ToolingU Fasteners

Military Standards

A United States system, often called mil-specs, used for standardization, quality, and security of products and equipment by the United States Department of Defense. Military standards are often used by industries needing high precision, such as the aerospace industry.

Thread Nicking

A condition in which the crests of external threads are damaged, usually by rough handling. Thread nicking can cause problems with assembly.

Black Oxide

A coating used to add mild corrosion resistance to metals. Black oxide changes the appearance of metals and also increases their life spans.

Tapered Key

A device similar to a standard bar key, except with a top surface that tapers and gradually decreases in size along its length.

Tool

A device such as a screwdriver or wrench used to perform mechanical work.

Nut

A fastener with a threaded hole that mates with a bolt. Nuts are often hexagon-shaped to accommodate a driving tool.

Nuts

A fastener with a threaded hole that mates with a bolt. Nuts have internal threads.

Chrome

A hard gray metal often used as an alloying element in steel. Chromium is highly resistant to corrosion and wear.

Carbon Steel

A common metal that is an alloy of iron and carbon. The amount of carbon in carbon steel affects its strength, ductility, and malleability.

Flat Washer

A common washer that consists of a flat metal disc with a center hole. Flat washers are also called plain washers.

Plain Washer

A common washer that consists of a flat metal disc with a center hole. Plain washers are also called flat washers.

Jaws

A component of a wrench that grips bolts and nuts. Jaws that are dull can cause a wrench to slip, creating a safety hazard.

Workholding Devices

A component used to hold and locate a workpiece. Workholding devices include jigs and clamps.

Hex Bit

A hexagonal tool that fits into the head of a drill or screwdriver. Hex bits are used to fasten socket head cap screws.

Spring Steel

A high-carbon steel that exhibits excellent strength and is used to make springs and other similar components.

Epoxies

A high-strength adhesive. Epoxies contain metallic elements.

Spring Pin

A hollow cylindrical pin with an open slot along the pin's length that allows the pin to compress and fit into a smaller hole.

Socket

A hollow tool that fits over a nut or bolt completely. Sockets attach to various devices that are used to tighten or loosen fasteners.

Shaft

A long cylindrical bar used to support rotating components or transmit motion. Shaft components are secured with set screws.

Bar Key

A long rectangular device with parallel sides and precise dimensions that is inserted into a matching keyway and key slot. Bar keys are typically used to assemble gears, handles, wheels, or similar components onto a shaft.

Leadscrews

A long, threaded bar that transfers power between machine tool components. Leadscrews often have multiple-start threads.

Punch Presses

A machine with a stationary base and an upper arm that moves along a vertical axis to shear, bend, or form sheet metal. Punch presses are often used to perform punching and stamping.

Head Marks

A manufacturer-specific identification marking on fasteners for lot tracking. Head marks may be raised on the surface of depressed into the fastener head.

Base Component

A material or object that is being joined by assembly. The place where a fastener attaches to the base component is called the point of operation.

Electrical Conductivity

A material's ability to act as a medium for conveying electricity. Electrical conductivity depends on the material's structure.

Tensile Strength

A material's ability to resist forces that attempt to pull it apart or stretch it. Tensile strength specifies the load a fastener can withstand before it breaks.

Driving Tool

A mechanical device that pushes one object into another object. Driving tools fit into matching driving recesses.

Hinges

A mechanical joint capable of movement. Hinges can be attached with fasteners.

Rivet Guns

A power-driven tool that uses compressed air to force rivets into an object. Rivet guns are commonly pneumatic tools.

Forklifts

A powered industrial vehicle with a pronged platform on the front for lifting material. Forklifts are used to lift and transport heavy loads.

Brazing

A process in which a filler metal is melted at a temperature above 840°F (449°C), but below the melting point of the base metals to form a joint between two base metals. Brazing can be used to join dissimilar metals like silver, aluminum, copper, nickel, and gold.

Assembly Line

A process in which products are mass-produced in stages.

Coupling Agent

A compound that assists in the bond between two adherents. Coupling agents can be used to pretreat surfaces before an adhesive is applied.

Lacquer

A compound that assists in the bond between two adherents. Lacquer can be used to pretreat surfaces before an adhesive is applied.

Strip

A condition in which a fastener's threads become damaged and ineffective. Fasteners strip when excess torque is applied or when their threads become misaligned.

Posture

How a person stands, sits, or arranges his or her body. Good posture can reduce the occurrence of ergonomic injuries.

Spatter

Liquid metal droplets expelled from the welding process. Spatter is a safety risk for welders.

Maintenance, Repair, And Overhaul

MRO. The range of activities that help keep products in operation. Maintenance, repair, and overhaul activities include planned or preventive service as well as rebuilding and alteration of products.

Outside Diameter

OD. The exterior surface of a spherical or cylindrical object. Threads on the outside diameter are called external or male threads.

Occupational Safety And Health Administration

OSHA. A government agency that sets the standards for working conditions in the United States. The Occupational Safety and Health Administration creates regulations that ensure that assemblers work in safe and healthy environments.

Brittle

Resistant to being drawn, stretched, or formed. Brittle materials are more likely to chip, shatter, or cause fasteners to ricochet.

Clearance

The amount of space or distance between two mating parts. Clearance is greater between threads with looser fits.

Duty Cycle

The amount of work a tool can perform in a given amount of time before it must rest to prevent it from overheating.

Included Angle

The angle between two defined features. Included angles are created by two adjacent flanks on a thread.

Stress

The applied force over a certain area that tends to deform an object or structure.

Torque

The applied force that attempts to twist or rotate a material. Torque is used to tighten threaded fasteners.

Bearing Surface

The area of a component that contacts another object. The bearing surface on fasteners is the underside of the fastener head that makes contact with the part.

Depth

The distance between the root and the crest of a thread. Depth is also known as thread height.

Thread Height

The distance between the root and the crest of a thread. Thread height is also known as depth.

Diameter

The distance from one edge of a circle or circular object to the opposite edge, as measured through the center. Diameter describes the size of round and cylindrical objects, such as fasteners, workpieces, and tools.

Thermal Expansion

The tendency of a material to increase in size as it increases in temperature.

Curing

The process during which an adhesive undergoes a chemical reaction and becomes a solid. Curing may require pressure, heat, UV radiation, or a specific amount of time.

Cam Out

The process of a driving tool slipping out of the driving recess. Camming out is common with Phillips drives.

Galvanizing

The process of adding a zinc coating to steel. Galvanized steel has superior corrosion resistance.

Assembly

The process of joining components together into a larger or completed part. Assembly methods include mechanical fastening, adhesive bonding, and welding.

Reassembly

The process of putting previously disassembled components back together. Reassembly is made possible using mechanical fasteners.

Disassembly

The process of taking apart a product, often with the intention of reassembly. Disassembly is made possible using mechanical fasteners.

Physical Properties

The properties that describe the way a material responds to external environment conditions, such as temperature, chemical exposure, and electricity. Corrosion resistance is the most important physical property for fasteners.

Mechanical Properties

The properties that describe the way a material responds to forces that attempt to bend, break, twist, dent, or scratch it. Mechanical properties are the most important properties for fasteners.

Cold Forming

A process that compresses or shapes metal into a finished product at low or room temperatures. Cold forming improves the strength of the metal.

Flat-Head Screwdriver

A screwdriver that has a flat blade and corresponds to slotted screws. Most properly referred to as a "slotted screwdriver."

Pozidriv Screwdriver

A screwdriver with four intersecting adjacent points that corresponds to pozidriv screws.

Phillips Screwdriver

A screwdriver with four intersecting perpendicular points that corresponds to Phillips screws.

Torx Screwdriver

A screwdriver with six points that corresponds to torx screws.

Push-Start Screwdriver

A screwdriving tool that is powered when it is pushed against a joint.

Slip-Clutch Screwdriver

A screwdriving tool that uses a continuous-drive clutch and "slips" once it achieves torque, instead of stopping. Slip-clutch screwdrivers are versatile and are convenient when applications differ from task to task.

