NFE 25-511 Conical Knurled Spring Washers
Conical (Belleville-form) spring washers with knurled bearing faces per the French standard NFE 25-511 — eight size-group grids covering nominal diameters 3 to 20, tabulating d1 bore, d2 outside diameter, disc thickness h, loaded height H, seating diameters d3/d4 and the proof test load in newtons per size.
Last updated: 2026-11
Specifications
Where a helical spring washer cannot hold preload — short bolts, hard joints, vibration with thermal cycling — the conical washer is the alternative, and NFE 25-511 is its knurled-face French-standard form: a dished disc whose spring action comes from flattening the cone rather than from a helix, with knurling on the bearing faces that grips the joint and the nut face against rotation. The eight collected grids read column-pairs per size under a "d -d2-h" header convention (e.g. "12 -32-2" = washer for M12, OD 32 mm, thickness 2 mm): d1 bore with min/max, d2 OD with nominal/min/max, h thickness with tolerances, H loaded height min/max (the cone height that flattens to generate clamp), the knurl seating diameters d3/d4, and a per-size test load in newtons that runs 2400 N at the M3 group up to 100,000 N at the M20 group — the figure that tells you whether the washer can actually follow the bolt's proof load rather than going flat for show. The series prints non-preferred sizes in parentheses ((14) alongside 16 and 20 in the last group) and carries the ① mark on the d4 row as the source prints it. Material, hardness and finish are not tabulated on the collected page — per RFQ, and for anything beyond size selection (stack arrangements, load/deflection curves) work from the standard's own engineering data.
| Standard / form | NFE 25-511 — conical knurled spring washers (French standard); dished disc with knurled bearing faces, spring action from cone flattening |
|---|---|
| Size coverage | Eight size-group grids, nominal diameters 3 / 4 / 5 / 6 / 8 / 10 / 12 / (14) / 16 / 20; each grid holds three size columns under the "d -d2-h" header convention (e.g. "3 -6-0.5", "20 -40-3.2") |
| Tabulated features | d1 bore (min/max); d2 OD (nominal/min/max); h disc thickness (nominal/max/min); H loaded height (min/max); d3 knurl seat min; d4 seat ① (min/max); test load in N per size |
| Anchor sizes (from the collected grids) | M3 group: d2 6, h 0.5, H 0.7-0.9, test load 2400 N; M8 group: d2 16/18/22, h 1.4-1.6, test load 17,500 N; M12 group: d2 24/27/32, h 1.8-2, test load 40,000 N; M20: d2 40, h 3.2, H 4.3-4.9, test load 100,000 N |
| Series notes | The (14) size prints parenthesized in the last grid (non-preferred as printed); the ① mark on d4 carries verbatim; blank first-row cells under "Nominal Diameter" are the source's merged header structure |
| Not tabulated | Material, hardness, spring characteristic curves (load vs deflection), finish — per RFQ |
| Nominal Diameter | 3 -6-0.5 | 3 -8-0.6 | 3 -10-0.6 | |
|---|---|---|---|---|
| d1 | min | 3.1 | 3.1 | 3.1 |
| max | 3.35 | 3.35 | 3.35 | |
| d2 | Nominal Size | 6 | 8 | 10 |
| max | 6.24 | 8.29 | 10.29 | |
| min | 5.76 | 7.71 | 9.71 | |
| h | Nominal Size | 0.5 | 0.6 | 0.6 |
| max | 0.53 | 0.63 | 0.63 | |
| min | 0.47 | 0.57 | 0.57 | |
| H | min | 0.7 | 0.8 | 0.95 |
| max | 0.9 | 1 | 1.2 | |
| d3 | min | 5.5 | 5.5 | 5.5 |
| d4^① | min | 3.6 | 3.6 | 3.6 |
| max | 4.1 | 4.1 | 4.1 | |
| test load(N) | 2400 | 2400 | 2400 |
