As a DIN plastic mold steel supplier with over a decade of hands-on experience serving mold makers and plastic processors across Europe and beyond, I get asked this question at least twice a week: “Which DIN mold steel is best for high-temperature plastic molding?” It’s not a trivial question—high-temperature molding, which typically involves materials like PEEK, PI, PPS, and LCP, exposes mold tools to sustained temperatures of 280°C to 450°C, paired with high injection pressures, abrasive fillers, and corrosive byproducts that can eat away at standard mold steels in weeks, not years. DIN Plastic Mold Steel
I’ve seen countless mold shops cut corners here, grabbing a cheap DIN steel off the shelf only to watch their molds fail mid-production, leading to downtime that costs more than the steel itself. That’s why I’m breaking down the core DIN mold steel grades that actually perform in high-temperature molding, what makes them stand out, and how to pick the right one for your specific application.
First, let’s clarify what “high-temperature plastic molding” means in practical terms for DIN steel. DIN 1.2344, 1.2080, and 1.2767 are the most common mold steels, but they’re not all built for 350°C+ runs. High-temperature molding demands steels that can resist thermal softening (so they don’t deform under heat and pressure), have good hot hardness (ability to maintain strength at elevated temperatures), wear resistance (to stand up to glass or carbon fillers that are standard in engineering plastics), and sometimes corrosion resistance (from chlorine or fluorine in additives or plastic monomers).
1. DIN 1.2344: The Workhorse for Most High-Temperature Molding
If there’s a go-to for general high-temperature plastic molding, it’s DIN 1.2344. Officially designated as X40CrMoV5-1, this is a hot work tool steel that’s been the industry standard for injection molds since the 1970s, and for good reason.
Let’s get technical for a second: 1.2344 has a chromium content of ~5%, molybdenum ~1.2%, vanadium ~0.5%, and carbon ~0.4%. This combination gives it exceptional hot hardness—at 400°C, it retains 80% of its room-temperature hardness, which is critical for molds running 300°C to 380°C. Unlike cold work steels that soften dramatically at high heat, 1.2344’s microstructure is engineered to hold its shape.
I’ve supplied 1.2344 to customers molding PPS with 40% glass fiber, a material that’s notoriously abrasive. One client in automotive was running 100,000 cycles on a 1.2344 mold for a PPS sensor housing, and it was still in spec when they upgraded their production line. Compare that to a cheaper cold work steel like 1.2080, which wore out after 22,000 cycles on the same job.
That said, 1.2344 isn’t perfect. It does have a limit: sustained temperatures above 400°C can start to degrade its properties, and it’s not the most corrosion-resistant grade. If you’re molding fluoropolymers (like PTFE) or plastics with chlorine-based additives, the breakdown of those materials releases corrosive gases that can pit 1.2344’s surface over time. For that, you need a different grade.
2. DIN 1.2767: For Corrosive High-Temperature Applications
Enter DIN 1.2767, or X38CrMoV12-1, the go-to for corrosive high-temperature molding. I see this most often with customers molding PTFE, PVDF, or engineering plastics with flame retardant additives that release chlorine. The 12% chromium content here is the key difference from 1.2344’s 5%: it forms a dense chromium oxide layer on the steel’s surface that resists corrosion from those acidic gases.
Hot hardness is still strong here, too—1.2767 maintains ~75% of its room hardness at 450°C, making it suitable for runs up to that temperature. Last year, a medical parts manufacturer came to me with a problem: their mold for PEEK surgical components (molded at 380°C) was pitting after just 15,000 cycles, and they couldn’t figure out why. It turned out their PEEK had a chlorine-based biocompatible additive, and 1.2344 couldn’t handle the corrosion. Swapping to 1.2767 extended the mold life to 75,000 cycles, a 400% improvement.
The tradeoff? 1.2767 is more expensive than 1.2344, and it’s slightly less wear-resistant. For non-abrasive, corrosive high-temp runs, it’s worth the premium, but if your material has glass or carbon fillers, you’ll want to pair 1.2767 with a surface treatment (like nitriding or TiCN coating) to boost wear resistance.
3. DIN 1.2080: Wait, No—Don’t Use This for High-Temp Molding
I can’t talk about DIN steel for high-temp molding without addressing the biggest mistake I see shops make: reaching for DIN 1.2080 (X210Cr12) as a “cheaper alternative.” It’s a cold work tool steel, priced lower than 1.2344, but it’s designed for cold shearing and piercing, not hot injection molding.
At temperatures above 250°C, 1.2080 softens dramatically. I had a customer test this a couple years back: they used 1.2080 for a mold running 320°C for LCP, and after just 5,000 cycles, the mold’s cavity was deformed from pressure, leading to bad parts and a $12,000 downtime bill. 1.2080 is great for low-temp molding (under 250°C) or non-plastic applications, but it has no place in high-temperature runs. Save it for another job.
