Spring preload + tooth-bite dual locking | M medium series, the general-purpose choice | OEM/ODM
NFE 25-511 M Type Serrated Conical Lock Washers: French NF E 25-511 medium series; AISI 304/316 or 65Mn; serrated + conical spring locking; OEM/ODM; custom sizes and finishes available.
Stamping parts manufacturer
Owned factory
Stamping capacity · 120 presses up to 450 T
Quotation response
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Non-standard dimensions can be produced from customer drawings or samples. Final dimensions and tolerances are confirmed before production.
NFE 25-511 M Type Serrated Conical Lock Washers are medium-series serrated conical lock washers defined by the French NF E 25-511 standard. The washer combines a conical spring section with radial serrations on one face.
When the fastener is tightened, the conical section is compressed and produces an elastic reaction force within the joint. The serrated face engages with the mating surfaces to resist relative movement. This combination makes the washer suitable for bolted connections where both preload retention and mechanical surface engagement are required.
The M series provides a middle-range outer diameter within the NFE 25-511 family. It is suitable for applications where the compact N series does not provide sufficient bearing area and the larger L series is unnecessary.
Ningbo Yinzhou Zhenhua manufactures NFE 25-511 M type washers in AISI 304, AISI 316 and 65Mn for machinery, automotive components, electrical equipment, rail applications and industrial assemblies.
The performance of the washer is determined by the relationship between its cone profile, material thickness, outer diameter and serration geometry.
The inclined washer section acts as an elastic element during tightening. Its deformation provides spring force within the bolted joint and can accommodate limited changes in joint compression caused by thermal movement or settling.
The radial teeth provide mechanical engagement with the mating surfaces. Their effectiveness depends on sufficient tightening force, suitable mating materials and proper installation orientation.
The M configuration provides a larger bearing footprint than the N series while requiring less radial space than the L series. This makes it suitable for conventional bolt heads and nuts where a moderate bearing area is required.
Material selection affects both environmental resistance and the mechanical behavior of the washer.
AISI 304 is suitable for general industrial and outdoor applications where moderate corrosion resistance is sufficient. It is commonly used for machinery, electrical equipment, enclosures and general fastening assemblies.
AISI 316 is preferred for environments with greater chloride or moisture exposure, including coastal equipment, outdoor installations, washdown areas and selected chemical-processing applications.
65Mn
For 65Mn orders, hardness, heat treatment and surface protection can be specified according to the application and drawing.
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The M type should be selected according to the fastener head or nut diameter, available seating surface and joint requirements. N, M and L versions should not be substituted solely according to nominal thread size.
The surface treatment is selected according to the material and service environment.
| Finish | Suitable consideration |
| Plain stainless | General stainless-steel applications |
| Passivated | Improved stainless surface condition after forming |
| Polished | Appearance and surface-finish requirements |
| Trivalent zinc | General corrosion protection for carbon-steel versions |
| Black oxide / phosphating | Machinery and indoor applications |
| Zinc-flake / Dacromet | Outdoor and higher corrosion-exposure applications |
| Custom finish | According to drawing or customer specification |
For coated 65Mn washers, coating thickness and process should be considered together with the washer's dimensional tolerances, particularly where the washer is used in a closely controlled assembly.
NFE 25-511 M type washers are produced through stamping and forming processes. Tooling controls the washer's inner diameter, outer diameter, cone profile and serration geometry.
Ningbo Yinzhou Zhenhua integrates stamping, progressive die production and machining, with tooling development and production traceability. The company's IATF 16949 quality management system supports process control and batch consistency.
For custom production, the approved drawing or sample is used as the manufacturing reference.
The NFE 25-511 M Type Serrated Conical Lock Washers have two functional faces and should be installed in the specified orientation.
Serrated face: toward the bolt head or nut.
Smooth conical face: toward the joint surface.
During tightening, the conical section compresses while the serrated face engages the mating surfaces.
The joint should be tightened according to the specified torque for the bolt, nut and assembled components. The condition of the mating surface should also be considered, particularly when the serrations are intended to engage with coated, painted or relatively soft materials.
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NFE 25-511 M should not be considered identical to DIN 6796 simply because both have a conical profile. The serrated face gives the NFE 25-511 design a different locking mechanism.
The M type is the medium series of NF E 25-511. It provides a bearing area between the narrow N series and large L series and is intended for applications requiring a balance between radial space and seating area.
Selection depends mainly on the fastener head or nut diameter, available bearing surface and installation space. The M type is suitable when the N version is too compact and the L version provides more bearing area than required.
The serrated face should normally face the bolt head or nut, while the smooth conical face seats against the joint surface. The final orientation should follow the approved application drawing where one is provided.
No. DIN 6796 is a conical spring washer, while NFE 25-511 incorporates serrations in addition to the conical spring geometry. Their locking mechanisms are therefore different.
AISI 304 is suitable for many ordinary outdoor environments. AISI 316 is more appropriate where chloride, salt spray or aggressive moisture exposure is expected. 65Mn can also be used where spring-steel properties are required, provided suitable surface protection is specified.
Yes. Zinc and zinc-flake coating systems can be specified for 65Mn according to the required corrosion protection and application conditions.
Yes. Inner diameter, outer diameter, thickness, free height, serration geometry, material and surface treatment can be customized according to drawings or samples.
Please provide the size, quantity, material, surface treatment and drawing or sample. For non-standard parts, information about the bolt/nut and mating component is also helpful for confirming the washer geometry.
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