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Views: 0 Author: Site Editor Publish Time: 2025-08-28 Origin: Site
In automotive injection molding, selecting the right mold steel is more than checking boxes on a material spec sheet. It directly shapes part quality, mold life, production efficiency, and long-term ROI. From precision lighting molds to durable interior and exterior trim tools, steel choice underpins performance at every level.
One key factor is steel hardness. Measured in HRC (Rockwell Hardness) or HB (Brinell Hardness), hardness determines how well a material stands up to wear, heat, and repeated cycles. In this article, we take a closer look at selecting steel for automotive molds, where accuracy and durability matter most.
Hardness measures how well a steel resists deformation and wear. It directly affects surface quality and mold life.
HRC: For hardened steels, typically in the HRC 28–60 range.
HB: For softer, pre-hardened steels, generally between HB 140–400.
Use HB for bases and support blocks; use HRC for heat-treated cores and cavities.
| Steel | HB | HRC | Application |
|---|---|---|---|
| P20 | 280–325 | 28–35 | Trim tooling, inserts |
| 718 | 290–340 | 30–34 | Lighting molds |
| S136 | 200 | 48–52 | Corrosion-sensitive parts |
| 2738 | 290–330 | 28–38 | Textured surfaces |
| 2344 | 180–210 | 48–52 | High-wear zones |
Not all steel grades are created equal—or serve the same purpose.
Lighting molds need high polish and tight tolerances: go with 718 or S136.
Interior trims often need texture: 2738 balances hardness and machinability.
Exterior trims benefit from P20 or NAK80 for wear and finish.
Cooling inserts demand BeCu for heat dissipation.
High-wear parts (sliders, lifters): 2344 or H13 are solid choices.
Some steels arrive pre-hardened, like P20 and 718H. Others, such as S136 and 2344, require post-machining heat treatment to achieve their full strength.
| Component | Material | Hardness | Notes |
|---|---|---|---|
| Ejector Pins | SKD61 + Nitriding | HRC 50–55 | High-cycle durability |
| Cavity Inserts | 718, S136 | HRC 30–52 | Finish + corrosion resistance |
| Sliders/Lifters | 2344, 2738 | HRC 32–52 | Wear-resistant |
| Guides | Suj2 | HRC 58–62 | Precision fit |
| Cooling Inserts | BeCu | HRC 32–38 | Fast cooling |
Use 718 over 2738 when surface finish is the top priority.
Swap P20 for S50C to boost base toughness.
Upgrade 45# to 2344 in high-wear zones.
Consider BeCu inserts where fast cooling counts.
Material decisions in mold design carry long-term consequences. For automotive molds like lighting systems and trim parts, thoughtful steel selection pays off in tool life, part quality, and production consistency.
We combine engineering know-how with hands-on experience to help teams choose smarter. If you’re planning your next tool, we’re here to support your process—start to finish.
