What should we pay attention to when designing the structure of metal casting parts?
what is the ifference between precision metal casting mold and sand casting mold?
Because the casting is cooled and solidified faster in the metal mold than in the sand mold, and the metal mold has no tolerance, so in the metal mold casting, the casting stress is larger than that in the sand mold casting, and the tendency of the crack is also larger, and it is also prone to insufficient pouring, cold separation, white mouth (for casting castings) and other defects. Generally speak:
(1) in the prevention of metal mold casting cracks should pay attention to the following structural problems:
- A in the wall thickness uniform, the transition between the wall and the connection to ease, the Angle of the appropriate fillet and other aspects of the requirements should be more stringent than the sand mold casting;
- B. The walls connected vertically shall be inclined to be connected;
- C for the relatively weak part of the structure should be set up ribs, bosses, etc., to strengthen, to prevent casting cracks;
- D the protruding parts of the boss, rib and flange that hinder the free shrinkage of the casting should be reduced as far as possible;
- E. When placing reinforcing ribs on castings, its effect on casting shrinkage should also be taken into account.
(2) in order to prevent the insufficient casting of metal mold casting, cold separation and other aspects should pay attention to the following structural problems:
- A casting wall thickness should be appropriate not too thin, especially when the casting profile size is large, it can not be too thin;
- B should avoid large horizontal plane, because it makes the casting in the pouring, the metal liquid rise slowly, and the surface in contact with the air is large, easy to oxidize, and because the metal heat dissipation is fast, the metal liquid quickly lose fluidity, easy to form defects such as insufficient pouring, cold separation, slag inclusion;
- C casting shape should be as far as possible with streamline to avoid sharp edges and sharp changes in the connection and other structural shapes, in order to facilitate the flow of metal liquid.
In the design of more complex shape of the metal mold casting, if the production process is more difficult, should not affect the use of the casting conditions, as far as possible to make the casting shape simple, strong structure change, in order to remove the casting from the metal mold.
In the design of the basic structural units of metal mold casting and the selection of its parameters, generally should also pay attention to:
- (1) due to the fast heat dissipation of the metal mold, so the minimum wall thickness of the metal mold casting should be larger than that of the sand mold casting;
- (2) the thickness of the inner wall and inner rib of the casting should generally be connected with the thickness of the outer wall of 0.6 ~ 0.7, otherwise due to the inner wall (rib) cold is slow, when the casting shrinkage is easy to crack at the junction of the inner and outer wall;
- (3) to prevent grey cast iron parts produced white, in addition to take measures from the technology, it is necessary to make the wall thickness too thin, pointed out some material, wall thickness, when more than 15 mm, the corner with a metal mold casting castings must use rounded corners, for aluminum alloy, magnesium alloy metal mold casting casting foundry rounded corners should not be less than 3 ~ 4 m;
- (4) because of the metal mold and core is not free, in order to facilitate the removal of casting and mold, the casting slope of metal mold casting should be larger than the sand mold casting, generally 30% ~ 50%, it should be pointed out that: Casting slope size in addition to the type of alloy, the height of the wall, but also related to the position of the casting surface, where the casting cooling shrinkage and metal surface has a tendency to break away from the casting surface can be designed with a smaller slope, and in the shrinkage of the casting tends to be pressed on the metal surface should be given a larger slope.
We are a large scale investment casting foundry located in northeast of China, Dalian city, we can cast different kind of steel materials, such as carbon steel castings, stainless steel castings, low alloy steel castings. And product weight is from 0.05-80 kgs, and the casting parts are widely used. If you have the RFQ of complex casting parts, or you want to learn more technics about metal casting, go to www.ltmetalcasting.com or get to contact us: firstname.lastname@example.org