The sand casting process entails patternmaking, molding, melting and pouring, and cleaning. The pattern, usually in two parts known as cope and drag, serves as the form around which sand is compacted. After replicating the pattern, the cope is removed, and the pattern is extracted. Subsequently, core boxes, or additional inserts, may be integrated before replacing the cope. Following the solidification of the poured metal, the casting is extracted, trimmed of risers and gates from the pouring process, and meticulously cleaned of any adhered sand and scale.
Investment casting, also known as lost-wax casting, employs disposable wax patterns for each cast part. The process involves injecting wax directly into molds, coating it with refractory material and a binding agent in multiple stages to create a substantial shell. Multiple patterns are grouped on common sprues. After hardening the shells, the patterns are inverted, and the wax is removed through heating in ovens. Molten metal is then poured into the remaining shells, solidifying into the desired shape. The refractory shell is subsequently broken away, revealing the finished casting. This method is frequently utilized in the automotive, power generation, and aerospace industries, particularly for manufacturing intricate components like turbine blades.
Plaster casting, akin to sand casting, employs a blend of gypsum, strengthening compounds, and water in lieu of sand. The plaster pattern is usually treated with an anti-adhesive compound to prevent adhesion to the mold, and the plaster has the ability to fill gaps around the mold. Post-casting, the plaster material often develops cracks or defects, necessitating replacement with fresh material.
Die Casting (Metal Casting Process)：
Die casting is a high-pressure molding method primarily utilized for non-ferrous metals and alloys like zinc, tin, copper, and aluminum. The reusable mold, coated with a lubricant for temperature control and ease of component ejection, undergoes rapid injection of molten metal under continuous high pressure until solidification. This ensures the prevention of any segment of the material from hardening prematurely during casting.
Permanent Mold Casting：
Permanent mold casting, akin to die casting and centrifugal casting, employs reusable molds made of materials like steel or graphite. This method is commonly used for casting materials such as lead, zinc, aluminum, magnesium alloys, specific bronzes, and cast iron. Utilizing a low-pressure process, pouring is typically done manually using multiple molds on a turntable. As molds rotate through various stations, they undergo successive coating, closing, filling, opening, and emptying. A variation, known as slush casting, involves filling the mold but emptying it before complete metal hardening, resulting in a hollow cast shell. This technique, similar to molding hollow chocolate products, utilizes metal molds for enhanced heat transfer, enabling the shell to harden while the core remains liquid.