Do you know the difference between MS and NAS bolts? They are two of the most common types of threaded fasteners used in the aerospace industry. MS and NAS bolts are used in commercial airliners, commuter jets, helicopters and light aircraft. While they both feature a threaded body or shank, however, MS and NAS bolts aren’t the same.
What Are MS Bolts?
MS bolts are threaded fasteners that follow Military Standard design (MS) specifications. To improve the consistency and quality of its vehicles and equipment, the United States military pioneered a set of design specifications for fasteners in the 1950s. Known as MS, it was the successor to the previously used Army-Navy (AN) specifications. MS consists of sizes, tolerances, materials, strength and other specifications that dictate the design of fasteners.
What Are NAS Bolts?
NS bolts are threaded fasteners that follow National Aerospace Standard (NAS) design specifications. NAS was pioneered by the Aerospace Industries Association (AIA) in the early 1940s. Like AN, it consists of design specifications for fasteners. NAS bolts are bolts that follow the NAS specifications.
Difference Between MS and NAS Bolts?
MS and NAS bolts are both used extensively in the aerospace industry, but they aren’t the same. For starters, they have different markings. MS bolts typically feature “MS,” followed by a part number. NS bolts, on the other hand, feature “NAS,” followed by the part number. In some cases, NAS bolts may also feature additional markings to identify their origin or material.
MS and NAS bolts have different tolerances. Tolerances, of course, represent the allowed variations in a given fastener or part. Bolts with tighter tolerances allow smaller variations than those with greater tolerances. NAS bolts typically have tight tolerances, whereas MS bolts have somewhat broader tolerances.
Many NAS bolts also have a higher tensile strength than their MS counterparts. Tensile strength represents the bolt’s ability to withstand a pulling force without breaking. The higher the tensile strength, the more pulling force the bolt can handle. NAS bolts are commonly used in airplanes and other types of aircraft where they are exposed to strong forces. Therefore, they typically have a very high tensile strength.
In Conclusion
While MS and NAS bolts may look similar, they serve different roles in aerospace engineering. MS bolts, rooted in military standards, are suitable for general-purpose applications with broader tolerances. NAS bolts, developed specifically for the aerospace industry, are built to tighter specifications and higher strength requirements.