Radially Assembled Snap Ring

A snap ring that is assembled by fitting the ring onto a shaft from the side. Radially assembled snap rings cannot be assembled into a hole.

Axially Assembled Snap Ring

A snap ring that is assembled by fitting the ring over the end of a shaft or through the opening of a hole.

Self-Locking Ring

A snap ring with small prongs around its circumference that grip into the mating part.

Cadmium

A soft, bluish-white metal found in zinc ores. Cadmium is commonly used in metal alloys and as a coating on base metals.

Dowel Pin

A solid, cylindrical semi-permanent pin mainly used to locate machine parts in a fixed position or to maintain alignment. Dowel pins are the most basic pins.

Straight Pin

A solid, cylindrical semi-permanent pin mainly used to locate machine parts in a fixed position or to maintain alignment. Straight pins are also referred to as dowel pins.

Cylinder

A solid, three-dimensional shape with circular ends and straight sides. Cylinders form the basic shape of threaded fasteners.

Model

A specific design of a product. Cars and appliances are examples of products that are available as many different models.

Batch

A specific quantity to be produced. Batch-model assembly lines produce products in groups.

Helix

A spiral structure with a repeating pattern. The helix of a thread can be right-handed or left-handed.

Neck

A square section under the fastener head that prevents slipping and turning after assembly. Square necks are used by carriage and plow bolts.

Right-Hand Thread

A thread that is driven by rotating it clockwise. Right-hand threads are found on most threaded fasteners.

Left-Hand Thread

A thread that is driven by rotating it counterclockwise. Left-hand threads are rare.

Square Threads

A thread with a symmetrical box-like profile. Square threads have straight flanks that are perpendicular to the crest and root.

V-Shaped Threads

A thread with a symmetrical peaked profile. V-shaped threads generally have 60° included angles.

Acme Threads

A thread with a symmetrical trapezoid-like profile. Acme threads have flat crests and 29° included angles for power and motion transfer.

Buttress Threads

A thread with an asymmetrical profile that has one straight and one angled flank. Buttress threads have flat crests and roots.

Threaded Fastener

A threaded device that holds objects together or grips material. Threaded fasteners include screws, nuts, and bolts.

Socket Screw

A type of capscrew with a round head and a hexagonal indentation for tightening purposes.

Continuous-Drive Clutch

A type of clutch that delivers power to the tool constantly.

Discontinuous-Drive Clutch

A type of clutch that delivers power to the tool in bursts.

Semi-Permanent Pin

A type of pin that requires pressure, force, or tools for installation or removal. Semi-permanent pins include straight pins, taper pins, cotter pins, and clevis pins.

Quick-Release Pin

A type of pin that is generally used for the manual assembly and disassembly of rigid machine components. Quick-release pins include push-pull pins.

Small Rivet

A type of rivet with a shank diameter of less than 0.500 of an inch. Small rivets are often used in the sheet metal and aircraft industries.

Large Rivet

A type of rivet with a solid shank and a diameter of 0.500 in. or more. Large rivets are mainly used for structural work on buildings, bridges, or tanks.

Hardness

The measure of a material's ability to resist penetration, indentation, and scratching. In some metals, the level of hardness can be controlled through heat treating.

Joint

The meeting point of the two materials that are joined together. Most fasteners create a joint that can be disassembled and reassembled.

Megapascal

The metric unit of pressure. Megapascal is abbreviated Mpa.

Weld Metal

The molten metal that becomes the welded joint upon solidification. Weld metal is composed of base metals and filler metal.

Density

The relative compactness of a material. Density is the mass of a material per unit volume.

Side Shields

Devices attached to safety glasses to protect the eyes from flying debris. Safety glasses with side shields must be worn during assembly operations.

Preload

The tension created in a fastener when it is first tightened. Preload must be greater than the external forces applied to the assembly to prevent joint failure.

Symmetrical

Having features on either side of a point, line, or plane that are identical in size, shape, and position. Symmetrical flanks are a characteristic of V-shaped threads.

Asymmetrical

Having features on either side of a point, line, or plane that differ in size, shape, or position. Asymmetrical flanks are a characteristic of buttress threads.

Hexagonal

Having six sides. Hexagonal fasteners like nuts often accommodate a driving tool.

Downtime

Unproductive blocks of time during which operations cease to function, normally due to setup procedures or mechanical problems.

Zinc

A bluish white metal that is corrosion resistant and has a relatively low melting point. Zinc is often used as a coating on steel.

T-Head Bolt

A bolt with a T-shaped head that matches the T-slots in a machine table. T-head bolts rotate to lock the bolt in place.

Twelve-Point Bolt

A bolt with a double hex, or twelve-pointed, head. Twelve-point bolts are common in the aerospace industry.

Plow Bolt

A bolt with a flat circular head and a square neck. A plow bolt's square neck prevents the bolt from turning while the nut is tightened.

Square-Head Bolt

A bolt with a four-sided head. Square-head bolts are often used in wooden assemblies.

Carriage Bolt

A bolt with a rounded circular head and a square neck. A carriage bolt's square neck prevents the bolt from turning while the nut is tightened.

Hex Bolt

A bolt with a six-sided head. Hex bolts are the most common type of bolt.

Respirator

A breathing device worn to prevent inhalation of hazardous substances. A respirator protects assemblers working with harmful fumes.

Trigger

A button or lever that, when depressed, delivers power to an automated device.

Medium-Carbon Steel

A carbon steel that contains between 0.3% and 0.6% carbon. Medium-carbon steels are strong, hard, and not as easily machined as low-carbon steels.

Low-Carbon Steel

A carbon steel that contains less than 0.30% carbon. Low-carbon steels are generally tough, ductile, and easily machined.

Engine Blocks

A casing that holds various moving parts in an automotive engine and provides channels for fluids to flow. Engine blocks on larger engines often use 8-UN series threads.

Adhesive

A chemical substance used to bond two or more materials together. Adhesives are made up of nonmetallic materials.

Grade

A classification that describes the quality of a material. The grade of material is important for avoiding fastener failure.

Pressure Vessels

A closed container whose contents are held at a pressure different from the pressure of the air outside the vessel. Pressure vessels often use 8-UN threads.

Fumes

A cloud of particles suspended in a gas. Fumes are a health hazard and disadvantage of the welding process.

Electroplated

A coating method that uses electricity and a conductive solution to deposit a layer of plating metal on a metallic or non-metallic workpiece. Electroplated zinc is a common coating on screws.

Cross Threading

A condition in which the internal and external threads of a fastener assembly are not properly aligned. Cross threading can cause threads to become damaged or locked together.

Belleville Washer

A cone-shaped locking washer with a raised section that flattens to prevent loosening without damaging parts. Belleville washers are also called conical spring washers.

Conical Spring Washer

A cone-shaped locking washer with a raised section that flattens to prevent loosening without damaging parts. Conical spring washers are also called Belleville washers.

Clutch

A coupling found inside a motorized device that engages or disengages parts to drive the mechanism.

Radius

A curved or rounded profile at the junction of two surfaces. Radius surfaces at the root are a characteristic of V-shaped threads.

Jigs

A customizable workholding device that holds a tool or workpiece in place. Jigs control the location or motion of a workpiece.

Stud

A cylindrical fastener that has external threads at both ends. A stud does not have a head.

Studs

A cylindrical fastener that has external threads at both ends. Studs do not have heads.

Shear Pin

A cylindrical pin made from a relatively soft material that is designed to shear and break from excessive damaging shocks or loads. The shear pin breaks to preserve the rest of the assembly.

Clevis Pin

A cylindrical pin with a head at one end and one or more holes running through the diameter. A clevis pin is typically locked in place with a cotter pin to provide motion between components where great accuracy is not required.

Screw

A cylindrical threaded fastener that either fits into a threaded hole or forms threads in a material. Screws may have blunt or pointed ends.

Screws

A cylindrical threaded fastener that either fits into a threaded hole or forms threads in a material. Screws may have blunt or pointed ends.

