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 Flat Head Screws
A286 flat head screws (also called countersunk screws, CSK screws, flush-mount screws) feature a conical head designed to seat in a countersunk hole and produce a flush surface finish. TorqBolt manufactures A286 flat head screws in two countersink angle conventions: 100° (US aerospace) per NAS 514 / MS 24693 and 90° (commercial / European) per DIN 7991 / ISO 10642 / DIN 963. Drive options: Phillips (most common), Torx (high-torque), hex socket (precision aerospace), and slotted (legacy). Heat-treated to ASTM A453 grade 660 Class A from AMS 5731 / 5732 bar, 130 ksi tensile, 95 ksi yield. Sizes M3-M30 metric and #4 to 1/2 inch. See parent A286 screws, sister CRES screws, cap screws, button head screws, and the canonical chemical composition + heat treatment.
About A286 Flat Head Screws
A286 flat head countersunk screws come in two countersink-angle conventions: 100° (US aerospace standard NAS 514 / MS 24693) and 90° (commercial and European DIN 7991 / ISO 10642). The 100° angle distributes load over a wider bearing surface than 90°, preferred for thin-skin aerospace applications where the countersink depth is limited. Each flat head screw is cold-headed from A286 bar, head-formed in a single-station press to the precise countersink angle, drive form punched (Phillips, Torx, hex socket), thread-rolled, then solution-treated 1650 °F + aged 1325 °F × 16 h per AMS 5737. Critical: countersink angle and surface finish (Ra ≤ 0.8 µm) must be verified at 100 %, out-of-tolerance angle produces a non-flush mount and stress concentration.
A286 Flat Head Screw Standards & Drive Configurations
TorqBolt produces A286 flat head screws in five primary standard / drive configurations:
- NAS 514 (100° flat head, US aerospace), Aerospace 100° flat head, Phillips drive most common, slotted available. Used on aircraft skin attach, panel mounting, fuselage internal hardware. AMS 5732 material default.
- MS 24693 (100° flat head, MIL-spec), Military equivalent of NAS 514, same 100° countersink, similar dimensional spec, used on US military airframe drawings.
- DIN 7991 / ISO 10642 (90° flat head, hex socket), European / commercial 90° flat head with internal hex (Allen) drive, precision flush-mount fastener for industrial and commercial applications.
- DIN 963 / ISO 2009 (90° flat head, slotted), European 90° slotted flat head, legacy commercial standard, still used in older European drawings and machinery.
- DIN 965 / ISO 7046 (90° flat head, Phillips), European 90° Phillips flat head, commercial industrial standard for general flush-mount applications.
A286 Flat Head Screw Sizes & Drive Reference
| Size | Thread | Standard | Angle | Drive | Head ⌀ | Min. tensile |
|---|---|---|---|---|---|---|
| #4 (3 mm) | 40 UNC | NAS 514P-04 | 100° | Phillips #1 | 0.225 inch | 950 lbf |
| #8 (4 mm) | 32 UNC | NAS 514P-08 | 100° | Phillips #2 | 0.357 inch | 1,600 lbf |
| #10 (5 mm) | 32 UNF | NAS 514P-10 | 100° | Phillips #2 | 0.401 inch | 2,400 lbf |
| 1/4 (6 mm) | 28 UNF | NAS 514P-04 (1/4) | 100° | Phillips #3 | 0.531 inch | 4,800 lbf |
| M3 | 0.5 | ISO 10642 | 90° | Hex socket 2 mm | 6.0 mm | 2.5 kN |
| M5 | 0.8 | ISO 10642 | 90° | Hex socket 3 mm | 10.4 mm | 7.2 kN |
| M8 | 1.25 | ISO 10642 | 90° | Hex socket 5 mm | 17.6 mm | 18.6 kN |
| M10 | 1.5 | ISO 10642 | 90° | Hex socket 6 mm | 21.0 mm | 29.4 kN |
| M16 | 2.0 | ISO 10642 | 90° | Hex socket 10 mm | 33.6 mm | 79.8 kN |
A286 Flat Head Screws Manufacturing Process
Every a286 flat 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:
- VIM-VAR melt sourcing: Bar to AMS 5731 / 5732 chemistry per ASTM A453 grade 660. AS9100D for aerospace lots.
