Selecting the right steel material for injection molds is essential for mold durability, quality, and cost-efficiency in production. Understanding common steel types helps manufacturers optimize their molding processes.

Commonly used steel materials for injection molds include P20, H13, and S7 steels. These offer a balance of hardness, corrosion resistance, and thermal conductivity. P20 is popular for general applications, while H13 is ideal for high-temperature molds in automotive industries.

Choosing the right steel material depends on the mold’s application, required precision, and durability needs. Dive deeper into the different steel types and how they impact mold performance in various industries.

What are the Requirements for Injection Mold Steel Materials?

Choosing the right steel material for injection molds is essential to ensure durability, precision, and cost-effectiveness. This selection affects mold lifespan, part quality, and manufacturing efficiency.

The ideal injection mold steel should have high hardness, corrosion resistance, and thermal conductivity. Common materials include P20, H13, and S7 steels, with H13 being favored for high-temperature applications due to its toughness and resistance to wear.

Sufficient Surface Hardness and Wear Resistance

Plastic molds are usually not very hard, usually less than 60HRC. Heat-treated mold materials can provide enough surface hardness to ensure that the mold has enough rigidity. The mold needs to withstand greater pressure and friction during injection molding .

To make sure the mold has a long service life, it’s important to keep it precise and stable. The steel’s chemical makeup and how hard it is from heat treatment determine how well the mold resists wear.

Good Machining Performance

You need to pick materials that are easy to cut and can get materials that meet production precision during processing. Generally, medium carbon steel¹ and medium carbon alloy steel are the most commonly used.

Excellent Polishing Performance

You gotta pick the right steel for the job based on what you’re gonna do to it.

What are the Criteria for Selecting Mold Steel?

Selecting the right mold steel is essential for ensuring optimal performance, longevity, and cost-effectiveness in the injection molding process.

Mold steel selection depends on factors such as strength, durability, corrosion resistance, and heat conductivity. Key criteria include the part’s design, material properties, production volume, and desired surface finish.

Requirements for Injection Molding Materials

Different plastics require different types of steel, such as steel² that can be highly polished and is resistant to corrosion.

Price

As long as the steel can be used, it is fine. The more expensive the better is not necessarily true. Considering the cost factor of the mold, the mold steel should be selected according to the life of the mold to avoid unnecessary waste.

P20’s life is generally about 300,000 times; 2738 and 500,000 are no problem, and H13/2344 is generally 800,000-1 million or more, which can be selected according to the situation;

Heat Treatment

The surface treatment of the mold is also very important. Nitriding can enhance the surface hardness of steel and effectively extend the life of the mold. Electroplating can effectively modify the mold steel.If you have some plastic parts that need to be shiny and corrosion resistant, you can electroplate them with steel to make them better.

What are the Commonly Used Steels for Injection Molds?

The choice of steel for injection molds impacts durability, mold performance, and cost. Different steels offer various benefits, depending on production needs and material characteristics.

Commonly used steels for injection molds include P20, H13, and S7. These steels provide a balance of toughness, wear resistance, and heat resistance, essential for producing high-quality injection-molded parts.

P20 Steel

P20 steel, hot work mold steel, is a P20 medium carbon Cr-Mo plastic mold steel introduced from the United States.It is good for making molds for plastic molds and die-casting low melting point metals. This steel has good machinability and mirror polishing performance.abrasive materials

P20 steel has been pre-hardened to 285-330HB (30-36HRC) and can be used directly for mold making. It has good dimensional stability. Pre-hardened steel can meet general use requirements, and the mold life can reach 50W mold times.

The steel is vacuum degassed and refined, pure, and suitable for plastic molds that require polishing³or etching. It is supplied in a pre-hardened state and can be used directly for mold processing without heat treatment, shortening the construction period.

After forging and rolling, the structure is dense, 100% ultrasonic inspection, no pores, pinhole defects. It has good machinability and can be mirror polished.

P20 steel is one of the most commonly used steels for injection molds. It’s cheap, easy to machine, hard, and wears well. It also has good thermal stability and corrosion resistance. So, it’s often used to make small and medium-sized injection molds.

718 Steel

718 steel is a high-strength steel and one of the most commonly used materials in the manufacture of injection molds. Compared to P20 steel, 718 steel is harder and can handle more pressure, making it suitable for making large molds. Additionally, 718 steel has good corrosion resistance and can handle different injection molding environments.

The steel is pre-hardened, with uniform material and high cleanliness. It has excellent polishing and photolithography properties. It also has high hardenability, good electrical discharge machining⁴ performance and leather grain processing performance.

You can use pre-hardened steel in the mold cavity without quenching, and you can flame harden the flange to increase the hardness to 52HRC.

The steel is easy to machine and has good wear resistance, and the hardness is consistent throughout. It also polishes well.

718 mold steel has the same uses as P20 mold steel, but because it has better hardenability and performance, it can be used to make large, high-quality plastic mold forming parts.

It is used for large-scale, long-life plastic injection molds, such as molds for home appliances, computer shells, etc. Blow molds for plastic products with high surface finish can be used as slider forming tools in plastic molds due to their high hardness.

