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Hardened steel

Hard-metal machining isn't a black art.

Die/mold carbide end mills built to cut hardened steel up to 65 HRc — dry.

65 HRc
hardened-steel capability
450%
longer life (D2, 58 HRc test)
909%
less wear than competitors
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Many shops treat hard milling like a black art. It isn't — with the right tool and a few principles it's a profitable, straightforward process. RobbJack's die/mold carbide is purpose-built for hardened steel: 3-D cavities and cores, ribs and helical bores, straight walls and flat floors.

The result is tighter tolerances, longer tool life, and surface finishes good enough to reduce or eliminate polishing — fewer interruptions and finished molds.

Why it wins

  • Carbide-and-coating combinations engineered for hardened steel.
  • Ball, corner-radius, bull-nose, and square geometries for every mold feature.
  • Dry-cutting capable; trochoidal-path friendly for exotics.
  • Smooth wear land — holds size through the cut without mid-job changes.
  • Finishes that reduce or eliminate hand polishing.

Best for

Pre-hardened steel (30–65 HRc)Hardened tool steelsGraphite electrodesDie & mold

Proof & technical depth

Case StudyIncreased Die/Mold Tool Life in Hardened SteelTested in D2 at 58 HRc, the DM/MDM end mill lasted 450% longer with 909% less wear than comparable hard-milling tools.Read it →ArticleChoosing the Right Cutting Tool for the Mold Making IndustryMold work splits into three jobs — pre-hard, annealed, and graphite — each with a right tool and a right tool path. A field guide to picking the cutter that pays dividends in finish and tool life.Read it →ArticleThe Common Ground Between Moldmaking and AerospaceThe techniques that conquer hardened mold steel transfer almost directly to difficult aerospace alloys — heat control, the right coating, and smart entry moves. Here's the crossover playbook.Read it →

130+ die/mold end mills — start here

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