{"id":11521,"date":"2026-05-13T15:53:00","date_gmt":"2026-05-13T07:53:00","guid":{"rendered":"https:\/\/www.cncmachiningshops.com\/?p=11521"},"modified":"2026-07-18T11:55:08","modified_gmt":"2026-07-18T03:55:08","slug":"aerospace-fasteners","status":"publish","type":"post","link":"https:\/\/www.cncmachiningshops.com\/tr\/aerospace-fasteners\/","title":{"rendered":"Havac\u0131l\u0131k ve Uzay Ba\u011flant\u0131 Elemanlar\u0131: T\u00fcrleri, Uygulamalar\u0131 ve M\u00fchendislik K\u0131lavuzu"},"content":{"rendered":"
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Quick Answer:<\/strong> Aerospace fasteners \u2014 bolts, rivets, Hi-Lok pins, lockbolts, and blind fasteners \u2014 are safety-critical components engineered for high strength-to-weight ratio, fatigue resistance, vibration stability, and corrosion resistance in aircraft and spacecraft structures. Unlike industrial fasteners, they are governed by strict standards (AN, MS, NAS, AS specifications) and require full lot traceability, material certification, and AS9100 compliance. Material selection between titanium, high-strength steel, and superalloys depends on the load path, temperature environment, and weight budget. Getting these decisions wrong is not a quality risk \u2014 it is an airworthiness risk.<\/p><\/blockquote>\n

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What Are Aerospace Fasteners?<\/h2>\n

Aerospace fasteners are engineered fastening components \u2014 bolts, rivets, screws, nuts, pins, and specialized locking systems \u2014 used to assemble aircraft structures, spacecraft, and propulsion systems. They are not upgraded versions of standard industrial fasteners. They are purpose-designed components where every material specification, dimensional tolerance, surface treatment, and installation parameter is governed by engineering analysis and regulatory requirement.<\/p>\n

A commercial aircraft contains between 500,000 and several million fasteners depending on size and construction. A wide-body airliner may have over 3 million fasteners across its airframe. At that scale, fastener choices affect total aircraft weight by thousands of kilograms, maintenance intervals by years, and \u2014 when failures occur \u2014 structural integrity in ways that have caused fatal accidents. Aerospace fasteners are not commodity procurement decisions. They are structural engineering decisions with regulatory consequences.<\/p>\n

For OEM manufacturers, procurement teams, and engineers sourcing aerospace fasteners or components assembled with them, understanding the type, material, standard, and installation requirement for each application is the foundation of responsible aerospace supply chain practice.<\/p>\n

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Why Aircraft Need Specialized Fasteners<\/h2>\n

Standard industrial fasteners fail in aerospace environments \u2014 not dramatically, but progressively and predictably. The operating conditions that aircraft fasteners must handle simultaneously are beyond the design envelope of hardware-store or general industrial fasteners.<\/p>\n

Cyclic Fatigue Loading<\/h3>\n

Aircraft structures experience cyclic loading throughout their operational life. Every takeoff and landing subjects the airframe to a pressurization cycle that stresses every fuselage fastener. Every flight subjects wing joints to bending, torsion, and dynamic load variations from turbulence, gusts, and maneuvers. A narrow-body commercial aircraft may complete 50,000\u201375,000 flight cycles over its service life. Each cycle is a fatigue event. Fasteners must survive this load history without crack initiation or propagation.<\/p>\n

Fatigue is the leading cause of structural degradation in aircraft. The Aloha Airlines Flight 243 fuselage failure in 1988 \u2014 a prominent case study in aircraft maintenance engineering \u2014 involved fatigue cracking at fastener holes in the fuselage skin, accelerated by corrosion. Aerospace fastener specifications exist partly because of lessons learned from this class of failure.<\/p>\n

Vibration and Self-Loosening<\/h3>\n

Aircraft engines produce broadband vibration that transmits through the entire airframe. Aerodynamic forces produce buffeting at control surfaces and high-speed structural elements. Without engineered anti-loosening systems, vibration progressively reduces fastener preload \u2014 reducing clamping force until joint integrity is compromised. Standard fasteners with no locking feature are simply not appropriate in high-vibration aerospace zones.<\/p>\n

Temperature Extremes<\/h3>\n

Commercial aircraft cruise at altitudes where ambient temperature approaches -55\u00b0C. Engine-adjacent structures experience temperatures above 300\u00b0C. Many aerospace structures cycle between these extremes multiple times per flight. Fastener materials must maintain mechanical properties \u2014 strength, ductility, fatigue resistance \u2014 across this entire temperature range without significant degradation or differential thermal expansion problems.<\/p>\n

Structural vs. Non-Structural Classification<\/h3>\n

Aerospace fasteners divide into two functional categories with fundamentally different specification requirements:<\/p>\n\n\n\n\n\n\n
Category<\/th>\nFunction<\/th>\nFailure Consequence<\/th>\nExamples<\/th>\n<\/tr>\n<\/thead>\n
Structural fasteners<\/td>\nCarry primary loads (wing, fuselage, landing gear)<\/td>\nMay compromise aircraft integrity<\/td>\nHi-Lok pins, Taper-Lok bolts, solid rivets<\/td>\n<\/tr>\n
Non-structural fasteners<\/td>\nSecure secondary components (panels, covers, interiors)<\/td>\nComponent separation, but not structural failure<\/td>\nScrews, turnlock fasteners, panel rivets<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Structural fasteners in primary load paths require the most rigorous material qualification, manufacturing control, and installation documentation. Non-structural fasteners still require aerospace-grade quality and traceability \u2014 they can still cause incidents if they depart the aircraft \u2014 but their structural failure mode is less immediately catastrophic.<\/p>\n

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Types of Aerospace Fasteners<\/h2>\n

Aerospace Rivets<\/h3>\n

Rivets are permanent fasteners installed by deforming one end to clamp the joined materials. Solid rivets \u2014 set by bucking bar or squeeze tool \u2014 have been the backbone of aircraft fuselage assembly since the earliest metal aircraft, and remain the dominant fastener in aluminum skin structures.<\/p>\n

Why rivets are used:<\/strong> Low weight per unit of load transferred, excellent fatigue performance under distributed shear loads, and simple, repeatable installation in thin-sheet structures. The deformation process creates favorable residual compressive stress around the fastener hole, improving fatigue life relative to clearance-fit bolts.<\/p>\n

