Analysis and control of two common defects in Die casting
1) Defect characteristics
Die-cast appearance or inclusions. Most of these inclusions are metal oxides, paint residues, and the like. The inclusions not only affect the appearance of the casting, but also reduce the internal tissue density of the casting.
When the metal melts, it easily reacts with oxygen to form oxides at high temperatures; molten metal coatings such as zinc oxide, water glass, etc., float on the surface of liquid metal; chemical reactions in metamorphic treatment, and the raw materials themselves contain more Inclusions. If the above material is not excluded and enters the mold cavity, it will get stuck in the casting to form inclusions.
3) Preventive measures
The melting temperature of the metal is tightly controlled within the process. Slag treatment should be carried out as much as possible before pouring. That is to say, the inclusions floating on the surface of the metal liquid should be removed, the cross-sectional area of the mold exhaust tank should be appropriately increased, and the slag collection package should be properly arranged.
2, shrink hole
1) Condensation characteristics
There are sparse tissues in the gypsum, and some even show a honeycomb shape, which affects the power of the actor.
After filling the cavity with liquid metal, it is insufficiently replenished during the shrinking process and is likely to occur on thin, uneven castings. In particular, the injection pressure is too low and the holding time is short, and such defects are more likely to occur.
3) Preventive measures
The gating system can be enlarged and opened in the thick section of the Die casting. The loose part of the mouth is set for retraction. The structural design of the part should be such as to avoid uneven thickness or to change the thickness of the steel part. The Die casting process is reasonable. If the pouring temperature is not too high, the shrinkage should be prevented, the pressure should be appropriate, and the holding time should be sufficient.
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