The selection of steel not only affects the service life of injection molds, but also the cost of mold opening. Some characteristic plastic products may require the use of specific materials. Because the selection of materials is particularly important when opening injection molds. The following is an introduction to the characteristics and applicable products of several commonly used mold materials.
What are the commonly used mold steels?
1、 P20 steel.
P20 steel is a pre hardened mold steel, with a domestic grade of 3Cr2Mo, widely used in the manufacture of injection molds with low to medium complexity and small to medium batch sizes.
core features
1. Pre hardened state
It has undergone quenching and tempering treatment before leaving the factory, pre hardened to 30-35 HRC, and can be directly processed without the need for secondary heat treatment. Uniform hardness distribution, suitable for high-precision machining.
2. Processing performance
Good machinability, suitable for CNC milling, electrical discharge machining (EDM), etc. Medium polishing performance, up to # 2000- # 4000 mesh.
3. Wear resistance and toughness
Moderate wear resistance, suitable for ordinary engineering plastics. Has good toughness and can withstand the impact load of small and medium-sized molds.
4. Corrosion resistance
Corrosion resistance is average, and long-term contact with corrosive plastics such as PVC and flame retardant materials can cause rusting, requiring surface chrome plating or nitriding treatment.
Applicable scenarios
1. Plastic type
Suitable molds for manufacturing ordinary engineering plastic products, such as ABS, PP, PE, PS, PC, etc. Not applicable to glass fiber reinforced plastics (easily worn molds) and highly corrosive plastics (such as PVC requiring surface treatment).
2. Product type
Suitable for producing products with low requirements for mirror gloss or requiring simple textures, such as daily necessities (bottle caps, toy shells, etc.), household appliance components, automotive interior parts, etc.
3. Product output
The lifespan of injection molds made of P20 steel is around 100000 to 300000 molds. Within this range, the output is determined by the number of mold cavities, usage, and maintenance.
precautions
1. Avoid using plastics containing corrosive substances such as chlorine and fluorine unless surface treatment is carried out.
2. When stored for a long time, anti rust oil should be applied to prevent rusting caused by humid environment.
3. Complex molds can be partially embedded (such as using P20 for the cavity and higher hardness steel for the core).
     2、 718H steel
718H steel corresponds to an improved and upgraded version of P20 steel, with a domestic grade of 3Cr2NiMo. It belongs to pre hardened mold steel and is optimized for purity, uniformity, and comprehensive performance by adding nickel (Ni) elements. It is suitable for manufacturing high-precision and long-life medium and large injection molds.
core features
1. Pre hardened state
The factory hardness is 35-40 HRC, with a more uniform hardness distribution and stronger resistance to deformation. It can be directly processed to avoid dimensional fluctuations caused by heat treatment.
2. Processing performance
Excellent machinability, suitable for CNC machining and electrical discharge machining (EDM) of complex structures. Polishing performance is better than P20, reaching # 6000- # 8000 mesh, approaching the mirror effect of NAK80.
3. Wear resistance and toughness
Significantly improved wear resistance, suitable for engineering plastics filled with fiberglass and minerals. High toughness, good fatigue resistance, suitable for multi cavity molds or large molds.
4. Corrosion resistance
Better than P20, but weaker than stainless steel (such as S136), long-term contact with corrosive plastics still requires surface treatment (such as chrome plating).
Applicable scenarios
1. Plastic type
Suitable for high demand engineering plastic products, such as PA (nylon)+glass fiber (GF), PBT, PC/ABS, POM and other reinforced plastics. Transparent plastics such as PC, PMMA (acrylic), etc. require products with high surface smoothness.
2. Product type
Precision electronic components (such as connectors, housings), automotive functional components (lampshades, instrument panels), home appliance highlight panels, etc. Molds with complex structures or thin walls (good fatigue resistance).
3. Product output
The service life is 300000 to 500000 molds, which is about 30% longer than P20.
precautions
1. It is recommended to regularly check the wear of the mold cavity containing fiberglass plastic and promptly polish and repair it.
2. Avoid long-term exposure to humid environments and apply rust proof oil when storing.
3. For highly transparent plastics such as optical grade PC, it is recommended to combine mold temperature control (50-80 ℃) to optimize surface quality.
