Step 5 of 6
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FNC vs nitriding — stop confusing them
How carbon in the atmosphere changes the compound layer, why FNC owns stamping and powder-metal tooling, and how to tell the two processes apart on a quote and a microsection.
Step 5 of 6Reading a quote
A nitriding quote and an FNC quote differ in four specific places. (1) Atmosphere composition: a nitriding quote lists NH₃ plus N₂ or H₂ dilution; an FNC quote lists NH₃ plus a carbon source (CO₂, propane, endogas) or a salt-bath chemistry (cyanate/carbonate, often called by trade name). (2) Cycle length: nitriding cycles run 20-80 hours; FNC cycles run 1-8 hours. (3) Target compound layer: FNC quotes specify a compound layer thickness in the 10-20 µm range and ε phase; nitriding quotes either specify γ' or mixed phase at 5-15 µm, or in controlled-nitriding work specify a compound-layer-free finish. (4) Target case depth: FNC quotes are 0.05-0.30 mm; controlled nitriding quotes are 0.20-0.60 mm.
A quote that says "nitriding" with a 4-hour cycle and a 15 µm compound layer is an FNC quote with the wrong label.
Quick check
A quote line item reads: "Nitriding per AMS 2759/10, 6-hour cycle, compound layer 18 µm ε, case depth 0.12 mm." What is wrong with the label, and what should the PO actually cite?