Characteristics of common casting structures / Raymond Machinery Co.,Ltd.

Characteristics of common casting structures

Category	Performance Feature	Structural Features
Grey iron casting parts	Good fluidity, body shrinkage and line shrinkage. The comprehensive mechanical properties are low, and the compressive strength is about 3 to 4 times higher than the tensile strength. Good vibration absorption. The elastic modulus is low.	Shapes can be complex and structures allow for asymmetry. There are box, barrel, etc., for example, used in engine cylinder body, barrel sleeve, various machine tool bed, base, plate, platform and other castings.
Ductile iron casting parts	The fluidity is similar to that of gray cast iron; The volume shrinkage is larger than that of gray cast iron, and the line shrinkage is reduced, which is easy to form shrinkage holes and loose. The comprehensive mechanical properties are higher, and the elastic modulus is higher than that of gray cast iron. Good wear resistance; Good impact toughness and fatigue strength. The vibration dissipation ability is lower than that of gray cast iron.	Generally, the design is uniform wall thickness; For thick and large sections, hollow structures can be used, such as nodular cast iron crankshaft journal parts.
Malleable cast iron casting parts	Poor fluidity than gray cast iron; The volume shrinkage is large, and after annealing, the final linear shrinkage is small. Before annealing, it is very brittle and the blank is easily damaged. The comprehensive mechanical properties are slightly inferior to nodular cast iron, and the impact toughness is 3 to 4 times larger than gray cast iron.	Because the casting state requires a white mouth, it is generally a thin-walled uniform part, and the common thickness is 5 ~ 16mm. In order to increase its rigidity, the section shape is mostly I-shaped, T-shaped or box-shaped to avoid cross section; The protruding parts should be reinforced with ribs.
Steel casting parts	The fluidity is poor, and the sensitivity of volume shrinkage, linear shrinkage and crack is large. High comprehensive mechanical properties; The compressive strength is almost equal to the tensile strength. Poor vibration absorption	The structure should have a minimum of thermal nodes and create conditions for sequential solidification. The connection and transition between neighbouring walls should be smooth; the casting cross-section should be box-shaped and groove-shaped and other similarly closed structure; some horizontal walls should be changed into sloping walls or wavy; the whole wall is changed into a wall with a window, the window shape is preferably elliptical or rounded, and the edge of the window should be made into a convex platform to reduce the possibility of cracking.
Tin bronze and phosphorus bronze parts	Casting properties are similar to gray cast iron. But the crystallization range is large, easy to produce shrinkage holes; Poor liquidity; High temperature performance is poor, easy to crisp. The strength decreases significantly with the increase of cross-section. Good wear resistance.	The wall thickness should not be too large; The protruding parts should be reinforced with thin ribs to avoid hot cracking; The shape is not too complicated.
Tin-free bronzes and brass parts	Large shrinkage, small crystallization range, easy to produce concentrated shrinkage holes; Good mobility. Good wear and corrosion resistance.	Similar to steel casting parts.
Aluminum die casting parts	Its casting properties are similar to cast steel, but the strength decreases more significantly as the wall thickness increases.	The wall thickness should not be too large; The rest are similar to steel castings.