3、 NAK80 steel
NAK80 steel is a pre hardened mirror mold steel designed specifically for high gloss, high-precision injection molds. Its core advantage lies in achieving high hardness without heat treatment and excellent polishing performance, making it the preferred material for manufacturing transparent parts and high gloss surface products.
core features
1. Pre hardened state
The factory hardness is 40-42 HRC, which can be directly processed to avoid deformation during heat treatment. Excellent hardness uniformity, suitable for complex precision molds.
2. Mirror polishing performance
Polishing can reach # 10000- # 15000 mesh, which is the top level in the industry. The surface roughness (Ra) is ≤ 0.01 μ m, suitable for optical grade transparent parts (such as lenses, light guide plates) or high gloss appearance parts (such as chrome plated automotive trim).
3. Wear resistance and corrosion resistance
The wear resistance is better than P20 and 718H, but weaker than S136 stainless steel. Moderate corrosion resistance, long-term contact with corrosive plastics requires surface treatment (such as nickel plating).
4. Processing performance
Good cutting performance, but high hardness, requiring the use of hard alloy cutting tools. After electrical discharge machining (EDM), a hardened layer is easily formed on the surface and requires fine polishing.
Applicable scenarios
1. Plastic type
Suitable for high transparency/high gloss plastic products such as PC, PMMA (acrylic) COP、 Transparent ABS, etc. Not applicable to plastics containing corrosive components (such as PVC, flame retardants).
2. Product type
Optical components (camera lens, light guide plate), cosmetic packaging (bottle caps, powder boxes), automotive high gloss grilles/interior parts. Molds with complex surface textures (bite patterns, imitation leather patterns) are required.
3. Product output
The service life of the mold is around 500000 to 1 million molds, suitable for mass production of products.
precautions
1. Avoid using release agents containing sulfur and chlorine to prevent corrosion of the mold surface.
2. When stored for a long time, rust proof oil should be applied, especially in high humidity environments.
3. When injecting transparent plastic, it is recommended to control the mold temperature at 80-120 ℃ to reduce weld lines and improve glossiness.
4、 H13 steel
H13 steel is a type of hot work die steel, with a domestic grade of 4Cr5MoSiV1, designed specifically for high-temperature working environments. Its core advantage lies in excellent heat resistance and thermal fatigue resistance, making it suitable for molds that can withstand high-temperature cyclic stress for a long time.
core features
1. Hardness and toughness
After heat treatment, the hardness can reach 48-52 HRC (quenching+tempering). High toughness, better impact resistance than ordinary tool steel, suitable for high stress mold structures.
2. High temperature resistance performance
Good heat fatigue resistance, can work at 500-600 ℃ for a long time, can withstand up to 650 ℃ in the short term, is not easy to crack under alternating cold and hot working conditions, suitable for rapid cycle production, such as hot runner molds.
3. Wear resistance and corrosion resistance
Moderate wear resistance, which can be improved through surface treatment such as nitriding. Corrosion resistance is average, and long-term contact with corrosive media requires chrome plating.
4. Processing performance
The hardness in annealed state is about 180-220 HB, which is easy to cut. When precision machining is required after quenching, it is recommended to use electrical discharge machining (EDM) or grinding technology.
Applicable scenarios
1. Plastic type
Suitable for high-temperature engineering plastic products such as PEEK, PEI, LCP (liquid crystal polymer), PPS, as well as glass fiber reinforced plastic products such as PA+GF, PBT+GF (requiring high wear resistance cavities).
2. Product type
Products produced with thick walls or rapid cycles, such as car engine hoods, battery casings, and home appliance casings (such as microwave oven frames), require quick demolding. Engineering components that require high dimensional accuracy, such as electronic connectors, 5G antenna covers (LCP material), medical devices (such as surgical tool handles, PEEK material).
3. Production scale
Suitable for long life requirements of over one million cycles, especially under high temperature and high pressure conditions.
