A fastener, abbreviated as FSTNR, is hardware that mechanically joins two or more objects together.

Science Branches

fastener Types

• Removable  -  These parts can be disconnected without damaging the fastener like nut and bolt.

• Semi-permanent  -  These parts can be disconnected, but some damage can occurs to the fastener like a cotter pin.

• Permanent  -  These parts will never be disassembled like rivets and welding.

fastener standards

ASME Standards

• ASME B1.20.1 - Pipe Threads, General Purpose, Inch
• ASME B1.20.3 - Dryseal Pipe Threads, Inch
• ASME B18.12 - Glossary of Terms for Mechanical Fasteners
• ASME B18.18 - Quality Assurance for Fasteners

Mathematics Symbols

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Nomenclature & Symbols for Engineering, Mathematics, and Science 

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Fastener Nomenclature & Symbols

• \( FSTNR \)  -  fastener
• \( ANPT \)  -  American National Taper Pipe
• \( ANPT \)  -  Aeronautical National Pipe Taper
• \( ANS \)  -  American National Standard replaced with UNS
• \( BA \)  -  British Association
• \( BSF \)  -  British Standard Fine
• \( BSP \)  -  British Standard Pipe
• \( BSW \)  -  British Standard Whitworth
• \( \lambda \)  (Greek symbol lambda)  -  elastic modulus
• \( f \)  -  friction
• \( ISO \)  -  International Organization for Standardization
• \( NPT \)  -  National Pipe Thread Tapered Thread
• \( NPTF \)  -  National Pipe Taper Fuel - Dryseal
• \( NPS \)  -  nominal diameter
• \( \tau \) (Greek symbol tau)  -  shear stress
•  \( f_s \)  -  static friction
•  \( \mu_s \)  (Greek symbol mu)  -  static friction coefficient
•  \( \epsilon \)  (Greek symbol epsilon)  -  strain
• \( \sigma \)  (Greek symbol sigma)  -  stress
• \( T \)  -  temperature
• \( UNS \)  -  Unified National Standard
• \( USS \)  -  United States Standard
• \( UTS \)  -  Unified Thread Standard
• \( \sigma \)  (Greek symbol sigma)  -  yield strength

Fastener Glossary

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A

• Alloy steel  -  A steel that one or more elements (other than carbon) have been added.

• Annealing  -  A process of heat treatment that changes the properties of metals.

B

• Bolt  -  A fastener with a head and threaded on one end only.

• Bolt head  -  Formed by heating the end of a round piece of steel round bar then forged in to a head shape.

• BSF  -  British Sandard Fine

• BSW  -  British Standard Whitworth

C

• Cold forming  -  A material is placed between two dies and compressed into a shape.

• Corrosion resistant  -  The ability to resist corrosin under certain conditions.

• Cut thread  -  A threading method produced by removing material from the surface with a form cutting tool.

D

• Deformation  -  Is measured by how much an object is deformed from its origional dimensions.

• Dynamic friction  -  Resistance to relative movement of two bodies that are already in motion.

E

• Effective diameter  -  See pitch diameter.

• Elastic modulus  -  The ratio of the stress applied to a body or substance to the resulting strain within the elastic limits.

• External thread  -  A screw thread that is formed on the external cylinder.  Also called male thread.

F

• Fastener length  -  Measured from the top of the head to the bottom of the threads.

• Force  -  The push or pull of an object resulting in a change from rest or motion.

• Forging  -  The process of forming raw steel by displacement under force into specified shapes.

• Friction  -  The mechanical resistance to the relative movement of two surfaces.

• Friction coefficient  -  The ratio between two contacting surfaces and the frictional force that resists the normal force of the object.

G

H

• Hex head bolt  - A bolt with six sided head.

• Hex head cap screw  -  A hex head screw with a flat and washer faced bearing surface under the head.

I

• IFI  -  Industrial Fasteners Institute

• Internal thread  -  A screw thread that is formed inside a hole.  Also called female thread.

J

K

L

• Left hand thread  -  A screw head that rotates counterclockwise.

• Lock nut  -  Resists loosening under vibration and torque.

M

N

• Major diameter  -  The largest diameter of a screw thread.

• Minor diameter  -  The smaller diameter of a screw thread.

• Nominal diameter  -  The external size diameter designated of pipe or threads.

O

P

• Pitch diameter  -  See thread pitch diameter.

Q

• Quenching  -  A process of quickly cooling an elevated temperature.

R

• Right hand thread  -  A screw head that rotates clockwise.

S

• Shank diameter  -  The smooth part of the bolt above the threads.

• Shear stress  -  Tends to deform the material by breaking rather than stretching without changing the volume by restraining the object.

• Static friction  -  The force that resists relative movement and keeps objects at rest.

• Static friction coefficient  -  The amount of force that resists motion that is on the verge of motion.

• Strain  -  The deformation, stretched or compressed, of a material compared to its original length.

• Stress  -  The force per unit area of cross-section.

T

• Tap bolt  -  A bolt that is threaded to the botom of the head.

• Temperature  -  The amount of heat or cold, but it is neither heat or cold.

• Tension strength  -  The capacity of a material to resist a force tending to stretch it.

• Thread angle  -  The angle between the thread flanks.

• Thread axis  -  The imaginary distance equally between the major and minor diameters.

• Thread count  -  The number of threads per inch (TPI), used for US threads.

• Thread crest  -  The peak of a thread at the major diameter.

• Thread flank  -  The side of a thread between the major and minor diameters.

• Thread height  -  The perpendicular distance between the major and minor diameters.

• Thread length  -  Length of the cylinder that is threaded.

• Thread pitch  -  The distance between threads measured in millimeters, used for metric threads.

• Thread pitch diameter  -  The imaginary diameter equal distance between the major and minor diameters.  Also called effective diameter.

• Thread root  -  The bottom of the thread.

• Torque  -  A rotational moment.

U

• Ultimate tensile strength  -  The maximum stress a material can resist before it starts to elongate.

• UNC  -  United National Course

• UNEF  -  United National Extra Fine

• UNF  -  United National Fine

• UNR  -  United National (UN)

V

W

X

Y

• Yield point  -  The point where an elastic material is permanent change in length with no extra load force.

• Yield strength  -  The minimum stress that leads to permanent deformation of the material.

Z

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