Limitations:<\/strong> Permanent (removal requires drilling out the rivet, risking hole enlargement), and solid rivet installation requires access to both sides of the joint. Blind rivets address the one-sided access requirement but at reduced load capacity.<\/p>\n

Best applications:<\/strong> Fuselage skins, wing panel skins, lightweight structural assemblies with distributed shear loading.<\/p>\n

Structural Bolts<\/h3>\n

Aerospace structural bolts are threaded fasteners designed for the highest-load applications \u2014 joints that carry primary structural loads and require controlled preload for proper function. They are removable, which is critical in locations requiring periodic maintenance or inspection.<\/p>\n

Why bolts are used:<\/strong> Very high tensile and shear strength, removable and replaceable, suitable for thick-section structural joints where rivet installation is impractical.<\/p>\n

Limitations:<\/strong> Heavier than equivalent-strength rivet configurations; require precise torque control to achieve correct preload; need compatible locking hardware in vibration-prone locations.<\/p>\n

Best applications:<\/strong> Wing-to-fuselage joints, engine mounts, landing gear attachments, structural fittings that carry flight loads.<\/p>\n

Hi-Lok Fasteners<\/h3>\n

Hi-Lok fasteners consist of a threaded pin and a separate collar. The collar has a controlled break-off feature: the hex wrenching element separates from the collar at a precise torque value, eliminating installation variability and ensuring consistent preload on every installation.<\/p>\n

Why Hi-Loks are used:<\/strong> The controlled torque-off feature removes human variability from the installation process \u2014 the fastener is correctly preloaded regardless of operator technique. This makes Hi-Loks particularly valuable in high-volume airframe assembly where installation consistency across thousands of joints is critical for fatigue performance.<\/p>\n

Best applications:<\/strong> Aircraft primary and secondary structures requiring consistent preload, fuselage frame-to-skin joints, wing rib attachments.<\/p>\n

Limitations:<\/strong> Higher cost than conventional fasteners; requires specialized collar installation tools.<\/p>\n

Lockbolts<\/h3>\n

Lockbolts use a swaged collar rather than a threaded nut to create a permanent, non-loosening joint. The installation tool pulls the pin while swaging the collar into the pin grooves, creating a cold-formed lock that maintains preload under vibration without any separate anti-loosening hardware.<\/p>\n

Why lockbolts are used:<\/strong> Superior vibration resistance \u2014 the swaged collar cannot loosen under any practical vibration level. Excellent fatigue performance from the controlled installation process. Used in high-vibration structural zones where threaded fasteners with locking hardware would still carry residual loosening risk.<\/p>\n

Limitations:<\/strong> Permanent installation (removal requires drilling out the collar); requires dedicated swaging installation equipment.<\/p>\n

Best applications:<\/strong> High-load structural connections in engine nacelles, landing gear structures, high-vibration structural zones.<\/p>\n

Blind Fasteners<\/h3>\n

Blind fasteners install from one side of the joint only \u2014 the installation tool sets the fastener while the opposite side (inaccessible to the installer) forms the bearing surface through the fastener’s expansion mechanism.<\/p>\n

Why blind fasteners are used:<\/strong> Many aircraft structural areas are inaccessible from both sides after assembly \u2014 complex fuselage sections, wing box interiors, enclosed tube structures. Blind fasteners allow these joints to be completed without requiring access to both sides.<\/p>\n

Limitations:<\/strong> Lower load capacity than equivalent-size solid rivets or bolts; not typically used in primary structural load paths requiring maximum joint efficiency.<\/p>\n

Best applications:<\/strong> Enclosed structures, areas with single-side access, secondary structural assemblies.<\/p>\n

Taper-Lok Fasteners<\/h3>\n

Taper-Lok fasteners have a tapered shank that creates an interference fit in a precisely reamed tapered hole. The interference eliminates clearance between fastener and hole, preventing micro-movement (fretting) that initiates fatigue cracks in clearance-fit fastener holes.<\/p>\n

Why Taper-Loks are used:<\/strong> Clearance-fit fastener holes in fatigue-critical structures are prone to fretting \u2014 microscopic relative motion between fastener and hole under cyclic loading that damages the hole surface and creates fatigue crack initiation sites. Taper-Lok interference fit eliminates this mechanism, significantly improving fatigue life in high-stress joints.<\/p>\n

Best applications:<\/strong> Wing-to-fuselage primary structural connections, fatigue-sensitive airframe joints, any location where clearance-fit fatigue is a design concern.<\/p>\n

Limitations:<\/strong> Requires precisely machined tapered holes with tight dimensional tolerances; more complex installation procedure than standard clearance-fit fasteners.<\/p>\n

Turnlock Fasteners<\/h3>\n

Turnlock fasteners (Dzus, Camloc, and similar proprietary systems) are quick-release panel fasteners that allow access panels, maintenance covers, and interior components to be opened and closed rapidly with minimal or no tooling.<\/p>\n

Why turnlock fasteners are used:<\/strong> Access panels on aircraft require frequent opening and closing by maintenance technicians. Standard bolts require torque tools and create secondary loose-hardware risk during maintenance. Turnlock fasteners capture the retention hardware, provide positive locking by quarter-turn engagement, and allow quick access in time-critical maintenance situations.<\/p>\n

Limitations:<\/strong> Not suitable for structural load-bearing applications; load capacity is low relative to structural fastener types.<\/p>\n

Best applications:<\/strong> Access panels, avionics bay covers, inspection doors, interior components.<\/p>\n

Aerospace Fastener Selection Guide<\/h3>\n\n\n\n\n\n\n\n\n\n\n\n
Application<\/th>\nLoad Level<\/th>\nKey Requirement<\/th>\nRecommended Type<\/th>\n<\/tr>\n<\/thead>\n
Fuselage skin panels<\/td>\nDistributed shear<\/td>\nFatigue life, weight<\/td>\nSolid rivets, Hi-Lok<\/td>\n<\/tr>\n
Wing primary structure<\/td>\nHigh structural<\/td>\nFatigue, preload control<\/td>\nTaper-Lok, structural bolts<\/td>\n<\/tr>\n
Engine mounts<\/td>\nVery high<\/td>\nVibration resistance, strength<\/td>\nLockbolts, high-strength bolts<\/td>\n<\/tr>\n
Landing gear<\/td>\nExtreme<\/td>\nImpact, fatigue, strength<\/td>\nHigh-strength steel bolts<\/td>\n<\/tr>\n
Enclosed structures<\/td>\nModerate<\/td>\nOne-side access<\/td>\nBlind fasteners<\/td>\n<\/tr>\n
Access panels<\/td>\nLow<\/td>\nQuick release<\/td>\nTurnlock fasteners<\/td>\n<\/tr>\n
High-fatigue-sensitive joints<\/td>\nHigh<\/td>\nEliminate fretting<\/td>\nTaper-Lok, interference-fit<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
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Aerospace Fastener Standards: AN, MS, NAS, and AS<\/h2>\n

