DIN 1587 Domed Cap Nuts
Hexagon domed cap nuts per DIN 1587 — a domed crown covers the thread run-out, M4 to M24 in coarse and fine pitch (series 2), steel class 6, stainless A2/A4, brass and thermoplastic. The nut that protects the thread and the everything the thread touches.
Last updated: 2026-11
Specifications
A cap nut closes the story of the bolted joint: after the hex flats take the wrench torque, the domed crown covers the protruding thread end completely, so there is no exposed sharp thread to catch gloves, fabric, or a cleaning cloth — and no bare thread end for moisture and dirt to attack. That combination makes DIN 1587 the standard choice where the joint faces people or weather: handrails and guards, spindles and lead screws, decorative exposed fastening, and food or pharma-adjacent equipment that must be wiped down. The collected table runs series 1 coarse threads M4 to M24 plus a series 2 fine-pitch line (M8×1 to M24×2) where a standard-pitch nut would loosen on a fine adjustment thread, and it remains a DIN designation with no ISO successor — DIN 1587 is the current norm itself. Strength is a single steel class (6) plus A2/A4 stainless, so it belongs on ordinary-strength studs and bolts, not on high-tensile assemblies; pair it with the mating strength deliberately, since the crown also means the nut gives no visual cue whether the bolt has fully engaged.
| Standard | DIN 1587 — hexagon domed cap nut; still a current DIN designation (no ISO successor) |
|---|---|
| Size range | Series 1 coarse M4 – M24; series 2 fine pitch M8×1 – M24×2 |
| Dimensions at M10 | Width across flats s = 16 mm; dome height h max 18 mm; nut portion m max 8.8 mm; head diameter dk max 15 mm |
| Series highlights (s × h max, mm) | M6 10 × 12 · M8 13 × 15 · M12 18 × 22 · M16 24 × 28 · M20 30 × 34 · M24 36 × 42 |
| Thread | 6H |
| Strength class | Steel class 6; stainless A2 / A4 |
| Materials | Steel; stainless A2 / A4; brass; thermoplastic (Pa) |
| Typical applications | Thread protection and covered fastening points: handrails, guards, spindles, decorative and wipe-down equipment |
| Nominal thread | Pitch, coarse (mm) | Pitch, fine-1 (mm) | Pitch, fine-2 (mm) | da max (mm) | da min (mm) | Dome dia dk min (= nominal) (mm) | dw min (mm) | e min, Grade A (mm) | e min, Grade B (mm) | Thread runout x max, coarse (mm) | Thread runout x max, fine (mm) | G max, coarse (mm) | G max, fine (mm) | Height h max (= nominal) (mm) | h min, Grade A (mm) | h min, Grade B (mm) | Height m max (mm) | m min (mm) | mw min (mm) | SR ≈ (mm) | Width across flats s max (= nominal) (mm) | s min, Grade A (mm) | s min, Grade B (mm) | t max (mm) | t min (mm) | w min (mm) | Weight ≈ (kg / 1000 pcs) | Weight ≈ (kg / 1000 pcs), fine thread |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M4 | 0.7 | / | / | 4.6 | 4 | 6.5 | 5.9 | 7.66 | 7.5 | 1.4 | / | 2.75 | / | 8 | 7.64 | 7.42 | 3.2 | 2.9 | 2.32 | 3.25 | 7 | 6.78 | 6.64 | 5.74 | 5.26 | 2 | 1.5 | / |
| M5 | 0.8 | / | / | 5.75 | 5 | 7.5 | 6.9 | 8.79 | 8.63 | 1.6 | / | 3 | / | 10 | 9.64 | 9.42 | 4 | 3.7 | 2.96 | 3.75 | 8 | 7.78 | 7.64 | 7.79 | 7.21 | 2 | 2.2 | / |
| M6 | 1 | / | / | 6.75 | 6 | 9.5 | 8.9 | 11.05 | 10.89 | 2 | / | 3.7 | / | 12 | 11.57 | 11.3 | 5 | 4.7 | 3.76 | 4.75 | 10 | 9.78 | 9.64 | 8.29 | 7.71 | 2 | 4.6 | / |
| M8 | 1.25 | 1 | / | 8.75 | 8 | 12.5 | 11.6 | 14.38 | 14.2 | 2.5 | 2 | 4.9 | 3.7 | 15 | 14.57 | 14.3 | 6.5 | 6.14 | 4.91 | 6.25 | 13 | 12.73 | 12.57 | 11.35 | 10.65 | 2 | 8.9 | 11 |
| M10 | 1.5 | 1.25 | 1 | 10.8 | 10 | 15 | 14.6 | 17.77 | 17.59 | 3 | 2.5 | 5.6 | 4.9 | 18 | 17.57 | 17.3 | 8 | 7.64 | 6.11 | 7.5 | 16 | 15.73 | 15.57 | 13.35 | 12.65 | 2 | 20.1 | 20.1 |
