Die steel classification and selection skills

We must first understand some basic common sense of the mold, both mold classification, according to the use of classification, mold is generally divided into hot mold, cold mold and plastic mold. In addition, it can be classified according to the length of service life: Level 1: more than 1 million times; Level 2:500,000 ~ 1 million times; Level 3:300,000-500,000 times; Level 4:100,000 ~ -300,000 times; Level 5: less than 100,000 times; The first and second level mold requires a die steel that can be heat treated with a hardness of about 50HRC, otherwise it will be easier to wear, so the choice of steel should have good heat treatment performance, but also have good cutting performance in the state of high hardness, of course, there are other considerations. Because there are many domestic mold steel manufacturers and grades, and the brand is confused, it does not have to be compared and studied as a reference material, and the materials mentioned below are imported materials. A large number of industrial mold manufacturing in China is after the reform and opening up, the mold technology import countries at that time are mainly Japan, Europe and the United States, Hong Kong and Taiwan and other regions, Hong Kong generally uses European and American technology and materials, while Taiwan uses Japanese materials and technology.

Currently commonly used mold materials are:

Sweden: S136 die steel, 8407 die steel, DF-2 die steel, 718 die steel;

USA: 420 die steel, H13 die steel, P20 die steel, D2 die steel;

Japan: SKD61 die steel, DC53 die steel, NAK80 die steel, SKD11 die steel, SKH-9 high speed steel;

Germany: 1.2379 die steel, 1.2083 die steel, 1.2316 die steel, 1.2344 die steel;

The injection molding material used in the injection molding mold has a great impact on the selection of mold steel, the addition of reinforcing agents or other modifying agents, such as glass fiber, the damage to the mold is large, and the selection of materials should be considered comprehensively. Strong acid plastic materials are PVC, POM, PBT; Weakly acidic plastic materials are PC, PP, PMMA, PA. Highly corrosive plastics are generally selected S136, 1.2316, 420 and other mold steels, and weakly corrosive plastics can be selected S136, 1.2316, 420, SKD61, NAK80, PAK90, 718 and so on. The appearance requirements of the product also have a great impact on the choice of mold materials, transparent parts and surface requirements mirror polishing products, optional materials are S136, 1.2316, 718, NAK80, PAK90, 420, mold with high transparency requirements should choose S136, followed by 420. If you only meet the product requirements without considering the price cost, may not be a good designer, mold manufacturing cost is also the most important, imported S136 and 1.2316 compared, the difference of dozens of pieces per kilogram, if you choose improperly it is difficult to make the factory get reasonable profits.

The mold of 300,000 to 500,000 molds uses more pre-hard materials, such as S136H, 1.2316H, 718H, 1.2083H and so on. P20, 718,738,618,1.2311, 1.2711, etc., are used for molds below 300,000 mold times. For ultra-low requirements of the mold can consider the use of S50C, 45# steel directly on the mold mold cavity. Cold work die steel is mainly used to manufacture molds for pressing and forming workpieces under cold conditions. Such as: cold blanking die, cold stamping die, cold drawing die, stamping die, cold extrusion die, thread pressing die and powder pressing die. The range of cold work die steels is very wide, from various carbon tool steels, alloy tool steels, high-speed steels to powder high-speed steels and powder high alloy die steels. Therefore, the recommendation and use classification of cold work die steel is more complex, and should be selected according to the actual situation. Hot work die steel is mainly used to manufacture molds for pressure processing of workpieces at high temperatures. Such as: hot forging die, hot extrusion die, die casting die, hot upsetting die, etc. Commonly used hot work die steels are: alloy die steels with medium and high carbon content adding Cr, W, Mo, V and other alloying elements; For hot work die steels with special requirements, high alloy austenitic heat resistant die steels are sometimes used. Aluminum alloy die casting mold material requirements are relatively high, should be based on the specific mold design requirements to choose the mold steel, die casting mold heat treatment technology requirements are higher, in the selection of reliable materials at the same time also fully consider the heat treatment, the preferred origin of materials 8418, H13, SKD61, 8407 and so on.