Trying to determine the right fastener for your application, but getting lost in all the jargon and technical specifications that are out there? Trust us, you鈥檙e not the only one.
The fastener industry can be complicated, especially if you need a part that鈥檚 more specialized than your typical Phillips-head screw. There are a ton of new, technical terms to learn 鈥斅燽ut we鈥檝e got you covered. Here鈥檚 a glossary-style list with some of the most important fastener terms and abbreviations you need to know.
A Guide to Fastener Terminology
Below is a list of about 50 different fastener terms and abbreviations, which are categorized into five different sections: types, manufacturing processes, measurement, testing, and standards and specifications.
While this is by no means a complete list of all the fastener terminology out there, it鈥檚 a good starting point for some of the most common terms to know going into your project.
If you have a question about a term or concept that isn鈥檛 defined on this list, don鈥檛 hesitate to reach out to us! We鈥檙e happy to help. Also, be sure to browse the links associated with some of these terms, as they鈥檒l lead you to our articles with more information regarding each subject.
RELATED: Need a specialty bolt, screw, or stud? 黑料大事记 can help.
Fastener Types
Bolt – An externally threaded fastener designed for insertion through holes in assembled parts. It鈥檚 normally intended to be tightened or released by torquing a nut.
Countersunk – Used to describe a fastener head that rests evenly with or below the material surface after installation. The design tapers toward the fastener shank, allowing the head to essentially 鈥渟ink鈥� into the surface.
Carriage bolt – A type of bolt with a threaded bar and a domed, enlarged head on one end that鈥檚 designed to keep the bolt from pulling through.
External drive – A fastener head that requires a tool, like a wrench, to wrap around the head for installation and removal.
External thread – Threading on the outside of a cylindrical fastener.
Head style – The type of head or top on a fastener, such as a round or hex head style.
Hex head – A fastener head with six vertical sides and a flat bearing surface.
Hex flange head – A fastener head with six vertical sides that expand out to a flat, washer-like bearing surface at the bottom.
Internal drive – A fastener head that requires a tool, like a screwdriver, to be inserted within the head for installation and removal.
Internal thread – Threading on the inside of a cylindrical, holed fastener.
MS fastener – Abbreviation for 鈥渕il-spec鈥� or 鈥渕ilitary specification.鈥� It鈥檚 a type of fastener that鈥檚 designed and maintained by the United States Military.
Non-countersunk – Used to describe a fastener head that protrudes from the material surface after installation, leaving the head fully exposed. The design includes a narrow shank that鈥檚 topped with an abrupt, wide head.
Place bolt – A self-locking, free-spinning hex head bolt that prevents loosening due to vibration. It offers up to seven times more vibration resistance than a conventional hex head cap screw.
Screw – An externally threaded fastener designed for insertion through holes in assembled parts, mating with a preformed internal thread, or forming their own thread. It鈥檚 tightened and released by torquing a head.
Specialty fastener – A fastener that鈥檚 designed and manufactured for a certain industry, application, or material. It鈥檚 made with unique specifications that set it apart from common fasteners you鈥檇 find at a hardware store or use in a widely practiced application.
Stud – An externally threaded fastener that typically looks like and operates as a threaded bar. It鈥檚 commonly used to join two components with internally threaded holes together
Washer – A thin plate with a hole in the middle, which is used to distribute the load and increase the bearing surface of a threaded fastener.
Fastener Manufacturing Processes
Cold forming – Also known as cold heading, this is a process of forming a fastener without heating up the material. It鈥檚 usually accomplished by striking or pressing the material within a form, or die, to create a part with desired specifications.
Fastener coating – A chemical that鈥檚 applied to the exterior of a fastener to improve its performance and longevity (e.g. zinc phosphate, cadmium electroplate, etc.)
Short-run production – Also known as limited-run production, this is a process in which a manufacturer accepts and fulfills orders involving relatively small quantities of product. At 黑料大事记, we use short-run production to manufacture specialty fasteners in smaller quantities.
Thread cutting – The process of producing external threads on a fastener by cutting away, or removing, material from a round bar.
Thread rolling – The process of producing external threads on a fastener by rolling it through a set of threading dies that displace the material to form threads, without removing any material or changing its grain structure.
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Body diameter – The diameter of the body (or smooth part) of the fastener, which is generally located above the threads.
