Home » NFE 25-511 M-Type Serrated Contact Conical Washers 430-500 HV Grade Zinc Cr3

NFE 25-511 M-Type Serrated Contact Conical Washers 430-500 HV Grade Zinc Cr3

NFE 25-511 M-Type Serrated Contact Conical Washers — 430–500 HV | 65Mn Spring Steel | Zinc Cr3

FULLERKREG NFE 25-511 M-Type Serrated Contact Conical Washers in 65Mn Spring Steel with Zinc Cr3 (trivalent chromium zinc plating) surface treatment deliver high hardness (430–500 HV), strong spring-back force, and reliable anti-loosening performance. Designed for demanding industrial assemblies where maximum pre-load retention and vibration resistance are required.

Product Overview

NFE 25-511 defines three washer types for different fastener head geometries. This listing covers Type M (M-Type) — designed for use with hex head screws and nuts. The M-Type features a larger outer diameter and is the most widely specified variant for general structural and industrial applications.

  • Standard: NFE 25-511 (French national standard, equivalent function to DIN 6796 serrated conical washers)
  • Type: M — For Hex Screws and Nuts
  • Material: 65Mn Spring Steel
  • Hardness: 430–500 HV
  • Surface Treatment: Zinc Cr3 (Trivalent Chromium Zinc Plating)
  • Thread Range: M3 – M12
  • Function: Anti-loosening, vibration damping, high pre-load maintenance

Dimensional Data — NFE 25-511 Type M (65Mn / Zinc Cr3)

All dimensions in mm. Data verified against NFE 25-511 standard catalogue.

Thread Size Inner Dia. d1 (Min) Outer Dia. d2 (Min) Outer Dia. d2 (Max) Height h (Min) Height h (Max) Thickness s (Min) Thickness s (Max)
M3 3.2 6.35 7.25 0.80 1.00 0.37 0.43
M4 4.3 8.55 9.55 1.00 1.20 0.47 0.53
M5 5.3 10.45 11.45 1.15 1.35 0.57 0.63
M6 6.4 12.61 13.61 1.30 1.50 0.67 0.73
M8 8.4 16.54 18.54 1.65 1.95 0.87 0.97
M10 10.5 20.58 22.58 2.00 2.40 1.07 1.23
M12 13.0 24.58 26.58 2.20 2.60 1.27 1.43

Note: Zinc Cr3 plating thickness is typically 5–12 μm. Actual installed dimensions may vary slightly due to plating layer. Confirm with FULLERKREG technical team for tight-tolerance applications.

Selection Guide — NFE 25-511 Type Comparison

Type Designed For Fastener Head Style Relative Outer Diameter
Type M (this page) Hex screws & nuts Hexagonal head / nut bearing face Largest OD
Type B Cylindrical head screws Socket cap head (ISO 4762 / DIN 912 style) Medium OD
Type C Flat nuts & countersunk fasteners Countersunk / flat bearing surface Smallest OD

Material Grade Comparison — 65Mn vs Stainless Steel

Property 65Mn Spring Steel + Zinc Cr3 (This Page) A2 Stainless Steel A4 Stainless Steel
Hardness 430–500 HV ~200–300 HV ~200–300 HV
Spring-back Force High Medium Medium
Pre-load Retention Excellent Good Good
Corrosion Resistance Good (Zinc Cr3 plated) Good (passivated) Excellent (passivated)
Suitable Environment General industrial, indoor Mild outdoor / indoor Marine / chemical
RoHS Compliant Yes (Cr3, not Cr6) Yes Yes

Surface Treatment — Zinc Cr3 Explained

Zinc Cr3 (Trivalent Chromium Zinc Plating) is an environmentally compliant electroplating process that replaces the legacy hexavalent chromium (Cr6 / yellow zinc) passivation. Key characteristics:

  • ✅ RoHS & ELV compliant — free of hexavalent chromium (Cr6), safe for automotive and electronics supply chains
  • 🛡️ Corrosion resistance — typically 120–200 hours neutral salt spray (NSS) per ISO 9227
  • 🌈 Appearance — bright silver / blue-silver finish; uniform and aesthetically clean
  • 🔧 Plating thickness — typically 5–12 μm electrolytic zinc with Cr3 passivation topcoat
  • ♻️ Environmentally responsible — compliant with REACH, RoHS Directive 2011/65/EU

Standard & Compliance

The NFE 25-511 standard is a French national standardisation specification governing serrated contact conical (Schnorr-type) washers. While largely superseded in new designs by DIN 6796 and ISO 10673, NFE 25-511 remains widely specified in:

  • French OEM and industrial legacy assemblies
  • Automotive and rail sector maintenance parts
  • Electrical panel and switchgear applications
  • Heavy machinery and construction equipment

FULLERKREG washers are manufactured to full NFE 25-511 dimensional and mechanical compliance. Material and surface treatment certification available on request for bulk orders.

Material & Surface Specification

Property Specification
Material 65Mn Spring Steel
Hardness 430–500 HV
Surface Treatment Zinc Cr3 (Trivalent Chromium Zinc Electroplating)
Plating Thickness 5–12 μm (typical)
Salt Spray Resistance ≥120 hours NSS (ISO 9227)
RoHS Compliant Yes — Cr3 (no hexavalent chromium)
REACH Compliant Yes
Temperature Range -40°C to +120°C (continuous service)

Key Features & Technical Advantages

  • 🔩 High hardness 430–500 HV — superior spring-back force vs stainless steel grades
  • 🔒 Radial serrations on both faces — bite into mating surfaces to resist rotation and self-loosening
  • 🛡️ Zinc Cr3 surface protection — RoHS-compliant corrosion resistance for general industrial use
  • ⚡ Electrical conductivity — zinc plating maintains conductivity for grounding applications
  • 📐 Precision manufactured — tight dimensional tolerances per NFE 25-511
  • 🏭 Bulk supply ready — available in full reels, bags, and custom packaging for production lines

Typical Applications

  • Automotive body, chassis, and powertrain assemblies
  • Industrial machinery and heavy equipment subject to vibration
  • Electrical cabinets, control panels, and switchgear
  • Rail and transportation equipment
  • Construction steel structures and prefabricated buildings
  • Agricultural and off-highway equipment
  • General mechanical engineering assemblies

Product Gallery

NFE 25-511 M-Type Serrated Conical Washers — 65Mn Spring Steel / Zinc Cr3

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Why Choose FULLERKREG?

🏆 Standard Compliance — Full NFE 25-511 dimensional conformance, with DIN/ISO cross-reference support
🔬 Material Traceability — 65Mn spring steel mill certificates and Zinc Cr3 plating reports available on request
📦 Flexible MOQ — Small batch samples to full production reels; custom packaging available
🌍 Global Shipping — Reliable export logistics to Europe, North America, Southeast Asia, and beyond
💬 Technical Support — Engineering team available for selection guidance, substitution advice, and custom specifications
⚙️ Broad Range — Complementary washer types (Type B, Type C) and related DIN/ISO standards stocked

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