Aerospace fastener standards define the design, material composition, mechanical properties, dimensional tolerances, inspection requirements, and documentation necessary for fasteners to be used in certified aircraft and aerospace systems. For OEM procurement, specifying the correct standard is not optional \u2014 it determines whether a fastener is airworthy.<\/p>\n

AN Fasteners (Air Force\u2013Navy Standard)<\/h3>\n

AN fasteners were among the first formally standardized aerospace fasteners, developed for U.S. military aviation in the mid-20th century. They define basic bolt, screw, nut, and rivet configurations with standardized dimensions and material requirements.<\/p>\n

Application context:<\/strong> AN fasteners remain widely used in general aviation (light aircraft, homebuilt), legacy military platforms, and maintenance replacement applications where the original design specified AN hardware. However, for new designs in commercial and advanced military aerospace, they have largely been superseded by higher-performance NAS and AS standards.<\/p>\n

MS Fasteners (Military Standard)<\/h3>\n

MS fasteners succeeded many AN specifications with improved material requirements, tighter dimensional tolerances, and enhanced fatigue and corrosion resistance specifications. They are the dominant standard for U.S. military aerospace applications.<\/p>\n

Application context:<\/strong> Military aircraft, defense systems, and structural applications requiring better performance than AN while maintaining military qualification.<\/p>\n

NAS Fasteners (National Aerospace Standard)<\/h3>\n

NAS fasteners are developed by the Aerospace Industries Association (AIA) and represent the primary high-performance fastener standard for commercial and advanced military aerospace applications. NAS specifications typically require higher strength grades, tighter dimensional tolerances, better surface finish, and more rigorous testing than equivalent MS or AN specifications.<\/p>\n

Application context:<\/strong> Primary structural joints in commercial aircraft, high-load fatigue-sensitive assemblies, applications where the tighter performance margins of NAS are required by the structural analysis.<\/p>\n

AS Standards (Aerospace Standards \u2014 SAE International)<\/h3>\n

AS standards are developed through SAE International’s Aerospace Standards process and represent the current state of the art in aerospace standardization. They incorporate modern material technology, advanced quality requirements, and align with AS9100 quality management system requirements.<\/p>\n

Application context:<\/strong> Modern commercial aerospace, defense programs with current generation certification requirements, OEM supply chains requiring globally harmonized standards.<\/p>\n

Standard Comparison<\/h3>\n\n\n\n\n\n\n\n\n
Standard<\/th>\nOrigin<\/th>\nPerformance Level<\/th>\nPrimary Application<\/th>\n<\/tr>\n<\/thead>\n
AN<\/td>\nU.S. military (historical)<\/td>\nBaseline<\/td>\nGeneral aviation, legacy aircraft, maintenance<\/td>\n<\/tr>\n
MS<\/td>\nU.S. military<\/td>\nImproved<\/td>\nMilitary aircraft and defense systems<\/td>\n<\/tr>\n
NAS<\/td>\nAerospace Industries Association<\/td>\nHigh performance<\/td>\nCommercial and military primary structures<\/td>\n<\/tr>\n
AS<\/td>\nSAE International<\/td>\nCurrent state of art<\/td>\nModern commercial, defense, space programs<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

For OEM buyers evaluating fastener suppliers, the relevant questions are: which standard does the application require, does the supplier have documented compliance and test data for that standard, and can they provide the lot traceability documentation required for airworthiness records?<\/p>\n

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Aerospace Fastener Materials: Selection and Trade-Offs<\/h2>\n

Material selection in aerospace fasteners is a system-level engineering decision that balances strength, weight, fatigue performance, corrosion resistance, temperature capability, and galvanic compatibility with adjacent structural materials.<\/p>\n

Titanium Fasteners (Ti-6Al-4V and CP Grades)<\/h3>\n

Titanium \u2014 primarily the Ti-6Al-4V alloy (Grade 5) \u2014 is the dominant material for weight-critical aerospace structural fasteners. Its density of approximately 4.43 g\/cm\u00b3 is 43% lower than steel at comparable strength levels, making it the material of choice when weight is a primary design driver.<\/p>\n

Performance characteristics:<\/strong><\/p>\n

    \n
  • Tensile strength: 895\u20131170 MPa depending on temper condition<\/li>\n
  • Density: 4.43 g\/cm\u00b3 (versus 7.85 g\/cm\u00b3 for steel)<\/li>\n
  • Corrosion resistance: excellent \u2014 titanium forms a stable TiO\u2082 passive layer<\/li>\n
  • Fatigue performance: good, particularly in salt-spray environments where steel would corrode at stress concentration sites<\/li>\n<\/ul>\n

    Weight savings at scale:<\/strong> If an aircraft uses 300,000 structural fasteners and switching from steel to titanium reduces average fastener weight by 3 grams, total weight reduction is 900 kg \u2014 roughly equivalent to 9 additional passengers. At $0.10\u2013$0.15 per seat-mile in fuel cost, this generates measurable operational savings over a 20-year aircraft life.<\/p>\n

    Key concern \u2014 thread galling:<\/strong> Titanium-to-titanium threaded contact (bolt into titanium nut or insert) is highly prone to galling \u2014 a form of adhesive wear where the mating surfaces seize and transfer material during tightening. Prevention requires careful torque procedure, lubrication (dry film or anti-seize), and careful thread form specification. In our production experience machining Ti-6Al-4V fasteners for aerospace customers, galling risk during installation is one of the most common failure modes we see in first-article testing \u2014 and it is almost always addressable through surface treatment specification and installation procedure review.<\/p>\n

    Galvanic compatibility:<\/strong> Titanium is relatively noble in the galvanic series. In direct contact with aluminum structure in the presence of moisture, aluminum is the anode and corrodes. Isolation sleeves, faying surface sealants, and anodizing of the aluminum are standard practice in titanium-on-aluminum fastener joints.<\/p>\n