- Vacuum-degassed bar (aerospace): Aerospace bar (NAS 514) uses vacuum-degassed input to minimize internal voids, critical for fatigue performance.
- Cold heading + countersink form: Single-station header forms the precise countersink angle (100° NAS / 90° DIN) in one stroke. Critical: countersink angle accuracy ±0.5° per drawing.
- Drive form (Phillips / Torx / hex socket): Phillips drive punched into head; Torx broached; hex socket cold-formed during head-stroke for ISO 10642.
- Thread rolling: MIL-S-8879 Class 3 (aerospace) or 6g (commercial). Roll-formed threads provide 30-40 % higher fatigue strength.
- Solution treatment: Vacuum heat-treat 1650 °F (899 °C) per AMS 5737 / ASTM A453 Class A.
- Precipitation aging: 1325 °F (718 °C) for 16 hours, air-cool. Hardness 277-302 HBW.
- Countersink angle inspection: 100 % countersink angle verified post-aging, gauge or optical comparator. Out-of-tolerance angle is a reject.
- Surface finish check: Bearing-face surface roughness Ra ≤ 0.8 µm verified by profilometer (sampling 1 per 200 screws).
A286 Flat Head Screws Inspection & Certification
Each lot ships with a signed inspection certificate. Aerospace orders default to AS9100D first-article reporting per AS9102. Industrial orders default to EN 10204 type 3.1; sour-service and offshore step up to type 3.2 with third-party witness.
- 100 % countersink angle verification, 100° (NAS 514) or 90° (DIN 7991) per drawing.
- 100 % thread-gauge GO/NO-GO per MIL-S-8879 (aerospace) or ISO 1502 (commercial).
- 100 % drive form check, Phillips bit-fit gauge, Torx gauge, or hex socket dimension.
- Head ⌀ and bearing-face surface roughness Ra ≤ 0.8 µm verified by profilometer.
- Hardness traverse 4-point Vickers per heat-treat batch.
- Magnetic permeability < 1.005 per ASTM A342 on every aerospace coil.
- LPI per ASTM E1417 Class 1 on every NAS 514 lot.
- AS9102 first-article on aerospace lots; EN 10204 3.1 mill cert standard.
A286 Flat Head Screws Torque & Assembly Practice
Flat head countersunk screws torque to seat the conical head against the countersunk hole, over-torque deforms the head bearing area and loses preload. Per Boeing 737 SOPM and similar OEM manuals: tighten to 60-65 % of room-temperature yield for cycling joints, 70-75 % for static. NAS 514 #10 typical: 30-40 in-lb finger-tight + 1/4 turn. Critical: countersink hole MUST be drilled to matching 100° (NAS 514) or 90° (DIN 7991), using a flat-head screw in a wrong-angle countersink causes head crush and joint failure. Above 540 °C apply nickel anti-seize to threads.
A286 Flat Head Screw Applications by Industry
Flat head countersunk screws provide flush-mount finishes, applications:
- Aircraft skin attach: NAS 514 100° flat head Phillips screws on aluminium and composite aircraft skin panels, Boeing, Airbus, Cessna, Embraer, Bombardier production. A286 aerospace fasteners.
- Engine cowling & nacelle: NAS 514 / MS 24693 on engine cowling fasteners, nacelle access panels, thrust reverser cowling.
- Spacecraft heat-shield: CRES A286 100° flat head on spacecraft heat-shield panel attach, where flush mount is critical for re-entry aerodynamics.
- Industrial machinery housings: DIN 7991 / ISO 10642 90° hex-socket flat head on machine-tool housing covers, electrical enclosures, hydraulic manifolds.
- Furniture / consumer (premium): DIN 7991 / DIN 963 commercial flat head on stainless-steel furniture, marine deck hardware, premium consumer products requiring corrosion resistance.
- Cabin interior & trim: NAS 514 / BACS A286 flat head on aircraft cabin sidewall, overhead bin attach, decorative trim panels.
