Many of peers who do plastic mold design do not understand common materials of plastic mold. I have summarized some commonly used materials to share with you!

 

American Standard Number: AISI 1050 ~ 1055; Japanese Standard Number: S50C ~ S55C; German Standard Number: 1.1730; Medium carbon steel or 45# steel, it is called Ace Steel in Hong Kong. Hardness of this steel is: HB170 ~ HB220, cheap, easy to process, used as mold base, top column, and some unimportant parts on mold. General standard formwork is made of such steel;

US, Japan, Singapore, Hong Kong, China Standard Number: AISI P20, Germany and some European countries Number: DIN: 1.2311, 1.2378, 1.2312. This kind of steel is pre-hardened steel, generally not suitable for heat treatment, but it can be nitrided. Hardness difference of this steel type is also very large, from 280HRC ~ 400 depending on standard of steel plant. Due to pre-hardening treatment, mechanical cutting is not too difficult, so it is suitable to make some low-cost mold inserts. Some of large-volume mold bases also use this steel (some customers specify this steel as a mold base). Advantage is that hardness is higher than that of carbon steel, and deformation is also more stable than that of medium carbon steel. P20 steel is widely used in plastic mold, so there are many brands. Among them, brands that are more common in South China are: ASSAB One Wins. There are two different hardnesses produced in Sweden, 718S HB290~HB330 (330~340HRC) and 718H HB330~HB370 (340~380HRC). Datong Steel Works, made in Japan: NAK 80 (hardness 400HRC+20) and NAK55 (hardness 400HRC+20). Under normal circumstances, NAK 80 is used as a fixed mold insert, and NAK55 is used as a movable mold insert. It should be noted that NAK55 cannot directly do EDM skin texture according to steel agent explained that it is a sulfur-containing relationship, so there is streaks after EDM; Desheng Steel Works THYSSEN, made in Germany, has several 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 for EDM texture. It is more common in Europe to make mold bases. Code of GS312 is 40 Cr MN Mo S8 , and BOHLER is made in China. Numbers are: M261 (380~420HRC), M238 (360~420HRC),
M202 (290~330HRC), M202 can't do EDM texture since it is also sulfur. There are other brands that can not be recorded.

US, China, Hong Kong, Singapore, standard number: AISI H13, DIN: (Europe) 1.2344; Japan SKD61. Hardness of this steel is: HB185 ~ HB230, and must be heat treated.
Hardness used on plastic mold is generally 480~520HRC, and it can also be nitrided. Because it requires heat treatment, processing is more difficult, so it is more expensive in the price of mold. If it is required to heat hardness to 40HRC or more, mold is generally difficult to machine. Therefore, roughing of workpiece must be done before heat treatment. Reason is: water hole, screw hole, and tapping must be done before heat treatment. Otherwise, it is time-consuming to anneal and redo. This kind of steel is also widely used in plastic mold, so there are also many brands. Japan's Datong Steel DAIDO STEEL HI(mostly designated by Japanese customers) still has a lots of brands, because our factory is not commonly used, so it can not be recorded here.

AISI 6F7 European number: DIN 1.2767, this steel has a hardness of HB260 and requires heat treatment. Application hardness is generally 500 ~ 540HRC, this steel is commonly used by European customers, this steel has good toughness and lighting effect, because this steel is not common in South China, so there are not many brands.

AISI: 420 STAVAX DIN: 1.2083 Factory hardness HB180~240, heat treatment required, application hardness 480~520HRC, not suitable for nitriding heat treatment (cracking at sharp corners). This steel has good corrosion resistance and polishing effect. Therefore, general transparent rubber parts and corrosive rubber compounds, such as PVC and fireproof materials, V2, V1, V0 plastics are suitable for this kind of steel. This steel is also very commonly used in plastic mold, so there are many brands. If using Desheng, please note that if it is a transparent part, then dynamic mold insert must be GS083ESR (according to steel plant data, ESR electroslag re-dissolution is to improve crystal of steel Uniform, better polishing effect). If it is not transparent plastic parts and generally do not need high gloss, you can use ordinary GS083, because steel price is relatively cheap and does not affect quality of mold. This steel material is sometimes required by customers to be used as a mold base. Because of anti-rust relationship, water supply of cooling pipe can be ensured smoothly, so as to achieve a stable production cycle. There are many brands of this steel type, which cannot be recorded here.

 

DIN: 1.2316, AISI 420 STAVAX, factory hardness HB265~380, depending on specifications of steel plant. If it is a transparent plastic part, this steel is not recommended to use, because when polishing to high finish, it is easy to have pits due to insufficient hardness. At the same time, it is easy to have scratch marks during injection. It should be re-polished frequently, so it is still easy to use 1.2083 ESR heat treatment to adjust hardness to 480 ~ 520HRC (although hardness of this steel is not high, mechanical cutting is easier, mold completion cycle is shorter).

“AISI H11” European DIN 1.2343, hardness of this steel is: HB 210~230 and heat treatment is required, general application hardness is: 50~540 HRC. According to data of steel plant, this steel has a slightly higher toughness than 1.2344 (H13) and is often used in Europe. Because this steel is not popular in Asia and Americas, there are not many brands, only 2~3 brands are in Hong Kong.

Factory hardness is: HB200~225. It needs heat treatment. Hardness is 540~580 HRC. This steel is generally required by American customers to be used in fixed/movable mold inserts and rows. It is not common in Europe and South China.

AISI D2 European No.: DIN 1.2379, Japan JIS SKD11. Factory hardness: HB240~255, application hardness: 560~600HRC, can be nitriding treated, this steel is mostly used in mold slider (most used by Japanese customers). Brands are: ASSAB XW-41, Datong Steel Factory (DAIDO) DC-53 / DC11, Desheng Steel Works (THYSSEN) GS-379.

AISI 01, DIN 1.2510 & AISI 02, DIN 1.2842 Factory hardness: HB220~230, and needs heat treatment, application hardness 580~600HRC, this steel is used in plastic mold specialized on the line of gaskets and garbage nails, brand has: ASSAB, DF2, THYSSEN GS-510 and GS-842, LKM 2510.

 

This material is generally used in plastic mold where it is difficult to cool, because heat dissipation effect of copper is much faster than steel. Brands are: MOLDMAX 30/40, hardness: 260~320HRC and 360~420HRC, Desheng (B2) factory hardness is 350HRC.

Hardness of this material is: HB 210. It is used on the place that is difficult to cool on the mold. Heat dissipation effect is also very good. It is softer than copper, strength is not as good as that of copper, and output is not so big. It can also be considered.