Hardness testing of stamping parts

Stamping parts are the most commonly used parts in metal processing and mechanical manufacturing. Stamping processing is a processing method that uses molds to separate or shape metal strips. Its application range is very broad.

Stamping processing includes punching, bending, deep drawing, forming, finishing and other processes. The materials processed by stamping parts are mainly hot-rolled or cold-rolled (mainly cold-rolled) sheet metal materials, such as carbon steel plate, alloy steel plate, spring steel plate, galvanized plate, tin plate, stainless steel plate, copper and copper alloy Plate, aluminum and aluminum alloy plate, etc.

The hardness test of metal materials is of great significance in the processing of stamping parts. Hardness testing in the stamping industry can be divided into the following three parts:

1. Incoming inspection of raw materials.

2. The hardness test of the mold.

3. Hardness testing of intermediate products of stamping parts and finished stamping parts.

The respective introductions are as follows:

1. Hardness testing of stamping materials

The main purpose of the hardness test of stamping parts is to determine whether the annealing degree of the purchased metal sheets is suitable for the subsequent stamping parts processing. Different types of stamping parts processing techniques require plates of different hardness levels.

Hot-rolled steel plates are usually thick, and the Brinell hardness tester is generally required in the steel standard to test the hardness. Rockwell hardness tester is also feasible to detect hot-rolled steel plates, and HRB scale can be used. The portable Rockwell hardness tester is used to test hot-rolled steel plates, which can be tested without sampling, and the operation is very simple.

A variety of cold-rolled steel plates used for stamping parts processing mainly use Rockwell hardness tester to test the hardness, usually HRB scale, and HRC scale for harder ones. Thin plate material can use Webster hardness tester, surface Rockwell hardness tester HRN or HRT scale can also be used.

The hardness of the brass plate used for stamping parts processing can be tested with the HRB scale of the Rockwell hardness tester. The softer brass plates and red copper plates use HRF scales. The thinner sheet adopts HRT scale.

The aluminum alloy plate used for stamping parts can be tested with a Webster hardness tester. When the thickness of the material is greater than 13mm, the Barcol hardness tester can be used. The pure aluminum plate or low hardness aluminum alloy plate should use the Barcol hardness tester.

The ultra-thin plates of various metals used for stamping parts processing can use the HR30T scale of the surface Rockwell hardness tester and cooperate with the diamond anvil to test the HR30Tm hardness value in this way. The thickness of the tested sheet can be less than 0.05mm. This test method is specified in Appendix A of the national standard GB/T 230.1-2004. The HR15T and HR45T scales of the surface Rockwell hardness can also be used, and the hardness value is converted into HR30Tm after the test.

2. Hardness testing of stamping die

　The main material of stamping parts die is die steel (including tool steel and high-speed steel), and sometimes cemented carbide is used.

　Stamping molds usually require high hardness and wear resistance, and heat treatment is essential.

　The hardness test of die steel mainly adopts Rockwell hardness tester to test HRC hardness value. When the mold is large and inconvenient to move, the Leeb hardness tester can be used. The hardness test of cemented carbide adopts Rockwell hardness HRA scale.