Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
A286 Button Head Screws
A286 button head screws (also called button head socket cap screws, dome head screws) feature a low-profile rounded dome head with internal hex socket drive — used where standard SHCS head height is excessive but flush mount is not required. TorqBolt manufactures A286 button head screws to ISO 7380, DIN 7380, DIN 6912 (low-head SHCS variant), and BS 4168 (UK) standards in M3-M16 sizes. Heat-treated to ASTM A453 grade 660 Class A from AMS 5731 / 5732 bar — 895 MPa tensile, 655 MPa yield. Lower preload capacity than standard SHCS (head-strip is the failure mode at high torque) but ideal for limited-axial-clearance applications and decorative finishes. See parent A286 screws, sister socket head cap screws (higher preload), flat head screws (flush mount), cap screws, and the canonical chemical composition, heat treatment.
About A286 Button Head Screws
A286 button head screws have a domed head ≈ 0.4 × nominal diameter in height — about 60 % of the height of a standard ISO 4762 SHCS head. The reduced height suits applications where vertical clearance is limited (machine guards, electronic enclosures, small mechanism housings) or where decorative dome aesthetic is preferred (consumer products, premium hardware, marine deck). Hex socket drive per ISO 2936 (smaller than ISO 4762 SHCS — M6 button head uses 4 mm hex vs 5 mm on standard SHCS). Each button head screw is cold-headed from A286 bar, head dome formed in a single-station press, hex socket forged during head-stroke, thread-rolled, then solution-treated 1650 °F + aged 1325 °F per AMS 5737. Magnetic permeability < 1.005 verified.
A286 Button Head Screw Standards & Variants
TorqBolt produces A286 button head screws in three primary standards:
- ISO 7380 (button head socket cap) — International standard — domed head, internal hex socket. Head ⌀ ≈ 1.75 × nominal, head height ≈ 0.55 × nominal. M3-M16 size range.
- DIN 7380 (button head socket cap) — German pre-cursor of ISO 7380 — dimensionally identical for M3-M16. Cited on older European drawings.
- DIN 6912 (low-head SHCS) — Reduced-height SHCS variant — between standard SHCS and button head. Head ⌀ ≈ 1.5 × nominal, head height ≈ 0.6 × nominal. Hex socket smaller than ISO 4762, requires knurled hex bit.
- BS 4168 (button head, UK) — British Standard equivalent — used on UK aerospace and railway hardware. Functionally identical to ISO 7380.
- Custom flange-style button head — Custom-drawing variant: button head with integral flange under head — spreads bearing pressure on softer mating material. Replaces button head + separate flat washer combo.
A286 Button Head Screw Sizes & Reference
| Metric size | Pitch | Head ⌀ (ISO 7380) | Head height | Hex socket | Min. tensile (kN) |
|---|---|---|---|---|---|
| M3 | 0.5 | 5.7 mm | 1.65 mm | 2 mm | 2.5 |
| M4 | 0.7 | 7.6 mm | 2.20 mm | 2.5 mm | 4.5 |
| M5 | 0.8 | 9.5 mm | 2.75 mm | 3 mm | 7.2 |
| M6 | 1.0 | 10.5 mm | 3.30 mm | 4 mm | 10.2 |
| M8 | 1.25 | 14.0 mm | 4.40 mm | 5 mm | 18.6 |
| M10 | 1.5 | 17.5 mm | 5.50 mm | 6 mm | 29.4 |
| M12 | 1.75 | 21.0 mm | 6.60 mm | 8 mm | 42.8 |
| M16 | 2.0 | — | — | — | — |
A286 Button Head Screws Manufacturing Process
Every a286 button head screws TorqBolt ships traces back to a vacuum-induction-melted plus vacuum-arc-remelted (VIM-VAR) ingot meeting AMS 5731 / 5732 chemistry. The complete process route:
- Bar input + cold heading: AMS 5731 bar drawn to ISO 7380 head-blank diameter. Single-station header forms dome head + cone + hex socket in one stroke.
- Hex socket cold-forging: Smaller hex socket than ISO 4762 SHCS — M6 button head uses 4 mm hex vs 5 mm on standard SHCS. Critical: socket depth ≥ 0.5 × head height for adequate Allen-key engagement.
- Thread rolling: Cylindrical or flat-die rolling to ISO 1502 6g (commercial) or 4g6g (aerospace). Roll-formed threads provide 30-40 % higher fatigue strength.