Bolt

A cylindrical threaded fastener with a head that usually mates with a nut. Bolts typically have blunt ends.

Bolts

A cylindrical threaded fastener with a head that usually mates with a nut. Bolts usually have blunt ends.

Specifications

A description of the essential physical and technical properties of a machine or device. Specifications describe a tool's capabilities, including its capacity.

Property Classes

A designation system that categorizes the strength of metric fasteners. Property classes consist of numbers where increasing numbers represent increasing tensile strengths.

Class Of Fit

A designation that indicates how loose or tight a Unified thread fits. Class of fit uses numbers to designate tightness, with higher numbers being the tightest.

Thread Series

A designation that indicates the coarseness or fineness of Unified threads. Thread series is usually either Unified coarse (UNC) or Unified fine (UNF).

Parts Feeders

A device for transporting parts from workstation to workstation. Parts feeders position the part so that it is ready for the next station.

Torque Regulator

A device found on automated screwdriving tools that indicates when desired torque has been obtained.

Cutting Tools

A device made of hard, tough material with one or more sharp edges used to create chips and remove material. Cutting tools are either single-point or multi-point tools.

Gib-Head Key

A device similar to a standard bar key, except with a head at one end that extends above the top surface of the key.

Sensors

A device that detects a change in physical and environmental conditions. Sensors allow robots and other devices to interact with their environment and operate with little human intervention.

Air Dryer

A device that extracts moisture from the air. Shops that use compressors may have to use air dryers to keep shop air free from moisture.

Fastener

A device that holds objects together or locates them in relation to one another. Fasteners can be threaded or non-threaded.

Fasteners

A device that holds objects together or locates them in relation to one another. Fasteners can be threaded or non-threaded.

Tool Balancer

A device that suspends a tool above the workstation using a retractable cord. Tool balancers are ergonomic and reduce clutter.

Tool Positioner

A device that suspends a tool just above the components using an adjustable bar or rod.

Indenter

A device used in a hardness test that is pressed into the test material.

Power Source

A device used to generate the energy needed to power a tool. The most common power sources for screwdriving tools are electricity, air, and batteries.

Parts Bin

A device used to hold parts or supplies. Parts bins are usually on wheels so they can be easily transported around a shop.

Back Brace

A device used to support the spine by limiting its motion. A back brace is a type of PPE for lifting.

Woodruff Key

A device with a flat top, flat sides, and a semi-circular curved bottom. Woodruff keys are used to assemble components on a shaft by fitting into a matching curved key slot.

Grinding Wheel

A disc made of a bonded abrasive used to remove material from a workpiece surface. Grinding wheels are typically mounted in a spindle that allows them to rotate.

Weld Defects

A discontinuity that causes a weld to fail. Weld defects must be repaired, or the part must be discarded.

Hex Socket

A driving recess with a six-pointed, hexagonal recess in the fastener head. Hex socket screw drives are one of the most common types of screw drive.

Non-Threaded Fasteners

A fastener that does not have threads. Common non-threaded fasteners include pins, retaining rings, and rivets.

Threaded Fasteners

A fastener that has threads to hold objects together or grip material. Threaded fasteners include screws, nuts, and bolts.

Light Curtains

A field of light that stops a machine when the light is blocked by an object. Light curtains should be checked to ensure they are operating properly before assembly begins.

Fire Shields

A flame-resistant, tarp-like device that is used to isolate a work area. Fire shields protect bystanders from UV radiation, flying debris, and sparks.

Washer

A flat metal disc with a hole through the center. Washers are often used with threaded fasteners to spread the load and control joint tightness.

Washers

A flat metal disc with a hole through the center. Washers are often used with threaded fasteners to spread the load and control joint tightness.

Snap Ring

A flat, circular non-threaded fastener with a hollow center and an open section. Retaining rings provide a shoulder and can be inserted onto a shaft or inside a hole with an internal groove.

Retaining Ring

A flat, circular, non-threaded fastener with a hollow center and an open section. Retaining rings provide a shoulder and can be inserted onto a shaft or inside a hole with an internal groove.

Retaining Rings

A flat, circular, non-threaded fastener with a hollow center and an open section. Retaining rings provide a shoulder and can be inserted onto a shaft or inside a hole with an internal groove.

Balancers

A flexible, retractable line of rope, wire rope, or strap. Balancers are a form of lanyard used for heavy tools.

Lanyards

A flexible, retractable line of rope, wire rope, or strap. Lanyards are commonly called balancers in assembly.

Shear Force

A force that attempts to cause the internal structure of a material to slide against itself.

Torsional Load

A force that is applied by clamping one end of an object and twisting the other.

Bending Load

A force that is applied in the middle or on the end of an object causing the object to bend in a curve.

Trapezoid

A four-sided shape that resembles a triangle with a flattened top. Trapezoid-shaped threads are called acme threads.

Keps Nut

A free-spinning lock nut with an attached locking washer. A Keps nut's locking washer provides extra resistance when tightened to prevent loosening.

Lot

A group of similar parts created during the use of a particular tooling setup. Lots of fasteners are tracked by the manufacturer head marks.

Torque Reaction

A jerk that assemblers feel in the handle of the tool they are using when torque is reached. Torque reaction is undesirable and is an ergonomic concern because it can cause injury.

Soldering

A joining process in which a filler metal is melted at temperatures below 840°F (449°C) to form a joint between two base metals. Soldering is often used for delicate projects such as jewelry and electronics.

Soft Joint

A joint in which it takes the fastener more than a 720° turn, or two full rotations, to get from fitting snugly to reaching torque.

Hard Joint

A joint in which less than a 30° turn will take the fastener from fitting snugly to reaching torque.

Lug Nut

A large nut that mates with a heavy bolt.

Structural Bolt

A large, heavy-duty bolt used for structural applications in buildings and bridges. A structural bolt is a type of hex bolt.

Assemblies

A larger part or product that consists of several other components that have been joined together. Assemblies are made up of multiple smaller subassemblies.

Protective Coating

A layer applied over metal that contains elements, which prevent the metal from damage.

Radial Lines

A line on the surface of a nut that extends out like a circle radius. Radial lines denote SAE grades on fasteners.

Repetitive Motion Injury

A localized musculoskeletal disorder or injury caused by performing persistent, continual movement. Repetitive motion injuries most commonly occur in the joints of the arms.

SEMs Screw

A locking fastener consisting of a machine screw with an attached free-spinning washer. A SEMs screw typically has a locking washer but may have a plain washer.

Free-Spinning Lock Nut

A locking nut that creates resistance only when the final torque is applied. Free-spinning lock nuts include special features to provide resistance, such as the locking washer on a Keps nut.

Nylon Insert Lock Nut

A locking nut with a nylon ring built into the top of the nut. Nylon insert lock nuts add interference to resist loosening.

All-Metal Lock Nut

A locking nut with deformed threads that add interference to resist loosening. All-metal lock nuts are also called distorted thread lock nuts.

Distorted Thread Lock Nut

A locking nut with deformed threads that add interference to resist loosening. Distorted thread lock nuts are also called all-metal lock nuts.

Slotted Hex Nut

A locking nut with notches cut into the top that are assembled with cotter pins to lock the nut in place. Slotted hex nuts are also called castle nuts.

Castle Nut

A locking nut with notches cut into the top that are assembled with cotter pins to lock the nut in place.Castle nuts are also called slotted hex nuts

Split Lock Washer

A locking washer with a split section that is intentionally bent out of shape. A split lock washer is forced back into a flat shape as the fastener tightens.

Tab Lock Washer

A locking washer with one or more flat extensions that are bent to lock the washer and nut in place. Tab lock washers may also have more than one hole.

Tooth Lock Washer

A locking washer with teeth that grip into materials. Tooth lock washers may have internal teeth, external teeth, or both.

Spiral-Wound Ring

A snap ring consisting of a strip of metal that is coiled back onto itself.

Base Metals

A metal component to be fused by welding or other joining methods. Base metals influence weld type and the welding process.

Steel

A metal consisting of iron and carbon, usually with small amounts of other elements. Steel is the most common screw material.

