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Fastener Acronyms

Fastener Acronyms

Fastener Acronyms can be confusing but they are a constant in the fastener world. At Albany County Fasteners we want to make your experience as simple as possible. To help you better find what you need, we have compiled a list of commonly used acronyms, what they stand for and what they mean.

Machine screws are mostly available in smaller sizes, these screws have a flat point and can be driven into a pre-tapped hole or used with a nut.UNJC+UNJFComparable to UNC and UNFSimilar to UNC and UNF in both external and internal threading. External threading on these have a much larger root radius. These larger roots lead to increased tensile stress and as a result, make them stronger. Below is a list of most of the fastener acronyms you are likely to come across.




Acronym – Term Description
AN
Aeronautical Standards Group
Precedes the dimensional specifications developed by the Aeronautical Standards Group.
ANSI
American National Standard Institute
The American National Standard Institute (founded 1918) was formed to create a national standard for sizing.
ASME
American Society of Mechanical Engineers
The American Society of Mechanical Engineers (founded 1881) was created to pursue research, education and improvement of the industry while also placing a strong emphasis on public safety.
ASTM
American Society for Testing & Materials
The American Society for Testing & Materials (founded 1898) aims to promote safety and health by sharing information about the reliability of different aspects in the manufacturing industry.
CS
Countersink
A drilled hole with a wider rim so that a screw or bolt can sit inside that area and be flush with the surface it is installed into.
DIN
Deutsches Institut Für Normung
Din, 1917, is the German institute for standardization. They focus on the technical and scientific creation of technical standards.
En-Standards (CEN)
European Committee of Standardization
CEN was created to be a mediator between the European Union and European Free Trade Association. They were to pass resolutions which both parties must adhere to.
FT
Fully Threaded
Threading that starts at the tip of the screw and goes all the way to the undercut of the head.
GR
Grade
A level of material that describes its composition.
HDG
Hot Dip Galvanized
A process that adds a layer of corrosion resistance by dipping fabricated steel into a kettle containing molten zinc.
IFI
Industrial Fastener Institute
Founded in 1931, the Industrial Fastener Institute is an association who supports standards for the mechanical fastener industry. They often develop standards when one does not exist until a national standard can be provided.
ISO
International Organization for Standardization
The ISO, is a federation of 158 countries from all over the world. Based in Switzerland, they propose, develop and implement new standards and then deliver them to the world.
LF
Large Flange
A wider surface area, often with a much greater outer diameter, than the typical surface area. Ex: Large Flange Washers.
MS
Military Standards
Standardized objectives created by the U.S. Department of Defense.
Prop 65
California’s Safe Drinking Water and Toxic Enforcement Act
A warning label that protects Californians from chemicals which can cause long-term health defects.
PT
Partially Threaded
Threading that starts at the tip of a screw and stops at some point allowing for the screw or bolt to have a shoulder.
REACH
Authorization and Restriction of Chemicals
A European regulation created to test and determine if chemicals are safe and can be used.
RoHS
Restriction of certain Hazardous Substances
RoHS is a directive to restrict hazardous substances in electrical and electronic equipment. Any fastener that is a component of electrical parts and placed on the European Union market must adhere to this restriction.
SAE
Society of Automotive Engineers
A society, founded in 1905, to test and create standards for the automotive industry. They also develop standards for heavy-duty and aerospace vehicles.
SD
Self Driller or Self Drilling Screws
Primarily used to drill into steel and join materials such as sheet metal today.
SEMS
Pre-assembled Screws
Pre-made screw and washer assemblies.
SLT
Slotted
A common drive style which is also commonly called a flat head.
SMS
Sheet Metal Screws
Sharp threaded screws used to cut into soft metals, wood or plastics.
UN
Thread Sizing
A series of threading for applications where UNC, UNF, UNEF and UNS are not applicable.
UNEF
Unified National Extra Fine
Threads even smaller than fine threading these extra fine threads are commonly used on very small screws to make the screw stronger.
UNC
Unified National Coarse
Coarse threading that is the prefered thread for general use.
UNF
Unified National Fine
Fine threading that is not as strong as coarse threading. They do offer finer adjustments than coarse threads.
UNR
Unified Round
The root radius must be rounded but does not necessarily have to be inspected.
UNS
Unified Special
Threads that are tip(threads per inch) specified but are limited to a specific diameter.

There are many fastener abbreviations, not all of which are listed here. Please let us know in the comments below which acronyms we forgot and help us to create a more informed fastener community!



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