In the field of injection molding mold manufacturing, the selection of materials is of crucial importance. It directly affects the performance, lifespan of the mold, and the quality of plastic products. With the continuous development of the manufacturing industry, the types of injection molding mold materials are becoming increasingly rich, and the technical parameters are becoming more precise and diverse. A deep understanding of these materials and their technical parameters is of great significance for optimizing mold design, improving production efficiency, and reducing costs.

1. P20 Pre - hardened Steel

• Characteristics: P20 steel is a widely used pre - hardened plastic mold steel with good comprehensive mechanical properties. Its hardness is usually between 28 - 34HRC. This allows it to be directly machined without complex heat treatment during the processing, greatly shortening the mold manufacturing cycle. At the same time, this steel has good polishing performance and can meet the high requirements of plastic products for surface finish.

• Application Scenarios: It is suitable for manufacturing general injection molds, such as small daily necessities molds and toy molds. These molds do not have particularly high requirements for the strength and wear resistance of the steel, but are more sensitive to processing costs and production efficiency.

• Key Technical Parameters: The tensile strength is about 1000 - 1200MPa, the yield strength is about 800 - 1000MPa, the elongation is 10% - 15%, and the impact toughness is between 50 - 70J/cm².

2. 718H Pre - hardened Steel

• Characteristics: 718H steel is an improved pre - hardened steel developed on the basis of P20 steel. It has higher purity and a more uniform structure. Its hardness is generally between 33 - 37HRC, slightly higher than that of P20 steel. Therefore, it has better wear resistance and dimensional stability. The processing performance of this steel is also excellent. While ensuring the mold accuracy, it can effectively reduce the deformation during the processing.

• Application Scenarios: It is commonly used for manufacturing large - scale and precision injection molds, such as automotive parts molds and home appliance shell molds. These molds bear large pressure and friction during use and require the steel to have high strength and wear resistance.

• Key Technical Parameters: The tensile strength can reach 1200 - 1400MPa, the yield strength is about 1000 - 1200MPa, the elongation is 8% - 12%, and the impact toughness is about 40 - 60J/cm².

3. NAK80 Mirror Steel

• Characteristics: NAK80 steel is a precipitation - hardened mirror plastic mold steel with extremely high mirror polishing performance. It can achieve a surface roughness of Ra0.01 - 0.02μm. Its hardness is uniform, between 37 - 43HRC, and the heat treatment deformation is extremely small. In addition, this steel also has good electrical discharge machining performance and welding performance.

• Application Scenarios: It is mainly used for manufacturing injection molds with extremely high surface quality requirements, such as optical lens molds and cosmetic packaging molds. These molds require the plastic products to have a mirror - smooth surface without any defects.

• Key Technical Parameters: The tensile strength is about 1300 - 1500MPa, the yield strength is about 1100 - 1300MPa, the elongation is 6% - 10%, and the impact toughness is in the range of 30 - 50J/cm².

4. SKD61 Hot - working Die Steel

• Characteristics: SKD61 steel is a medium - alloy hot - working die steel with good hot strength, thermal fatigue resistance, and hot wear resistance. At high temperatures, its hardness and strength can remain stable and are not prone to softening and deformation. After quenching and tempering treatment of this steel, the hardness can reach 40 - 45HRC.

• Application Scenarios: It is suitable for manufacturing injection molds that work in high - temperature and high - pressure environments, such as die - casting molds and hot extrusion molds. During the injection molding process, the mold needs to withstand the repeated scouring of high - temperature plastic melt and high - pressure action, and SKD61 steel can meet these harsh working conditions.

• Key Technical Parameters: The high - temperature tensile strength is 800 - 1000MPa (600℃), the thermal fatigue crack initiation life can reach 10000 - 20000 cycles, and the thermal expansion coefficient is 1.2×10⁻⁵/℃ (20 - 600℃).

1. ADC12 Aluminum Alloy

• Characteristics: ADC12 aluminum alloy is a commonly used die - casting aluminum alloy with good fluidity and filling performance. It can quickly fill the mold cavity during die - casting to form complex shapes. Its density is relatively low, only about one - third of that of steel. Therefore, it can effectively reduce the weight of the mold and lower the mold manufacturing and transportation costs. In addition, this aluminum alloy has good thermal conductivity, which helps to dissipate heat quickly during the injection molding process and improve production efficiency.

