Structure of the casting and air contact surface

Because the casting in the metal mold cools and condenses faster than in the sand mold, the metal mold has no tolerance. Therefore, when the metal mold is cast, the casting stress that occurs in the casting is larger than that of the sand mold. In the process, the phenomenon of lack of pouring and cold separation also simply occurred.

The wall thickness of the casting is uniform, the transition between the walls and the joint should be smooth, and the requirements of the product to be rounded at the corners are more stringent than those for sand casting. The equipment should change the vertically connected walls to skew. Connected.

The thinner parts of the casting should be strengthened by ribs and bosses. This can effectively avoid cracks in the casting. In the process of use, the bosses, ribs and flanges that prevent the casting from shortening should be reduced as much as possible. And so on.

When a useful arrangement is required on the casting to strengthen its ribs, it is necessary to consider its effect on the shortening of the casting during the application process. This can avoid the lack of pouring and cold insulation of the metal mold casting. The following structural problems should be noted.

The wall thickness of the casting should be too thin, especially when the general size of the casting is large. The product must be useful. In the process of application, it is necessary to avoid a large horizontal surface, because it is the casting at the time of pouring. The metal liquid rises slowly.

The air touching surface of the casting is large and easy to be oxidized. At the same time, due to the rapid heat dissipation of the metal, the metal liquid will quickly lose its fluidity, which is very simple to form defects such as lack of pouring, slag inclusion, and cold insulation.