What is casting technology?

Casting refers to the process of melting metal into a liquid that meets specific requirements, then pouring it into a mold after cooling, solidification, and cleaning—resulting in a casting (part or blank) with a predetermined shape, size, and performance. It is a fundamental process in modern mechanical manufacturing.

Casting offers low costs for producing blanks, making it particularly economical for manufacturing parts with complex shapes—especially those featuring intricate cavities. At the same time, casting provides excellent versatility and delivers strong, well-balanced mechanical properties. However, casting production requires a wide range of materials (such as metals, wood, fuels, and molding materials) as well as specialized equipment (including metallurgical furnaces, sand mixers, molding machines, core-making units, sandblasting machines, shot blasting machines, and cast iron plates), which can generate dust, harmful gases, and noise, ultimately leading to environmental pollution.

Casting is one of the earliest metalworking techniques mastered by humankind, with a history spanning approximately 6,000 years. As early as 3200 BCE, copper frog figurines appeared in Mesopotamia. By the 13th to 10th centuries BCE, China had already entered the golden age of bronze casting, during which the technology reached remarkably advanced levels. Examples include the 875-kilogram Simuwang Tripod from the Shang Dynasty, the Yi Hou Zun Pan from the Warring States period, and the translucent mirror from the Western Han Dynasty—each representing iconic achievements of ancient casting. In its early stages, casting was heavily influenced by pottery traditions, with cast objects often serving as tools or implements for agricultural production, religious rituals, and daily life, while also showcasing a strong artistic flair. By 513 BCE, China produced what is believed to be one of the world’s earliest recorded cast iron pieces—the Golden Tripod (weighing about 270 kilograms). Around the 8th century CE, Europe began manufacturing its own cast iron artifacts. Following the Industrial Revolution in the 18th century, casting entered a new era, increasingly supporting large-scale industrial applications. Throughout the 20th century, the field of casting experienced rapid advancements. Innovations included the development of ductile iron, malleable iron, ultra-low-carbon stainless steel, as well as aluminum-copper, aluminum-silicon, and aluminum-magnesium alloys, alongside titanium-based and nickel-based alloys. Additionally, groundbreaking casting materials like gray iron were enhanced through innovative processes such as inoculation. In the latter half of the 20th century, new technologies emerged, including high-pressure molding using wet sand, chemical-hardened sand molding with core-making capabilities, vacuum-assisted molding, and other specialized casting methods. Meanwhile, advancements in surface treatment—such as shot peening and cleaning—further refined the quality and performance of cast components.

There are many types of castings, traditionally categorized as follows: ① Conventional sand casting, which includes wet sand molds, dry sand molds, and chemically hardened sand molds. ② Special casting processes can also be divided into two main groups based on the molding materials: special casting processes that primarily use natural mineral sands (such as investment casting, clay mold casting, shell mold casting, vacuum casting, full-mold casting, and ceramic mold casting) and special casting methods that rely mainly on metals as the molding material (e.g., die casting, pressure casting, continuous casting, low-pressure casting, and centrifugal casting).

The casting process typically includes:

① Prepare the casting mold (the container that transforms liquid metal into a solid form through casting). Casting molds can be classified according to their materials into sand molds, metal molds, ceramic molds, clay molds, graphite molds, and more. The quality of mold preparation is a key factor influencing the quality of the castings.

② Melting and pouring of cast metals; casting metals (casting alloys) primarily include cast iron, cast steel, and cast non-ferrous alloys.

③ Casting handling and inspection, including removing cores and foreign objects from the casting surface, eliminating sprues and risers, eliminating burrs, cracks, and other protrusions, as well as performing heat treatment, shaping, rust-proofing, and rough machining.