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 Flat 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). A286 wins the 540-700 °C cost-per-MPa-of-retained-preload comparison cleanly. See the consolidated A286 equivalent grades reference for full alloy alternatives.
How to Specify A286 Flat Head Screws
A complete a286 flat head screws callout should include: material spec, heat-treatment condition, dimensional standard, size, thread tolerance class, surface finish, marking, inspection certificate. Example callout:
NAS 514P-08-08, A286 / UNS S66286, ASTM A453 grade 660 Class A, ST+A, 8-32 UNC × 0.50 inch, 100° flat head Phillips #2 drive, MIL-S-8879 Class 3 thread, magnetic permeability < 1.005, passivated per A967, head-marked ‘A286’ + lot.
A286 Flat Head Screws, Frequently Asked Questions
What is the difference between 100° and 90° flat head countersink?
100° countersink = NAS 514 / MS 24693 (US aerospace standard), wider bearing area, suitable for thin-skin aircraft applications. 90° countersink = DIN 7991 / ISO 10642 / DIN 963 (commercial / European), narrower bearing area, preferred for industrial and machinery applications. Critical: countersink hole MUST match screw angle.
What drive style for A286 flat head screws?
NAS 514 default: Phillips (Phillips #1 for #4, #2 for #6/#8/#10, #3 for 1/4 inch). DIN 7991 / ISO 10642 default: hex socket (Allen), 2 mm for M3, 3 mm for M5, 5 mm for M8, 6 mm for M10. Torx and slotted variants available on custom drawings.
Are A286 flat head screws magnetic?
No. Magnetic permeability < 1.005 verified on every aerospace lot per ASTM A342. Critical for avionics, magnetometer, and electromagnetic-sensitive aerospace applications.
Can A286 flat head screws replace stainless 18-8 flat heads?
For high-temperature service (> 425 °C), yes, A286 retains strength to 700 °C. For corrosion resistance + magnetic isolation, yes. For ambient-temperature commercial applications, A286 is over-spec; 18-8 stainless suffices at 1/4 the cost.
What countersink hole angle for an A286 flat head?
Match the screw angle: 100° hole for NAS 514 / MS 24693 screws; 90° hole for DIN 7991 / ISO 10642 / DIN 963 screws. Wrong-angle hole crushes the screw head and causes joint failure under preload.
Is the head ⌀ flush with the surface?
When properly installed in a matching countersunk hole, yes, the head bearing surface sits flush with the workpiece surface, providing aerodynamic flush mount. Non-flush mounting indicates wrong-angle hole, oversize hole, or inadequate countersink depth.
Can A286 flat head screws be used on composite aircraft skin?
Yes, NAS 514 100° flat-head Phillips screws are the standard aircraft skin attach on aluminium AND composite skin (CFRP, GFRP). Use a slightly oversize countersink on composite to prevent fibre tear-out.
What surface finish on the A286 flat head bearing area?
Ra ≤ 0.8 µm (32 µin) per NAS 514 / ISO 10642, verified on the conical bearing face by profilometer (sampling). Aerospace flush-mount applications may specify Ra ≤ 0.4 µm for fatigue performance.
What is the longest A286 flat head screw available?
NAS 514: up to 2.0 inch length in #4-1/4 inch. DIN 7991 / ISO 10642: up to 80 mm length in M3-M16, 120 mm in M20-M30. Custom-drawing parts to 200 mm in special orders.
Why TorqBolt for A286 Flat Head Screws
Three reasons aerospace and gas-turbine OEMs place a286 flat 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.
30+ years in fastener manufacture; ISO 9001:2015 + AS9100D + PED 2014/68/EU + NORSOK M-650 QTR all current.
Recent A286 Flat Head Screws Order Patterns
Recurring flat head screw orders: NAS 514P-08 100° flat-head Phillips on business-jet skin panels, NAS 514P-10 on commercial-aircraft cabin sidewall, DIN 7991 M5/M6 hex-socket flat head on hydraulic manifold covers, and ISO 10642 M8 on European machine-tool housings.
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