5、 S136 steel
S136 steel is a high chromium stainless steel mold steel, with a domestic grade of 4Cr13, known for its excellent corrosion resistance and polishing performance. It is specifically designed for injection molds of high cleanliness, high glossiness, and corrosive plastics, especially suitable for harsh scenarios such as medical and food packaging.
core features
1. Hardness and Wear Resistance
After heat treatment, the hardness can reach 48-52 HRC (quenching+tempering). Moderate wear resistance, can be improved by nitriding or PVD coating (such as contact with fiberglass reinforced plastic).
2. Corrosion resistance
The high chromium content (13.6%) endows it with extremely strong corrosion resistance and can be exposed to corrosive media such as PVC, flame retardants, and acidic plastics for a long time. The rust resistance ability far exceeds that of ordinary mold steel (such as P20, 718H), and no additional coating is required in humid environments.
3. Polishing property
Polishing can reach # 8000- # 12000 mesh, with a surface roughness (Ra) of ≤ 0.015 μ m, approaching the mirror effect of NAK80. Suitable for transparent plastics (such as PC, PMMA) and medical grade high cleanliness products.
4. Processing performance
The hardness of the annealed state is about 215-235 HB, and the cutting performance is good, but it is necessary to avoid sticking the tool. After electrical discharge machining (EDM), fine polishing is required to remove the white layer.
Applicable scenarios
1. Plastic type
Corrosive plastic products, such as PVC, halogen containing flame retardant materials (such as V0 grade ABS), and biodegradable plastics (containing acidic components). High transparency/medical grade plastic products, such as PC, PMMA, medical grade PP, PE (such as syringes, medication bottles).
2. Product type
Medical equipment (surgical instruments, dialysis components), food containers (bottle caps, freshness boxes), optical lenses, mobile phone lenses, cosmetic packaging (requiring mirror polishing).
3. Product output
The lifespan of the mold is over 500000 to 1 million mold cycles, especially in corrosive environments where the lifespan far exceeds that of ordinary steel.
precautions
1. Medical mold specialized machine processing to prevent oil stains or iron filings from remaining and avoid cross contamination.
2. Long term storage still requires the application of rust proof oil, especially in coastal or high humidity environments.
6、 2344 steel
2344 steel is a chromium molybdenum vanadium alloy hot work die steel with similar characteristics to H13 steel. It is designed specifically for high temperature and high pressure working conditions and has excellent heat fatigue resistance, making it suitable for harsh production environments with frequent cold and hot cycles.
core features
1. Hardness and toughness
After heat treatment, the hardness is 48-52 HRC (quenching+tempering), which balances high hardness and impact toughness. It is suitable for complex mold structures (such as thin-walled deep cavities) and reduces the risk of stress cracking.
2. High temperature performance
Can work for a long time at 500-600 ℃ and withstand 650 ℃ in the short term. Excellent thermal fatigue resistance, outstanding anti cracking ability under alternating cold and hot working conditions (such as die-casting molds), and significantly extended service life.
3. Wear resistance and corrosion resistance
Moderate wear resistance, can be improved by nitriding or coating (such as PVD). Corrosion resistance is average, and contact with corrosive plastics requires surface chrome plating.
4. Processing performance
The annealed state has a hardness of 180-220 HB, making it easy to cut, mill, and perform electrical discharge machining (EDM). When precision machining is required after quenching, it is recommended to use grinding or wire cutting processes.
Applicable scenarios
1. Plastic type
High temperature engineering plastics, such as PEEK, PEI, LCP, PPS (processing temperature>300 ℃). Containing glass fiber reinforced plastics such as PA66+GF, PBT+GF (requiring high wear resistant cavities).
2. Product type
Automotive components (such as dashboard, door panels, center console, car bumper, rearview mirror housings), electronic product housings (such as phone housings, computer housings), daily necessities (such as disposable lunch boxes, storage boxes), etc
3. Product output
Suitable for long lifespan requirements of over 1 million cycles.
precautions
Inspect the surface of the mold cavity every 50000 to 100000 mold cycles and promptly repair any microcracks or wear.
The above types of mold steel can basically meet the mold making needs of most plastic products.

steel listing:

1.2083 is a plastic mold steel produced in Germany, with a hardness of 215~240HBW.