| Nominal Diameter | 4 -8-0.8 | 4 -10-0.9 | 4 -14-1 | |
|---|---|---|---|---|
| d1 | min | 4.1 | 4.1 | 4.1 |
| max | 4.4 | 4.4 | 4.4 | |
| d2 | Nominal Size | 8 | 10 | 14 |
| max | 8.29 | 10.29 | 14.35 | |
| min | 7.71 | 9.71 | 13.65 | |
| h | Nominal Size | 0.8 | 0.9 | 1 |
| max | 0.83 | 0.94 | 1.04 | |
| min | 0.77 | 0.86 | 0.96 | |
| H | min | 1 | 1.15 | 1.4 |
| max | 1.2 | 1.4 | 1.8 | |
| d3 | min | 7 | 7 | 7 |
| d4^① | min | 4.7 | 4.7 | 4.7 |
| max | 5.2 | 5.2 | 5.2 | |
| test load(N) | 4200 | 4200 | 4200 |
| Nominal Diameter | 5 -10-1 | 5 -12-1.1 | 5 -16-1.2 | |
|---|---|---|---|---|
| d1 | min | 5.1 | 5.1 | 5.1 |
| max | 5.4 | 5.4 | 5.4 | |
| d2 | Nominal Size | 10 | 12 | 16 |
| max | 10.29 | 12.35 | 16.35 | |
| min | 9.71 | 11.65 | 15.65 | |
| h | Nominal Size | 1 | 1.1 | 1.2 |
| max | 1.04 | 1.14 | 1.24 | |
| min | 0.96 | 1.06 | 1.16 | |
| H | min | 1.25 | 1.45 | 1.7 |
| max | 1.5 | 1.8 | 2.1 | |
| d3 | min | 8 | 8 | 8 |
| d4^① | min | 5.7 | 5.7 | 5.7 |
| max | 6.2 | 6.2 | 6.2 | |
| test load(N) | 6800 | 6800 | 6800 |
| Nominal Diameter | 6 -12-1.2 | 6 -14-1.3 | 6 -18-1.4 | |
|---|---|---|---|---|
| d1 | min | 6.1 | 6.1 | 6.1 |
| max | 6.4 | 6.4 | 6.4 | |
| d2 | Nominal Size | 12 | 14 | 18 |
| max | 12.35 | 14.35 | 18.35 | |
| min | 11.65 | 13.65 | 17.65 | |
| h | Nominal Size | 1.2 | 1.3 | 1.4 |
| max | 1.24 | 1.34 | 1.44 | |
| min | 1.16 | 1.26 | 1.36 | |
| H | min | 1.55 | 1.75 | 2.1 |
| max | 1.85 | 2.1 | 2.5 | |
| d3 | min | 10 | 10 | 10 |
| d4^① | min | 6.8 | 6.8 | 6.8 |
| max | 7.4 | 7.4 | 7.4 | |
| test load(N) | 9500 | 9500 | 9500 |
| Nominal Diameter | 8 -16-1.4 | 8 -18-1.4 | 8 -22-1.6 | |
|---|---|---|---|---|
| d1 | min | 8.2 | 8.2 | 8.2 |
| max | 8.56 | 8.56 | 8.56 | |
| d2 | Nominal Size | 16 | 18 | 22 |
| max | 16.35 | 18.35 | 22.42 | |
| min | 15.65 | 17.65 | 21.58 | |
| h | Nominal Size | 1.4 | 1.4 | 1.6 |
| max | 1.44 | 1.44 | 1.65 | |
| min | 1.36 | 1.36 | 1.55 | |
| H | min | 1.8 | 1.9 | 2.2 |
| max | 2.2 | 2.35 | 2.7 | |
| d3 | min | 13 | 13 | 13 |
| d4^① | min | 9.2 | 9.2 | 9.2 |
| max | 9.8 | 9.8 | 9.8 | |
| test load(N) | 17500 | 17500 | 17500 |
| Nominal Diameter | 10 -20-1.6 | 10 -22-1.6 | 10 -27-1.8 | |
|---|---|---|---|---|
| d1 | min | 10.2 | 10.2 | 10.2 |
| max | 10.56 | 10.56 | 10.56 | |
| d2 | Nominal Size | 20 | 22 | 27 |
| max | 20.42 | 22.42 | 27.42 | |
| min | 19.58 | 21.58 | 26.58 | |
| h | Nominal Size | 1.6 | 1.6 | 1.8 |
| max | 1.65 | 1.65 | 1.85 | |
| min | 1.55 | 1.55 | 1.75 | |
| H | min | 2.1 | 2.25 | 2.6 |
| max | 2.6 | 2.75 | 3.1 | |
| d3 | min | 16 | 16 | 16 |
| d4^① | min | 11.2 | 11.2 | 11.2 |
| max | 11.9 | 11.9 | 11.9 | |
| test load(N) | 27500 | 27500 | 27500 |
| Nominal Diameter | 12 -24-1.8 | 12 -27-1.8 | 12 -32-2 | |
|---|---|---|---|---|
| d1 | min | 12.4 | 12.4 | 12.4 |
| max | 12.83 | 12.83 | 12.83 | |
| d2 | Nominal Size | 24 | 27 | 32 |
| max | 24.42 | 27.42 | 32.5 | |
| min | 23.58 | 26.58 | 31.5 | |
| h | Nominal Size | 1.8 | 1.8 | 2 |
| max | 1.85 | 1.85 | 2.05 | |
| min | 1.75 | 1.75 | 1.95 | |
| H | min | 2.4 | 2.6 | 3.1 |
| max | 2.9 | 3.1 | 3.6 | |
| d3 | min | 18 | 18 | 18 |
| d4^① | min | 13.7 | 13.7 | 13.7 |
| max | 14.4 | 14.4 | 14.4 | |
| test load(N) | 40000 | 40000 | 40000 |
| Nominal Diameter | (14) -30-2.4 | 16 -32-2.8 | 20 -40-3.2 | |
|---|---|---|---|---|
| d1 | min | 14.4 | 16.4 | 20.5 |
| max | 14.83 | 16.83 | 21.02 | |
