EKINSUN is a custom parts manufacturer that turns flange nuts to drawing above M20 and outside the DIN geometry: a flange diameter for a slot, a height for a long engagement, a fine or left-hand pitch, a plain flange in 316L, a serrated flange in a hardened grade. The size ranges are those a distributor stocked in 2026.
A typical request: an M20 serrated flange nut in class 10 whose flange has to be 45 mm to cover a slot, where DIN gives 42.8 and nobody stocks anything wider.
The flange is where custom flange nuts start; the pitch and the material are the next two reasons.
Flange nut types and size ranges
| Type | Standard | Size range | Common materials | Notes |
|---|---|---|---|---|
| Serrated flange nut | DIN 6923 / ISO 4161 / EN 1661 | M2.5–M20 | 304 stainless; zinc, yellow-zinc, nickel and black steel; brass M3–M12 | the serrations lock against the mating face |
| Plain flange nut | DIN 6923 (plain) | M2.5–M20 | 304; zinc steel | for painted, anodised or soft faces that serrations would gouge |
| Fine-pitch flange nut | maker series | M8–M12 (M8×1, M10×1.25, M12×1.5); 10.9 zinc-flake M10–M20 | 304; 10.9 steel | automotive and machine spindles |
| Left-hand flange nut | maker series | M8–M12 | 304 | counter-rotating shafts |
| Flange nyloc nut | DIN 6926 / ISO 7043 | M4–M16 (plain), M4–M8 (serrated); steel M3–M8 | 304; zinc steel | prevailing torque plus flange |
| All-metal flange lock nut | ISO 7044 form | M5–M12 | 304; steel | prevailing torque without nylon; high temperature |
| High-strength flange nut | class 10 / 10.9 | M6–M20 black; M10–M16 zinc-flake | steel | pairs with 10.9 flange bolts |
| Flange nut with captive washer (flange nut and washer) | maker series | M8–M30 (8.8 black) | steel | wide bearing face on large sizes |
| Nylon flange nut | — | M3–M12 | nylon 66, black and white | insulating; see plastic fasteners |
Flange diameter under DIN 6923 runs at roughly 2.2 to 2.4 times the thread diameter; the exact value per size is in the standard.
Need flange nuts in a size, thread or material no catalogue lists? EKINSUN is a custom parts manufacturer: we make flange nuts to your drawing, sketch or sample, steel, 304 or 316L stainless steel or brass, from 1 piece, quoted in 12 hours and shipped duties paid. If the size is standard, ask anyway, it may be in stock, and the unit price drops as the quantity rises. All custom fasteners
Flange nut, or nut and washer
| Situation | Choice | Why |
|---|---|---|
| Assembly line, one part per joint, plain steel or zinc face | serrated flange nut | one part, no washer to drop, serrations resist loosening from vibration |
| Painted, powder-coated, anodised or plastic face | plain flange nut, or nut plus washer | serrations cut the coating and start corrosion; a plain flange or a washer spreads the load without cutting |
| Soft aluminium 6061 face, thin sheet | plain flange nut with a large-OD washer | a serrated flange embeds in aluminium and the preload relaxes |
| Slotted hole wider than the DIN flange | custom flange diameter | the flange must overlap the slot on both sides; DIN 6923 does not go wider |
| Vibration with a soft face | flange nyloc | prevailing torque holds without serrations |
| Above M20 | turned flange nut | the standard sizes stop at M20 |
What to send for a flange nut that is not on the shelf
- Thread and pitch; fine and left-hand are the commonest reason a flange nut is turned.
- Flange diameter and whether it is serrated or plain; the hole or slot it must cover.
- Height, or the thread engagement you need, if DIN height is wrong.
- Across-flats, if the spanner space is limited.
- Material and grade: 304, 316L, class 8 or 10.9, brass; and the mating bolt grade.
- Quantity and finish.
