Casting Technology: Complete Collection of Graphic Casting Process(2)
(4) Low pressure casting
Low-pressure casting: refers to a method in which a liquid metal is filled under a lower pressure (0.02 to 0.06 MPa) and crystallized under pressure to form a casting.
1. The pressure and speed during pouring can be adjusted, so it can be applied to various casting types (such as metal type, sand type, etc.), casting various alloys and various sizes of castings;
2, using the bottom injection type filling, the metal liquid filling type is stable, no splash phenomenon, can avoid the entrapment of gas and the scouring of the type wall and the core, and improve the pass rate of the casting;
3. The casting is crystallized under pressure. The casting has compact structure, clear outline, smooth surface and high mechanical properties, which is especially beneficial for the casting of large thin-walled parts;
4, eliminating the need to replenish the riser, the metal utilization rate increased to 90 ~ 98%;
5, low labor intensity, good working conditions, simple equipment, easy to achieve mechanization and automation.
Application: Mainly based on traditional products (cylinder head, wheel hub, cylinder block, etc.).
(5) centrifugal casting
Centrifugal casting: A casting method in which a molten metal is poured into a rotating mold and filled with a mold under centrifugal force to solidify and form.
1. There is almost no metal consumption of the gating system and the riser system, which improves the process yield;
2. The core can be used in the production of hollow castings, so the metal filling ability can be greatly improved when producing long tubular castings;
3. The casting has high density, less defects such as pores and slag inclusion, and high mechanical properties;
4. It is convenient to manufacture composite metal castings of cylinders and sleeves.
1. There are certain limitations when used to produce shaped castings;
2. The diameter of the inner hole of the casting is not accurate, the surface of the inner hole is rough, the quality is poor, and the machining allowance is large;
3. Castings are prone to segregation of specific gravity.
Centrifugal casting was first used to produce cast pipes. At home and abroad, centrifugal casting technology was used in metallurgy, mining, transportation, irrigation and drainage machinery, aviation, national defense, automobile and other industries to produce steel, iron and non-ferrous carbon alloy castings. Among them, the production of castings such as centrifugal cast iron pipes, internal combustion engine cylinder liners and bushings is the most common.
(6) Gravity die casting
Metal casting: refers to a molding method in which a liquid metal is filled with a metal mold under the action of gravity and cooled and solidified in a mold to obtain a casting.
1. The thermal conductivity and heat capacity of the metal type are large, the cooling rate is fast, the microstructure of the casting is dense, and the mechanical properties are about 15% higher than that of the sand casting.
2. Castings with higher dimensional accuracy and lower surface roughness values can be obtained with good quality stability.
3, because of the use and rarely use sand core, improve the environment, reduce dust and harmful gases, reduce labor intensity.
1. The metal type itself has no gas permeability, and certain measures must be taken to derive the air generated by the cavity and the gas generated by the sand core;
2, the metal type has no repellent property, and the casting is prone to crack when solidified;
3. The metal type has a long manufacturing cycle and high cost. Therefore, only when a large number of batch production, can show good economic results.
Application: Metal casting is suitable for mass production of non-ferrous alloy castings such as aluminum alloys and magnesium alloys with complex shapes, as well as castings and ingots for the production of steel and metal.
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