Fasteners

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Introduction

This article is an in depth study of fasteners and their uses.

You will learn more about topics such as:

• What is a fastener?
• What are non-permanent threaded fasteners
• What are permanent fasteners
• How fasteners are made
• And much more &#;

Chapter One: What is a Fastener?

A fastener is a mechanical tool used to connect or attach two surfaces or objects together, either permanently or non-permanently. Non-permanent fasteners can be easily removed without damaging the materials they join. In contrast, removing permanent fasteners often requires significant force and may cause damage to the connected surfaces. Permanent fasteners are designed to provide a long-lasting, secure connection.

Fasteners encompass a diverse range of types, including screws, nails, nuts, bolts, and washers, each available in various sizes, types, and configurations. They are essential tools used extensively in building, fabricating, and assembling a wide array of products and industrial equipment.

Chapter Two: What are non-permanent threaded fasteners?

Fasteners come in an extensive array of shapes, sizes, lengths, and types, from common nails to large bolts designed to secure heavy-duty manufacturing equipment. They can be either generic or specially designed for specific applications. Each industry and manufacturer has unique requirements for these versatile tools.

The variability among fasteners is a result of the extreme forces they must endure. Fasteners are designed to hold parts, components, and machinery together under significant vibrations and pressure, while still allowing for disassembly when needed.

Fasteners can be categorized in several ways, including permanent versus non-permanent and threaded versus non-threaded. Permanent fasteners, such as rivets and couplings, are not meant to be removed. Threaded fasteners include screws and bolts, while non-threaded and permanent fasteners include dowel pins and blind fasteners.

Bolts are a common type of fastener used to secure two non-threaded pieces together. They feature a head, available in various shapes, attached to a threaded male end. Bolts are categorized based on the shape and type of their head.

Anchor Bolts

Anchor bolts, also known as "cast-in-place" bolts, are incorporated into the fabrication of a component or part and are permanently attached. These specialized bolts are embedded in concrete to secure columns and supports to foundations, with various types designed for specific applications.

Arbor Bolts

Arbor bolts feature a permanently attached washer and reverse threading. The head of an arbor bolt has a sunken design, creating a ridge, and is typically finished in dark or black to distinguish it from other bolts. These bolts are specifically designed for use with tools like miter saws to secure the blade in place.

Carriage Bolts

Carriage bolts feature a smooth, rounded head with a square section beneath it to prevent the bolt from turning when tightened. Their versatility, allowing use with various materials from stainless steel to wood, contributes to their popularity. Originally used to secure carriages and carriage wheels, carriage bolts are also known as plow or coach bolts.

Wheel Bolts

Wheel bolts feature a threaded stem and a tapered head designed to secure a car's wheel. The bolt passes through the brake rotor hat into the hub, locking the wheel in place.

Wheel Nuts

Wheel nuts, or lug nuts, are hexagonal fasteners that screw onto wheel studs to secure the wheels of cars and trucks. They come in various shapes and designs to meet different vehicle requirements. While wheel nuts are commonly made of chrome-plated steel, they can also be produced from aluminum or titanium.

Elevator Bolts

Elevator bolts, originally developed for elevator construction, feature a large flat head and a square neck underneath to ensure a secure connection even under vibrations and shock. The flat head is designed to sit flush against the surface of the attached material, providing stability and load-bearing capacity.

The hex head bolt is named for its hexagonal head shape, which allows for easy tightening with a box, socket, or crescent wrench. The six-sided design provides the necessary grip for fastening in challenging locations. Hex head bolts may have threads that extend halfway or fully to the head, with partially threaded bolts offering higher shear strength.

Double End Bolts

A double end bolt features threads on both ends and lacks a head. It can be fitted with a nut on one end and inserted into a threaded hole. Typically, double end bolts have class 5 threads on one end for tapping and class 2A threads on the other end for the nut.

Eye Bolts

Eye bolts feature a loop or circular end in place of a traditional head. This loop is used for securing electrical lines, holding chains, or guiding ropes. Eye bolts come in two types: open eye bolts, which have an incomplete loop, and closed eye bolts, which have a fully enclosed loop.

U Shape Bolts

U bolts consist of two threaded arms joined by a U-shaped bend and lack a head. The threaded ends are intended to secure nuts and washers. Made from carbon, alloy, or stainless steel through cold or hot forging, U bolts provide clamping force when the nuts and washers are tightened. This effectively connects parts or holds components in place, preventing movement.