| d2 | Nominal Size | 30 | 32 | 40 |
| max | 30.42 | 32.5 | 40.5 | |
| min | 29.58 | 31.5 | 39.5 | |
| h | Nominal Size | 2.4 | 2.8 | 3.2 |
| max | 2.46 | 2.86 | 3.26 | |
| min | 2.34 | 2.74 | 3.14 | |
| H | min | 3.2 | 3.6 | 4.3 |
| max | 3.7 | 4.1 | 4.9 | |
| d3 | min | 21 | 24 | 30 |
| d4^① | min | 15.7 | 17.7 | 23.1 |
| max | 16.4 | 18.4 | 22.8 | |
| test load(N) | 55000 | 75000 | 100000 |
Materials
- Conical spring washers live or die on spring quality: the steel, its heat treat and the shot peen (where specified) decide whether the cone survives its first flattening cycle, so state the duty on the RFQ rather than ordering by size alone. Sizes here are washer dimensions — the mating bolt class and the joint's preload target determine whether the tabulated test load is adequate
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (NFE 25-511 Conical Knurled Spring Washers) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
How does the test load column guide washer selection for a given bolt?
Read it as the washer's capacity ceiling, not the joint's target. A conical washer works by sitting pre-loaded at part flattening and following the bolt as it stretches; for that to hold, the washer's test load should be matched to the bolt's preload band, so the cone still has travel when the bolt is at working tension. The grids make the match visible at the extremes: the M3 group's 2400 N suits the small-torque hardware its sizes serve, while the M20 washer's 100,000 N tracks an M20 high-strength bolt's preload. Under-size the washer and it flattens solid at assembly — contributing nothing after the first minutes of service, which is the classic failed-cone failure; over-size it and the joint never reaches the cone's working band. Where the tabulated load sits between your bolt's requirements, that is a stack-design question (single vs series/parallel stacks change both load and travel) and a per-RFQ discussion, since the collected page tabulates single-washer data only.
Why knurled faces, and when would I pick this over a DIN 6796 conical washer or a plain Belleville?
The knurling locks the washer against both joint faces, so rotation and slip are arrested mechanically instead of by friction alone — useful where a plain cone would walk under micro-slip (vibration with light clamp load, tubular hardware, paint surfaces that creep). The trade-off is contact: knurl teeth bite the bearing surfaces, so soft or sealed faces can be marked, and the grip changes the torque-tension behaviour at assembly slightly. Versus DIN 6796 (the conical spring washer for high-strength bolted connections), the NFE 25-511 form is the French-standard counterpart with its own size/height ladder — the collected tables here give you the geometry to compare cell by cell, and the designation on the drawing should decide the order: a callout to NFE 25-511 is not interchangeable by eye with a DIN 6796 part, because the loaded heights H differ at matching sizes. Versus plain Belleville stacks (DIN 2093 disc springs), the NFE washer is a fastener-grade component sized to bolt threads, not a calibrated spring element — for engineered stack design with documented load/deflection curves, that is a disc-spring conversation, per RFQ.
Request a Quote
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What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support