1.2085 is a pre hardened plastic mold steel produced in Germany that improves mechanical processing performance and has strong corrosion resistance.
1.2311 pre hardened plastic mold steel, after heat treatment, has good processing and polishing performance, making it more suitable for electrical discharge machining.
1.2312 is suitable for plastic molds, with average polishing performance and excellent machining performance. Similar to AISI P20+S. Application status: 280-325 HB
1.2316 VICTORY mold steel is an imported electroslag remelting (ESR) mold steel.
1.2316 plastic mold steel is a chromium nickel manganese alloy mold steel with a factory hardness of 265-315HB after hardening and tempering.
1.2711 is pre hardened plastic mold steel, oil quenched and gas quenched plastic (rubber) mold steel, with a factory hardness of 310-345HB.
1.2714 is a pre hardened plastic mold steel from Germany, with a soft annealed hardness of up to 248HB. Application status: 36-52HRC.
1.2738HH plastic mold steel is refined using vacuum melting technology and is a type of Cr Ni Mo alloy steel.
1.2738 is a pre hardened plastic mold steel material produced according to German DIN standards, which is vacuum melted chromium Cr nickel Ni molybdenum Mo alloy steel.
1.2767 is a pre hardened plastic mold steel material produced by Goerlitz, Germany, with an annealed hardness of up to 285HB.
168H imported plastic mold steel can meet the requirements of injection molds for material toughness, corrosion resistance, and overall hardness balance
168 imported mold steel can meet the requirements of material toughness, corrosion resistance, and overall hardness balance for injection molds, and is a new type of alloy mirror corrosion-resistant stainless steel.
618HH is a vacuum melted chromium nickel molybdenum alloy steel that has undergone quenching and tempering treatment before leaving the factory
618H imported high-quality pre hardened plastic mold steel, 618H steel is an alloy steel produced by vacuum degassing, with high purity
618T Sweden is a pre hardened plastic mold steel suitable for large-sized molds and tools
618 steel Swedish universal pre hardened plastic mold steel. Good photo etching and polishing properties, pre hardened steel can be used for mold cavities without quenching.
68 mold steel is a plastic mold steel imported from Sweden, which is easy to cut, highly resistant to acid corrosion, and has undergone quenching and tempering treatment before leaving the factory.
718HH is a chromium nickel molybdenum alloy steel produced by vacuum melting, which has been pre hardened to 36-38HRC through heat treatment before leaving the factory.
718H steel is a Swedish pre hardened mirror acid resistant plastic mold steel. This steel has undergone pre hardening treatment, resulting in uniform material, high cleanliness, excellent polishing performance, and photo etching properties
AS136-VIP mold steel Scana from Sweden factory hardness: 3220HBA
AS136 die steel annealed pre hardened 220HB, 30-36HRC
ASGM mold steel is a grade of Scandinavian steel from Sweden, belonging to plastic mold steel
ASHM mold steel is a grade of Scandinavian steel from Sweden, belonging to plastic mold steel! Characteristics of ASHM Mold Steel: 1. High Purity, Hardness, and Uniformity of Microstructure
ASPM-VIP mold steel is a mirror plastic mold steel with a typical hardness of 40HRC, low deflection, high purity, and good toughness
ASPM mold steel is a mirror plastic mold steel with a typical hardness of 40HRC, low deflection, high purity, and good toughness
ASTM-VIP mold steel is a pre hardened mirror mold steel that combines high toughness and high hardness
CALMAX 635 chromium molybdenum vanadium cold work alloy tool steel, good toughness and wear resistance, hardness HRC56-60
CENA1 is a new type of stainless steel with pre hardened 40HRC hardness, easy machinability, and corrosion resistance.
CENA1 plastic mold steel is a new type of corrosion-resistant stainless steel imported from Japan, while CENA-V mold steel has excellent polishing properties
CORRAX is a highly corrosion-resistant plastic mold steel of stainless steel type in Sweden
CORRAX is a new type of chromium molybdenum vanadium alloy stainless tool steel and plastic injection mold steel.
CPM40 is a pre hardened plastic mold steel from Germany. It is a type of Cr Ni Mo alloy steel, belonging to precipitation hardening or age hardening mold steel.
