Injection Molding Tool Steel: Mold Steel Best Practice

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Injection molding tool steel is used to make injection molds for producing plastic parts. Naturally, the choice of plastics takes precedence in custom injection molding projects. After all, the parts’ quality and performance are most strongly influenced by the plastic materials utilized to create them.
However, selecting the right grade of injection molding tool steel for manufacturing is as important and can have a big impact on how projects turn out. Cycle times, part standards, production volume, pricing considerations, and maintenance expectations are just a few of the factors that must be carefully considered to make sure that the steel chosen will meet the unique needs of the project.
Costly errors can result from skipping this stage or failing to understand the complex interaction between the material being injection molded and the substance acting as the molding tool. Waste, flaws, rework, and prolonged production downtime are just a few problems that can quickly get out of hand.
But which kind of injection molding tool steel is right for your project. Sungplastic will talk about it.

injection molding tool steel - mold steel

P-20 Pre-Hardened Tool Steel (28-30 RC)

P-20 is widely acknowledged as the go-to choice for general-purpose tool steel in injection molding. It boasts several advantages:

  • It can be cast and put into service directly.
  • Typically, it does not necessitate further heat treatment.
  • Its versatility extends beyond tooling; it is commonly used in prototypes and holder blocks.

However, despite its strengths, P-20 has its share of challenges, notably its inability to meet ASTM-A681 minimum standards. It performs best with plastics that lack abrasive components like glass fibers. Additionally, non-coated or surface-hardened P-20 may not endure high-volume production demands.

S-7 Pre-Hardened Tool Steel (56 RC)

When your injection molding project demands precision and high volumes, S-7 is the pre-hardened tool steel of choice. The benefits of S-7 are numerous, with few downsides:

  • It maintains stability during heat treatment and resists softening at elevated temperatures.
  • Exceptional wear properties, particularly crucial for preventing galling in slides and lifters.
  • Strong impact and shock resistance.

H-13 Tool Steel

For high-volume production runs of plastic parts containing abrasive materials, H-13 is the robust tool steel solution. It offers:

  • Versatility for both hot work and cold work applications.
  • Resistance to thermal fatigue cracking.
  • Excellent strength and machinability.

Over time, H-13 tooling surfaces may become vulnerable to corrosion due to chemically enhanced plastics, moisture, humidity, and contamination from cooling water.
It is often used for making various types of tools, including injection molds, die-casting dies, and forging dies.
H-13 tool steel is typically produced by forging or machining and is available in various forms, including rounds, flats, and sheets.

420 Stainless Steel

Containing 13% chromium, 420 stainless steel is a premium tool steel favored for custom injection molding. Its high carbon content delivers several benefits:

  • Maximum corrosion resistance when fully hardened.
  • Outstanding wear resistance and edge retention.
  • It ranks as the hardest among all stainless steel grades.

420 stainless steel is relatively easy to machine unless it’s hardened beyond 30 HRC. Moreover, when used at temperatures exceeding the relevant tempering temperature, its mechanical properties may diminish.

S136 Stainless Steel

S136 is a high-quality stainless steel widely used for crafting high-precision injection molds.
It possesses excellent corrosion resistance and wear resistance, making it suitable for processing a variety of plastic materials.
Its exceptional performance and durability make it a preferred choice for molds requiring precision and extended service life.

By systematically addressing these injection molding flash issues, you can work towards minimizing flash and ensuring the production of high-quality parts.

NAK80 Pre-Hardened Steel

NAK80 is a pre-hardened steel known for its excellent wear resistance and high hardness.
It is often employed in the production of precision injection molds, where minimizing wear and extending mold life are paramount.
NAK80’s pre-hardened state simplifies the mold-making process and contributes to overall mold longevity.

H-13 Cast Steel

H-13 cast steel is a type of cast steel alloy that includes H-13 as one of its components. It is commonly used for casting processes where the molten metal is poured into molds to create various components. While typically used for molding plastic parts with high material content, H-13 cast steel can also find application in injection molding.

It offers exceptional resistance to thermal fatigue cracking, making it suitable for high-temperature injection molding processes.
H-13’s robust properties make it a versatile choice for molds handling various plastic materials.
H-13 cast steel may exhibit different properties compared to H-13 tool steel due to the casting process, which can introduce variations in microstructure and mechanical properties.

718 Steel

718 steel exhibits excellent thermal stability and wear resistance, making it a suitable choice for demanding injection molds.
It is particularly well-suited for molds used with thermoplastic materials and those that require consistent performance under elevated temperatures.
718 steel is favored for its ability to maintain mold integrity and produce high-quality plastic parts.

Specialty Tool Materials

In the realm of project budgets, the design and fabrication of steel tools represent a significant allocation of resources. While this investment is often justified, there are scenarios where the utilization of specialty materials in tool design may be particularly advantageous.

Tools crafted from specialty materials boasting high thermal conductivities have the potential to reduce overall production costs by approximately 25% when compared to conventional steel tools. If you’re seeking to expedite the cooling process for your upcoming project, it’s worth considering the incorporation of tools constructed from high thermal conductivity specialty materials such as MoldMAX®, aluminum, or tungsten carbide.

The choice of injection molding tool steel is a critical and meticulously evaluated aspect of any custom injection molding endeavor. Collaborating with an experienced molder like Sungplastic ensures a harmonious selection of materials and maximizes the value of your investment in tooling. Explore the myriad possibilities and optimize your choices with our comprehensive services.

Injection Molding at Sungplastic

Our manufacturing capacities:
We can produce plastic parts and products in large quantities. Support injection molds fabrication from various materials, including injection molding tool steel, aluminum, silicone, composite materials and special tool materials.

Advanced injection molding presses
Comprehensive production line
Strict quality control
Professional designers, engineers, workers
Loyalty and high-quality customer service

If you are looking for a injection molder and a mold fabricator, please contact us. Sungplastic will implement the most practical action for you.

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