There are many more types of bolts beyond those mentioned, including J bolts, flanged bolts, plow bolts, and shoulder bolts, among others. Bolts are essential components for creating secure and durable connections in a wide range of applications.

Screws

Screws are similar to bolts in that they have male threads that run from the tip and various head types for driving the threads. However, unlike bolts, screws do not rely on nuts for fastening. Instead, screws require internal threads in the material they are being driven into. Most screws are self-tapping or self-threading, meaning they create their own threads as they are inserted.

Like bolts, screws come in numerous types designed for specific applications. Common features among screws include pointed or flat tips, with variations such as threaded or drill-bit tips depending on the intended use.

Self-drilling screws are designed to create internal threads as they are installed. These screws are fully threaded from tip to head, with threads engineered to be harder and more rigid than the materials they are joining. They feature a range of tip designs, including notched or drill-bit tips, which allow them to cut through and create their own space in the substrate.

Sheet Metal Screw

Sheet metal screws are specifically designed for joining metal pieces and feature a fully threaded shank along their entire length, with either a rounded or flat head. Their sharp tip is intended to pierce through metal substrates. Sheet metal screws can be either self-drilling or self-tapping, and are made from hardened metals to effectively penetrate metal surfaces.

Machine Screw

A machine screw resembles a bolt but is typically smaller, with a diameter of 0.75 inches or less, as specified by the American Society of Mechanical Engineers (ASME). Machine screws are designed for joining or connecting metal pieces and are inserted into pre-threaded holes. They feature consistent thread size and helical ridges from the head to the tip, ensuring a secure fit within the threaded hole.

Dowel Screw

A dowel screw resembles a double-ended bolt but features wood screw threads on both ends and lacks a head. These screws can be inserted into pre-drilled holes or create their own threads in the material. They function similarly to dowels but provide a more permanent bond between joined pieces. Commonly used in woodworking, dowel screws are threaded from end to end, ensuring a secure connection without gaps.

Thread Cutting Screw

Thread cutting screws are a type of self-tapping screw designed to create new threads in existing holes. They are ideal for equipment that requires regular maintenance and come in several thread types, including Type 1, Type 23, Type 25, and Type F. Available with various head styles and body configurations, thread cutting screws are adaptable to different applications and materials.

Wood Screws

Wood screws are designed for joining pieces of wood and come in various metals. They feature a pointed tip, threads, a head, and a shank. Typically, the shank is partially threaded, covering about three-fourths of the screw&#;s length, although some wood screws are fully threaded from tip to head.

A common design includes a tapered head that allows the screw to sit flush with the wood surface, similar to a countersunk effect. There is a wide variety of wood screws available, catering to different types of wood and applications, including specialized screws for decking, cabinetry, and shelving.

Sems Screws

Sems screws are a distinctive type of screw featuring one or two permanent, free-spinning washers attached above the threads. Known as combination screws, they integrate washers that are secured by the major diameter of the screw&#;s threads, which is larger than the washer's hole. This design enhances the screw's stability and strength when connecting parts and surfaces.

The presence of the washer with a sems screw greatly improves its effectiveness and durability in fastening applications.

Sems screws are available in numerous configurations, including various thread types, drive types, washers, and head styles, offering versatile solutions for different fastening needs.

• Thread Types &#; machine screw, self tapping, thread cutting, and thread forming
• Drive Types &#; pozi, phillips, slotted, combi, 6lobe, and hex
• Washer Types &#; flat, spring, square, conical, internal tooth, external, single, or double
• Head Types &#; hexagon, pan, socket cap, and round

A nut is a fastener with internal threads designed to mate with a bolt of the same size. Nuts come in various types, including box and hexagonal shapes, as well as numerous specialty designs and configurations tailored for specific applications.

Cap Nuts

Also known as dome or acorn nuts, cap nuts feature a domed shape on the closed end. This design helps protect the bolt-nut assembly and adds a finished look.

Castle Nuts

Castle nuts are distinguished by their notched end, which allows for the insertion of a cotter pin. This feature secures the nut in place and prevents loosening.

Weld Nuts

Weld nuts are attached to surfaces through welding, making them ideal for fastening in hard-to-reach areas. They provide a secure connection where traditional methods might be impractical.

