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Common surface casting defects in aluminum alloy castings

  • Author:Bai Yihan
  • Source:Www. xy-global .com
  • Release on:2021-11-04
Aluminum alloy materials are widely used by car parts die casting enterprises as one of the lightweight materials of the market. Aluminum alloy die castings will affect quality due to various factors during actual production. The following are the type, characteristics, causes and treatment of the surface casting defects of aluminum alloy castings:

First, surface casting defects

1.1 straw

(1) Features:

1 The surface of the casting in the opening direction is laminated, there is a certain depth, and it is a whole surface.

2 The metal solution is adhered to the surface of the mold, causing the surface of the casting.

(2) Cause:

1 Damage in the mold cavity surface

2 no slope or slope in the direction of the mold

3 an unbalanced

4 mold loose

5 The cast temperature is too high or too low, and the mold temperature is too high to cause the alloy liquid adhesion.

6 Release agent is not good

7 The amount of aluminum alloy ingredient is less than o. 8%; the mesh cooling time is too long or too short.

(3) Treatment method:

1 repair mold surface damage

2 correcting the slope, improve the surface of the mold surface

3 Adjust the rod to make the top out force balance

4 fastening mold

5 Control reasonable cast temperature and mold temperature 180-250

6 Replace the release agent

7 Adjust the aluminum alloy iron content

8 Adjust the cooling time

⑨ Modify the inner gate and change the direction of the aluminum liquid.

1.2 bubble

(1) Features:

The surface of the casting surface has a hole in the raised epidermis of the rice particles.

(2) Cause

1 The alloy liquid is full in the pressing chamber, which is easy to generate, is too high; 2 mold exhaust; 3 melt is unleaded, the melting temperature is too high; 4 mold conditions are too high, the metal solidification time is not enough In enough strength, the mold is opened early, and the pressure gas expands; 5 release agent is too much; 6 inner gate is not open, filling the direction.

(3) treatment method

1 change the diameter of the small pressure chamber, improve the metallic liquid fullness; 2 extend the pressure time, reduce the first stage of the pressure speed, change the low speed and high speed reflection point; 3 reduce the mold temperature, maintain heat balance; 4 additional exhaust tank, Overflow tank, sufficient exhaust, timely remove the oil, waste; 5 adjust the smelting process, perform an air treatment; 6 rendering time is appropriately extended: 7 Reduce the amount of release agent.

1.3 crack

(1) Features:

1 The surface of the casting has a straight line or wavy ripple, a small and long, which has a development trend under external force; 2 cold fracture crack metal is not oxidized; 3 thermal crack-crack metal has been oxidized.

(2) Cause:

1 The iron content of alloy is too high or the silicon content is too high;

2 He Yi's harmful impurities is too high, reducing the plasticity of alloy;

3 Aluminum silicon copper alloy is too high or the amount of copper is too low;

4 mold, especially the overall temperature of the cavity is too low;

5 The wall thickness of the castings, the strenuous changes are hindered, and the sharp position is stressed;

6 The time is too long, the stress is large;

7 The force is uneven during the top out.

(3) Treatment method:

1 Correctly control alloy ingredients, in some cases, adding aluminum ingots in alloy in the alloy to reduce the silicon-containing silicon-containing silicon in the alloy to improve silicon content;

2 Changing the casting structure, adding angle, changing the mold slope, reducing wall thickness;

3 Change or increase the top out position, so that the top is uniform;

4 Shorten the mold and the core time to improve the mold temperature, keep the mold heat balance.

1.4 deformation

(1) Features:

1 overall deformation or local deformation;

2 Die casting geometric shape drawings do not match.

(2) Cause:

1 poor casting structure;

2 Opening is too early, the rigidity of castings is not enough

3 is not properly set, and the force is uneven during top out;

4 The inlet position or the gate thickness is too thick, and it is easy to deform when the gate is cut;

5 The mold is roughly caused by large resistance, and the product is deformable at the top of the product; the product is too high, the product is not completely cured, and the ejective force is large, causing product deformation.

(3) Treatment method:

1 improve the casting structure;

2 rationally adjust the pressure and opening day 3 reasonably set the number of top outlets and the number of top rods, preferably use 4, open places; 4 changes the gate position, so that the gate has - a point, reduce the gate thickness, The product is not easy to deform when the casting quality of the product is quasi-to-end; 5 to enhance the mold processing, reduce the demolding resistance; 6 pairs of local mold temperatures, keep the mold heat balance.

1.5 flow marks, pattern

(1) Features:

There is a clearly visible ripple that is significantly visible to the direction of the metal fluid flow in the surface of the casting surface, no development trend.

(2) Cause:

1 First entering the metal solution of the cavity forms - after the thin and incomplete metal layer, the traces left by the later metal solutions;

2 The mold temperature is too low, the mold temperature is uneven:

3 Invented inverse range of varices and improper positions are generated;

4 The pressure of the metal solution is insufficient;

5 pattern: too much amount of paint.

(3) Treatment method:

1 Improve the metal liquid temperature of 620% to 650C;

2 Improve mode temperature, maintain 200 ~ C-250 "(2 thermal balance;

3 thickened inner row cross-sectional area change the import position;

4 Adjust the filling speed and the length of the pressure time trip;

5 Use the appropriate coating and adjustment of the contrast concentration.

1.6 cold separation

(1) Characteristics

The surface of the die-casting member is obvious, irregular, down-to-penetrating linear road (with penetration and non-penetrating two types), and some of the intersection is smooth, and it is developed under external force.

(2) Cause:

1 Two metal flows are connected to each other, but there is no incisor of the incispadum without complete fusion, and the two metal binders are weak;

2 Pouring temperature or die-casting temperature is low;

3 Select improper alloy and poor liquidity;

4 The row position is not or the flow path is too long;

5 low filling speed and low voltage ratio.

(3) Treatment method:

1 Advantages to the casting temperature and mold temperature;

2 Improve the voltage ratio pressure, shorten the fill time;

3 Improve the voltage speed while increasing the cross-sectional area of ​​the inner gate;

4 improve exhaust, filling conditions;

5 Correctly select alloys to improve alloy fluidity.