    High-Strength Alloy Steel Fasteners<\/h3>\n

    Alloy steel fasteners (300M, H-11, 4340, 8740) provide the highest absolute tensile strength of any common aerospace fastener material \u2014 up to 1930 MPa (280 ksi) for 300M \u2014 making them the material of choice in applications requiring maximum strength in a fixed envelope, where weight is less critical than load capacity.<\/p>\n

    Application context:<\/strong> Landing gear assemblies, where extreme impact and dynamic loading requires maximum strength in compact geometry; engine attachment structures where high loads are concentrated; any application where the structural analysis drives an extremely high load-in minimum fastener diameter.<\/p>\n

    Key concern \u2014 corrosion:<\/strong> High-strength steels are susceptible to corrosion, particularly stress corrosion cracking (SCC) in high-strength grades above approximately 1380 MPa (200 ksi). Cadmium plating has been the traditional protection system, though environmental regulations are driving transition to cadmium-free alternatives (electroless nickel, zinc-nickel) in new programs. All steel fasteners in aerospace assemblies require surface protection.<\/p>\n

    Hydrogen embrittlement:<\/strong> High-strength steels are susceptible to hydrogen embrittlement during plating processes. Aerospace specifications (AMS 2759\/9 and similar) require controlled plating processes and post-plating bake procedures to prevent embrittlement failures.<\/p>\n

    Superalloy Fasteners (Inconel, A-286)<\/h3>\n

    Nickel-based superalloys \u2014 primarily Inconel 718 and A-286 (iron-nickel superalloy) \u2014 are used in high-temperature applications near jet engines, in exhaust systems, and in any structural zone where operating temperatures exceed the capability of titanium or steel.<\/p>\n

    Performance characteristics:<\/strong><\/p>\n

      \n
    • Inconel 718 maintains useful strength at temperatures up to approximately 650\u00b0C<\/li>\n
    • Excellent oxidation resistance prevents surface degradation in high-temperature oxidizing environments<\/li>\n
    • High fatigue strength under thermal cycling conditions typical of engine structures<\/li>\n<\/ul>\n

      Limitations:<\/strong> High material cost and difficult machinability \u2014 both Inconel 718 and A-286 are notoriously challenging to machine, requiring slow cutting speeds, aggressive coolant, and specialized tooling to achieve the dimensional accuracy and surface finish required for aerospace fasteners.<\/p>\n

      Aluminum Rivets (2117, 2024, 7075 Series)<\/h3>\n

      Aluminum rivets are used extensively in fuselage and wing skin assemblies where their low density (2.7 g\/cm\u00b3), excellent corrosion resistance in appropriate alloy\/temper combinations, and easy installation make them cost-effective in high-volume thin-sheet applications.<\/p>\n

      Application context:<\/strong> Fuselage skin panels, lightweight structural skins, secondary structural assemblies. Not suitable for high-load structural joints where titanium or steel fasteners are required.<\/p>\n

      Material Comparison Summary<\/h3>\n\n\n\n\n\n\n\n\n\n
      Material<\/th>\nTensile Strength<\/th>\nDensity (g\/cm\u00b3)<\/th>\nTemperature Limit<\/th>\nCorrosion Resistance<\/th>\nPrimary Application<\/th>\n<\/tr>\n<\/thead>\n
      Ti-6Al-4V<\/td>\n895\u20131170 MPa<\/td>\n4.43<\/td>\n~315\u00b0C sustained<\/td>\nExcellent<\/td>\nStructural airframe<\/td>\n<\/tr>\n
      300M steel<\/td>\nUp to 1930 MPa<\/td>\n7.85<\/td>\nModerate<\/td>\nNeeds coating<\/td>\nLanding gear, high-load joints<\/td>\n<\/tr>\n
      A-286 superalloy<\/td>\n~1000 MPa<\/td>\n7.92<\/td>\n~700\u00b0C<\/td>\nGood<\/td>\nHigh-temp structural<\/td>\n<\/tr>\n
      Inconel 718<\/td>\n~1380 MPa<\/td>\n8.19<\/td>\n~650\u00b0C<\/td>\nExcellent<\/td>\nEngine, exhaust zones<\/td>\n<\/tr>\n
      Aluminum 2117<\/td>\n~295 MPa<\/td>\n2.71<\/td>\nLow<\/td>\nGood (anodized)<\/td>\nFuselage\/wing skin rivets<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
      \n

      How Aerospace Fasteners Prevent Structural Failure<\/h2>\n

      Aerospace fastener engineering is fundamentally about failure prevention \u2014 designing and installing fastening systems that maintain structural integrity through the entire operational life of the aircraft.<\/p>\n

      Preload: The Foundation of Joint Integrity<\/h3>\n

      Preload \u2014 the clamping force created when a fastener is tightened \u2014 is the most important parameter in aerospace fastener performance. A properly preloaded bolt keeps the joint interfaces in compression. External loads acting on the joint must first overcome this clamping force before the fastener experiences tension. This means the fastener’s stress fluctuation under cyclic loading is dramatically lower than it would be in an unpretensioned joint \u2014 which directly improves fatigue life.<\/p>\n

      According to ASME standards for bolted joint design, a properly preloaded bolt experiences only a small fraction of the external load as stress variation \u2014 typically 10\u201320% for a well-designed joint with an appropriate preload ratio. An underpreloaded bolt experiences the full external load as stress variation, which can reduce fatigue life by an order of magnitude.<\/p>\n

      The practical implication for assembly: aerospace fastener torque specifications are not suggestions. They are the result of fatigue analysis that requires a specific preload to achieve design-life fatigue performance. Under-torquing reduces preload and fatigue life; over-torquing can yield the bolt or damage threads, also reducing fatigue life and joint reliability.<\/p>\n

      Self-Locking Mechanisms<\/h3>\n

      Self-locking features prevent vibration-induced preload loss. Common aerospace locking systems include:<\/p>\n

      All-metal self-locking nuts<\/strong> \u2014 distorted threads or interference insert that creates a prevailing torque requiring force to turn, maintaining engagement under vibration.<\/p>\n

      Collar-based locking (Hi-Lok, lockbolts)<\/strong> \u2014 the installation tool controls locking engagement; once set, the collar provides positive retention that vibration cannot overcome through gradual rotation.<\/p>\n

      Safety wire<\/strong> \u2014 traditionally used on critical engine and flight control fasteners; wire threaded through drilled bolt heads prevents rotation in the loosening direction. Labor-intensive but highly reliable.<\/p>\n