Hex Nuts

Hex nuts are among the most commonly used types of nuts. Their hexagonal shape makes them easy to install with standard tools.

Nylon Lock Nuts

Similar in shape to hex nuts, nylon lock nuts are equipped with a nylon collar that grips the bolt threads, preventing the nut from loosening over time.

Flange Nuts

Flange nuts feature a wide flange on one side, which helps distribute pressure evenly across the surface being secured, similar to a flange bolt or screw.

The image below illustrates some of the various types of nuts available. As with other types of connectors, a wide range of nuts is designed to match different bolt types and applications.

Heads

The heads of screws and bolts are a key feature that determines their functionality and application. With a wide range of designs, each type of head serves a specific purpose. Here are some common head types:

Flat Screw Heads

Flat screw heads are countersunk and designed to sit flush with the surface they are securing. They come with varying angles from the top of the head to the threads, allowing them to blend seamlessly into the material.

Hex Washer Heads

Hex washer heads incorporate a built-in washer to enhance load distribution and provide a more secure connection.

Raised Screw Heads

Raised or oval screw heads feature a domed shape, distinguishing them from flat head screws and offering a more prominent appearance.

Bugle Screw Heads

Bugle screw heads are characterized by their curved shape below the head, which helps to prevent surface damage during installation.

Domed Screw Heads

Domed screw heads have a rounded surface that offers a larger area to stop the screw from turning and provides a more finished look.

Truss Screw Heads

Truss screw heads are wide and low-profile, with a slightly rounded shape and an extensive surface area for better grip and stability.

Binding Screw Heads

Binding screw heads resemble pan heads but are thicker and have a deeper slot, offering a larger bearing surface by about 10% for enhanced fastening strength.

Flange Screw Heads

Flange screw heads include an integrated washer, providing a broad surface area to distribute pressure evenly across the connected material.

Pan Screw Heads

Pan heads are slightly rounded with short vertical sides, similar in appearance to carriage bolts but without the square section underneath the head.

Drivers

The drive part of a bolt or screw is crucial as it transmits torque or force from the driver to the fastener, enabling it to be secured into the material. There are various types of drivers, including specialty options designed for specific applications. Here are some common driver types:

Slotted Driver

The slotted driver is a traditional tool used with flat head screws. It features a single flat blade, but its lack of centering can cause the bit to slip out of the slot, especially under high torque.

Phillips Driver

The Phillips driver has a cross-shaped tip that provides more surface contact with the screw, reducing the amount of force needed to turn it. This design helps to improve grip and minimize slipping.

Pozi Driver

Similar to the Phillips driver, the Pozi drive features additional grooves that create a star-shaped pattern with four extra marks around the cross. This design enhances grip and reduces cam-out compared to Phillips drivers.

Torx Driver

The Torx driver, also known as TX, 6-lobe, or hexalobular, has a six-pointed star shape. This design is trademarked and can handle high torque without camming out, making it ideal for demanding applications.

Hexagonal Interior Driver

The hexagonal interior driver, or Allen wrench, fits into the hexagonal recess of a screw head. This shape provides a large surface area for transferring force, allowing for efficient torque application.

Hexagonal Exterior Driver

The hexagonal exterior drive is used with sockets and spanners, offering a broad contact surface for applying significant force. This type of driver is commonly used in mechanical and automotive applications.

Combination Driver

Combination drivers feature screw heads that accommodate multiple driver types, such as flat and Phillips. This versatility allows one driver to be compatible with different types of fasteners.

Square Recessed Driver

Square recessed drivers have a square-shaped tip that fits into the corresponding square recess of the screw head. This design helps to prevent slipping and cam-out, providing a secure grip.

One Way Driver

The one-way driver is a variation of the slotted or Phillips driver, designed to be tightened with a standard screwdriver. Its unique design allows it to be tightened but requires a special tool for removal, making it useful for tamper-proof applications.

Leading Manufacturers and Suppliers

Chapter Three: What are permanent fasteners?

Permanent fasteners are designed to create lasting connections between surfaces, with the intention of remaining in place indefinitely. Unlike threaded fasteners, permanent fasteners do not have threads and are typically installed quickly without needing additional fastening components. Examples of permanent fasteners include wooden dowels, nails, various types of rivets, and different kinds of pins.