| M12 | 1.75 | 1.5 | 1.25 | 13 | 12 | 17 | 16.6 | 20.03 | 19.85 | 3.5 | 3 | 6.4 | 5.6 | 22 | 21.48 | 21.16 | 10 | 9.64 | 7.71 | 8.5 | 18 | 17.73 | 17.57 | 16.35 | 15.65 | 3 | 28.3 | 28.3 |
| (M14) | 2 | 1.5 | / | 15.1 | 14 | 20 | 19.6 | 23.35 | 22.78 | 4 | 3 | 7.3 | 5.6 | 25 | 24.48 | 24.16 | 11 | 10.3 | 8.24 | 10 | 21 | 20.67 | 20.16 | 18.35 | 17.65 | 4 | 39.7 | 39.7 |
| M16 | 2 | 1.5 | / | 17.3 | 16 | 23 | 22.5 | 26.75 | 26.17 | 4 | 3 | 7.3 | 5.6 | 28 | 27.48 | 27.16 | 13 | 12.3 | 9.84 | 11.5 | 24 | 23.67 | 23.16 | 21.42 | 20.58 | 4 | 54.3 | 54.3 |
| (M18) | 2.5 | 2 | 1.5 | 19.5 | 18 | 26 | 24.9 | 30.14 | 29.56 | 5 | 4 | 9.3 | 7.3 | 32 | 31.38 | 31 | 15 | 14.3 | 11.44 | 13 | 27 | 26.67 | 26.16 | 25.42 | 24.58 | 5 | 79.1 | 95 |
| M20 | 2.5 | 2 | 1.5 | 21.6 | 20 | 28 | 27.7 | 33.53 | 32.95 | 5 | 4 | 9.3 | 7.3 | 34 | 33.38 | 33 | 16 | 14.9 | 11.92 | 14 | 30 | 29.67 | 29.16 | 26.42 | 25.58 | 5 | 104 | 104 |
| (M22) | 2.5 | 2 | 1.5 | 23.7 | 22 | 33 | 31.4 | 37.72 | 37.29 | 5 | 4 | 9.3 | 7.3 | 39 | 38.38 | 38 | 18 | 16.9 | 13.52 | 16.5 | 34 | 33.38 | 33 | 29.42 | 28.58 | 5 | / | / |
| M24 | 3 | 2 | / | 25.9 | 24 | 34 | 33.3 | 39.98 | 39.55 | 6 | 4 | 10.7 | 7.3 | 42 | 41.38 | 41 | 19 | 17.7 | 14.16 | 17 | 36 | 35.38 | 35 | 31.5 | 30.5 | 6 | 216 | 216 |
Materials
- Steel
- Stainless steel A2
- Stainless steel A4
- Brass
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 (DIN 1587 Domed Cap Nuts) 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
When should a cap nut replace a standard hex nut?
Whenever the exposed thread end is the problem: safety (a domed crown removes the sharp protruding thread on handrails and guards), hygiene and cleaning (no thread pocket to collect dirt on wipe-down equipment), corrosion and appearance (the crown shields the thread end from weather and finishes the joint visually), and fine threads on spindles where the series 2 pitch options keep the covered form. It does not add strength — DIN 1587 is a class-6/steel nut — so on high-tensile studs keep the load-carrying nut structural and use the cap nut where protection, not clamp load, is the requirement.
How do I order a cap nut so it fits my bolt?
Three things fix the fit, and all three are in the DIN 1587 table: the thread designation (series 1 coarse, or series 2 fine pitch such as M10×1 or M20×2 for adjustment and fine-thread studs), the width across flats so your wrench matches, and the two heights — overall dome height h and the threaded nut portion m. The height check matters most: a cap nut that is too short will bottom out on the bolt end before the joint is clamped, so confirm h and m against the stud's protrusion rather than ordering by diameter alone.
What is the MOQ and lead time for this nut type?
The minimum order quantity is 10,000 pieces. Stock items ship in 3–7 days; non-stock items are confirmed at quotation. Common diameters in this nut type are widely stocked; confirm the exact schedule against quantity and size mix at quotation.
What should an RFQ for this nut type state?
State the standard designation (for example DIN 985 or DIN 6923), nominal thread size and pitch (metric coarse unless fine pitch is required), material and strength pairing with the mating bolt, finish (plain, zinc, or hot-dip galvanized where compatible), required certificates such as a mill test report per EN 10204 3.1, and quantity per size — plus destination country.
Request a Quote
Get factory-direct pricing from the manufacturer.
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