CPM50 mold steel factory hardness: pre hardened to 36-41HRC
CRMHP ESR plastic mold steel is a type of Cr Ni Mo alloy steel.
D-STAR is a Japanese steel grade, high-quality series martensitic stainless steel that can achieve optical grade ultra-high mirror effect.
EM38 mold steel is pre hardened high hardness mold steel (350-410HB).
FS136 steel is a Fushun corrosion-resistant mirror mold steel with high purity, high mirror finish, good polishing performance, and excellent rust and acid resistance
FS139M (HPM38) Fushun Special Steel Mold Steel is suitable for high hardness plastic molds that require high corrosion resistance and mirror polishing.
After heat treatment, the hardness of FS139 can reach HRC: 52-58, and it also has high toughness, improving productivity and economic benefits.
FT61 (P20) Fushun mold steel has been pre hardened to 285-330HB (30-36HRC)
FT64 (2083) Fushun mold steel with high toughness, corrosion resistance, excellent polishing performance, and pure and fine steel structure
GEST80 ESR is a new type of chromium nickel molybdenum alloy precipitation and age hardening plastic mold steel from Germany, with a uniform hardness of approximately 40HRC.
GS-638 German mold steel is a conventional melted EF+LF+VD mold steel that can be polished and nitrided.
G-STAR high corrosion resistant plastic mold steel is used for manufacturing highly corrosive plastic molds such as PVC
HPM1, Hardness: Pre hardened at around 40HRC, HPM1 steel is a fast cutting pre hardened steel.
HPM2 hardness reaches HCR29-33, and pre hardened mold steel can be directly used for mold production without the need for reheating treatment.
HPM31 has a hardness of 56-60HRC and is a wear-resistant plastic mold steel with small deformation, suitable for use in precision molds.
HPM38 mold steel: pre hardened to HB 300-330, heat treated hardness 48-52HRC.
HPM50 steel is a high hardness, high polishing mirror plastic mold steel
HPM729-33HRC grade pre hardened steel has good mirror finish and discharge machinability.
HPM75 non-magnetic steel has a hardness of 40-45HRC.
HPM77 hardness 52HRC, high corrosion resistance mold steel, with high mirror finish
HPM-MAGIC, A new type of universal plastic mold steel with a hardness of 37-41HRC
M200 imported is a sulfur-containing chromium manganese molybdenum alloy plastic mold steel with excellent purity, which can achieve toughness and excellent mechanical processing performance
M238/M238HH mold steel is a pre hardened plastic/plastic mold steel that is not corrosion-resistant
M261 plastic mold steel is a new type of precipitation hardening steel with excellent purity, corrosion resistance, and wear resistance
M268 is a plastic mold steel with excellent purity, suitable for plastic molds with high requirements for polishing and fatigue strength
M300 plastic mold steel, belonging to martensitic stainless chromium steel, has excellent purity,
M303 plastic mold steel is a new type of corrosion-resistant martensitic stainless chromium steel with good toughness, excellent purity, corrosion resistance, and wear resistance.
M310 martensitic stainless high chromium plastic mold steel has excellent purity and strength, as well as excellent corrosion resistance and wear resistance
M314 plastic mold steel, belonging to martensitic stainless chromium steel, has excellent purity
M315 pre hardened corrosion-resistant frame steel is a new type of martensitic stainless chromium steel with excellent purity, corrosion resistance, and wear resistance.
M333 mold steel has excellent corrosion resistance, polishing performance, photo corrosion resistance, and electrical discharge machining performance.
M340 plastic mold steel has good wear resistance, corrosion resistance, toughness, etching and polishing properties.
M461 is a pre hardened high-performance mirror plastic mold steel with excellent purity
M461 is a pre hardened high-performance mirror plastic mold steel with excellent purity
MAS1C, Hardness 28~32HRC, mold steel is used to manufacture high-precision, super mirror, and complex cavity plastic molds
Mirrax ESR is a fully hardened corrosion-resistant steel with excellent polishing properties.
