What Are the Differences Between Castings and Stampings?

Stamping is classified by process into two major categories: separation processes and forming processes. Separation processes, also known as blanking, aim to separate stampings from sheet metal along a specific contour line while ensuring the quality requirements of the separated section.

Stamping is an efficient production method. By using compound dies, especially multi-station progressive dies, multiple stamping processes can be completed on a single press, enabling fully automated production that covers coil uncoiling, leveling, blanking, forming, and finishing of strip materials. It features high production efficiency, good working conditions, and low production costs—generally, hundreds of parts can be produced per minute. The purpose of forming processes is to cause plastic deformation of the sheet metal without breaking it, so as to manufacture workpieces with the required shape and size. In actual production, multiple processes are often comprehensively applied to a single workpiece. Blanking, bending, shearing, deep drawing, bulging, spinning, and straightening are several main stamping operations.

Castings refer to metal-formed products obtained through various casting methods. Specifically, molten metal (after smelting) is poured, injected, suctioned, or introduced into a pre-prepared mold using other casting methods. After cooling, processes such as shakeout, cleaning, and post-treatment are carried out to obtain products with a specific shape, size, and performance.

Differences Between Hardware Stampings and Castings

Hardware stampings are characterized by being thin, uniform, lightweight, and strong. Stamping can produce workpieces with reinforcing ribs, ribs, undulations, or flanges—features that are difficult to manufacture by other methods—thereby improving the rigidity of the workpieces. Thanks to the use of precision dies, the dimensional accuracy of workpieces can reach the micrometer level, with high repeatability and consistent specifications. Additionally, stampings can be fabricated with holes, sockets, bosses, and other structures.

Hardness Testing Methods

• For hardware stampings: Rockwell hardness testers are used. For small-sized stampings with complex shapes—where the testable flat surface is extremely small and cannot be measured on ordinary bench-top Rockwell hardness testers—specialized testing methods may be required.

• For castings: The properties of castings directly affect the quality of subsequent processing, among which hardness is a key indicator determining the machinability of castings. Common hardness testing methods for castings include:

• HRA: Primarily used for high-hardness workpieces, measuring materials with hardness above HRC67 and surface hardness (e.g., cemented carbides, nitrided steel). The measurable range is HRA > 70.

• HRC: Mainly used to measure the hardness of steel parts (e.g., carbon steel, tool steel, alloy steel) after quenching or tempering. The measurable range is HRC 20–67.

1. Brinell Hardness (HB): Mainly used to measure the hardness of castings, forgings, non-ferrous metal workpieces, hot-rolled blanks, and annealed parts. The measurable range is ≤ HB450.

2. Rockwell Hardness (HR):

3. Vickers Hardness (HV): Used to measure the hardness of thin workpieces and steel plate products. It can also measure the hardness of surface-hardened parts (e.g., carburized, cyanided, nitrided parts).