Major diameter – The largest diameter of a fastener thread. It鈥檚 measured from the crest (top) of a thread on one side to the crest of a thread on the other side.
Minor diameter – The smallest diameter of a fastener thread. It鈥檚 measured from the root (bottom) of a thread on one side to the root of a thread on the other side.
Nominal diameter – This is shorthand for 鈥渘ominal major diameter鈥� 鈥斅燼nd, in most cases, 鈥渘ominal鈥� just means 鈥渂asically.鈥� So it鈥檚 an estimated major diameter.
Pitch – The distance from a point along one thread to that same point on the next thread. You can measure pitch from the crest, the trough, or any point in between.
Pitch diameter –聽 The diameter of a theoretical cylinder that exists halfway between the major and minor diameters.
TPI – Abbreviation for threads per inch. As the name suggests, it鈥檚 calculated by counting the number of thread peaks along a 1-inch length.
UNC – Abbreviation for Unified National Coarse thread. It鈥檚 the United States鈥� standard for fasteners with coarse threads. Coarse threads are bigger, and there are therefore fewer of them on a fastener.
UNF – Abbreviation for Unified National Fine thread. It鈥檚 the United States鈥� standard for fasteners with fine threads. Fine threads are smaller, and there are therefore more of them on a fastener.
Fastener Testing
Bearing surface testing – Fastener testing method that measures how much the amount of surface area and roughness of the bottom of the fastener head or washer will affect friction.
Coefficient of friction – Fastener testing method that measures the kinetic and static resistance of the surfaces of a bolted joint as it鈥檚 being tightened.
Hardenability testing – The testing of a material that provides data on the changes in hardness of a material as it鈥檚 heated to various temperatures.
NSS testing – Abbreviation for neutral salt spray testing. It鈥檚 a fastener testing method that measures corrosion resistance by inserting it in a test chamber with salt spray for a specified number of hours.
Proof load – The minimum amount of force a fastener must be able to withstand for a given amount of time without experiencing permanent deformation.
Tensile strength – The maximum force that a fastener can withstand before fracturing.
Torque-tension testing – Fastener testing method that measures the input torque required for a bolted joint to achieve a specified tension.
Yield strength – The load that鈥檚 carried at the point where a fastener experiences permanent deformation.
Fastener Standards and Specifications
ASME – Abbreviation for The American Society of Mechanical Engineers. It鈥檚 an organization that creates quality standards for five main industries: bioengineering, robotics, clean energy, manufacturing, and pressure technology.
ASTM – Abbreviation for The American Society for Testing and Materials. It鈥檚 an organization that created one of the first quality standards sets, and it now focuses on six types of standards related to the manufacturing process: test method, specification, classification, practice, and guide and terminology.
DIN – Abbreviation for Deutsches Institut f眉r Normung, or the German Institute for Standardization. It鈥檚 an organization that creates quality standards, but many of those standards have been outright replaced by ISO standards.
IATF – Abbreviation for The International Automotive Task Force. It鈥檚 an organization of automotive manufacturers and their trade associations 鈥斅燼ll of who work to provide consistent quality management standards for automotive suppliers worldwide.
ISO – Abbreviations for The International Standards Organization. It鈥檚 an organization that establishes widely used standards for a multitude of manufacturing applications. It鈥檚 by far the most common standard for establishing an overreaching quality management system (QMS).
Grade – A set of characteristics, defined by a standard, that determines the material, hardness, and strength of a fastener. Many standards require distinct head markings to make the grades easier to identify.
Property class – The metric equivalent to the standard (or inch) term 鈥済rade.鈥�
QMS – Abbreviation for quality management system. It outlines all the policies and procedures put in place by a company to ensure that its products and services meet customer requirements.
SAE – Abbreviation for The Society of Automotive Engineers. It鈥檚 a United States-based organization that鈥檚 composed of automotive and aerospace engineers, and that creates its own quality standards for manufacturing applications.
Have More Questions on Fastener Terminology? 黑料大事记 Us.
The fastener industry can get a bit technical and confusing 鈥斅燽ut by working with 黑料大事记, it doesn鈥檛 have to be. Our specialty fastener experts are here to help you decipher the details and find the right solution for your application. 黑料大事记 us to learn more about our products, processes, and how we can best support you.
