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Lesson 09·Application

Application playbook — forge dies, stamping, plastic molds, gears, extrusion

Five tool classes, five different recipes: typical steel, target case depth, target compound layer, preferred process, and the failure mode each recipe is designed to defend against.

11 min readLesson 9 of 12

Tying it together

Cross-cutting principles

Case depth scales with tool size and contact stress, not with operator preference. A 0.6 mm case on a plastic mold cavity is wrong for the same reason a 0.2 mm case on a forge die is wrong: the load profile dictates the depth, and a deeper case on a low-stress application buys distortion with no service-life return.

Compound layer phase matches the wear mode: ε for sliding and adhesive wear, γ' for impact and thermal cycling. A vendor who does not control phase delivers whichever phase the cycle happened to produce.

Distortion budget rules out high-temperature gas cycles for precision tooling. Plastic mold cavities, precision gears, long thin punches run plasma at 480-510°C, not gas at 560°C.

The wrong process for an application produces a worse part than the right process, full stop. A salt-bath cycle on a precision plastic mold cavity that should have been plasma typically scraps the cavity. The recipe has to match the substrate, the geometry, and the failure mode you are defending against; substituting a faster or cheaper process is not a substitute for the right metallurgy.

Up next: failure modes.

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