Ferrous Metals

A metal containing iron, generally as a primary ingredient. Ferrous metals are the most commonly used metal in the manufacturing of fasteners.

Ferrous

A metal that contains iron. Carbon steels are common ferrous metals.

Nonferrous Metals

A metal that does not contain iron as the main element. Aluminum, copper, and zinc are nonferrous metals.

Nonferrous

A metal that does not contain iron. Aluminum, copper, and zinc are nonferrous metals.

Punch

A metal tool with an end that can be hammered that is used to either indent material or aid in removing components.

Yield Strength

A metal's ability to resist gradual progressive force without permanent deformation. Yield strength of fastener materials is usually expressed in pounds per square inch or megapascals.

Brinell Scale

A method for testing a material's hardness that forces a hard steel sphere under a specified load into the surface of a material and measuring the diameter of the indentation left after the test.

Vickers Scale

A method for testing a material's hardness that uses a pyramid-shaped diamond to exert pressure on the surface of a material for a standard length of time. The diagonal of the indentation is measured under a microscope to determine the hardness value.

Rockwell Scale

A method for testing a material's hardness that uses an indenter to test the material's resistance to deformation as a load is applied.

Thread Rolling

A method of producing threads by forcing hard dies into a solid blank or workpiece. Thread rolling is an example of cold forming and produces stronger threads than thread cutting.

Thread Cutting

A method of producing threads by using cutting tools to remove material from a solid blank or workpiece. Thread cutting produces weaker threads than thread rolling and is often used to manufacture internal threads.

Lockout/Tagout

A method of protecting employees from accidental machine startup by locking and labeling devices. Lockout/tagout renders a tool or machine inoperable.

Conveyors

A moving strip of material that carries parts or other components from one area of an assembly site to another. Conveyors improve the efficiency of an assembly line by keeping parts moving.

Rivets

A non-threaded fastener that consists of a shank and a head made of deformable material. Rivets are inserted through holes and the shank is formed into a head on the other side of the part.

Brass

A nonferrous alloy containing copper and zinc. Brass has moderate strength and good corrosion resistance.

Aluminum

A nonferrous metal that is silvery white in color and lightweight. Aluminum fasteners resist corrosion and are good conductors of electrical energy.

Copper

A nonferrous metal that is very ductile, thermally and electrically conductive, and corrosion resistant. Copper alloys, such as brass, are often used to make fasteners for the electronics industry.

Impact Drivers

A power-driven tool that uses compressed air to force large fasteners into an object. Impact drivers are commonly pneumatic tools.

Tolerance Class

A number and letter combination that indicates a thread's degree of fit and whether it is an internal or external thread. Tolerance class identifies the degree of fit with a number and the tolerance position and type of thread with a letter.

Locking Nut

A nut designed to prevent loosening of the joint when assembled onto a bolt. Locking nuts are used for joints that require extra security.

Locking Nuts

A nut designed to prevent loosening of the joint when assembled onto a bolt. Locking nuts are used for joints that require extra security.

Subassemblies

A part that consists of smaller parts or sub-components and is used in the assembly of larger parts. Subassemblies are joined with other components to create larger assemblies.

Platform

A permanent open-sided structure that is elevated above the surrounding floor or ground. A platform allows assemblers to work at elevated heights.

Assemblers

A person who assembles parts. Assemblers must be aware of workplace safety regulations and guidelines.

Assembler

A person who assembles parts. Assemblers perform mechanical fastening, adhesive bonding, and welding tasks.

Cotter Pin

A pin with two ends positioned parallel to each other before use. Cotter pins are inserted through holes and then bent back to lock the pin and other components in place.

Conduit

A pipe line or tubing that channels air or fluids. Pneumatic tools use conduits to channel the air that is delivered to the tools.

Standards

A policy and guideline established to ensure fastener compatibility, mechanical properties, performance, and other characteristics. Standards may designate the characteristics of fastener threads, or of the entire fastener.

Thread Standards

A policy and guideline established to ensure thread compatibility and interchangeability. Thread standards include metric and Unified thread standards.

Automatic Fastening Tool

A power tool, usually a screwdriver, that is automatically supplied with fasteners. The tool can be guided by an operator or a machine.

Impact Wrenches

A power-driven tool that uses a discontinuous drive clutch and compressed air to achieve torque. Impact wrenches should never be connected unless they will be used immediately.

Nail Guns

A power-driven tool that uses compressed air to automatically force a nail into an object. Nail guns are commonly pneumatic tools.

Blow Guns

A power-driven tool that uses compressed air to clear away industrial debris from parts, workstations, and machines. Blow guns should not be connected unless they will be used immediately.

Conditioning

A process that prepares the surface of a part for subsequent operations, including adhesive bonding. Conditioning creates a rough surface on adherents that makes the adhesive bond more effective.

Face Shield

A protective device that guards the face and eyes. Face shields can be required PPE for some assembly operations.

Tension

A pulling force that is directed away from an object and attempts to move, stretch, or elongate it. Tension is applied to fasteners when they are tightened.

Tension Load

A pulling force that is directed away from the object and attempts to stretch or elongate the object.

Force

A push or pull that gives energy to an object. Assemblers exerting excess force is an ergonomic concern.

Compression Load

A pushing or pressing force that is directed toward the center of an object.

Push-Pull Pin

A quick-release pin with a button that is pressed to retract locking balls on the opposite end that hold the pin in the mating component.

Threads

A raised helical ridge around the interior or exterior of a cylindrical object or hole. Threads help fasteners grip material and hold components together.

Thread

A raised, helical ridge around the interior or exterior of a cylindrical object or hole. Threads help fasteners grip material and hold components together.

Proof Load

A rating that specifies the stress that can be applied to a fastener and released without causing damage. Proof load is often used interchangeably with yield strength.

Keyway

A rectangular groove inside the hole of a gear, wheel, or similar component that is designed to be assembled with a key.

Key Slot

A rectangular groove running parallel to the axis of a shaft that is designed to be assembled with a key.

Key

A rectangular metal component with parallel sides and accurate dimensions. The key is inserted into a matching keyway and key slot to assemble gears, wheels, and other components onto a shaft.

Spindle

A rotating component of a machine tool. Spindles can hold and rotate grinding wheels.

Burr

A rough, sharp edge remaining on a part after machining or stamping. Burrs pose an injury risk and interfere with the fitting of parts.

Body Harness

A safety device composed of straps connected around the legs, waist, and shoulders that is attached to a hoist. A body harness may be required when working at elevated heights to prevent falls.

Self-Tapping Screws

A screw that forms or cuts threads in materials without pre-tapped holes. Self-tapping screws have pointed ends.

Set Screw

A screw that is usually headless used to lock a component onto a shaft. Set screws come with a variety of points designed to fit into or create a matching recess.

Socket Head Cap Screw

A screw that is very similar to a bolt with a driving recess inside the head. Socket head cap screws require a hex key or a hex bit for assembly.

Machine Screw

A screw with a blunt end that is assembled into a threaded hole. Machine screws are very common threaded fasteners that are similar to bolts.

Machine Screws

A screw with a blunt end that is assembled into a threaded hole. Machine screws are very common threaded fasteners that are similar to bolts.

Stamped Ring

A snap ring made from sheet metal, with a relatively flat design.

Automatic-Shutoff Screwdriver

A screwdriving tool that uses a continuous-drive clutch and results in little torque reaction. Automatic-shutoff screwdrivers are used for repetitive, but precise applications.

Direct-Drive Screwdriver

A screwdriving tool that uses a continuous-drive clutch and stops once it achieves torque. Direct-drive clutch screwdrivers use air pressure to obtain torque and are mainly used on wood.

Impact Wrench

A screwdriving tool that uses a discontinuous drive clutch and compressed air to achieve torque. Impact wrenches are often used to tighten lug nuts on cars when changing a tire.

Pulse Tool

A screwdriving tool that uses a discontinuous drive clutch and hydraulics to generate torque. Pulse tools are common for applications that use large bolts.