- Solution treatment: Vacuum 1650 °F (899 °C) per AMS 5737 / ASTM A453 Class A. 1 hour per inch, oil-quench.
- Precipitation aging: 1325 °F (718 °C) for 16 hours, air-cool. Aerospace lots ±5 °C control. Hardness 277-302 HBW post-aging.
- Hex socket re-check: 100 % hex socket dimension verified post-aging — aging causes 0.05 % linear shrinkage that may drop socket size below tolerance.
- Passivation per ASTM A967: Pickle + HNO₃ rinse + passivate Type II.
- Marking + pack: Smaller head than SHCS — marking limited to 'A286' + lot abbreviated. Bulk pack 250 / 500 / 1000 pcs depending on size.
A286 Button Head Screws Inspection & Certification
Each lot ships with a signed inspection certificate. AS9100D-compliant aerospace lots include AS9102 first-article reporting on every new drawing or revision. Industrial orders default to EN 10204 type 3.1; sour-service and offshore step up to type 3.2 with third-party witness.
- 100 % thread-gauge GO/NO-GO per ISO 1502 (commercial) or MIL-S-8879 (aerospace).
- 100 % hex socket dimension per ISO 2936 — across-flats and corner-to-corner check.
- Head ⌀ and head height verified by snap gauge per ISO 7380.
- Hardness traverse 4-point Vickers per heat-treat batch.
- Magnetic permeability < 1.005 per ASTM A342 on every aerospace coil.
- LPI per ASTM E1417 on aerospace lots.
- AS9102 first-article on aerospace lots; EN 10204 3.1 mill cert standard.
- Salt-spray ASTM B117 96-hour pass for passivated lots.
A286 Button Head Screws Torque & Assembly Practice
Button head screws have lower preload capacity than standard SHCS — head-strip is the failure mode at high torque. Torque to 60-65 % of yield only (vs 75 % for standard SHCS). M6 button head ISO 7380: 6 N·m oil / 4.5 N·m anti-seize (vs 8 / 6 for standard SHCS). M10: 25 N·m oil / 18 N·m anti-seize (vs 35 / 25). Use a calibrated hex-socket bit; never use ball-end Allen for final torque (head-strip risk). Above 540 °C apply nickel anti-seize. For high-preload applications use standard SHCS (ISO 4762) instead.
A286 Button Head Screw Applications by Industry
Button head A286 screws used where reduced head profile and decorative finish matter:
- Aerospace cabin & interior: NAS-equivalent button-head A286 on aircraft cabin sidewall, overhead bin attach, lavatory bulkhead — decorative dome finish, non-magnetic.
- Aerospace electronic enclosures: Avionics rack, autopilot enclosure, flight management housing — limited vertical clearance favours button head over standard SHCS.
- Industrial machine guards: ISO 7380 M5 / M6 button-head on machine-tool guard panels, conveyor covers, pneumatic enclosures.
- Premium consumer products: Stainless-steel kitchen appliances, marine deck hardware, premium furniture — decorative button head dome aesthetic.
- Robotics & automation: Robot arm cover plates, gripper finger attach, vision-system housings — limited clearance + non-magnetic isolation.
- Medical / instrumentation: MRI peripheral hardware, surgical robot arm covers, lab instrument enclosures — non-magnetic + decorative.
Governing Standards & Material Specifications
Every A286 fastener is released against the applicable industry standard. EN 10204 type 3.1 mill certificates ship with every order. See the consolidated A286 AMS / ASTM specifications hub for full spec scope.
| Authority | Specification | Coverage |
|---|---|---|
| ASTM | A453 grade 660 Cl. A/B/C/D | High-temperature bolting material |
| ASTM | A638 grade 660 Type 1/2 | Forged bolting stock |
| AMS | 5731 | Bar / forging — solution-treated |
| AMS | 5732 | Bar / forging — solution-treated and aged |
| AMS | 5737 | Bar — solution-treated and aged (precision) |
| UNS | S66286 | Material designation |
| DIN | 1.4980 / X5NiCrTiMoVB25-15-2 | European designation |
| EN | 10204 3.1 / 3.2 | Mill / third-party-witness certification |
| NACE | MR0175 / ISO 15156-3 | Sour-service hardness limit ≤ HRC 35 |
A286 Button Head Screws vs Alternative Materials
When selecting a fastener material engineers compare A286 against three alternatives: A286 vs Inconel 718 (top-end performance, 3× cost), A286 vs 17-4 PH (cheaper but limited to 315 °C), and A286 vs Waspaloy (sustained service > 700 °C). Across the 540-700 °C operating window, A286 delivers the lowest cost per MPa of retained preload. See the consolidated A286 equivalent grades reference for full alloy alternatives.