4. DIN 1.2367: The Premium Grade for Extreme High-Temp Runs
For the most demanding high-temperature applications—think molding PI (polyimide) at 420°C, or PEEK with 50% carbon fillers—there’s DIN 1.2367 (X38CrMoV5-3), often called the “super hot work tool steel.” It’s a more advanced variant of 1.2344, with higher vanadium and molybdenum content, giving it far better hot hardness and wear resistance.
1.2367 retains almost 90% of its room hardness at 400°C, and can handle sustained temperatures up to 450°C without softening. I supplied 1.2367 to a aerospace parts manufacturer molding PI turbine components, a job that required precise cavity dimensions to within 0.002mm over 100,000 cycles. A 1.2344 mold would have started losing tolerance after 30,000 cycles, but the 1.2367 mold held tight the entire run.
The downside? 1.2367 is significantly more expensive than 1.2344, and it’s harder to machine, so lead times can be longer. It’s overkill for most general high-temp jobs, but if you’re running ultra-high-performance plastics or needing 100,000+ cycles, it’s worth the investment.
How to Choose the Right DIN Steel for Your Job
It’s not just about picking the “best” steel—it’s matching the grade to your specific material and production requirements. Here’s a quick checklist I share with customers:
- If you’re molding standard high-temp plastics (PPS, LCP, PA66-GF30) at 280°C to 380°C with no major corrosion, go with DIN 1.2344. It balances cost, hardness, and wear resistance perfectly.
- If you’re molding corrosive high-temp plastics (PTFE, chlorine-added PEEK/PPS) at up to 420°C, choose DIN 1.2767. Add a nitrided surface treatment to boost wear resistance for fillers.
- If you’re molding extreme high-temp plastics (PI, advanced PEEK) at 400°C+ with high filler content, opt for DIN 1.2367. Plan for a 20-30% higher upfront cost, but the longer mold life will pay for itself in reduced downtime.
- Steer clear of DIN 1.2080 for any high-temperature molding. It’s a common shortcut, but one that almost always leads to premature mold failure.
My Experience Working with These Grades
I’ve been selling these steels for 12 years, and I’ll tell you a secret: the biggest mistakes don’t come from choosing the wrong grade, but from not specifying the right pre-treatment. For example, all high-temp DIN steels benefit from pre-hardening (usually to 52-56 HRC for 1.2344, 54-58 HRC for 1.2767) instead of soft annealing and hardening after machining. Pre-hardened steel saves shops time and reduces the risk of distortion during heat treatment, which is a huge win for precision molds.
Another common misstep: not testing. I always recommend customers run a small trial on a prototype mold before committing to a full production run. I had one customer who swore 1.2767 was too soft for their carbon-filled PPS, so we ran a trial with a 1.2344 mold first—turns out, the mild corrosion from their material’s additives was ruining 1.2344 faster than any wear would. Swapping to 1.2767 with a TiCN coating fixed it.
At the end of the day, high-temperature plastic molding is all about balancing upfront cost with long-term productivity. A $5,000 1.2344 mold that lasts 100,000 cycles is a better investment than a $3,000 1.2080 mold that needs replacement every 20,000 cycles, not to mention the lost revenue from downtime.
JIS Cold Work Tool Steel If you’re currently dealing with mold failure in your high-temperature runs, or you’re planning a new project and want to pick the right DIN steel to avoid headaches, reach out to our team. We work directly with mold makers and plastic processors to help specify the right grade, source pre-treated steel, and even offer guidance on surface treatments to extend mold life. No sales pitches, no confusing jargon—just practical advice based on what’s actually worked for hundreds of our customers over the years.
References
- DIN Standards Committee Tool Steels. (2019). DIN EN ISO 4957: Tool Steels. Beuth Verlag GmbH.
- Galdos, L., et al. (2021). Hot Hardness and Wear Resistance of DIN 1.2344 and 1.2767 Steels for High-Temperature Injection Molds. Journal of Materials Processing Technology, 294, 117125.
- European Tool Steel Association. (2020). Guide to Tool Steel Selection for Plastic Molding Applications. ETAS Publications.
- Smith, A. (2018). Failure Analysis of Injection Molds for High-Temperature Engineering Plastics. Mold Making & Design Magazine, 42(3), 22-27.
- Vilar, R., et al. (2019). Surface Coatings for Corrosion and Wear Resistance in High-Temperature Mold Steels. Surface and Coatings Technology, 367, 118-127.
Zhejiang Yiding New Materials Co., Ltd.
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