      Liquid thread-locking compounds<\/strong> \u2014 used in specific applications where metal locking hardware would add unacceptable weight or complexity; not appropriate for high-temperature applications.<\/p>\n

      Fatigue Crack Prevention Through Design<\/h3>\n

      The locations where fatigue cracks most commonly initiate in bolted joints are: fastener hole edges (stress concentration factor 2\u20133\u00d7 for a circular hole in a plate under tension), thread roots (stress concentration from thread geometry), and fretting damage zones where micro-motion occurs between fastener and hole.<\/p>\n

      Aerospace fastener design addresses each of these:<\/p>\n

        \n
      • Cold expansion of fastener holes<\/strong> \u2014 a mandrel is pulled through the hole before fastener installation, creating a compressive residual stress field around the hole that opposes fatigue crack opening. Cold-expanded holes in aircraft primary structure can improve fatigue life by a factor of 3\u20135\u00d7 compared to standard drilled holes.<\/li>\n
      • Interference-fit fasteners (Taper-Lok)<\/strong> \u2014 eliminate fretting by removing clearance that permits micro-motion.<\/li>\n
      • Smooth surface finish specifications<\/strong> \u2014 fastener shank and hole surfaces specified to controlled Ra values; surface roughness provides crack initiation sites that reduce fatigue life.<\/li>\n
      • Thread rolling rather than thread cutting<\/strong> \u2014 rolled threads have compressive residual stress at the thread root from the cold-forming process, improving fatigue life compared to cut threads.<\/li>\n<\/ul>\n
        \n

        Common Aerospace Fastener Failure Modes<\/h2>\n

        Understanding failure modes allows engineers to specify appropriate fastener types and installation procedures, and allows maintenance engineers to interpret in-service findings correctly.<\/p>\n

        Fatigue Failure<\/h3>\n

        Fatigue failure in aerospace fasteners typically initiates at the first thread engagement below the nut face \u2014 the location of highest stress concentration \u2014 or at the fastener hole edge in the loaded plate. It is progressive: micro-cracks form under cyclic loading and propagate cycle-by-cycle until the remaining cross-section is insufficient to carry static load. Sudden fracture occurs with no visible warning in routine inspection.<\/p>\n

        Prevention:<\/strong> Correct preload (reduces stress fluctuation), interference-fit installation where fretting is a risk, surface treatments (cold expansion, shot peening) that introduce beneficial compressive residual stress, and fatigue-rated fastener specifications that verify minimum cycles to failure in standardized testing.<\/p>\n

        Galvanic Corrosion<\/h3>\n

        Galvanic corrosion occurs when two metals of different electrochemical potential contact each other in the presence of an ionic conductor (typically moisture with dissolved salts). The more anodic metal corrodes preferentially. In aerospace, the most common galvanic pair concern is titanium fasteners in aluminum structure \u2014 aluminum is significantly more anodic than titanium and corrodes at the contact interface.<\/p>\n

        Prevention:<\/strong> Sealant application at faying surfaces before fastener installation (the sealant creates an ionic barrier), isolation sleeves on titanium fasteners in aluminum holes, anodizing of aluminum structure in the fastener zone.<\/p>\n

        Thread Galling<\/h3>\n

        Galling is adhesive wear between threaded surfaces \u2014 particularly problematic with titanium (titanium-on-titanium, or titanium bolt in titanium structure) because the passive oxide layer that gives titanium its corrosion resistance breaks down under the high contact stress of thread engagement, exposing bare reactive metal that bonds to the mating surface.<\/p>\n

        Prevention:<\/strong> Dry film lubricant (MoS\u2082 or similar) on fastener threads before installation; controlled assembly torque with calibrated tools; using steel or coated inserts in titanium tapped holes where repeated fastener removal is required.<\/p>\n

        Stress Corrosion Cracking (SCC)<\/h3>\n

        High-strength steel fasteners above approximately 1380 MPa (200 ksi) are susceptible to stress corrosion cracking in the presence of moisture and corrosive species. SCC combines tensile stress (from preload or external loading) with corrosive attack to produce crack growth at stress levels well below the material’s yield strength.<\/p>\n

        Prevention:<\/strong> Cadmium or zinc-nickel plating to prevent corrosive exposure; careful material specification (avoiding susceptible heat treat conditions); design to limit sustained tensile stress in high-humidity environments.<\/p>\n

        Over-Torque Damage<\/h3>\n

        Excessive installation torque can yield the fastener shank, cause thread stripping, or \u2014 in high-strength materials \u2014 cause hydrogen embrittlement if the stress exceeds the material’s threshold. Over-torqued fasteners typically do not fail immediately but show reduced fatigue life and may fracture prematurely in service.<\/p>\n

        Prevention:<\/strong> Calibrated torque tools; torque values that account for friction coefficient (lubrication and coating condition affect the torque-to-preload relationship significantly); installer training and quality verification.<\/p>\n

        \n

        Aerospace Fasteners and Aircraft Weight<\/h2>\n

        An aircraft may contain 500,000 to over 3 million fasteners. At this scale, individual fastener weight differences that seem trivial become significant structural weight decisions.<\/p>\n

        Replacing steel fasteners with titanium equivalents in primary airframe structure saves approximately 40% in fastener weight per unit \u2014 roughly 2\u20135 grams per fastener depending on size. Across 300,000 structural fasteners, this yields 600\u20131,500 kg of weight savings. Aircraft manufacturers quantify fuel savings in terms of kilograms of structural weight: at $1\u2013$3 in fuel savings per kilogram per year at current fuel prices and typical utilization rates, a 1,000 kg weight reduction generates $1,000\u2013$3,000 in annual fuel savings per aircraft \u2014 multiplied by a fleet of hundreds of aircraft and a 25-year service life, the total value is substantial.<\/p>\n

        The lifecycle economics consistently justify titanium’s upfront cost premium for primary structure. The engineering calculation is not “is titanium more expensive?” \u2014 it is “what is the 25-year fuel cost of carrying the weight difference?”<\/p>\n

        Beyond material selection, fastener count optimization \u2014 reducing the number of fasteners through joint redesign and use of structural bonding in composite assemblies \u2014 provides additional weight savings without compromising structural integrity. Modern composite aircraft structures (Boeing 787, Airbus A350) use significantly fewer fasteners per unit area than equivalent aluminum structures, because composite panels can be manufactured in larger sections, and adhesive bonding carries load without fasteners.<\/p>\n