MLQ plastic mold steel has excellent comprehensive mechanical properties, high hardenability, and can achieve uniform hardness for steel with larger cross-sectional dimensions
NAK101, Time hardening to 30-35HRC, belonging to ultra-high corrosion resistant pre hardened plastic mold steel
NAK55, Japan, high-performance precision plastic mold steel, is a nickel Ni aluminum Al copper Cu precipitation age hardening steel
NAK80, Pre hardened 40HRC grade mold steel. NAK80 has good processability and mirror finish.
NAK-PRM, Japanese high mirror anti cracking plastic mold steel
Nimax, a new type of plastic mold steel imported from Sweden, is a low-carbon plastic mold steel with a factory hardness of approximately 40 HRC
P20+Ni American mold steel is suitable for large molds and is a trace alloy vacuum degassing steel
The hardness of P20HH plastic mold steel has been increased to 310-352HB (33-38HRC), with higher polishing performance.
P20 pre hardened plastic mold steel has good comprehensive mechanical properties, high hardenability, and can achieve uniform hardness for steel with larger cross-sectional dimensions.
P21 Fencola mold steel is a time hardened plastic mold steel, and the time hardening treatment can provide an average hardness of 40HRC-42 HRC.
PAC5000, Pre hardened steel with a hardness of 36~39HRC
PAT868S - Steel for high mirror finish, high toughness, and corrosion-resistant plastic molds.
PD613m Japan is a high hardness, high mirror plastic mold steel.
PDX18 hardness above 50HRC, mold steel - high toughness and rust resistant plastic mold steel
PM-35 breathable steel is a new type of exhaust material imported from Japan, also known as exhaust steel or breathable steel in China
POLMAX uses two new melting processes, ESR (electroslag remelting) and VAR (vacuum melting), to reduce impurities in steel to a lower level
PX4 plastic mold steel is a pre hardened steel with a factory hardness of 30-33HRC
PX88, Hardness of 30-33HRC, mold steel has * * mechanical properties and machinability
PXA30 has a hardness of 30-33HRC and is a pre hardened high gloss plastic mold steel.
Compared with 1.2085 and 420F mold steel, RoyAloy has improved machining performance, dimensional stability, and surface smoothness
S136 SUP mold steel has excellent corrosion resistance and polishing properties; Excellent wear resistance and hardenability
S136H mold steel belongs to Swedish imported plastic mold steel, and S136H pre hardened corrosion-resistant mirror mold steel is suitable for mirror molds
S136 mold steel belongs to Swedish imported plastic mold steel, which has a pure and fine structure, excellent corrosion resistance, polishing performance, and good wear resistance
S-STAR, Hardness: up to 53HRC, stainless plastic mold steel, also known as PAK90 mold steel.
Stavax ESR soft annealing to approximately 190 HB; pre hardening: 27-35 HRC
STAVAX Sweden has excellent polished surface quality. AISI: 420 mold steel WNr: Improved 1.2083 mold steel JIS: SUS420J2 stainless steel.
SW718H steel is a pre hardened alloy mold steel. Hardness of 290-340HBW.
Toolox33, Swedish imported Toda steel is a new type of pre hardened tool steel with high strength, low internal stress, and dimensional stability
Toolox40 is a pre hardened steel with excellent impact toughness and ultra-low residual stress, suitable for optical polishing requirements, and stable mechanical processing performance
Toolox44, Application of Tuoda Steel: Metal stamping molds, punching with a thickness of 6mm or more, high toughness requirements, hot stamping, stretching, cold extrusion, plastic molds
Unimax imported Swedish hot work die steel is a new type of high-performance chromium molybdenum vanadium alloy tool steel.
VIDAR 1 ESR is suitable for hot work and plastic molds, which require high toughness and large plastic molds with surface quality obtained through polishing and skin treatment.
WR15E is a precipitation or age hardening mold steel with a hardness of approximately 40HRC. This is a very clean and uniform grain steel with a uniform structure, hardness, and good dimensional stability.
X15TN, In Oberdua, France, the plastic mold steel adopts the electroslag remelting process, and X15TN plastic mold steel can achieve good polished surface quality.
XPM mold steel is a chromium nickel molybdenum alloy steel, belonging to the category of pre hardened plastic mold steel,