Thread-Forming Screw

A self-tapping screw that displaces the material in a hole to form threads. Thread-forming screws do not produce chips.

Thread-Cutting Screw

A self-tapping screw that removes material in a hole to create threads. Thread-cutting screws produce chips.

Taper Pin

A semi-permanent, cylindrical pin that has a slight taper along its length. Taper pins are often used on parts that require frequent assembly and disassembly.

8-UN Series

A set of coarse-pitch Unified threads that have 8 threads per inch. 8-UN series threads are used in place of UNC threads for diameters over 1 inch.

16-UN Series

A set of fine-pitch Unified threads that have 16 threads per inch. 16-UN series threads are used in place of UNF threads for diameters over 1 inch.

12-UN Series

A set of medium-pitch Unified threads that have 12 threads per inch. 12-UN series threads are used in place of UNF threads for diameters over 1 inch.

Socket Wrench Set

A set of wrenches that includes a set of sockets and different types of wrenching tools that can be attached to the sockets for tightening.

Spring Clip

A simple device made from soft, bendable material that expands to fit over a shaft.

Chamfer

A small angled surface added on the end of a shaft, around the opening of a hole, or along an edge. A chamfer removes the sharp edge and helps remove burrs.

Forklift

A small powered industrial vehicle that has two prongs on the front for lifting material. Forklifts are used to transport heavy loads.

Pallet Jack

A small vehicle used in manufacturing that contains a platform for lifting and transporting heavy loads.

Allen Wrench

A small, six-sided driving tool used for assembly that is compatible with a hex socket. Allen wrenches are also called hex keys.

Hex Key

A small, six-sided driving tool used for assembly that is compatible with a hex socket. Hex keys are also called Allen wrenches.

Alloy Steel

A steel containing intentionally added materials that change the property of the metal. Alloy steels often have improved properties when compared to those of carbon steels.

Priming

A step in the adhesive bonding process, priming prepares a surface for an adhesive. Priming typically uses a coupling agent, lacquer, or other adhesive-promoting substance.

Unified Thread Standard

A system for cataloging and defining threads based on inches. The Unified thread standard was developed by the United States, Canada, and the United Kingdom.

ISO Metric Thread Standard

A system for cataloging and defining threads based on millimeters. The ISO metric thread standard was developed in Europe by the International Organization for Standardization (ISO), and is also known as the metric thread standard.

Metric Thread Standard

A system for cataloging and defining threads based on millimeters. The metric thread standard was developed in Europe by the International Organization for Standardization (ISO), and is also known as the ISO metric thread standard.

Metric Thread System

A system for cataloging and defining threads based on millimeters. The metric thread standard was developed in Europe by the International Organization for Standardization (ISO), and is also known as the ISO metric thread standard.

Scaffold

A temporary raised platform that is usually constructed of metal or wooden crosspieces, supports or cables, and metal or wooden planking. A scaffold allows assemblers to work at elevated heights.

Torsion Test

A test that involves twisting an object to test a material's shear strength.

Jam Nut

A thin locking nut that is assembled onto a bolt in addition to a regular nut. The jam nut provides extra resistance that helps prevent the joint from loosening.

Pin

A thin, often straight, cylindrical non-threaded fastener used to secure the position of two or more machine parts.

Pins

A thin, often straight, cylindrical non-threaded fastener used to secure the position of two or more machine parts. Pins are inserted through holes.

Nails

A thin, pointed non-threaded fastener that is driven into an object with a hammer. Nails are typically used with nonmetallic materials.

Single-Start Thread

A thread consisting of one ridge wrapped around the cylinder. A single-start thread gives a fastener a lead that equals its pitch.

Double-Start Thread

A thread consisting of two parallel ridges wrapped around the cylinder. A double-start thread gives a fastener a lead that equals two times its pitch.

Hex-Head Bolt

A type of bolt that has a head with six sides.

Interference Fit

A tight fit designed so that the smallest permissible shaft is larger than the largest permissible hole. Force is required to assemble parts with an interference fit.

Battery-Powered Tool

A tool powered by a battery. Battery-powered tools are the most portable of all the power tools.

Power Tools

A tool powered by an external source of energy such as electricity or compressed air. Power tools require more safety precautions in addition to those for hand tools.

Hand Tools

A tool powered by an operator's manual force. Hand tools must be in good working condition to avoid injury.

Electric Tool

A tool powered by electricity. Electrical tools operate quietly and cleanly.

Screwguns

A tool similar to a drill with multiple cutting edges used to drive fasteners into workpieces. Screwguns are common tools for assembly.

Screwdriving Tool

A tool that assembles a screw into a joint. Screwdriving tools can be manual or powered by compressed air, electricity, or batteries.

Drill

A tool that drives screws and creates holes. Drills do not contain a clutch and therefore do not control torque.

Straight-Grip Tool

A tool that has a barrel-like grip. Straight-grip tools are typically recommended for horizontal projects.

Pistol-Grip Tool

A tool that has a grip shaped to fit the hand. Pistol-grip tools are typically recommended for vertical projects.

Hand Tool

A tool that is "powered" by an operator. The most common manual assembly tools are wrenches and screwdrivers.

Electric Tools

A tool that is powered by an electrical current. Electric tools pose the risk of electric shock and other injuries.

Power Tool

A tool that is powered by an external source such as electricity or compressed air.

Pneumatic Tool

A tool that is powered by compressed air. Pneumatic tools are good for repetitive tasks and for applications with a high torque value.

Pneumatic Tools

A tool that is powered by compressed air. Pneumatic tools should not be connected or loaded unless they will be used immediately.

Fastening Tool

A tool used for assembling a fastener into a base component. Fastening tools include hand and power tools such as screwdrivers, wrenches, rivet guns, and more.

Wrenches

A tool used for fastening nuts and bolts. Wrenches contain fixed or moving jaws or a round attachment that grips nuts or bolts.

Wrench

A tool used for fastening nuts and bolts. Wrenches contain fixed or moving jaws or a shaped feature that grips nuts or bolts.

Screwdriver

A tool used to fasten and tighten screws. Screwdrivers have a handle on one end and a blade on the other that fits into the recess in the head of a corresponding screw.

Pozidriv

A type of X-shaped driving recess with an additional cross recess that intersects the X-shape. Pozidriv drives allow for more torque.

Mixed-Model Assembly Line

A type of assembly line in which assemblers work on all different models of a product in the same assembly line.

Single-Model Assembly Line

A type of assembly line in which assemblers work on the same design of the same product.

Moving Assembly Line

A type of assembly line in which large products, like cars or airplanes, move slowly along the line while the assemblers work on them.

Batch-Model Assembly Line

A type of assembly line in which products are assembled in groups at a time.

Robertson

A type of driving recess that has a four-sided indentation designed to accept a special power-tool bit or screwdriver. Robertson drives are often used in construction.

Phillips

A type of driving recess that has an X-shaped indentation designed to accept a Phillips screwdriver. Phillips drives are prone to camming out.

Torx

A type of driving recess with a six-pointed indentation to resist slippage. Torx technologies were developed by Camcar Textron, Inc. and are currently trademarked by Acument Global Technologies, Inc.

Frearson

A type of driving recess with an X-shape. Frearson drives are less tapered than Phillips drives.

Vibration Loosening

A type of fastener failure that occurs in a bolted joint due to excessive motion, which causes the bolt to rotate loose.

Bolt Fracture

A type of fastener failure that occurs when a fastener is over-tightened and causes the bolt to break.

Thread Stripping

A type of fastener failure that occurs when a fastener is over-tightened. Thread stripping causes the fastener threads to appear deformed.

Fatigue

A type of fastener failure that occurs when a fastener is subjected to repetitive loading or stressing. Fatigue can cause catastrophic failure.

Overloading

A type of fastener failure that occurs when an excessive load is applied to a bolt, which causes the bolt to yield or fracture.

Truss Head

A type of fastener head similar to the pan head but with a round top. Truss heads are good for covering holes in metal.

Round Head

A type of fastener head that is dome shaped with a flat bearing surface. Round heads cannot be countersunk.