        \n

        Aerospace Fastener Manufacturing Process<\/h2>\n

        Aerospace fasteners are produced through tightly controlled manufacturing sequences that differ fundamentally from standard industrial fastener production.<\/p>\n

        Thread Rolling vs. Thread Cutting<\/h3>\n

        Thread rolling \u2014 producing threads by plastic deformation rather than material removal \u2014 is mandatory for fatigue-critical aerospace fasteners in most specifications. Rolled threads have compressive residual stress at the thread root from the cold-forming process, compared to the tensile residual stress produced by thread cutting. In standardized aerospace fastener fatigue testing, rolled-thread specimens consistently outperform cut-thread specimens by significant margins (typically 2\u20134\u00d7 fatigue life improvement).<\/p>\n

        AMS 2432 and related standards specify thread rolling for aerospace fastener production. Suppliers offering cut-thread aerospace fasteners should be questioned \u2014 cut threads are a disqualifying deviation for most fatigue-critical applications.<\/p>\n

        CNC Machining of Complex Geometry<\/h3>\n

        Cold heading is cost-effective for high-volume simple fastener shapes, but many aerospace fastener types \u2014 Hi-Lok pins, Taper-Lok bodies, custom structural bolts \u2014 require CNC machining to achieve the complex geometry and tight dimensional tolerances (shank diameter \u00b10.005 mm or better, concentricity within 0.003 mm) that their structural function demands.<\/p>\n

        Titanium CNC machining for aerospace fasteners requires particular care: slow cutting speeds, high-pressure coolant delivery, sharp tooling with low tool engagement time to limit heat buildup, and careful attention to surface integrity. The thermal sensitivity of titanium means that machining-induced residual stress and microstructural damage can reduce fatigue life \u2014 making process control a quality issue, not just a dimensional one.<\/p>\n

        Heat Treatment and Verification<\/h3>\n

        Heat treatment to achieve specified strength grade must be conducted under documented, controlled conditions with verification testing (tensile testing, hardness testing) on each lot. AMS 2759 series specifications govern heat treatment of aerospace steel fasteners; AMS 2801 governs titanium heat treatment. Post-heat treatment inspection catches heat treatment anomalies before fasteners are installed in aircraft where detection is far more difficult.<\/p>\n

        Quality System Requirements<\/h3>\n

        Every aerospace fastener lot must be produced under a documented quality management system (AS9100 Rev D for aerospace) and accompanied by:<\/p>\n

          \n
        • Material certifications<\/strong> \u2014 confirming chemical composition, heat treatment condition, and material properties meet the applicable AMS or ASTM specification<\/li>\n
        • Dimensional inspection records<\/strong> \u2014 showing that sampled fasteners from the lot meet all drawing requirements<\/li>\n
        • Mechanical test results<\/strong> \u2014 tensile, shear, or proof load testing as required by the applicable standard<\/li>\n
        • Lot traceability<\/strong> \u2014 batch identifier traceable through all production steps to raw material heat number<\/li>\n<\/ul>\n

          For OEM procurement teams, these documents are not optional paperwork \u2014 they are the evidence base for the airworthiness of installed fasteners. A fastener without complete traceability documentation cannot be used in type-certificated aircraft, regardless of its physical condition.<\/p>\n

          \n

          DFM Guidelines for Aerospace Fastener Applications<\/h2>\n

          Optimize Fastener Count Through Joint Analysis<\/h3>\n

          Every fastener added to an aircraft assembly adds weight, installation time, inspection requirement, and potential failure mode. Modern FEA-based joint analysis can precisely determine the minimum fastener count and spacing that provides required load transfer with appropriate fatigue margins. In many legacy designs, fastener count was conservatively specified using hand analysis methods that overestimated the required density.<\/p>\n

          Reducing fastener count through validated analysis \u2014 not intuition \u2014 lowers weight and assembly cost without compromising structural integrity.<\/p>\n

          Control Hole Tolerance and Preparation<\/h3>\n

          Fastener hole quality directly determines the fatigue life of the joint. Requirements vary by fastener type:<\/p>\n

            \n
          • Clearance-fit holes:<\/strong> Diameter tolerance typically +0.000\/+0.010″ (NASM 33588 class); surface finish Ra \u2264 1.6 \u00b5m; no burrs, drill breakout damage, or tool marks at hole edge.<\/li>\n
          • Interference-fit holes (Taper-Lok):<\/strong> Taper angle and diameter tolerance \u00b10.0005″ or better; requires precision reaming after drilling.<\/li>\n
          • Cold-expanded holes:<\/strong> Mandrel oversize relative to hole produces 0.4\u20134% interference; controlled process per NASM 1312-8.<\/li>\n<\/ul>\n

            Poor hole preparation \u2014 oversize holes, rough surface finish, burrs, bell-mouth entry \u2014 creates stress concentration and fretting damage that negates the fatigue advantages of high-quality fasteners.<\/p>\n

            Prevent Galvanic Corrosion in Design<\/h3>\n

            The design stage is the correct time to specify material compatibility and corrosion isolation \u2014 retrofitting corrosion protection after the design is released is expensive and often incomplete.<\/p>\n

            Design rules for galvanic compatibility:<\/p>\n

              \n
            • Avoid titanium fasteners directly contacting aluminum structure without sealant at the faying surface<\/li>\n
            • Specify faying surface sealant (MIL-PRF-81733 or equivalent) in all titanium-on-aluminum fastener joints<\/li>\n
            • Avoid carbon fiber-to-aluminum direct contact in composite-metal hybrid structures (carbon fiber is cathodic to aluminum)<\/li>\n
            • Select fastener materials close in galvanic potential to the adjacent structure where possible<\/li>\n<\/ul>\n

              Design for Installation and Inspection Access<\/h3>\n

              Fasteners that cannot be properly torqued are fasteners that will be improperly preloaded. Tool clearance for the torque wrench head must be built into the design \u2014 minimum clearances vary by tool type (box wrench, torque wrench, pneumatic driver) but must be explicitly verified in the design model.<\/p>\n

              Similarly, fasteners in locations that cannot be visually inspected for installation condition, corrosion, or crack initiation should either be eliminated through redesign, provided with borescope access, or scheduled for disassembly inspection at defined maintenance intervals.<\/p>\n

