Tool Steel Injection Molding — Which Steel is Best for Your Project?

What is tool steel injection molding ?

Tool steel injection molding refers to the use of specialized steel grades designed for creating molds that shape plastic materials through the injection molding process. The selection of the appropriate tool steel is crucial, as it directly impacts the durability, performance, and cost-effectiveness of the molds.

When it comes to selecting the right tool steel for injection molding projects, the choice depends heavily on the specific requirements of the application, including the production volume, the complexity of the part design, and the type of plastic being molded. Here’s a breakdown to help determine which tool steel might be best for your project:

1. P20 Steel

• Characteristics: P20 is a pre-hardened, low-alloy tool steel that is commonly used in the injection molding industry. It has good machinability and can be polished to a high finish.
• Applications: Suitable for low to medium production runs and for molding non-abrasive materials.
• Benefits: Offers a good balance of toughness, strength, and thermal conductivity.
• Limitations: Not suitable for high-volume production or for abrasive materials as it can wear out more quickly.

2. H13 Steel

• Characteristics: H13 is a hot-work tool steel with excellent heat resistance and hardness. It can withstand higher temperatures without losing its temper, making it ideal for high-temperature applications.
• Applications: Best for high-volume production and for molding abrasive materials like PVC.
• Benefits: Provides excellent wear resistance and toughness, can be polished to a high sheen, and is able to handle corrosive materials.
• Limitations: More expensive to process and machine compared to P20 due to its hardness.

3. S7 Steel

• Characteristics: S7 is a shock-resistant tool steel with high impact resistance. It possesses good hardness and retains its properties even under sudden changes in temperature.
• Applications: Ideal for molds that require high impact resistance or are subject to sudden stresses.
• Benefits: Excellent toughness and durability, suitable for complex and intricate part designs.
• Limitations: Can be more difficult to machine and polish than other steels.

4. 420 Stainless Steel

• Characteristics: 420 is a high-carbon stainless steel with high chromium content, offering excellent corrosion resistance.
• Applications: Suitable for applications demanding a high surface finish and corrosion resistance, such as medical device molds.
• Benefits: Resistant to rusting and staining, can be polished to a mirror finish.
• Limitations: Harder to machine and more expensive than other tool steels.

5. NAK80 Steel

• Characteristics: NAK80 is a pre-hardened mold steel with a uniform microstructure. It provides excellent polishability and wear resistance.
• Applications: Ideal for both high-volume production and applications requiring a very high surface finish.
• Benefits: Does not need heat treatment after machining, reducing production time and costs.
• Limitations: Higher cost compared to other steels like P20.

Conclusion

Choosing the right tool steel for injection molding depends on assessing the specific needs of your project, including the expected production volume, the materials being molded, and the desired longevity of the mold. For high-volume or abrasive material applications, H13 or NAK80 might be preferable. For lower volumes or less abrasive materials, P20 could be adequate. Consider factors like corrosion resistance and surface finish requirements to further narrow down your options.