Military Bolts — Hex, Clevis & 12-Point
Military bolts are precision-manufactured, externally threaded fasteners engineered to handle severe shear and tensile loads in structural aerospace and defense assemblies. Unlike commercial bolts, every dimension, material, and finish is controlled by a governing MIL, NAS, or federal specification — with full lot traceability from raw alloy to finished part.
Bolt Configurations We Manufacture
Each configuration serves a different structural role, from tension-critical airframe joints to rotating clevis connections.
Hex Head Bolts
Standard six-sided head for wrench or socket drive, used across general structural and mechanical assembly where external wrenching access is available.
Clevis Bolts
Smooth, undrilled or castellated shank designed to pivot within a clevis fork, typically secured by a nut and cotter pin rather than torqued to a clamp load.
12-Point Bolts
Twelve-point external wrenching flange head allows higher installation torque in confined spaces, common on close-tolerance shear and structural applications.
Overview
A military bolt differs from its commercial counterpart in three critical ways: material pedigree, dimensional control, and testing. Base materials are qualified to specific AMS, ASTM, or QQ material specifications with certified chemistry and mechanical properties; thread classes are typically held to Class 3A (tighter than commercial Class 2A) for better vibration resistance; and every lot is tested for tensile strength, hardness, and — for corrosion resistant steel — magnetic permeability.
Close-tolerance bolt families such as NAS6603 add a precision shank fit for shear-critical joints, while high-temperature families like MS14181 use nickel superalloys such as Inconel 718 for jet engine and exhaust applications rated well above what standard alloy steel can tolerate.
- Structural aerospace bolts are typically drilled for safety wiring or paired with a self-locking nut or cotter pin.
- Finish (cadmium plate, zinc-nickel, dry film lubricant, or passivate) is selected based on the base material and the operating environment.
Material Selector
Choosing the right bolt material depends on temperature, strength, and environment.
Applicable Standards
Explore the individual military bolt specifications Ananka manufactures to.
Military Bolts — Frequently Asked Questions
What's the difference between a hex bolt and a clevis bolt?
A hex bolt is torqued to a clamp load using its wrenched head. A clevis bolt has a smooth shank designed to pivot within a fork-shaped fitting and is secured with a nut and cotter pin rather than clamped for tension — it carries shear load, not tensile preload.
Why use a 12-point head instead of a standard hex?
A 12-point external wrenching head allows a socket to engage the bolt in half the rotational increment of a hex head, useful in tight clearance spaces, and typically allows higher applied torque without rounding.
What thread class do military bolts use?
Most structural and aerospace bolts use UNJF or UNJC Class 3A threads with a controlled root radius — tighter and more fatigue-resistant than the Class 2A threads typical of commercial bolts.
Can't Find the Exact Specification You Need?
Our engineering team sources and manufactures to MIL, NAS, MS, and FF specifications not yet listed here. Send us your drawing or specification number for a fast quotation.
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