How to Specify A286 Button Head Screws
A complete a286 button head screws callout should include: material spec, heat-treatment condition, dimensional standard, size, thread tolerance class, surface finish, marking, inspection certificate. Example callout:
Button head socket cap screw, ISO 7380, A286 / UNS S66286, ASTM A453 grade 660 Class A, ST+A, M6 × 1.0 × 25 mm, 6g, passivated, head-marked ‘A286’ + lot, EN 10204 3.1.
A286 Button Head Screws — Frequently Asked Questions
What is an A286 button head screw?
A socket cap screw with a domed head profile lower than standard SHCS — head height ≈ 0.55 × nominal diameter (vs 1.0 × for standard SHCS). Internal hex socket drive, M3-M16 size range. Used where reduced head height or decorative dome finish is required.
Button head vs flat head A286 screws — which to use?
Button head = domed head, partially protrudes above surface. Flat head = 90° or 100° countersunk, sits flush with surface. Use button head for limited clearance + decorative finish; flat head for flush aerodynamic / mechanical mount.
What hex key fits an A286 M6 button head screw?
4 mm hex key (Allen wrench) per ISO 7380. Note: smaller than the 5 mm hex used on standard ISO 4762 M6 SHCS — the smaller socket fits the smaller dome head.
Why do button head screws have lower torque rating?
The reduced head height means thinner head section above the hex socket — head-strip becomes the failure mode at high torque. Torque to 60-65 % of yield only (vs 75 % for standard SHCS). For high-preload applications use ISO 4762 SHCS instead.
Can A286 button head screws be used in aerospace?
Yes for cabin, interior, and electronic-enclosure applications. NOT typically used on primary structure or engine bolting — those applications use standard SHCS (NAS 1351) or 12-point bolts (NAS 6603). Button head is an aerospace secondary-structure fastener.
Are A286 button head screws magnetic?
No. Magnetic permeability < 1.005 verified on every aerospace lot per ASTM A342. Suitable for avionics, MRI, magnetometer, and electromagnetic-sensitive applications.
What is the difference between ISO 7380 and DIN 6912?
ISO 7380 = button head — domed head, ≈ 0.55 × nominal height, head ⌀ ≈ 1.75 × nominal. DIN 6912 = low-head SHCS — flatter cylindrical head, ≈ 0.6 × nominal height, head ⌀ ≈ 1.5 × nominal. DIN 6912 is between standard SHCS and button head; less common.
Can A286 button head screws be re-used?
Industrial / commercial: yes, multiple cycles permitted with thread inspection. Aerospace cabin/interior: yes with inspection. Aerospace primary structure: not applicable — button head not used there.
What's the head ⌀ tolerance on an A286 button head screw?
Per ISO 7380: head ⌀ ±0.30 mm at M6, ±0.50 mm at M16. Head height ±0.20 mm at M6, ±0.30 mm at M16. Aerospace lots may tighten by 50 % per drawing requirement.
Why TorqBolt for A286 Button Head Screws
Three reasons aerospace and gas-turbine OEMs place a286 button head screws orders with us:
- Vertically integrated supply — VIM-VAR melt sourcing from approved AMS-conforming mills, in-house cold heading + thread rolling + vacuum heat-treatment.
- Aerospace AQMS — AS9100D-certified factory in Mumbai with published quality manual covering A286 fastener-specific failure-mode analysis.
- Lead time discipline — 4-6 weeks for ASTM A453 grade 660 standard sizes, 8-12 weeks for custom-drawing aerospace parts.
Over thirty years in fastener manufacture with current ISO 9001:2015, AS9100D, PED, and NORSOK M-650 quality system audits.
Recent A286 Button Head Screws Order Patterns
Active button-head screw orders: ISO 7380 M5/M6 on automotive turbocharger waste-gate covers, DIN 7380 M4/M5 on machine-tool guard panels, aerospace cabin sidewall ISO 7380, and decorative marine deck hardware.
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