In mold work, the first question is always what process the tool has to survive. Injection molds, blow molds, extrusion dies, die-casting dies, forging dies, and stamping dies all sit under the same "mold" umbrella, but they see very different loads. Injection and stamping are the two workhorses. For injection tooling, pre-hardened steels like P20, 718, and NAK80 are common choices because they machine well and hold a polish. NAK80 is a good example: it ships at roughly 40HRC, which is hard enough to resist wear but still friendly to fine finishing, making it a go-to for transparent parts that demand a high-gloss, mirror-polished cavity. On the stamping side, the priority shifts to abrasion resistance. Cr12MoV and SKD11 are standard picks for blanking and forming dies, especially where high-volume runs chew up the cutting edges.

What ties material selection together is hardness and heat treatment. Two molds cut from the same steel can live very different lives depending on how they are hardened, tempered, and stress-relieved. A die that runs millions of strokes needs a different heat-treat recipe than a short-run prototype tool. In practice, I look at the production volume, the material being formed or injected, and the surface finish spec before locking in a steel grade. Get that wrong, and you are either paying for overkill or replacing worn inserts far too soon.

None of this is guesswork once you have the process and the numbers in front of you. Matching mold type to steel grade, then dialing in heat treatment, is what separates a tool that lasts from one that fights you every shift. For more mold sourcing and supplier information, visit MoldWorld at www.moldw.com.