Process characteristics of Squeeze Casting Technology

From the study of material usability of squeeze casting technology, almost all kinds of alloys, including casting alloy, forging alloy and even refractory alloy, can be squeeze cast. At present, aluminum alloy, copper alloy, magnesium alloy, ferroalloy and zinc base alloy are widely used, especially aluminum, magnesium alloy and its composite materials. With the development of aerospace, shipbuilding, automobile, electromechanical and instrument light industry, which requires lightweight, low cost, high quality and high reliability, aluminum magnesium alloy and its composites become one of the preferred structural materials for its parts. The advantages of squeeze casting can be more prominent.

The mechanical properties of a series of high-strength wrought aluminum alloy parts for aviation by squeeze casting can approach the level of conventional forgings. There are also relevant researches on casting heat-resistant Al Cu alloy, but its application is still limited. Squeeze casting is a good way to save energy and promote the development of low-carbon environmental protection. Squeeze casting technology has its own characteristics. At present, squeeze casting technology can be classified into direct squeeze casting and indirect squeeze casting according to processing methods. Direct squeeze casting refers to the direct forming of liquid metal poured into the mold cavity under the pressure exerted by the punch or upper die. It is suitable for the production of parts with larger wall thickness, relatively simple shape and higher performance requirements. The microstructure of the parts shows a small amount of plastic deformation. Indirect squeeze casting means that the liquid metal poured into the closed mold cavity is solidified by filling the whole mold cavity through a certain sprue under the action of the injection punch. It is suitable for the production of parts with more complex shape and more uniform wall thickness. There is almost no plastic deformation structure in the microstructure observation of the parts. Squeeze casting technology has its own characteristics

(1) In the process of squeeze casting, the UN solidified metal melt has been subjected to isostatic pressure, filling flow and solidification under high pressure. The microstructure of squeeze casting parts is compact, the grain is fine, and the mechanical properties are better than those of conventional castings and close to those of forgings.

(2) When the solidified metal melt is formed, it will produce certain plastic deformation under high pressure, which makes the surface of the part closely fit with the mold cavity wall. The appearance quality of the part is excellent, and the surface roughness can reach ra6.3 ~ Ra1.6.

(3) When a certain plastic deformation occurs in the solidification layer, part of the energy will be consumed, and the isostatic pressure on the metal melt will change, and the value of isostatic pressure will decrease with the increase of solidification degree.

(4) Solid phase and liquid phase mixing zone, under the action of larger pressure, will carry out certain mandatory feeding, which can eliminate the internal defects such as conventional shrinkage cavity, shrinkage porosity and air hole, and improve the quality of products significantly, and can produce complex shape parts that can not be manufactured by general die forging process.

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