Overview of Non-Threaded Fasteners 241

axially assembled ring

A retaining ring that is installed by fitting the ring over the end of a shaft or through the opening of a hole. Axially assembled rings can be used for internal and external applications.

axis

An imaginary straight line that passes through the center of an object. An axially assembled ring is installed in parallel with the axis of a part, while a radially assembled ring is installed perpendicular to the axis.

ball lock pin

A self-locking quick-release pin that uses a button and internal spring to control one or more balls at the end of the pin. A ball lock pin's balls retract for installation and return to their original position to hold the pin in place.

blind fastener

A fastener that can be installed when only one side of the assembly is accessible. Blind rivets are a common type of blind fastener.

blind holes

A hole that begins on one side of a workpiece and ends inside the workpiece. Blind holes only have one opening because they do not extend through the entire thickness of a workpiece.

blind rivet

A rivet with a tubular shank that is installed with access to only one side of the part. Blind rivets, also known by the brand name POP rivets, are generally used to simplify assembly and improve appearance.

body

The tubular shank of a blind rivet. The body expands to hold the rivet in place when the mandrel pulls through it.

bolt

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

burrs

A rough, sharp edge remaining on a part after machining. Burrs can cause injury and prevent parts from fitting together correctly.

chamfer

An angled surface added to the edge of a feature such as the end of a cylindrical part or the entrance of a hole. A chamfer is added to pins to make them easy to insert and help eliminate sharp edges and burrs.

clearance fit

A fit between a shaft and a hole with a slightly larger diameter. A clearance fit allows for easy joining or pin removal.

clevis pin

A cylindrical semi-permanent pin with a head at one end and one or more through holes at the other end. A clevis pin is typically secured in place with a cotter pin to provide motion between components.

coil pin

A spring pin that is shaped like a spiral. Coil pins are not as common as roll pins.

cotter pin

A semi-permanent pin with two ends positioned parallel to each other before use that are fitted through a hole and then bent backward to secure the pin in place. Cotter pins can be used to secure clevis pins or certain styles of washers.

diameters

The distance from one edge of a circle to the opposite edge, as measured through the center. Diameter describes the size of round or cylindrical objects.

dowel pin

A cylindrical semi-permanent pin that has one chamfered end and one radius end. Dowel pins are mainly used to locate machine parts in fixed positions or to maintain alignment.

E-rings

A radially assembled retaining ring that consists of a flat clip. E-rings fit around a shaft from the side.

external rings

A retaining ring that is installed on the outside of a shaft to position or limit the movement of components on the shaft. External rings can be installed axially or radially and are held in place by matching grooves.

fasteners

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

gib-head key

A semi-rectangular key with a head at one end that extends above the top surface. A gib-head key is easy to remove because the head protrudes from the rest of the key.

head

The end of a fastener that provides a surface for bearing loads. The head of a rivet is often shaped like a mushroom cap, but other shapes and styles are available.

internal rings

A retaining ring that is installed inside a hole to position or limit the movement of components inside the hole. Internal rings must be installed axially and are held in place by matching grooves.

key slot

A groove running parallel to the axis of a shaft that is designed to accept a key. Key slots are typically rectangular but may be shaped differently to accommodate specific key shapes.

keys

A non-threaded fastener that consists of a piece of metal that fits into matching recesses to hold components in position on a cylindrical shaft. Keys are inserted into key slots in shafts and keyways in components such as gears, handles, cranks, and wheels.

keyway

A groove inside the hole of a gear, wheel, or similar shaft component that is designed to accept a key. Keyways are typically rectangular but may be shaped differently to accommodate specific key shapes.

large rivets

A solid rivet with a shank diameter that measures 0.50 in. (1.27 cm) or greater. Large rivets are often used in steel fabrication.

light press-fit holes

Holes that have a diameter that is only a small amount smaller than the mating shaft. Light press-fit holes require force for assembly, but the necessary force is less than that required for press-fit holes.

load

Force or pressure placed on an object. A load can cause a fastener to break if it exceeds the fastener's specifications.

mandrel

A thin rod with a head on one end that pulls through and expands the body of a blind rivet. The mandrel breaks off and falls away at a pre-determined point after it is pulled through the rivet body.

non-threaded fasteners

A type of fastener that does not contain threads. Common types of non-threaded fasteners include pins, keys, retaining rings, and rivets.

nut

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

pins

A thin, often straight, cylindrical non-threaded fastener used to secure the position of two or more machine parts. Some pins are permanent, while others are removable.

