DIN 6923 Serrated Flange Nuts — Hex Flange Lock Nuts, M3 to M24
Structure and Design
| Element | What the photos show | Function |
|---|---|---|
| Hex body | Six flats, standard wrench drive | Same handling as a hex nut, no special tool |
| Integrated flange | Circular collar at the bearing face, wider than the hex | Spreads clamp load and removes the need for a separate washer |
| Serrations | A ring of angled teeth around the flange face | Bites the mating surface to resist vibration loosening |
| Serration direction | Teeth lean in one rotational direction | Grips when tightened; the direction matters when the joint is reversed |
| Through thread | Internal thread runs the full height | Full engagement on the bolt |
| Chamfered thread entry | Lead-in chamfer at both ends | Faster starting and fewer cross-threads |
| Coating | Blue-white zinc or yellow zinc | Barrier plus sacrificial protection for carbon steel |
How the Serrated Flange Locks
| Stage | What happens |
|---|---|
| Before tightening | Teeth sit clear of the surface; the nut spins freely by hand |
| Seating | Flange contacts the part and clamp load starts to build |
| Biting | Tooth tips press into the surface, creating a mechanical interlock |
| Under vibration | Interlock plus friction resists rotation, so the nut does not walk loose |
| On removal | Teeth leave a shallow ring of marks; the fastener can be reused, but grip on that exact spot is reduced |
Flange Nut vs Plain Hex Nut vs Flange Nut with Washer
| Configuration | Bearing area | Parts to handle | Anti-loosening | Typical use |
|---|---|---|---|---|
| Plain hex nut | Small, on the hex face | Nut only, washer often added | Depends on washer and torque | General assembly |
| Hex flange nut, plain flange | Large, integrated | Nut only | Friction only | Sheet metal, castings, slots |
| Serrated flange nut (this page) | Large, integrated | Nut only | Mechanical bite plus friction | Vibration-prone joints, earth-moving, appliances |
| Hex nut + separate washer | Large, but two parts | Nut and washer | Friction only | Where the washer must be replaced separately |
Size Table
Units are millimetres for dimensions and grams for weight, per the source table.
| Size | Flat across (mm) | Thickness (mm) | Flange size (mm) | Weight / bag (g) | Qty / bag | Weight / pc (g) |
|---|---|---|---|---|---|---|
| M3 | — | — | — | 65 | 38462 | 0.65 |
| M4 | 7 | 4.5 | 9 | 57.5 | 21739 | 1.15 |
| M5 | 8 | 5.4 | 11 | 49.5 | 15152 | 1.65 |
| M6 | 10 | 5.7 | 12.7 | 52 | 9615 | 2.60 |
| M6 | 10 | 6 | 13 | 60 | 8333 | 3.00 |
| M8 | 12 | 7 | 15.5 | 43.5 | 5747 | 4.35 |
| M8 | 12 | 8 | 16 | 57.5 | 4348 | 5.75 |
| M8 | 13 | 7 | 16.5 | 57.5 | 4348 | 5.75 |
| M8 | 13 | 8 | 17.5 | 63 | 3968 | 6.30 |
| M10 | 14 | 9 | 18.5 | 58.5 | 3419 | 7.31 |
| M10 | 14 | 8 | 18 | 51 | 3922 | 6.38 |
| M10 | 15 | 10 | 19 | 50 | 2500 | 10.00 |
| M12 | 18 | 10 | 22 | 53 | 1887 | 13.25 |
| M12 | 18 | 11 | 22–23 | 48 | 1563 | 16.00 |
| M12 | 18 | 12 | 22–23 | 52.5 | 1429 | 17.50 |
| M14 | 21 | 13 | 28 | 50 | 1000 | 25.00 |
| M16 | 24 | 15 | 31 | 57 | 658 | 38.00 |
| M18 | 26.5 | 19 | 35 | 52.5 | 381 | 65.63 |
| M20 | 29.5 | 18.5 | 39 | 52.5 | 333 | 75.00 |
| M22 | 31 | 21 | 42 | 46 | 272 | 92.00 |
| M24 | 36 | 20.3 | 45.5 | 51.5 | 194 | 128.75 |
Read this before ordering: one size, several variants
| Size | Rows in the table | Spread in thickness | Spread in weight per piece |
|---|---|---|---|
| M6 | 2 | 5.7 to 6 mm | 2.60 to 3.00 g |
| M8 | 4 | 7 to 8 mm | 4.35 to 6.30 g |
| M10 | 3 | 8 to 10 mm | 6.38 to 10.00 g |
| M12 | 3 | 10 to 12 mm | 13.25 to 17.50 g |
Grades 4.8 and 5.8
| Grade | Nominal tensile strength | Nominal yield strength | Typical use |
|---|---|---|---|
| 4.8 | 400 MPa | 320 MPa (0.8 × 400) | General assembly, low preload, mild steel joints |
| 5.8 | 500 MPa | 400 MPa (0.8 × 500) | Medium-strength joints, light machinery, appliances |
Coating Options
| Finish | Appearance in the photos | Note |
|---|---|---|
| Blue-white zinc | Bright silver with a slight blue tint | Standard for indoor and general outdoor use |
| Yellow zinc | Iridescent yellow-gold | Common where a thicker zinc layer or a different passivation is wanted |
| Other | On request | Confirm colour and thickness with a sample |
Typical Applications
| Application | Why a serrated flange nut fits |
|---|---|
| Automotive and motorcycle assembly | Vibration resistance without a separate lock washer |
| Sheet metal and chassis work | Flange bridges slots and thin material |
| Agricultural and earth-moving equipment | High vibration, coarse surfaces that accept tooth bite |
| Appliances and HVAC | One-piece fastening speeds line assembly |
| Electrical cabinets and trays | Flange spreads load on thin panels |
| Furniture and shelving | Clean appearance without a visible washer |
| Machinery guards and covers | Removable joints that must stay tight |
Installation Notes
| Point | Guidance |
|---|---|
| Mating surface | Best on steel, cast iron and stamped sheet; avoid soft plastics and fresh paint |
| Surface flatness | A flat, burr-free face lets all teeth contact evenly |
| Torque | No torque value is published in the images; set it from the bolt class and joint requirement |
| Reuse | The nut can be reused, but teeth re-seat less effectively on the same marks |
