{"id":657,"date":"2026-11-03T22:30:04","date_gmt":"2026-11-03T14:30:04","guid":{"rendered":"http:\/\/www.floristflora.com\/blog\/?p=657"},"modified":"2026-11-03T22:30:04","modified_gmt":"2026-11-03T14:30:04","slug":"what-is-the-difference-between-din-1-2312-and-1-2738-4876-c65144","status":"publish","type":"post","link":"http:\/\/www.floristflora.com\/blog\/2026\/11\/03\/what-is-the-difference-between-din-1-2312-and-1-2738-4876-c65144\/","title":{"rendered":"What is the difference between DIN 1.2312 and 1.2738?"},"content":{"rendered":"

If you\u2019re in the business of plastic injection molding, you know that choosing the right mold steel can make or not just the quality of your parts, but also your production schedule and bottom line. After 12 years as a supplier of DIN plastic mold steel, I\u2019ve lost count of how many walk-in clients and long-time partners have paused in front of our 1.2312 and 1.2738 inventory shelves, asking the same question: \u201cWhat\u2019s the real difference between these two?\u201d It\u2019s a fair question\u2014at first glance, both are pre-hardened, medium-alloy tool steels marketed specifically for plastic molds, and their DIN numbers don\u2019t exactly scream \u201cirreconcilable differences.\u201d But let me tell you, the split between these two steels comes down to three tangible factors that will change how you spec your next mold: hardness, machinability, and long-term performance. DIN Plastic Mold Steel<\/a><\/p>\n

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I first encountered this confusion 9 years ago, when a small medical device startup brought me a set of prototypes for insulin pen caps. They\u2019d ordered 1.2738 from another supplier, only to find their CNC shop was running 20% longer cycle times than quoted. By the time they reached out, they were already $12,000 over budget on mold machining, and their launch was 6 weeks behind. That experience made me stop just \u201cselling steel\u201d and start mapping out exactly what makes these two grades perform differently\u2014because for a lot of mold makers, the wrong pick here isn\u2019t just a material mix-up; it\u2019s a hit to their profit margin, too.<\/p>\n

Let\u2019s start with hardness, because this is the first thing that differentiates the two, and it\u2019s not a small number. DIN 1.2312 is a pre-hardened steel, supplied right out of the furnace with a Rockwell hardness between 32 and 36 HRC. That\u2019s a solid, workable hardness for most prototype and low-volume molds, where you won\u2019t be running millions of shots. But DIN 1.2738? It\u2019s supplied with a range of 36 to 40 HRC\u2014four points higher, on average. That gap might sound minor on paper, but in mold machining and production, it\u2019s huge. For every HRC point above 30, material removal rate can drop by 5 to 7%, and tool wear on end mills and finishers jumps almost in lockstep. That startup I mentioned? They\u2019d used 1.2738, which required their CNC machines to spin slower and change tools twice as often as they would have needed with 1.2312.<\/p>\n

But hardness isn\u2019t a one-size-fits-all advantage. The higher hardness of 1.2738 means it\u2019s more resistant to surface wear from repeated mold opening and plastic flow, especially when you\u2019re running glass-filled plastics. Fillers like glass or carbon fiber are abrasive\u2014over time, they can etch small divots into mold surfaces, leading to part defects like flash or uneven wall thickness. If you\u2019re running a high-volume production mold for 500,000+ shots with a glass-filled polypropylene part, that extra 4 HRC from 1.2738 will pay off. But if you\u2019re making 1,000 prototype parts out of unfilled ABS, that extra hardness is just wasted. You\u2019re paying a 15 to 20% premium for 1.2738 over 1.2312, and in that prototype case, you\u2019re not getting any return on that investment.<\/p>\n

Next up is machinability, and this is where I\u2019ve seen even experienced mold makers slip up. Both steels are advertised as \u201cpre-hardened to avoid post-mold heat treatment,\u201d which saves you from distorting the mold during quenching or tempering. But their alloy makeup changes that machinability in subtle, frustrating ways. DIN 1.2312 has a lower content of vanadium and molybdenum\u2014alloying elements that add strength but make material harder to cut\u2014than 1.2738. That means 1.2312 machines faster, with less tool wear, and finishes smoother right out of the mill. For mold shops that rely on fast turnaround times for low-volume jobs, that\u2019s a massive win. I\u2019ve had a client who makes custom toy molds tell me that switching from 1.2738 back to 1.2312 for their short-run orders cut their machining time by 18%, and their tooling costs per mold by 12%.<\/p>\n

But the tradeoff here is in polishability and consistency. 1.2738 has a more uniform microstructure than 1.2312, because of its slightly higher chromium and nickel content. That uniformity means you can get a mirror polish better than 800 grit on 1.2738 without pitting or unevenness\u2014something that\u2019s critical for parts like cosmetic packaging or medical device components where surface finish is non-negotiable. 1.2312 can polish to a fine finish, but it\u2019s not as consistent across large mold surfaces. If you\u2019re making a mold for a cosmetic lip gloss tube, where a flawless, scratch-free surface is required for consumer appeal, 1.2738 is worth the extra work and cost. But if you\u2019re making a mold for a rigid plastic crate, where a basic medium polish is fine, 1.2312 will get the job done faster and cheaper.<\/p>\n

Then there\u2019s long-term performance, which is tied directly to how the steel resists corrosion and heat checking over time. Both steels have good resistance to the acidic byproducts that come from melting certain plastics, but 1.2738 has a slight edge here. Higher alloy content means it can handle more thermal cycles\u2014another way of saying it won\u2019t crack or develop micro-fractures as easily when it\u2019s heated to 200+ degrees Celsius over and over again, then cooled rapidly for each injection shot. For molds that run 24\/7, 365 days a year for high-volume production, that thermal stability translates to a longer mold life. I have a client in automotive manufacturing who\u2019s been using 1.2738 for door panel molds for 7 years, and they replace those molds every 2 to 3 million shots. When he switched a secondary mold for interior trim to 1.2312, the mold started developing small heat cracks after 1.2 million shots, and he had to repair it six times in 18 months.<\/p>\n

