Common surface casting defects in 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.