| Washer | Normally unnecessary; add one only if the surface must be protected |
| Removal marks | Expect a shallow ring on the surface; this is normal for serrated fasteners |
| Grade matching | Match the nut class to the bolt class, or the thread strips first |
Quality Checkpoints
| Checkpoint | What is checked | Method |
|---|---|---|
| Thread | Size, pitch, go/no-go, run-through | Thread gauges and matching bolt |
| Flat across | Width across flats within tolerance | Calliper per batch |
| Thickness | Nut height within tolerance | Micrometer per batch |
| Flange diameter | Flange OD within tolerance | Calliper per batch |
| Serration | Tooth count, depth, angle, uniformity | Visual and sample comparison |
| Coating | Coverage, colour, no bare patches, no hydrogen embrittlement risk for high classes | Visual and process record |
| Thread after coating | Hand-thread a bolt after plating | Functional check |
| Grade | Hardness or property check against the declared class | Hardness test or mill certificate |
Customization — Product and Packaging
| Area | Adjustable | Buyer provides |
|---|---|---|
| Size | M3 to M24; other sizes on request | Size list |
| Thickness and flange | Per drawing or table variant | Drawing or chosen variant |
| Serration | Tooth profile and depth | Drawing or sample |
| Grade | 4.8, 5.8 or higher on request | Grade requirement |
| Coating | Blue-white zinc, yellow zinc, thicker layer | Coating standard and thickness |
| Marking | Grade stamp, logo, size marking | Artwork and position |
| Packaging | Poly bag, box, carton, bulk | Packing method and quantity |
| Label | Logo, size table, barcode | Artwork and label copy |
| Carton | Mark, packing list, carton size | Marking file and shipping data |
FAQ
Q1. What is the difference between a flange nut and a plain hex nut?
A flange nut has a built-in collar at the bearing face. On plain versions the collar is smooth; on serrated flange nuts the collar face carries a ring of teeth. Either way the collar spreads clamp load over a larger area, so a separate washer is usually unnecessary and assembly handles one part instead of two.
Q2. How do the serrations stop the nut loosening?
The angled teeth press into the mating surface as the nut tightens, creating a mechanical interlock. Under vibration the interlock and friction resist rotation, so the nut does not back out. That bite is why they are sold as hex flange lock nuts — the locking action is mechanical, not a nylon insert.
Q3. Is this DIN 6923?
The product name cites DIN 6923, so the item is quoted as DIN 6923 flange nuts. Because serrated and plain-flange versions sit under neighbouring DIN designations, confirm the governing standard on your drawing if the standard number is contractual.
Q4. What does grade 4.8 or 5.8 mean?
They are property classes: 4.8 gives 400 MPa nominal tensile with 320 MPa nominal yield, and 5.8 gives 500 MPa with 400 MPa. Note that these are bolt-style classes; nut standards often express class differently, so confirm the marking when the grade matters.
Q5. Can I use a class 4.8 nut on a class 8.8 bolt?
No. The nut would strip before the bolt reaches its preload. Match the nut class to the bolt class, or specify a higher nut grade.
Q6. Why does the table show several rows for M8?
Because the range includes multiple thickness and flange-diameter variants under the same nominal size. Weight per piece for M8 spreads from 4.35 to 6.30 g, so always specify flat across, thickness and flange diameter.
Q7. Which sizes are in spot supply?
M6, M8, M10, M12, M16 and M20 per the product listing. Other sizes in the table are produced to order, and stock levels should be confirmed at the time of enquiry.
Q8. Blue-white zinc or yellow zinc — which should I choose?
Both protect carbon steel. Blue-white is the common default; yellow zinc is often chosen where a different passivation or thicker layer is wanted. Confirm the coating thickness and any salt-spray requirement rather than choosing by colour.
Q9. Will the serrations damage the part surface?
They leave a shallow ring of marks on steel and cast iron, which is normal. On painted, plated or soft surfaces the teeth can damage the finish, so use a plain flange nut or add a washer there.
Q10. Can the nut be reused?
Yes, if the thread and teeth are intact, but the teeth re-seat less effectively on the same marks. For joints that are opened often, plan on replacing the nut.
Q11. Do I still need a washer?
Normally no. Add one only when the surface must be protected or when the hole is oversized and needs a larger bearing area.
Q12. Can thickness or flange diameter be customized?
Yes. Thickness, flange diameter, serration profile and thread can be produced to a drawing or sample.
Q13. Can you mark our logo or the grade?
Yes, grade stamps, size markings and logos can be applied, with position and depth agreed before production.
Q14. How are they packed?
Poly bag, box, carton or bulk, with custom labels and barcodes. The table also lists bag weight and quantity per bag as a packing reference; confirm the final packing for your order.
Send the size, flat across, thickness, flange diameter, grade and coating you need, or attach your drawing, to receive a quotation for DIN 6923 serrated flange nuts, with samples for fit and a stock check on the M6 to M20 range.