting system before die casting to remove metal or non-metal adhesive substances;

(2) The cast alloy should also be cleaned;

(3) Choose the right coating, coating to uniform.

7. Lamination (peeling and peeling)

Appearance inspection or damage inspection: marked metallic layering in a casting site.

The reasons are as follows:

(1) The mold is not rigid enough. During the filling process of liquid metal, the template will shake;

(2) Creep of the punch occurs in the process of injection;

(3) Improper design of runner system.

Solutions and prevention methods are as follows:

(1) Strengthen the stiffness of the mold, tighten the mold parts, so that it is stable;

(2) Adjust the cooperation between the injection punch and the pressure chamber to eliminate creep;

(3) Reasonable design of internal runner.

The eighth. The ablation of friction

Appearance inspection: the surface of die casting produces a rough surface in some places.

The reasons are as follows:

(1) Improper location, direction and shape of the inner runner caused by the die casting mold (die);

(2) Insufficient cooling of the metal liquid scour violent parts at the inner runner caused by casting conditions.

Solutions and prevention methods are as follows:

(1) To improve the position and direction of the internal runner which is not suitable for internal pouring;

(2) To improve the cooling conditions, especially to improve the metal liquid scour violent parts;

(3) Add coating to the ablative part;

(4) Adjust the flow velocity of alloy liquid so that it does not produce cavitation

(5) The alloy adhesive on the elimination type (mold).

9. erosion

Appearance inspection: pitting or convex on local position of die casting.

The reasons are as follows:

(1) Improper placement of the internal runner;

(2) Poor cooling conditions.

Solutions and prevention methods are as follows:

(1) The thickness of the inner runner should be appropriate;

(2) Modify the position, direction and setting method of the inner runner;

(3) To strengthen the cooling of the eroded part.

The first ten. The crack

Appearance inspection: casting is placed in alkaline solution and the crack is dark gray. The failure and fracture of the metal matrix are linear or wavy, with narrow and long grooves, which tend to develop under the action of external forces.

Aluminum alloy casting crack.