Mold parts can be flame hardened or nitrided according to production needs. Steel type: Pre-hardened plastic mold steel Steel features: Polishing, electro-corrosion⁵, good weldability and cutting performance Factory status: Hardened and tempered to HB290-330

NAK80 Steel

NAK80 is a pre-hardened plastic mold steel. The factory hardness can reach HRC37-43. It has good polishing and carving performance, and good discharge processing performance.

It is used in mirror polishing molds, automotive parts discharge processing molds, thin plates with a thickness of no more than 2MM, high-efficiency blanking molds, punching molds and stamping molds⁶, various scissors, inlay blades, woodworking blades, thread rolling molds and wear-resistant sliders, cold heading molds, thermosetting resin forming molds, deep drawing molds, cold extrusion molds.

NAK80 steel is a high-hardness, high-wear-resistant alloy steel, and it is also one of the ideal materials for making injection molds. The characteristics of NAK80 steel are good processing performance, high hardness, strong wear resistance, good thermal expansion, and low thermal conductivity.

So, NAK80 steel is used a lot in making injection molds, especially for making really good and really precise molds. People usually use it for making molds that you can see yourself in, molds that keep dust out, TV filter plates, makeup boxes, molds that make things with little lines on them, office machines, and molds that make car parts.

Transparent products or products that need to be smooth, such as transparent product molds on household, automobile, camera, computer and other supplies. Mirror polishing molds, dustproof, TV filter plates, cosmetic boxes, precision wrinkle processing molds.

office automation equipment, automotive parts discharge processing molds; transparent products or products that require smoothness, such as car ceiling lights, refrigerator vegetable boxes, lighting lamps and other transparent product molds.

H13 Steel

H13 steel is a type of hot working die steel. It follows the GB/T1299-2000 standard. The unified digital code is A20502, and the brand is 4Cr5MoSiV1. Alloy tool steels is also known as alloy steel. It is a type of steel that is made by adding alloy elements to carbon steel.

Among them, alloy steel includes: steel for measuring tools and cutting tools, steel for impact-resistant tools, cold working die steel, hot working die steel, non-magnetic die steel, and plastic mold steel.

H13 steel is a type of steel that is used at high temperatures. It is mainly used to make hot runner injection molds. It has high hardness, great wear resistance, and good heat resistance and fatigue resistance. So it is suitable for making high-temperature and high-pressure injection molds.

S7 Steel

S7 is super hard and wear resistant. It’s used to make molds, cutting tools, and high-load tool parts like molding machines. S7 can get up to 60-62HRC hard. It’s got good hardenability and hardenability. It stays stable and doesn’t corrode under high heat and high pressure. Plus, S7 cuts good and is tough. It does great in high-speed and heavy cutting.

S7 material is widely used in modern industrial production because it performs so well. When you’re making tool parts like plastic molds, stamping molds, and deep drawing molds, S7 material’s excellent performance can make your tools last longer and work better. That means you can make more stuff faster and better. And that’s good for business.

S7 steel is also a steel widely used in injection mold manufacturing. It has the characteristics of high hardness, good toughness and strong crack resistance, and is suitable for the production of large molds. In addition, S7 also has good processing performance and thermal stability, which makes it widely used in the manufacture of injection molds.

S136 Steel

S136 steel is a mold steel with maximum corrosion resistance and high polishability. It has excellent mechanical properties and fatigue resistance. It is suitable for making injection molds and optical molds that require high precision. S136 steel is widely used in plastic products, optical products and other fields.

S136 steel has excellent corrosion resistance, excellent polishing, excellent wear resistance, excellent machinability, excellent stability during quenching, low maintenance costs, and the mold cavity surface remains smooth after long-term use.

The mold does not require special protection when operating or storing in a humid environment. Suitable for various plastic product molds, more suitable for molds with special requirements. Suitable for making molds used in weak acid and humid environments. Suitable for transparent plastic product molds such as CD discs and optical instruments.

2312 Steel

2312 pre-hardened large plastic mold steel is a type of steel material that has uniform hardness, good polishing performance, and good machining performance. It is in a pre-hardened state, which means it can be directly processed. Compared to 2311, it has improved machinability and wear resistance.

2312 steel is mainly used for large and long-life plastic injection mold, such as home appliances, computer shells, and other molds.

2312 mold steel material has uniform hardness and good polishing performance.

It has good machinability, is pre-hardened, can be processed directly, and has better machinability than 1.2311 ISO-BM.

Other Steels

Besides the above-mentioned commonly used injection mold steels, there are many other steels that can also be used to make injection molds, such as H13 steel, 2311 steel, semi hardened tool steel , pre hardened tool steel ,etc.

These steels have their own characteristics, and the choice of which steel depends mainly on the specific requirements of the injection molded products.

When choosing the steel for your injection mold, you need to think about a lot of things. You need to think about what the mold is made of, what kind of injection molding you’re doing, stainless steel grades , and what you need the parts to look like. You need to think about all of these things so you can pick the right steel for your mold.

Conclusion

In short, choosing the right steel is crucial for making injection molds. By understanding the performance characteristics and applicable scope of different steels, we can choose the best manufacturing material according to actual needs, thereby improving the quality and service life of injection molds.

If you have any injection molding project, please contact Zetar Mold. Zetar Mold has a large number of injection molding machine and is a top plastic injection molding company in China.