But don\u2019t write off 1.2312 for durability entirely. For molds that run fewer than 2 million shots, or that use unfilled plastics, the difference in lifespan is negligible. I\u2019ve seen 1.2312 molds hold up for 5 million shots on non-abrasive resins, especially if you add a standard surface coating like nitriding. The nitriding process, which adds a hard surface layer to the mold, works just as well on both steels, so you can level the playing field in terms of wear resistance without switching grades. The mistake many people make is assuming 1.2738 is \u201cbetter\u201d in every case\u2014when it\u2019s really just a step up for specific high-demand jobs.<\/p>\n

Now, let\u2019s talk about something that\u2019s top of mind for every mold buyer: cost. I mentioned earlier that 1.2738 is roughly 15 to 20% more expensive than 1.2312, and that gap stays consistent whether you\u2019re buying bar stock or finished mold plates. But that cost difference isn\u2019t trivial. For a 500 x 500mm mold plate, that\u2019s a $300 to $500 difference right there. If you\u2019re building 10 prototype molds, that\u2019s $3,000 to $5,000 you could put toward design tweaks or material testing. But if you\u2019re building a production mold that you\u2019ll use for 500,000 parts, that extra $400 is pennies compared to the cost of mold downtime or part defects from a mold that wears out too soon.<\/p>\n

This is why I always tell new clients to ask themselves two questions before picking a grade: How many shots will this mold run, and what type of plastic will I use? If it\u2019s a prototype or low-volume run (under 200,000 shots) with unfilled resins like ABS, PP, or HDPE, 1.2312 is the practical, cost-effective choice. It machines faster, polishes well enough for most parts, and holds up perfectly for short runs. If it\u2019s a high-volume production mold (over 500,000 shots) with glass-filled, acidic, or high-temperature plastics, 1.2738 is the better investment\u2014its higher hardness and alloy content will save you money on repairs and replacements down the line.<\/p>\n

I\u2019ll also add a common misconception I hear all the time: that 1.2312 is \u201cinferior\u201d because it\u2019s lower grade. That\u2019s not true. Both steels are DIN-standard, designed for plastic mold use, and they both work well when spec\u2019d for the right job. I\u2019ve seen too many clients overspend on 1.2738 when they didn\u2019t need it, and too many others cut corners on 1.2312 for a high-volume job and end up with a mold that fails halfway through production. The key isn\u2019t choosing the \u201cbest\u201d steel\u2014it\u2019s choosing the right steel for your specific project.<\/p>\n

If you\u2019re still not sure which is right for your next mold, don\u2019t guess. I\u2019ve worked with mold makers, product designers, and production teams for years, and I can help you break down your requirements, from shot volume to plastic type, to pick the steel that balances cost and performance for your needs. Whether you\u2019re building a prototype mold that needs to be machined in a week, or a production mold that will run for years, we have both 1.2312 and 1.2738 in stock, ready to cut to your exact dimensions.<\/p>\n

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Reach out to our team to discuss your DIN plastic mold steel needs, and we\u2019ll help you find the right grade for your project.<\/p>\n

Plastic Mold Steel<\/a> References
\nDIN Standards Committee. (2019). DIN 1.2312: Hot-worked tool steel for plastic molds. Deutsches Institut f\u00fcr Normung.
\nDIN Standards Committee. (2020). DIN 1.2738: Pre-hardened plastic mold steel. Deutsches Institut f\u00fcr Normung.
\nASM International. (2021). Properties of tool steels for plastic injection molding. ASM Handbook Volume 4: Materials Characterization.
\nMachining Industry Association. (2022). Machinability of pre-hardened tool steels for mold making. National Tooling and Machining Association.<\/p>\n

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Zhejiang Yiding New Materials Co., Ltd.<\/a>
As one of the most professional din plastic mold steel manufacturers and suppliers in China, our products have good reputation in the market. Please feel free to wholesale high quality din plastic mold steel made in China here from our factory. Also, custom service is available.
Address: Xingwang Industrial Park, Huzhen Town, Jinyun County, Zhejiang Province, China
E-mail: jun.wang@ydmat.com
WebSite: https:\/\/www.ydmat.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

If you\u2019re in the business of plastic injection molding, you know that choosing the right mold … What is the difference between DIN 1.2312 and 1.2738?<\/span>Read more<\/a><\/p>\n","protected":false},"author":368,"featured_media":657,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[620],"class_list":["post-657","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-din-plastic-mold-steel-43fb-c6fddb"],"_links":{"self":[{"href":"http:\/\/www.floristflora.com\/blog\/wp-json\/wp\/v2\/posts\/657","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.floristflora.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.floristflora.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.floristflora.com\/blog\/wp-json\/wp\/v2\/users\/368"}],"replies":[{"embeddable":true,"href":"http:\/\/www.floristflora.com\/blog\/wp-json\/wp\/v2\/comments?post=657"}],"version-history":[{"count":0,"href":"http:\/\/www.floristflora.com\/blog\/wp-json\/wp\/v2\/posts\/657\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.floristflora.com\/blog\/wp-json\/wp\/v2\/posts\/657"}],"wp:attachment":[{"href":"http:\/\/www.floristflora.com\/blog\/wp-json\/wp\/v2\/media?parent=657"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.floristflora.com\/blog\/wp-json\/wp\/v2\/categories?post=657"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.floristflora.com\/blog\/wp-json\/wp\/v2\/tags?post=657"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}