Inside the Thread: Why the All‑Metal Lock Nut Still Wins

I’ve walked enough fastener plants to know the smell of cutting oil and heat-treat furnaces before I see them. One place that stuck with me sits in Hanguang Industrial Park, Yongnian District, Handan City, Hebei Province—where the humble yet relentless
All Metal Lock Nut
is treated like a mission‑critical component (because, honestly, it is). In industries obsessed with reliability and vibration resistance, this is the staple that doesn’t flinch.

Trends? We’re seeing a steady shift back from polymer-insert nuts to All Metal Lock Nut designs in high‑temp zones (turbomachinery, exhaust systems, rail bogies). No nylon to soften, nothing to melt. Also, offshore wind and mining OEMs tell me they want fewer torque checks in the field—so prevailing torque types with predictable performance are getting the nod.

Quick Specs (practical, not just brochure-speak)

Thread Range	Metric M5–M36; Inch 1/4″–1-1/2″ (ISO 965-1/2; ASME B1.1/1.13M)
Property Class / Grades	8, 10, 12; ASTM A563 / SAE J995 equiv. for inch
Materials	Medium carbon steel, alloy steel; SS 304/316; high‑temp alloys on request
Coatings	Zinc flake, Dacromet, zinc‑nickel, hot‑dip galvanizing, phosphate + oil (salt spray per ISO 9227)
Standards	ISO 7042 / ISO 2320 (prevailing torque); DIN 980; ISO 898‑2
Temperature	≈ −50°C to 300°C (carbon steel coatings); up to ≈ 800°C for high‑temp alloys (real‑world use may vary)
Reuse Cycles	Around 5–10 per ISO 2320 if threads are clean and within tolerance
Test Data (example)	M10 Class 10 first removal torque ≈ 13–36 N·m (ISO 2320); lab mean 21 N·m on n=30 lot

Where they shine

• Rail and rolling stock, bogie assemblies, brake housings
• Wind turbines (tower flanges, nacelle frames), surprisingly low maintenance
• Heavy equipment, crushers, and vibratory screens—think relentless shock loads
• Petrochemical skids and high‑temp exhausts where nylon inserts would surrender
• General construction steelwork needing secure, repeatable torque checks

Process flow (how the reliability is built)

Material incoming (mill certs) → cold heading or hot forging → precision thread forming → heat treatment (quench & temper) → stress relief → surface finish → 100% thread GO/NO‑GO gauging → prevailing torque test (ISO 2320, first/5th removal) → salt spray (ISO 9227, as applicable) → packing with batch traceability.

Advantages? A All Metal Lock Nut doesn’t rely on inserts; the locking feature is metal‑to‑metal deformation, so torque values stay more stable across temperature cycles. Also fewer FOD concerns compared with nylon fragments—maintenance crews like that.

Vendor snapshot (you’ll want options)

Vendor	Material/Grades	Certs	MOQ	Lead Time	Notes
FastenBoen (Hebei)	Class 8/10/12; SS	ISO 9001, IATF 16949; PPAP on request	≈ 5k pcs	2–5 weeks	Good for custom coatings, lot traceability
Global Brand A	High‑temp alloys	AS9100	Low	Stock/short	Premium pricing, aerospace focus
Local Job Shop	Carbon steel	ISO 9001 (varies)	Flexible	Varies	Fast prototypes; check torque data

Customization

Threads (metric/inch), tall or low height, all‑metal top‑lock vs. oval‑distort styles, coatings for 480–1,000+ h salt spray, laser etch lot codes. Documentation: material certs, torque curves, PPAP Level 3 if you need it.

Mini case files

• Wind OEM retrofitted tower connections with All Metal Lock Nut; field torque checks dropped ≈ 30% over two seasons (operator logs, coastal site).
• Quarry screen housings switched from nylon‑insert to All Metal Lock Nut; fewer loosening incidents after 6 months of high‑vibe duty, per maintenance tickets.

Customer note: “We stopped seeing melted inserts on hot exhausts—simple as that.” Pragmatic, and frankly expected.

Testing & compliance

Prevailing torque per ISO 2320 (first/5th removal), mechanical per ISO 898‑2, chemistry per ASTM/AISI, coating durability per ISO 9227. Inch series verified to ASTM A563/SAE J995. Keep threads clean and aligned—real‑world performance depends on mating bolt grade and finish.

Citations

1. ISO 2320: Prevailing torque type steel nuts — Test methods.
2. ISO 7042: Prevailing torque type hex nuts — Mechanical and performance requirements.
3. ISO 898‑2: Mechanical properties of fasteners — Nuts.
4. ASTM A563 / SAE J995: Carbon and alloy steel nuts for bolts.
5. ISO 9227: Corrosion tests in artificial atmospheres — Salt spray tests.