Introduction outline of commonly used steel for plastic molds


(1) C45W medium carbon steel

American Standard Number: AISI1050~1055; Japanese Standard Number: S50C~S55C German Standard Number: 1.1730. Medium-carbon steel or 45# steel is called the king steel in Hong Kong. The hardness of this steel is: HB170~HB220. It is cheap and easy to process. It is used as a mold base, top pillar, and some unimportant parts in plastic molds. The above general standard formwork is made of this kind of steel.

(2) 40CrMnMo7 pre-hardened plastic mold steel

The United States, Japan, Singapore, Hong Kong, China Standard Code: AISIP20, Germany and some European countries code: DIN: 1.2311, 1.2378, 1.2312. This kind of steel is pre-hardened steel, which is generally not suitable for heat treatment, but it can be nitrided. The hardness of this steel grade is also very different. From 280HRC to 400 depending on the standard of the steel plant, because it has been pre-hardened, mechanical Cutting is not too difficult, so it is very suitable to make inserts for some medium and low price molds. Some mold bases for mass production also use this steel (some customers specify to use this steel as a mold base). The advantage is that the hardness is better than that of medium carbon. The steel is high and the deformation is more stable than that of medium carbon steel. Because P20 is widely used in plastic molds, there are many brands. Among them, the more common brands in southern China are: ASSAB, and there are two types made in Sweden. Different hardness, 718SHB290~HB330 (330~340HRC), 718HHB330~HB370 (340~380HRC). Datong Steel Plant, made in Japan: NAK80 (hardness 400HRC+20) and NAK55 (hardness 400HRC+20). Under normal circumstances, NAK80 is used for fixed mold inserts and NAK55 is used for movable mold inserts. Please note that NAK55 cannot be directly used for EDM According to the steel agent’s explanation, the skin texture is related to sulfur, so there are stripes after EDM; Desheng Steel Works THYSSEN, made in Germany, there are several serial numbers: GS-711 (hardness 340~360HRC),

GS738 (hardness 320~350HRC), GS808VAR (hardness 380~420HRC), GS318 (hardness 290~330HRC), GS312 (hardness 290~330HRC), GS312 contains sulfur and cannot be used as EDM pattern. It is more common to make mold bases in Europe. The code is 40CrMNMoS8, made in BOHLER Austria, and the numbers are: M261 (380~420HRC), M238 (360~420HRC), M202 (290~330HRC), M202 can not be made of EDM pattern, it also contains sulfur, there are other brands , Can not be exhausted.

Introduction outline of commonly used steel for plastic molds

(3) X40CrMoV51 hot work steel

The United States, China, Hong Kong, Singapore, standard number: AISIH13, DIN: (Europe) 1.2344; Japan SKD61, the factory hardness of this kind of steel is: HB185 ~ HB230 must be heat treated.

The hardness used on plastic molds is generally 480~520HRC. Nitriding treatment is also available. Because heat treatment is required and processing is more difficult, the machining price of the mold is more expensive. If heat treatment is required to a hardness above 40HRC, the mold generally uses machinery Machining is more difficult, so the rough machining of the workpiece must be done before the heat treatment, which is: water holes, screw holes, and tapping must be done before heat treatment, otherwise it will be time-consuming and troublesome to rework after annealing. This kind of steel is also commonly used in plastic molds, so there are many brands. The brands commonly used in our factory are: ASSAB (ASSAB), their serial number is 8407; THYSSEN, their serial number is GS344ESR or GS344EFS . (We generally use GS344ESR for ordering parts and GS344EFS for moving parts); Japan’s Datong Steel DAIDOSTEELHI (mostly designated by Japanese customers), there are still many brands, because our factory is not commonly used, so we can not list all .

(4) X45NiCrMo4 cold work steel

AISI6F7 European number: DIN1.2767. This kind of steel has a factory hardness of HB260 and requires heat treatment. The general application hardness is 500~540HRC. European customers often use this steel. This steel has good toughness and good polishing effect. Because this steel is in South China The region is not common, so there are not many brands. Our company uses THYSSEN GS767.

(5) X42Cr13 (stainless steel)

AISI: 420STAVAXDIN: 1.2083 Factory hardness HB180~240, heat treatment is required, application hardness 480~520HRC, not suitable for nitriding heat treatment (cracking at sharp corners). This steel has good corrosion resistance and polishing effect, so generally transparent rubber parts and corrosive rubber materials, such as PVC and fireproof materials, V2, V1, and V0 plastics are very suitable for this steel, and this steel is also very common. It is used in plastic molds, so there are many brands. Our company’s commonly used ones are: ASSAB S-136ESR THYSSEN GS083-ESR, GS083GS083VAR; If you use Desheng, pay attention, if it is a transparent part, Then the fixed and movable mold inserts must be GS083ESR (according to the data of the steel plant, ESR electroslag remelting is to improve the crystal uniformity of the steel, and the polishing effect is better). It is not a transparent plastic part. The movable mold generally does not need high finish, and ordinary can be used. GS083, because the price of steel is relatively cheaper, and does not affect the quality of the mold. Sometimes customers also request this steel to be used as a mold base. Because of the anti-rust relationship, it can ensure the smooth water transportation of the cooling pipe to achieve the production cycle. Stable, there are still many brands of this steel grade, which cannot be listed.

(6) X36CrMo17 (pre-hardened stainless steel)

DIN: 1.2316, AISI420STAVAX, factory hardness HB265~380, depending on the specifications of the steel plant, if it is a transparent plastic part, our company generally does not use this steel, because when polishing to a high finish, it is easy to have pits due to insufficient hardness, and at the same time Beer plastics are also prone to flower marks and need to be polished frequently, so the 1.2083ESR is heat treated and hardened to 480~520HRC to save a lot of trouble (although the hardness of this steel is not high, mechanical cutting is easier, and the mold completion cycle is shorter ).

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