              DFM Checklist for Aerospace Fastener Systems<\/h3>\n\n\n\n\n\n\n\n\n\n\n
              Design Question<\/th>\nDFM Action<\/th>\n<\/tr>\n<\/thead>\n
              Is fastener count minimized through FEA joint analysis?<\/td>\nDocument load path analysis supporting fastener layout<\/td>\n<\/tr>\n
              Are material combinations specified with galvanic compatibility?<\/td>\nSpecify faying sealant, isolation, or compatible pairing<\/td>\n<\/tr>\n
              Do holes specify surface finish, tolerance, and any cold expansion?<\/td>\nInclude hole preparation requirements on drawing<\/td>\n<\/tr>\n
              Is torque tool clearance verified in the assembly model?<\/td>\nCheck clearance for required installation tool at each location<\/td>\n<\/tr>\n
              Are structural fasteners specified to the correct standard (AN\/MS\/NAS\/AS)?<\/td>\nConfirm standard compliance with structural analysis<\/td>\n<\/tr>\n
              Is lot traceability and material certification required in procurement spec?<\/td>\nInclude documentation requirements in purchase order<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
              \n

              Applications by Aircraft Structure<\/h2>\n

              Fuselage<\/h3>\n

              Fuselage fasteners must survive pressurization cycles \u2014 typically 75,000+ cycles over aircraft service life for narrow-body commercial aircraft. The combination of hoop stress from pressurization and bending stress from flight loads creates biaxial fatigue at every fastener hole in the fuselage skin. Solid rivets and Hi-Lok fasteners in pre-treated or cold-expanded holes are the dominant approach. Faying surface sealant at all skin-to-frame joints is standard practice to prevent corrosive moisture intrusion into fastener holes.<\/p>\n

              Wing Primary Structure<\/h3>\n

              Wing box fasteners carry the highest structural loads on the aircraft \u2014 up to several hundred kilonewtons in static conditions, with significant fatigue cycling from gust and maneuver loading. Taper-Lok interference-fit fasteners at critical wing box panel joints eliminate fretting and provide fatigue performance that clearance-fit alternatives cannot achieve. Material is typically titanium for weight-critical primary structure, with high-strength steel in localized high-load fittings.<\/p>\n

              Landing Gear<\/h3>\n

              Landing gear fasteners experience impact loads at touchdown that impose instantaneous loads far exceeding steady flight loads. Ultra-high-strength steel (300M, H-11 at 1724\u20131930 MPa) is used to carry these loads in compact cross-sections. Stress corrosion cracking protection through plating, careful sealant application, and controlled installation procedure is critical \u2014 landing gear operates in wet, dirty, and corrosive environments that create high SCC risk in unprotected high-strength steel.<\/p>\n

              Jet Engines<\/h3>\n

              Engine fastener requirements differ fundamentally from airframe requirements. Temperature is the dominant constraint: Inconel 718 and A-286 are standard materials for fasteners operating in the hot section of turbofan engines, where ambient temperature exceeds the capability of titanium and high-strength steels. Creep resistance \u2014 the ability to maintain preload at elevated temperature over extended time \u2014 is as important as room-temperature strength. Standard aerospace quality certifications apply, but engine-specific qualification (FAA PMA or OEM approval) is typically also required.<\/p>\n

              Spacecraft<\/h3>\n

              Spacecraft fasteners operate in vacuum environments with extreme temperature cycling (\u00b1150\u00b0C or more for LEO satellites between sun and shadow) and must survive the mechanical loads of launch without allowing any fastener to become a foreign object hazard. Titanium is widely used for structural fasteners. Outgassing requirements (contamination control for optical and electronic systems) govern lubricant and coating selection. Locking mechanisms must function reliably after thermal cycling and must not loosen under the broadband vibration of launch.<\/p>\n

              \n

              Key Takeaways<\/h2>\n
                \n
              • Aerospace fasteners are safety-critical structural components<\/strong>, not commodity hardware \u2014 material, standard, installation procedure, and traceability documentation all directly affect airworthiness.<\/li>\n
              • Seven main fastener types<\/strong> (rivets, bolts, Hi-Lok, lockbolts, blind, Taper-Lok, turnlock) each address a specific combination of load, access, maintenance, and fatigue requirements. Selection is a structural engineering decision.<\/li>\n
              • Four principal standards<\/strong> (AN, MS, NAS, AS) reflect increasing performance requirements; NAS and AS are the current standards for primary commercial and advanced military aerospace structures.<\/li>\n
              • Material selection<\/strong> is a system-level decision: titanium for weight-critical structural fasteners, high-strength steel for maximum load in compact geometry, superalloys for high-temperature zones, aluminum for thin-sheet riveted structures.<\/li>\n
              • Preload is the foundation of fatigue performance<\/strong> \u2014 properly preloaded fasteners experience a fraction of the cyclic stress of unpretensioned joints, extending fatigue life by an order of magnitude.<\/li>\n
              • Rolled threads are mandatory<\/strong> for fatigue-critical aerospace fasteners \u2014 cut threads produce adverse residual stress that significantly reduces fatigue life.<\/li>\n
              • For OEM procurement teams<\/strong>: full lot traceability, material certification to AMS\/ASTM specifications, and AS9100-certified manufacturing are non-negotiable requirements for aerospace fastener procurement. Fasteners without complete documentation cannot be used in type-certificated aircraft.<\/li>\n<\/ul>\n
                \n

                Frequently Asked Questions<\/h2>\n

                What are aerospace fasteners and why are they different from standard fasteners?<\/h3>\n

                Aerospace fasteners are bolts, rivets, screws, nuts, and specialized fastening systems engineered specifically for aircraft and spacecraft assembly. Unlike standard industrial fasteners, they are designed for simultaneous high strength-to-weight ratio, fatigue resistance across millions of load cycles, vibration resistance, corrosion resistance in harsh environments, and precision dimensional control. They are produced under certified quality management systems (AS9100), accompanied by material certifications and lot traceability documentation, and must comply with specific aerospace standards (AN, MS, NAS, or AS). The distinction is not incremental \u2014 aerospace fasteners exist because the failure modes and consequences in aircraft structures are categorically different from typical mechanical applications.<\/p>\n

                What is the difference between AN, MS, NAS, and AS aerospace fastener standards?<\/h3>\n

