In the forming process of aluminum alloy die castings, some parts are not filled completely, which is called under casting. When the under cast part is serious, it can be regarded as the shape of the casting does not meet the requirements of the drawing. Generally speaking, under casting is not allowed.
The causes of under casting are as follows
1. The filling condition is not good, and there is irregular condensed metal in the under cast part;
When the pressure is insufficient, the metal in the active front solidifies too early, resulting in under casting at the corner, deep concave, thin wall (even thinner than the average wall thickness) and cylindrical hole wall.
The mold temperature is too low;
The pouring temperature of alloy is too low;
The location of the inner gate is not good, which results in large moving resistance.
2. The surface of the under cast part is lubricated, but the shape is irregular
Where it is difficult to set up the overflow system, the gas accumulates;
When the molten metal moves, the turbulence is violent and the gas is wrapped up.
3. There is residue in the cavity of plastic mold
The amount of coating or spraying method is improper, resulting in local coating deposition.
成型零件的镶拼缝隙过大,或滑动合作间隙过大,填充时窜入金属,铸件脱出后,并未能被彻底带出而呈现片状夹在缝隙上。当之种片状的金属(金属 片,其厚度即为缝隙的大小)又凸于周围型面较多,便在合模的情况下将凸出的高度变成适为铸件的壁厚,使今后的铸件在该处产生穿透(对壁厚来说)的沟槽。这 种穿透的沟槽即变成欠铸的一种特殊形式。这种欠铸现象多在由镶拼构成的深腔的情况下出现。
When filling, the metal will run into the metal when filling. After the casting is pulled out, it can not be brought out completely and the flake is clamped on the gap. When the sheet metal (the thickness of the metal sheet is the size of the gap) is more convex on the surrounding mold surface, the height of the projection will be changed into the wall thickness of the casting under the condition of closing the mold, so that the future casting will have a groove penetrating (for the wall thickness). This penetrating groove is a special form of under casting. This kind of under cast phenomenon often occurs in the case of deep cavity composed of mosaic.
The pouring material is insufficient (including the surplus material section is too thin).
On the vertical die casting machine, the lower punch moves down to get away from the nozzle orifice, resulting in a series of poor filling conditions.
The above is about the causes of aluminum alloy die casting under casting, hope to help you, if you want to know more, welcome to click Shandong Aluminum alloy die casting http://www.jnhjgs.cn Website.