Pan Head

A type of fastener head that is very wide with a flat or slightly rounded top and rounded sides. Pan heads provide excellent clamping strength.

Flat Head

A type of fastener head with a blunt top and a beveled bearing surface. Flat heads are used with countersunk holes.

Oval Head

A type of fastener head with a round, elliptical shape and a tapered bearing surface for use in a countersunk hole. Oval heads improve joint appearance.

Hex-Washer Head

A type of fastener head with six sides and an included washer. Hex-washer heads prevent surface damage.

Hexagonal Head

A type of fastener head with six sides. Hexagonal heads are the most common bolt head.

Chamfer Point

A type of fastener point with a beveled tip that guides the fastener into a hole. Chamfer points are very common and allow for easy assembly.

Flat Point

A type of fastener point with a flat or blunt end. Flat points are used in applications where the fastener might be frequently reset.

Flat Points

A type of fastener point with a flat or blunt end. Flat points are used in applications where the fastener might be frequently reset.

Oval Point

A type of fastener point with a rounded end. Oval points allow for adjustments without causing surface damage.

Gimlet Point

A type of fastener point with a sharp tip for penetrating a surface with the thread extending to the end of the point. Gimlet points are used on self-tapping fasteners.

Cone Point

A type of fastener point with a sharp, angled end. Cone points allow for deep penetration and are used for the permanent assembly of parts.

Cone Points

A type of fastener point with a sharp, angled end. Cone points allow for deep penetration and are used for the permanent assembly of parts.

Pilot Point

A type of fastener point with a straight tip with a smaller diameter that extends past the thread to help guide the fastener into a hole. Pilot points make assembly easier.

Non-Threaded Fastener

A type of fastener that does not contain threads. Pins, retaining rings, and rivets are examples of non-threaded fasteners.

Pistol Grip

A type of handle grip that is curved and designed to fit with the anatomy of the hand.

Straight Handle

A type of handle grip that is straight up and down.

Structural Adhesive

A type of heavy-duty adhesive used for large-scale projects. Structural adhesives are durable and can withstand heavy loads.

Thread-Locking Compound

A type of liquid adhesive applied to fastener threads to seal the joint and prevent joint loosening and corrosion. Thread-locking compounds are often used with studs.

Rivet

A type of non-threaded fastener that consists of a shank and a head made of deformable material. Rivets are inserted through holes, and the shank is formed into a matching head on the other side of the part.

Blind Rivet

A type of rivet with a tubular shank that is installed with access to only one side of the part. Blind rivets are generally used to simplify assembly and to improve appearance.

Thread Forming Screw

A type of screw that forms the material around a hole until it wraps around the screw threads. Thread-forming screws do not remove any material from the engaged section.

Set Screws

A type of screw that is fully threaded from end to end with a rounded or cone-shaped end and a driving recess or external drive. Set screws are typically used to fit into a machining recess and lock a component onto a shaft.

Cup Point

A type of set screw point with an indented tip. Cup points are used for permanent and semi-permanent applications and offer good security.

Alloy-Steel

A type of steel that contains additional elements to improve the properties of a fastener.

Fillister Head

A type of thick fastener head with a deep slot and a large, rounded top. Fillister heads provide better appearance.

Binding Head

A type of thick fastener head with a deep slot and rounded sides. Binding heads are often used in electrical work.

Cheese Head

A type of thick fastener head with a deep slot for increased driving power. Cheese head slots are often used in electrical work.

Conical Washer

A type of washer with a raised, cone shape. Conical washers prevent loosening, without damaging parts, by flattening under pressure.

Staples

A typically u-shaped fastener. Staples have no threads and can only be used once.

Pounds Per Square Inch

A unit of pressure that measures the amount of load pressure per inch. Pounds per inch is abbreviated psi, or pounds per square inch.

Locking Fasteners

A vibration-resistant fastener that protects against joint loosening. Locking fasteners can be threaded or non-threaded and often use multiple components to lock the fastener in place.

Cracked Welds

A visible fracture or point of separation in the surface of the weld. Cracked welds must be repaired, or the part must be discarded.

Locking Washer

A washer designed to help prevent joint loosening. Locking washers are used for joints that require extra security.

Locking Washers

A washer designed to help prevent joint loosening. Locking washers are used for joints that require extra security.

Clamps

A workholding device that holds a tool or workpiece in place. Clamps hold an object by using inward pressure by tightening.

Sitting Workstation

A workplace in which assemblers perform their tasks sitting down.

Standing Workstation

A workplace in which assemblers perform their tasks standing up.

Open-End Wrench

A wrench that contains a set of jaws that tighten or loosen nuts and bolts. Open-end wrenches are ideal for use when the bolt or nut is not easily accessible.

Box Wrench

A wrench with a closed, box-like end that covers the nut or bolt completely.

Combination Wrench

A wrench with one open-end and one box end.

Ratchet

A wrenching device attached to a socket that turns a fastener in one direction only.

T-Handle

A wrenching device in the shape of a "T" that attaches to a socket and tightens a nut or bolt. T-handles contain a mechanism that prevents over-torquing.

American National Standards Institute

ANSI. A private, non-profit organization that administers and coordinates voluntary standards and systems in the United States. The American National Standards Institute provides guidelines that ensure workplace safety.

American Society For Mechanical Engineers

ASME. An organization that publishes technical materials and sets industrial and manufacturing standards. The American Society of Mechanical Engineers provides standards for fasteners.

American Society For Testing And Materials

ASTM. The organization that develops standards for industry, government, and the environment to make products safer and more cost-effective. ASTM develops standards for fasteners.

Fatigue Resistant

Able to withstand load conditions that normally cause failure. Fatigue-resistant threads are manufactured by thread rolling.

ANSI

American National Standards Institute. A private, non-profit organization that administers and coordinates voluntary standards and systems in the United States. ANSI provides guidelines that ensure workplace safety.

Bronze

An alloy of copper and tin. Bronze is highly corrosion resistant.

Interference

An amount of overlap between two objects. Interference between threads can be used to prevent fasteners from loosening.

Flank

An angled side of a thread that connects the root to the crest. Flanks occur in pairs.

Cells

An arrangement of workstations structured around the design of similar processes. Cells encourage smooth part flows and use space efficiently.

Assembly Lines

An arrangement of workstations used to mass-produce products in stages. Assembly lines are a main feature of assembly sites.

Manual Assembly Line

An assembly line in which the majority of tasks are performed by assemblers. Manual assembly lines typically rely on assemblers to transfer parts between workstations.

Automated Assembly Line

An assembly line in which the majority of tasks are performed by automated machines. Automated assembly lines require little or no human interaction.

Torque-Absorbing Arm

An attachment used with a fastening tool that absorbs torque reaction so the assembler can avoid injury.

Rotary Index System

An automated assembly system designed so that operations are carried out at workstations by tooling mounted on a central column or around the periphery of an indexing table. The rotary index system is also known as the dial index machine.

Dial Index Systems

An automated assembly system designed so that operations are performed as an indexing table rotates from workstation to workstation. The dial index system is also known as the rotary index system.

Carousel Systems

An automated assembly system that combines the features of dial and in-line index systems. Carousel systems make it possible to increase the production of complex parts.

In-Line Index Systems

An automated assembly system that moves components in a straight line along a path. In-line index systems are used for assembling more complex parts.

Axis

An imaginary straight line that passes through the center of an object.

Grade 2

An inch series strength grade represented by no radial lines. Grade 2 is made from low-carbon steel.

Grade 8

An inch series strength grade represented by six radial lines. Grade 8 is made from alloy steels that have been quenched and tempered.

Grade 5

An inch series strength grade represented by three radial lines. Grade 5 is made from medium-carbon steels that have been quenched and tempered.

Phosphate

An inorganic chemical salt of phosphoric acid. Phosphate improves the corrosion and wear resistance of a steel surface.

Through Hole

An internal hole that completely passes through an object or material. Through holes are often used with bolts and nuts.