• Application Scenarios: It is suitable for manufacturing some injection molds with high requirements for weight, complex shapes, and large production batches, such as electronic product shell molds and automotive interior part molds.

• Key Technical Parameters: The tensile strength is 220 - 280MPa, the yield strength is 150 - 200MPa, the elongation is 1% - 3%, the Brinell hardness is 80 - 100HBW, and the thermal conductivity is 96W/(m·K).

2. 6061 Aluminum Alloy

• Characteristics: 6061 aluminum alloy is a heat - treatable aluminum alloy with medium strength and good corrosion resistance. After heat treatment, its hardness and strength are significantly improved, and it also maintains good processing performance and welding performance. The cost of this aluminum alloy is relatively low, with high cost - effectiveness.

• Application Scenarios: It is commonly used for manufacturing some injection molds with certain requirements for strength and corrosion resistance but more sensitive to weight and cost, such as small plastic container molds and simple toy molds.

• Key Technical Parameters: The tensile strength is 205 - 310MPa, the yield strength is 110 - 276MPa, the elongation is 8% - 16%, the Brinell hardness is 65 - 95HBW, and the thermal conductivity is 155W/(m·K).

1. C17200 Beryllium Copper

• Characteristics: C17200 beryllium copper is an age - hardened beryllium copper alloy with extremely high strength, hardness, and wear resistance. Its elastic limit and fatigue strength are also very excellent, and it is not prone to deformation and damage under repeated stress. In addition, this alloy also has good electrical conductivity and thermal conductivity, as well as excellent corrosion resistance and stress relaxation resistance.

• Application Scenarios: It is mainly used for manufacturing some injection molds with extremely high requirements for mold performance, such as precision connector molds and high - speed injection molds. These molds need to withstand high pressure, high speed, and high - frequency impacts during operation. C17200 beryllium copper can meet these harsh working conditions and ensure the high precision and long lifespan of the mold.

• Key Technical Parameters: The tensile strength can reach 1200 - 1400MPa, the yield strength is 1000 - 1200MPa, the elongation is 2% - 6%, the Rockwell hardness is HRC38 - 44, the electrical conductivity is 22%IACS, and the thermal conductivity is 105W/(m·K).

1. The Shape and Size of Plastic Products: For plastic products with complex shapes and high requirements for dimensional accuracy, mold materials with good processing performance and high dimensional stability, such as 718H pre - hardened steel or NAK80 mirror steel, need to be selected. For plastic products with simple shapes and large sizes, cost - effective P20 pre - hardened steel or aluminum alloy materials can be considered.

2. The Production Batch of Plastic Products: If the production batch of plastic products is large, the lifespan of the mold becomes a key factor. Materials with good wear resistance and high strength, such as SKD61 hot - working die steel or C17200 beryllium copper, should be selected. For molds with small production batches, materials with low cost and convenient processing can be selected.

3. Injection Molding Process Parameters: Different injection molding process parameters, such as injection pressure, temperature, and speed, also have different requirements for mold materials. Under high - temperature and high - pressure injection conditions, materials with good hot strength and excellent thermal fatigue resistance, such as SKD61 steel, need to be selected.

1. Mechanical Properties: Including strength, hardness, toughness, wear resistance, etc. Strength and hardness determine the resistance of the mold when 承受压力和摩擦力，toughness affects the anti - fracture performance of the mold when subjected to impact loads, and wear resistance is directly related to the lifespan of the mold.

2. Physical Properties: Such as thermal conductivity, thermal expansion coefficient, etc. Materials with high thermal conductivity can dissipate heat quickly, which helps to improve the injection molding efficiency; materials with a small thermal expansion coefficient have good dimensional stability when the temperature changes, which is conducive to ensuring the dimensional accuracy of plastic products.

3. Processing Performance: Including cutting processing performance, electrical discharge machining performance, welding performance, etc. Good processing performance can reduce the difficulty and cost of mold manufacturing and improve production efficiency.