Castings are metal formed objects obtained by various casting methods. By pouring smelted liquid metal into prefabricated molds, they are cooled, solidified, cleaned, and processed to obtain blanks or parts with certain shapes, sizes, and properties. The following are its main characteristics, classifications, and applications:
1、 Core Features
Technological advantages
Can produce parts with complex shapes, especially suitable for structures with complex internal cavities (such as engine cylinder blocks).
The material has a wide adaptability, and almost all metal alloys (steel, iron, copper, aluminum, etc.) can be cast, with casting weights ranging from a few grams to hundreds of tons.
Raw materials mostly come from scrap steel and scrap parts, with low cost and near net forming.
Process limitations
Mechanical properties are usually lower than forgings, and defects such as porosity and shrinkage porosity are prone to occur.
Sand casting has a high labor intensity for single piece production, and the quality stability is affected by the process steps.
2、 Classification method
By material type
Cast iron parts: gray cast iron, ductile iron, etc. (such as car wheels).
Steel castings: high-strength components (such as mining machinery).
Nonferrous metal castings: aluminum alloy (automotive cylinder head), copper alloy (bearings), etc.
According to the molding process
Sand casting: accounting for 80%, used for engine cylinder blocks, crankshafts, etc.
Special casting:
Die casting: High efficiency production of precision parts (such as phone cases).
Investment casting: high-precision complex parts (such as turbine blades).
Centrifugal casting: tubular parts (such as water pipes).
3、 Application Fields
Mechanical manufacturing: Machine tool bed (gray cast iron), crankshaft (ductile iron), etc., accounting for 50-90% of the weight of mechanical products.
Automotive industry: Aluminum alloy castings such as steering knuckles and control arms replace cast iron, reducing weight by over 50%.
Daily life: door locks, radiators, cooking utensils, etc.
4、 Quality requirements
It is necessary to meet the standards of defect free appearance, dimensional accuracy, internal tissue density, and mechanical properties (such as tensile strength), and control the quality through X-ray, ultrasonic and other testing methods.