Standards
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
NAS6303 tension 12-point bolts
NAS6303 is the 3/16" body diameter member of the NAS6300-series 12-point external-drive aerospace tension cap-screw family (the dash number indicates body diameter in 1/16" increments, so -3 is 3/16"). It is widely used in light structural attachment fittings, instrument-panel hardware, electrical-harness brackets and small-bore engine accessories where the joint preload requirement is moderate but full aerospace traceability is mandatory. NAS6303 is typically produced to 160 ksi tensile in A286 (UNS S66286) and matches the dimensional envelope of the equivalent MS21250 dash-size for retrofit kits.
TorqBolt manufactures NAS6303 cap-screws in A286, AISI 8740 chromoly heat-treated, Inconel 718 and Ti-6Al-4V (Grade 5) to AS9100D Rev D and ISO 9001:2015 quality systems. Each cap-screw head carries the struck tB manufacturer ligature plus the alloy grade marking, and every lot ships with a mill test report (MTC 3.1 standard, MTC 3.2 critical with third-party witness inspection of chemistry, hardness, tensile, and dimensional records).
Common Alloys for NAS6303
| Alloy | Tensile | Service envelope |
|---|---|---|
| A286 (UNS S66286) | 160 ksi | up to 700 °C |
| Inconel 718 (UNS N07718) | 180 ksi | up to 700 °C, jet-engine |
| AISI 8740 chromoly | up to 220 ksi (HT) | standard high-strength |
| Ti-6Al-4V (Grade 5) | 130 ksi | 56% lighter than steel |
UNJ-3A External Thread Dimensions (Common 12-Point Bolt Sizes)
Per SAE AS8879 (controlled-root-radius UNJ external thread). 12-point aerospace bolts under MS21250, NAS1351, AS3216, NAS6303 to NAS6320 are produced to UNJ-3A external thread tolerances. Root radius 0.150 P to 0.180 P (where P = pitch) for fatigue resistance, this is the difference vs standard UN-3A and the reason aerospace specifies UNJ.
| Nominal | TPI | Pitch P (mm) | Major Dia Min (mm) | Major Dia Max (mm) | Pitch Dia Min (mm) | Pitch Dia Max (mm) | Minor Dia Min (mm) | Minor Dia Max (mm) |
|---|---|---|---|---|---|---|---|---|
| 1/4-28 UNJF-3A | 28 | 0.907 | 6.297 | 6.350 | 5.706 | 5.770 | 5.156 | 5.296 |
| 5/16-24 UNJF-3A | 24 | 1.058 | 7.875 | 7.938 | 7.185 | 7.249 | 6.553 | 6.711 |
| 3/8-24 UNJF-3A | 24 | 1.058 | 9.462 | 9.525 | 8.773 | 8.840 | 8.139 | 8.298 |
| 7/16-20 UNJF-3A | 20 | 1.270 | 11.051 | 11.113 | 10.227 | 10.297 | 9.467 | 9.652 |
| 1/2-20 UNJF-3A | 20 | 1.270 | 12.638 | 12.700 | 11.815 | 11.887 | 11.051 | 11.243 |
| 9/16-18 UNJF-3A | 18 | 1.411 | 14.225 | 14.288 | 13.310 | 13.385 | 12.466 | 12.673 |
| 5/8-18 UNJF-3A | 18 | 1.411 | 15.812 | 15.875 | 14.897 | 14.973 | 14.054 | 14.262 |
| 3/4-16 UNJF-3A | 16 | 1.588 | 18.991 | 19.050 | 17.961 | 18.040 | 17.018 | 17.246 |
| 7/8-14 UNJF-3A | 14 | 1.814 | 22.166 | 22.225 | 21.001 | 21.085 | 19.926 | 20.181 |
| 1-12 UNJF-3A | 12 | 2.117 | 25.336 | 25.400 | 23.974 | 24.064 | 22.717 | 22.985 |
| 1 1/4-12 UNJF-3A | 12 | 2.117 | 31.687 | 31.750 | 30.328 | 30.418 | 29.072 | 29.343 |
| 1 1/2-12 UNJF-3A | 12 | 2.117 | 38.037 | 38.100 | 36.678 | 36.768 | 35.422 | 35.693 |
| 1 15/16-12 UNJF-3A | 12 | 2.117 | 49.149 | 49.213 | 47.791 | 47.886 | 46.535 | 46.812 |
| 2-12 UNJF-3A | 12 | 2.117 | 50.737 | 50.800 | 49.378 | 49.473 | 48.122 | 48.399 |
Internal thread (UNJ-3B, mating nut) tolerances and metric M-J equivalents available on request. Send drawing or spec callout to info@torqbolt.com.
Request a Quote
Send drawing or PO line referencing NAS6303 to info@torqbolt.com or call +91-22-66157017.
Related aerospace specs
For broader 12-point aerospace specification context, see also the parent aerospace fasteners hub and the full 12-point catalog, plus sibling specs:
- NAS1351, close-tolerance 12-point external-wrenching
- MS21250, 160 ksi 12-point external-drive aerospace bolt
- AS3216, 180 ksi superalloy 12-point for turbine section
- MIL-DTL-7838, legacy mil-spec, replaced by NAS series
- NAS6304, 1/4" body NAS 6300-series tension cap-screw
- NAS6305, 5/16" body NAS 6300-series tension cap-screw
- NAS6308, 1/2" body NAS 6300-series tension cap-screw
- NAS6310, 5/8" body NAS 6300-series tension cap-screw
- NAS6312, 3/4" body NAS 6300-series tension cap-screw
- NAS6315, 15/16" body NAS 6300-series tension cap-screw
- NAS6320, 1-1/4" body NAS 6300-series tension cap-screw
- DIN 12-Point, European metric 12-point M5 to M30, grade 12.9
Frequently Asked Questions
What diameter does NAS6303 specify?
NAS6303 covers 3/16-inch (0.190) nominal diameter close-tolerance 12-point external-wrenching bolts to the NAS6300 series geometry, used in airframe assemblies where 3/16-inch shear-pin fit is required.
What is the typical NAS6303 application?
NAS6303 bolts are used in control-surface hinge attachments, secondary structural joints, and bracketing where the 3/16-inch diameter provides adequate single-shear capacity at minimum weight.
Which alloys does TorqBolt supply to NAS6303?
A286 (UNS S66286) per AMS 5731 in the H1025 condition for the standard 160 ksi tensile band, with AISI 8740 per AMS 6322 as an alternate for cost-sensitive non-corrosive environments.
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