POP rivets

A rivet with a tubular shank that is installed with access to only one side of the part. POP rivets is the brand name for blind rivets.

press fit

A fit between a shaft and a hole with a slightly smaller diameter. A press fit is achieved through the use of force.

punch

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

push-on retainers

A retaining ring with small prongs that grip into the mating part. A push-on retainer, also known as a self-locking ring, does not require grooves to stay in place, but it cannot withstand heavy loads.

quick-release pins

A type of pin that can be installed and removed quickly and easily. Quick-release pins typically have movable components that expand and contract.

radially assembled ring

A retaining ring that is installed by fitting the ring onto a shaft from the side. Radially assembled rings can be used for external applications but not internal applications.

radius

A curved feature on a tool or part. Dowel pins have a radius on one end and a chamfer on the other.

retaining rings

A flat, circular non-threaded fastener with a hollow center and an open section. Retaining rings, also known as snap rings, position and limit part movement along a shaft or within a hole.

rigging

The process of lifting and moving heavy loads with ropes, chains, and mechanical devices. Rigging operations often use shackles that contain clevis and cotter pin assemblies.

rivet gun

A fastening tool used to assemble blind rivets. A rivet gun may be manual or powered by an external source.

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 matching head on the other side of the part.

roll pin

A spring pin that has an open slot along its length. Roll pins have a simpler design than coil pins.

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.

self-locking ring

A retaining ring with small prongs that grip into the mating part. A self-locking ring, also known as a push-on retainer, does not require grooves to stay in place, but it cannot withstand heavy loads.

semi-permanent pins

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

set screws

A screw that is usually headless and is used to lock a component onto a shaft. Set screws are often used with keys.

shackles

A U-shaped piece of metal that is closed at the end with a pin or bolt. Shackles often use clevis and cotter pin assemblies.

shaft

A cylindrical bar used to support rotating components or transmit motion. Shaft components are often secured with keys.

shank

The cylindrical length of a rivet that extends from the underside of the head to the point or end. The shank is deformed to hold the rivet in place.

shear forces

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

shear pin

A cylindrical semi-permanent pin made from a relatively soft material that is designed to break when it experiences damaging shocks or loads. The shear pin breaks to preserve the rest of the assembly.

small rivets

A solid rivet with a shank diameter that measures less than 0.50 in. (1.27 cm). Small rivets are often used in sheet metal.

snap rings

A flat, circular non-threaded fastener with a hollow center and an open section. Snap rings, also known as retaining rings, position and limit part movement along a shaft or within a hole.

soft-faced hammer

A hammer designed to provide driving force without damaging surfaces. A soft-faced hammer is used to install pins and keys.

solid rivet

A rivet with a shaft and head made of one continuous piece of material that requires access to both sides of the part for installation. Solid rivets are categorized as either large or small, depending on their shank diameter.

spiral-wound ring

A retaining ring consisting of a strip of metal that is coiled back onto itself. A spiral-wound ring is sturdy and provides a seamless outer surface.

spring pin

A cylindrical semi-permanent pin shaped like a hollow tube that compresses to fit inside a hole. A spring pin has a diameter that is slightly larger than the recommended hole diameter.

spring steel

A high-carbon steel that exhibits excellent hardness and yield strength. Spring steel is used to make retaining rings because it allows them to expand and contract slightly and still return to their original shape.

square key

A rectangular key with flat, parallel sides and very precise dimensions. A square key may be assembled by hand or with a soft-faced hammer.

stamped ring

A retaining ring that is made from sheet metal and has a relatively flat design. Typical stamped rings have small holes that allow pliers to grip them for installation.

taper pin

A cylindrical semi-permanent pin that slightly decreases in diameter along its length. Taper pins are often used on parts that require frequent assembly and disassembly.

tapered key

A semi-rectangular key with a top surface that gradually decreases in size along its length. A tapered key's top surface is designed to match a tapered keyway in the mating component.

threaded fasteners

A type of fastener that contains threads. Bolts, screws, and nuts are examples of threaded fasteners.

threads

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

through hole

A hole that begins on one side of an object and exits on another side, passing completely through the object. A through hole is found on the end of a clevis pin that is opposite the head.

tolerances

An acceptable deviation from a specified measurement. Tolerances determine how much objects can vary from desired dimensions and still meet specifications.

Woodruff key

A key with a flat top, flat sides, and a semi-circular bottom. Woodruff keys are assembled with matching curved key slots.