Injection Mold Materials
In any custom injection molding project, which injection mold steel to use needs to be carefully weighed. Choosing the right mold steel can have a significant impact on the outcome of an injection molding project. Common considerations include: mold life, surface finish, molding cycle, whether there is any long core that can't be cooled, whether there are any shut offs that could wear etc.
There are generally two types of injection mold steel available: pre-hardened steel and hardened steel. Commonly used pre-hardened tool steels include P-20, 718H, etc., and hardened tool steels include S-7, H-13, 420stainless steel, S136H etc.
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Injection Tooling Materials
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Aluminum alloy is made by adding copper, silicon, magnesium, zinc and other elements to pure aluminum to improve the shortcomings of pure aluminum being too soft. Aluminum alloy has the advantages of High mechanical properties,high ductility, easy processing, excellent corrosion resistance, high toughness, fatigue resistance, and low cost, and is widely used in manufacturing various engineering components.
  • Aluminum – 6061
  • Aluminium – 6082
  • Aluminium – 7050
  • Aluminium – 7075
  • Aluminum – 1050
  • Aluminum – 1060
  • Aluminum – 2024
  • Aluminum – 5052
  • Aluminum – 5083
  • Aluminum – 6063
High hardness and stiffness, abrasion resistant. Special varieties of steel have high corrosion resistance, can be quenched and processed, and the hardness can reach 50-60HRC.
  • Pre-hardened mold steel (P-20,718H, 2738H...)
  • Hardened mold steel (NAK80, 420, S136H...)
BeCu(beryllium copper)
For high-demand molds that require rapid cooling, beryllium copper can be used as the core and cavity.
How to Choose the Right Plastic Mold Steel?
The right mold steel will directly affect the quality of the injection mold. The quality of the steel of the mold parts directly determines the life of the mold, the appearance and competitiveness of the injection molded product. Here is some key factors when selecting injection mold steel:
Wear Resistance
Wear resistance is one of the most critical characteristics of mold steel, which has a profound impact on mold life, precision management, flash removal and other post-processing. Wear resistance varies with carbide type, quantity and shape.
Steel is often hardened by quenching to increase its hardness for higher production volumes or its ability to withstand abrasives. Hardness is described as the ability of a material to resist indentation and abrasion.
Hardness is the main reason affecting wear resistance. The higher the hardness of the mold steel, the smaller the wear amount and the better the wear resistance.
Fatigue resistance
During the repeated heating and cooling process of the mold, the surface of the mold cavity is subjected to tension, pressure, and stress. Under the long-term action of this cyclic stress, fatigue fracture is often caused, leading to mold failure. The main factors that determine the fatigue fracture performance of the mold are the strength, toughness, hardness and inclusion content of the steel.
When selecting mold steel, the cost of the material must be considered to save costs and improve competitiveness. When materials meet performance requirements, choose lower-priced materials whenever possible.
Corrosion resistance
Some plastics contain elements chlorine and fluorine (such as PVC, PFA). After heating, they decompose into highly corrosive gases such as HCl and HF, which corrode the surface of the mold cavity and accelerate mold wear and failure.
Case Studies
By reading our classic successful injection molding cases, You can gain a deeper understanding of the profound impact mold steel has on molds and injection molding, and bring new ideas and innovative solutions to your plastic projects.
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Injection Tooling Materials FAQs

Does injection mold material affect the quality of plastic parts?

Yes, the material chosen for the injection mold significantly impacts the quality of plastic parts. Attributes like heat transfer rate, hardness, wear resistance and corrosion resistance of the mold material directly determine consistency in dimensional tolerances, surface finish and conformity to specifications for molded components.

What material is commonly used for injection mold bases?

45 # Tool steel is typical choices for mold bases due to their strength, hardness and corrosion resistance properties.

What properties should cavity and core blocks have?

Cavity and core blocks require high hardness above 48HRC for wear resistance as well as good thermal conductivity to facilitate rapid cooling. Materials like P20 or SCM420 stainess steel are suited.

What materials are typically used for sliders and lifter?

Sliders, lifters, and other movable mold components are wear-prone parts. When selecting injection tooling materials, hardness and toughness should be considered. Using hardened tooling steel can prevent wear, thereby maintaining strict tolerances during long-term production operation. For high-volume injection molds, S136 mold steel can be considered, for medium and low-volume molds, 2738 and 718H can be considered.

Can aluminum be used for prototype molds?

Aluminum is an economical choice for prototypes or low-volume tooling. However, its softness limits use to small runs with non-abrasive plastic materials.

Why electroplate the cavities of injection molds?

Electroplating chromium on the cavities of plastic molds can prevent corrosion and prolong the service life of molds, especially for molds used with abrasive injection resins such as PFA and PVC. It can also improve the overall smoothness, reduce scratches, and improve quality, especially for transparent molded parts made of materials like polycarbonate and Nylon 10.

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