Through Holes

An internal hole that completely passes through an object or material. Through holes are often used with bolts and nuts.

Blind Threaded Hole

An internally threaded hole that does not go completely through a material or object. Blind threaded holes are typically used with screws.

Chips

An unwanted piece of metal that is removed from a workpiece. Chips are formed by thread-cutting screws.

Torque Tolerance

An unwanted, but acceptable deviation from the desired torque.

Beveled

Angled in comparison to the major surfaces of a part. Beveled bearing surfaces are a feature of flat head fasteners.

Chamfered

Angled or beveled along an edge. Chamfered surfaces allow parts to fit together, remove sharp corners, and protect against damage.

Cold Working

Any metal shaping process that takes place when the metal is below its recrystallization temperature. Cold working adds certain properties to the metal, such as increased strength and improved surface finish.

Personal Protection Equipment

Any of various articles of clothing or safeguarding devices that assemblers or operators are required to wear. Personal protection equipment (PPE) varies from shop to shop.

Pinch Point

Any place where two components meet. Pinch points can trap body parts and cause serious injury.

Linear

Arranged or moving in a straight line. Linear assembly lines perform tasks in a sequence that connects workstations.

Clearance Fit

Assembled into a matching hole with a slightly larger diameter to allow for easy joining or removal.

Press Fit

Assembled into a matching hole with a slightly smaller diameter through the use of force.

Inventory

Assembled products that are stored before being shipped. Inventory allows manufacturers to have parts available to sell, but inventory requires additional storage costs.

Identification Marking

Characters appearing on a fastener that often indicate the manufacturer and the standard specifications. Identification markings are helpful during fastener replacement.

Quality

Conformance to a set of standards or specifications that results in customer satisfaction in a product or service. Quality products are free of defects and meet the requirements of their anticipated use.

Earmuffs

Ear wear that covers the entire outer ear to protect hearing. Earmuffs protect the entire ear from debris or sparks as well.

Earplugs

Ear wear that is inserted into the ear to protect hearing. Earplugs protect the inner ear from noise.

Flammable

Easily ignited and capable of starting a fire. Flammable materials should be kept away from electric tools.

Radiation

Energy emitted by light sources in the form of particles and waves. Radiation from ultraviolet lights can burn the skin and eyes.

Labor Costs

Expenses associated with employees, including wages, insurance, taxes, and other compensation. Labor costs can make manual assembly expensive.

Parallel

Extending in the same direction and equally distance from one another at all points. The number of parallel threads on a fastener is equal to the number of starts.

Seated

Fixed in place. Seated free spinning lock nuts provided joint resistance.

Safety Shoes

Footwear that protects the feet and ankles from hazards such as impact, heat, and electric shock. Safety shoes often have reinforced toe areas.

Inside Diameter

ID. The interior surface of a spherical or cylindrical object. Threads on the inside diameter are called internal or female threads.

Industrial Fasteners Institute

IFI. A nonprofit organization that represents the leading National American manufacturers of fasteners and publishes related standards. The Industrial Fastener Institute is responsible for publishing the frequently used IFI Book of Fastener Standards, which compiles the most commonly used standards into one volume..

International Organization For Standardization

ISO. An organization based in Switzerland that develops and publishes and maintains many types of standards. The International Organization for Standardization developed the metric thread standard and many metric fastener standards.

Perpendicular

Intersecting at a right, or 90° angle. Perpendicular flanks are found on square threads.

Filler Metal

Metal that may be added to a joint during a fusing process like welding, soldering, or brazing. Filler metals add to the strength and mass of a welded joint.

Megapascals

Mpa. A metric unit of pressure. A megapascal is equal to one million pascals (Pa).

OSHA

Occupational Safety and Health Administration. A government agency that sets the standards for working conditions in the United States. OSHA creates regulations that ensure that assemblers work in safe and healthy environments.

Personal Protective Equipment

PPE. Any clothing or device worn to minimize exposure to hazards and prevent injury. Personal protective equipment may include eye and ear protection, safety footwear, gloves, and other devices.

PPE

Personal protective equipment. Any clothing or device worn to minimize exposure to hazards and prevent injury. PPE may include eye and ear protection, safety footwear, gloves, and other devices.

Robots

Programmable mechanical devices used to perform a variety of complicated, repetitive tasks. Robots are used in automated assembly lines to enable a higher degree of accuracy.

Safety Glasses

Protective eyeglasses with metal or plastic frames and impact-resistant lenses. Safety glasses must always be worn during assembly operations.

Safety-Toed Boots

Protective footwear with a reinforced toe area. Safety-toed boots prevent foot injury from falling objects.

Society Of Automotive Engineers

SAE. An organization that writes specifications and other data used in a broad range of industries. The Society of Automotive Engineers developed the AISI-SAE classification system along with the American Iron and Steel Institute.

Grounded

Safely connected to a neutral body, like the earth, that can absorb stray electrical charges. Electric tools must be grounded to help prevent electric shock.

Suspension Ropes

Safety equipment that consists of ropes that are suspended from the ceiling and attached to the assembler. Suspension ropes may be required when working at elevated heights to prevent falls.

Barrier Guards

Safety equipment that prevents assembler's hands from entering the point of operation. Barrier guards should never be tampered with.

Synthetic

Something that is produced artificially. Synthetic materials include plastic and nylon.

Workstations

Specific areas of an assembly site that are designated for performing specific tasks or work duties. Workstations are organized to increase the efficiency of an assembly site.

Stainless Steel

Stainless steel exhibits moderate strength and ductility and a unique microstructure. Stainless steel fasteners are popular for their corrosion resistance.

T-Slots

T-shaped openings that run the length of a machine table. T-slots enable machinists to clamp vises and other workholding components onto the table.

Threads Per Inch

TPI. The number of threads in one linear inch. Threads per inch depends on the pitch and is used in Unified thread specifications.

Ductility

The ability of a fastener material to deform before it fractures.

Shear Strength

The ability of a fastener material to resist internal sliding.

Environmental Resistance

The ability of a fastener to resist forces in the environment that attempt to deform it. Environmental resistance can affect a fastener's performance.

Thermal Conductivity

The ability of a material to conduct heat.

Corrosion Resistance

The ability of a material to resist deterioration due to chemical or environmental exposure. Corrosion resistance is one of the most important physical properties for fasteners.

Corrosion Resistant

The ability of a material to resist deterioration due to chemical or environmental exposure. Corrosion resistant coatings are added to steel and alloy steel fasteners.

Strength

The ability of a material to resist stress caused by forces attempting to break or deform the material.

Torsional Strength

The ability of the fastener to resist a torque that attempts to twist a fastener off its axis.

Traceability

The ability to trace the history, application, or location of an item using documentation.

Point Of Operation

The area where work is performed, often where the tool comes into contact with the workpiece. In fastening, the point of operation is the place where the fastener contacts the base component.

Properties

The characteristics of a material that distinguish it from other materials.

Index Table

The circular component of a dial index machine on which parts are placed. The indexing table rotates to position parts at workstations.

Washer Face

The completely flat side of a nut or the bearing surface of a screw head. A washer face is intended to contact the surface of a washer or a part.

Clamping Force

The compressive force that a fastener exerts on a joint.

Heat Treating

The controlled heating and cooling process used to change the structure of a material and alter its physical and mechanical properties. Annealing, quenching, and tempering are heat treatments.

Stress Area

The cross-sectional area of a threaded fastener that is subjected to a tensile force. Stress area is the weakest, and usually smallest, cross section of the fastener, and therefore determines the fastener's strength.

Shearing

The cutting and separating of material through its cross section.

Countersunk

The cutting of a beveled edge at the end of a hole. Countersunk holes allow the head of a fastener to rest level with the workpiece surface.

Shank

The cylindrical length of a fastener that extends from the underside of the head to the point. The shank includes the threaded and unthreaded parts of the fastener.

Torque Value

The decided amount of force required to properly tighten a fastener.