Read the pitch before you order the flange nut. Lay a steel rule along ten thread crests and divide by ten: 10 mm over ten pitches is a 1 mm pitch (M6 coarse), 12.5 mm is M8 coarse, 15 mm is M10 coarse, 17.5 mm is M12 coarse. A reading that is not a round number of millimetres is an inch thread, and a reading that is shorter than the coarse pitch for that diameter is a fine thread. If diameter, pitch and the size range in the table all agree, the part is a standard size: buy it off the shelf, or have it made to order from 1 piece. If any of the three falls outside the table, we make it to your reading. The full measuring routine, including the inch traps
Where the flange nut catalogue stops
| What you need | In the catalogue? | What we make |
|---|---|---|
| Serrated or plain flange nut M2.5–M20 in 304 or zinc steel, coarse pitch | Yes | Buy it from stock, or have it made to order from 1 piece. No one-off competes with a cold-formed DIN 6923 nut. Standard parts: ask us too, we may have them in stock. |
| Class 10 / 10.9 flange nut M6–M20, black or zinc-flake | Yes | Standard sizes: buy them with the matching 10.9 flange bolt, or have them made to order from 1 piece. Standard parts: ask us too, we may have them in stock. |
| Fine-pitch or left-hand flange nut in a size or pitch outside M8–M12 | No | Turned from bar and tapped or single-pointed to your reading; from 1 piece. |
| A flange diameter wider than DIN 6923 for a slot or an oversize hole | No | Flange turned to your diameter; serrations cut if wanted. |
| A height above or below DIN, or a reduced across-flats | No | Machined to the pocket or the engagement. |
| A flange nut above M20 — M22, M24, M27, M30 | No | Turned from bar in class 8 territory steel or stainless; see also large custom nuts. |
| A flange nut in 316L / 1.4404, brass above M12, or titanium | No | Same geometry, your material. |
| A flange nut in aluminium 6061 or 7075 | Partly | Anodised aluminium flange nyloc nuts M2–M8 exist as standard parts; larger or plain aluminium flange nuts are turned, and we say they are not for high preload. |
Materials
| Material | Designation | Where it fits here |
|---|---|---|
| Stainless 304 | 1.4301 / A2-70 | the standard stainless flange nut M2.5–M20 |
| Stainless 316L | 1.4404 / A4-80 | turned to order for marine and chemical joints |
| Free-machining stainless | 303 / 1.4305 | custom turned flange nuts where corrosion duty allows |
| Carbon steel class 8 | zinc, yellow-zinc, nickel, black | standard steel flange nuts |
| Carbon steel class 10 / 10.9 | black oxide or zinc-flake | high-strength flange nuts M6–M20 |
| Alloy steel | 42CrMo4 / 1.7225 | turned flange nuts above M20 in class 8 territory |
| Brass | CW614N / C36000 | standard M3–M12; turned above |
| Aluminium 6061 | AlMg1SiCu | turned light-alloy flange nuts for low-preload joints |
| Aluminium 7075 | AlZn5.5MgCu | anodised standard flange nyloc M2–M8; turned larger sizes |
| Nylon 66 | PA66 | insulating flange nuts M3–M12 |
Related pages
- the nut, bolt, washer and pin chart, all families with standard and size range
- Large custom nuts, M30 and up
- Tall and thin nuts, when the height is the problem
- acorn and dome nuts, closed dome
- pressed and cast wing nuts, hand-tightened
- flat, spring, tooth and wedge-lock washers, the washer a plain flange replaces
- Hex bolts, the mating bolt
A flange on a long nut is the same idea stretched: the flanged, sight-hole and blind coupling nuts page gives the flange proportions and the other forms cut on a coupling-nut body.
Frequently asked questions
The serrated flange has radial teeth on its underside that bite into the mating face and resist loosening; the plain flange is smooth and only spreads the load. Serrated nuts suit bare or zinc-plated steel; plain nuts suit painted, anodised, plastic or soft aluminium faces that serrations would cut.
In most joints, yes: the flange is the washer, formed in one piece and always the right size for the thread. It cannot replace a washer that is larger than the DIN flange, a hardened washer under a 10.9 bolt in soft material, or a washer chosen to protect a coating.
Roughly 2.2 to 2.4 times the thread diameter, fixed per size by the standard. A hole or slot wider than that is the usual reason a flange nut is turned to a custom flange diameter.
As standard parts only for M8, M10 and M12 in 304, and in 10.9 zinc-flake for M10–M20 fine. Any other size, pitch or hand is turned and tapped to order, from 1 piece.
EKINSUN is a custom parts manufacturer that turns flange nuts in stainless 304 and 316L, carbon and alloy steel, brass and aluminium, in any pitch from M3 to M64, with the flange diameter, height and across-flats the drawing calls for, from 1 piece, with a quote within 12 hours.
No list price; the price follows size, material, whether the flange is serrated, the pitch and the quantity. A batch of M12 fine-pitch flange nuts in 304 is a short lathe job; a single M30 serrated flange nut in 42CrMo4 is a turned and milled part and priced as one. The quote names the drivers.
Send the thread and the flange
Thread and pitch, flange diameter, serrated or plain, height or across-flats if they matter, material and grade, quantity. From 1 piece, quote within 12 hours.