                AN (Air Force\u2013Navy) is the oldest U.S. aerospace fastener standard, commonly used in general aviation and legacy aircraft maintenance. MS (Military Standard) superseded many AN specifications with improved material and testing requirements for military aerospace applications. NAS (National Aerospace Standard) represents higher-performance commercial and military fastener specifications with tighter tolerances and better fatigue characteristics, used in primary structural joints. AS (SAE Aerospace Standard) is the current standard aligned with modern material technology and AS9100 quality system requirements. For new commercial aerospace programs, NAS and AS standards are the applicable specifications; AN hardware is appropriate only where the original design certification was based on AN requirements.<\/p>\n

                Why are titanium fasteners preferred in aerospace primary structures?<\/h3>\n

                Titanium alloy fasteners (primarily Ti-6Al-4V) are preferred for aerospace primary structures because their density of 4.43 g\/cm\u00b3 is 43% lower than steel at comparable strength levels, delivering direct weight savings across the thousands of fasteners in an airframe. Titanium also has excellent corrosion resistance without surface coatings, good fatigue performance, and maintains mechanical properties across the temperature range of most airframe applications. At aircraft scale \u2014 where 300,000 structural fasteners switching from steel to titanium saves 600\u20131,500 kg \u2014 the weight savings generate measurable fuel efficiency improvements over the aircraft’s 20\u201325-year service life, providing lifecycle economics that justify titanium’s higher upfront material and machining cost.<\/p>\n

                What causes fatigue failure in aerospace fasteners and how is it prevented?<\/h3>\n

                Fatigue failure initiates at stress concentration locations \u2014 typically the first thread engagement below the nut face or the fastener hole edge in the loaded plate \u2014 under the cumulative effect of cyclic loading from takeoff\/landing pressurization cycles, flight maneuvers, and turbulence. Prevention strategies include: proper preload to reduce cyclic stress amplitude (a correctly preloaded fastener experiences only 10\u201320% of the external load as stress variation); cold expansion of fastener holes to introduce beneficial compressive residual stress; interference-fit fasteners (Taper-Lok) to eliminate fretting at clearance-fit holes; thread rolling instead of cutting to produce favorable thread root residual stress; and rigorous surface finish specification to eliminate crack initiation sites.<\/p>\n

                How do Hi-Lok and lockbolt fasteners differ from standard bolts?<\/h3>\n

                Hi-Lok fasteners consist of a threaded pin and a separate collar with a controlled break-off hex feature. During installation, the collar tightens against the pin until the hex wrenching element shears at a precise torque value \u2014 eliminating installation variability and ensuring consistent preload on every fastener regardless of operator technique. Lockbolts use a swaged collar rather than a threaded nut: the installation tool pulls the pin while hydraulically swaging the collar into pin grooves, creating a permanent cold-formed lock that maintains preload under vibration without any additional locking hardware. Standard bolts require separate locking features (locknuts, safety wire) to prevent vibration-induced loosening. Both Hi-Lok and lockbolts are used where the consistency and permanence of joint preload is critical to fatigue performance.<\/p>\n

                What is thread galling and why is it a concern for titanium aerospace fasteners?<\/h3>\n

                Galling is adhesive wear between mating threaded surfaces, particularly problematic with titanium because the passive TiO\u2082 oxide layer that gives titanium its corrosion resistance breaks down under the high contact stress of thread engagement. The exposed reactive titanium metal bonds to the mating surface, causing seizing, surface tearing, and potentially making the fastener impossible to remove. Galling risk is highest with titanium-on-titanium threading (titanium bolt into titanium tapped hole or titanium insert). Prevention requires dry film lubricant (molybdenum disulfide or similar) on fastener threads before installation, calibrated assembly torque, controlled tightening procedure, and \u2014 in applications requiring repeated removal \u2014 steel inserts in titanium tapped holes rather than direct titanium threading.<\/p>\n

                What documentation is required for aerospace fastener procurement?<\/h3>\n

                Complete aerospace fastener documentation includes: material certification confirming chemical composition and mechanical properties meet the applicable AMS or ASTM specification; heat treatment certification (for steel and titanium fasteners requiring specific temper conditions); dimensional inspection report confirming sampled lot measurements meet drawing requirements; mechanical test results (tensile, shear, or proof load as required by the applicable standard); surface finish and coating certification; and lot traceability documentation linking the batch identifier through all production steps to the original material heat number. For AS9100-certified suppliers, these documents are generated as part of the standard quality management system. Fasteners without complete documentation cannot be installed in type-certificated aircraft \u2014 they must be quarantined and returned or scrapped.<\/p>\n

                How do aerospace fasteners affect aircraft weight at fleet scale?<\/h3>\n

                A commercial narrow-body aircraft may contain 500,000 to 2 million fasteners depending on size and construction method. Replacing steel fasteners with titanium equivalents in primary airframe structure saves approximately 40% of fastener weight \u2014 roughly 2\u20135 grams per fastener for typical structural sizes. Across 300,000 structural fasteners, this produces 600\u20131,500 kg of weight reduction. At current jet fuel prices and typical narrow-body utilization (3,000+ flight hours per year), a 1,000 kg structural weight reduction saves $1,000\u2013$3,000 in annual fuel cost per aircraft. For a fleet operator with 200 aircraft, this represents $200,000\u2013$600,000 per year in fuel savings \u2014 a return that justifies titanium’s higher initial procurement cost within a few years of operation.<\/p>\n

                \n

                Written by the CMS engineering team with 15+ years of precision CNC machining experience in aerospace fastener manufacturing, titanium alloy components, and AS9100-certified production for commercial aviation and defense OEM programs. Technical references: AS9100 Rev D (Aerospace Quality Management Systems), AMS 4928 (Ti-6Al-4V Bar and Billet), NASM 33588 (Aircraft Fastener Hole Quality), SAE ARP1312 (Aerospace Fastener Traceability), FAA Advisory Circular AC 43.13-1B (Acceptable Methods for Aircraft Maintenance).<\/em><\/p>\n

                \n

                Sourcing Aerospace-Grade CNC Machined Fasteners and Structural Components?<\/strong><\/p>\n

                At CMS, we produce Hi-Lok pins, structural bolts, Taper-Lok bodies, and custom aerospace fasteners in Ti-6Al-4V, Inconel 718, 300M steel, and A-286 with full material certification, rolled thread specifications, and AS9100-documented lot traceability. Every aerospace fastener order includes dimensional inspection records, material certs, and engineering review for thread form, surface finish, and galvanic compatibility \u2014 not just machined parts with a certificate attached.<\/p>\n

                [Request a feasibility review and aerospace fastener quote \u2192]<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

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