Pitch Diameter

The diameter of an imaginary cylinder that passes through the thread form in such a way that it intersects the thread groove and the thread ridge equally. Pitch diameter is larger than the minor diameter but smaller than the major diameter and marks the theoretical point where threads of a fastener and threads of a hole meet.

Shank Diameter

The diameter of the part of the fastener extending from the underside of the head to the point. Shank diameter is approximately the same as major diameter.

Allowance

The difference in dimension or space between parts. Allowance on threaded parts is a specific amount of clearance or interference between threads.

Lead

The distance a threaded part advances in one revolution. Lead is equal to the pitch multiplied by the number of starts.

Pitch

The distance between corresponding points on consecutive threads. Pitch can be determined by measuring the distance between two adjacent crests or roots.

Head

The end of a fastener that provides a surface for gripping and turning and allows it to bear loads. Head shape and style varies depending on the type of fastener.

Ultimate Tensile Strength

The final amount of stress sustained in a tensile test at the exact moment the object ruptures.

Electric Shock

The flow of electricity through the body. Electric shock can cause falls, burns, and even death.

Load

The force applied to an object by another object. Prolonged or heavy loads can cause deformation.

Off-Torque

The force that is proportional to torque in the opposite manner. An off-torque condition causes the fastener to rotate loose.

Chassis

The frame of a machine. The chassis of an automated assembly machine holds tooling and keeps workstations together.

Corrosion

The gradual chemical attack on a metal by atmosphere, moisture, or other agents.

Root

The groove at the base of a thread. The root is formed by the meeting of two flanks on the body of the fastener.

Heat Treatment

The heating and cooling processes used to change the structure of a material and alter its mechanical properties.

Welding

The joining of materials, usually metals, through the use of heat, pressure, and/or chemicals. Welding fuses two materials together permanently.

Adhesive Bonding

The joining of two or more materials using adhesive substances such as pastes, gels, glues, and tape. Adhesive bonding can be used to join similar and dissimilar materials.

Mechanical Fastening

The joining of two or more materials with devices called fasteners. Mechanical fastening is often used for parts that require disassembly and reassembly.

Major Diameter

The largest diameter of a thread. Major diameter is measured from crest to crest on an external thread and from root to root on an internal thread.

Thread Length

The length of the threaded section of a fastener's shank. Thread length is measured from the first thread to the point.

Grip Length

The length of the unthreaded section of a fastener 's shank. Grip length is measured from the bearing surface to the starting thread.

Metric Designation

The letter "M" that identifies all metric threads. The metric designation appears at the beginning of all metric thread specifications and distinguishes metric threads from other types of threads.

Callout

The listed designations for a specific thread. The callout for Unified threads and metric threads include different information relating to nominal size, pitch, fit, and type of thread, among others.

Grade Identification

The marking on the head of a bolt that indicates tensile strength.

Capacity

The maximum amount of power that a tool can operate at safely. Capacity is outlined in a power tool's specifications.

Fatigue Strength

The maximum stress a fastener can withstand for a specific number of repeated applications prior to its failure.

Elastic Limit

The maximum stress a material can support before it deforms. Elastic limit is also known as yield strength.

Start

The number of individual parallel threads that wrap around a fastener. The start affects the lead of a threaded fastener.

Adherents

The object that is joined to another object with an adhesive. Adherents can be of similar or dissimilar materials.

Nominal Diameter

The overall diameter of the fastener, which may be different from its actual, measurable size. Nominal diameter is used to indicate a fastener's nominal size in metric and Unified thread specifications.

Jaw

The part on an open-end wrench that grips the bolt. Jaws can be fixed or adjustable.

Assembly Site

The place where assembly is performed. Employees at an assembly site require PPE for safety.

Power-To-Weight Ratio

The power the tool generates divided by the weight of the tool.

Ergonomics

The scientific study of equipment, workspace, and production environment design to increase comfort, safety, and productivity. Ergonomic concerns include force, posture, and repetition.

Driving Recess

The shape of the indentation on the top of a fastener head. The driving recess is designed to accept a matching driving tool.

Nominal Size

The size by which something is known, which may be different from its actual, measurable size. Nominal size of fasteners is given as the nominal diameter in metric and Unified thread designations.

Minor Diameter

The smallest diameter of a thread. Minor diameter is measured from root to root on an external thread and from crest to crest on an internal thread.

Flats

The straight surfaces on the sides of a fastener's head. The flats allow a wrench to grip the head and tighten the fastener.

Permanent Deformation

The stress that causes a fastener to lose its original shape and appearance.

Machine Table

The surface on which stock or work is held and located on many types of machines. Machine tables have t-slots that fit t-head bolts.

Melting Point

The temperature at which a material changes from a solid to a liquid. Melting point varies based on the properties of the metal involved.

Point

The threaded end opposite the head of a fastener. Points may be flat, pointed, or another variety.

Crest

The top or peak of a thread. The crest is formed by the meeting of two flanks away from the body of the fastener.

Thread Form

The unique shape or profile of a thread. Thread forms vary depending on the shape of their crests, roots, and flanks.

Tolerance

The unwanted but acceptable deviation from a desired dimension. Tolerance determines how much an object can vary from the desired dimension and still meet specifications.

Tolerances

The unwanted but acceptable deviation from a desired dimension. Tolerance determines how much an object can vary from the desired dimension and still meet specifications.

Hydraulics

The use of fluids to power a device. Pulse tools use hydraulics to achieve torque.

Automation

The use of self-regulated equipment, processes, or systems that meet manufacturing requirements with limited human intervention. Automation is an efficient means of assembly.

Grip

The way in which an object, such as a screwdriving tool, is grasped. Tools are designed with different grips to accommodate specific tasks.

Thread-Rolling Dies

Thread-forming components with grooves and ridges that shape metal into threads when extreme pressure is applied. Thread-rolling dies produce strong and fatigue-resistant threads.

Female Threads

Threads formed on the inside of a cylinder or hole, such as in nuts. Female threads are also called internal threads.

Internal Threads

Threads formed on the inside of a cylinder or hole. Internal threads can be found in nuts.

Male Threads

Threads formed on the outside of a cylinder, such as on bolts and screws. Male threads are also called external threads.

External Threads

Threads formed on the outside of a cylinder. External threads can be found on bolts and screws.

TPI

Threads per inch. The number of threads in one linear inch. TPI depends on the pitch and is used in Unified thread specifications.

Coarse Threads

Threads with larger pitches and thread depths. Coarse threads are easier to assemble and disassemble than fine threads.

Fine Threads

Threads with smaller pitches and thread depths. Fine threads have a greater stress area than coarse threads.

Safety Goggles

Tight-fitting eye protection that completely covers the eyes and the area surrounding the eyes. Safety goggles are sometimes worn instead of safety glasses during assembly operations.

Elongate

To extend the length of an object.

Ricochet

To rebound from a surface. Fasteners ricochet more often when used with hard or brittle materials.

Contract

To squeeze together. Muscles contract when used to perform a task.

Unified Coarse

UNC. A Unified thread series that identifies threads with larger pitches and thread depths. Unified coarse threads are easier to assemble and disassemble than Unified fine (UNF) threads.

Unified Fine

UNF. A Unified thread series that identifies threads with smaller pitches and thread depths. Unified fine threads have a greater stress area than Unified coarse (UNC) threads.

Ultraviolet

UV. Potentially harmful light that is invisible to the naked eye because it consists of wavelengths shorter than those of visible violet light. Ultraviolet light produces radiation that can burn the skin and the eyes.

UV

Ultraviolet. Potentially harmful light that is invisible to the naked eye because it consists of wavelengths shorter than those of visible violet light. UV light produces radiation that can burn the skin and the eyes.

UNC

Unified coarse. A Unified thread series that identifies threads with larger pitches and thread depths. UNC threads are easier to assemble and disassemble than Unified fine (UNF) threads.

UNF

Unified fine. A Unified thread series that identifies threads with smaller pitches and thread depths. UNF threads have a greater stress area than Unified coarse (UNC) threads.

Helical

Winding in the shape of a spiral or coil. Helical ridges called threads appear on screws and other fasteners.