Removing a permanent fastener often requires significant force and can potentially damage the surfaces of the connected materials. Disassembling components that have been permanently fastened is time-consuming and labor-intensive.

Nails

Nails are distinguished by their smooth shafts, which allow them to connect surfaces when driven in with a hammer or nail gun. Each nail consists of a head, shank or shaft, point, and sometimes gripper marks near the head for enhanced grip.

Common Nails

Common nails are widely used in carpentry and construction due to their heavy shank, which provides robust support for structural projects. They are known for their strength and durability, making them suitable for a variety of building applications.

Box Nails

Box nails resemble common nails but feature a thinner shaft, making them ideal for use with thin wood and plastics. While they are less sturdy than common nails, they are perfect for finishing tasks like cabinetry and paneling due to their thinner design.

Brad Nails

Brad nails are small and have a thin head that becomes nearly invisible when driven into wood. Typically, they have an 18-gauge diameter, which allows them to be used discreetly on trim and molding. Their slender design prevents splitting in delicate materials.

Finishing Nails

Finishing nails are similar to brad nails but larger, with gauges ranging from 15 to 16. They provide strong holding power, suitable for items that need to be securely mounted on walls or ceilings. Despite their larger size compared to brads, finishing nails maintain a small head for a clean finish.

Cut Nails

Cut nails feature a blunt point and tapered shank designed to reduce splitting. Their four-sided, square-like shape resists bending during installation, and once driven in, cut nails are very difficult to remove, providing a strong, secure hold.

Drywall Nails

Drywall nails are specifically designed for securing drywall. They have ringed shafts that enhance gripping power and prevent slipping. These nails are driven into drywall to sit flush with the surface, allowing for easy coverage with drywall tape.

Flooring Nails

Flooring nails come in various designs to improve grip and strength. Some are similar to drywall nails but feature spiral shanks for a tighter fit. These nails are engineered to provide a secure hold in flooring applications.

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Concrete Nails

Concrete nails are robust and durable, made from hardened steel to penetrate masonry and concrete. They have fluted shafts that help them grip securely into brick, concrete, and other masonry materials.

Roofing Nails

Roofing nails are equipped with a wide head to seal against leaks. They feature a ringed or twisted shank for increased holding power and are galvanized to resist corrosion and rust, making them ideal for roofing applications.

Nail Design Features

Nails come in a range of sizes, from as short as one inch to over five inches in length. Nails measuring six inches or longer are classified as spikes. The gauge of a nail indicates its diameter, with higher gauges representing smaller diameters. Nail heads can vary in design, including flat, checkered, or countersunk (which has a conical shape to be recessed below the surface).

Nail points are categorized as dull, diamond, or blunt. Dull points help prevent wood from splitting, while diamond points are partially blunt. The blunt point is the most common and effective for general use due to its versatility and ease of driving.

Nail shanks are typically smooth but can be designed with features to enhance their holding strength. Ringed shanks have a series of raised rings that provide a tighter fit. Barbed shanks, known for their secure grip, are ideal for rough carpentry and dense wood. Spiral shanks resemble screws and provide additional grip as they twist into the material.

Modern nails often feature coatings to ease installation by lubricating the shank. Common coatings include galvanization with zinc and vinyl. These coatings make driving nails simpler without compromising their holding power.

Nail Sizes

Historically, the length of nails was classified based on their price in England, measured in "d," which stood for the English penny. This traditional system, known as penny size, indicated the cost of 100 nails in pence. Despite its age, this method of classification remains in use today in both England and the United States. The length of a nail is still denoted by a number followed by the letter "d."

Rivets are lightweight fasteners known for their strong resistance to shearing forces. Featuring a head at each end, rivets provide support for axial loads and can be installed with a rivet gun, eliminating the need for pre-drilled holes or threads. Among permanent fasteners, rivets are among the most durable, offering a wide range of strength-to-weight ratios.

Solid Rivets

Solid rivets are among the oldest types of fasteners, featuring a simple design with a shaft and head. They are installed using impact hammers, rivet guns, or compression tools, which can be hydraulic, pneumatic, or electromagnetic. Solid rivets are chosen for applications where reliability and safety are paramount.

Tubular Rivets

Tubular rivets resemble solid rivets but include a partial tube at the tip. This design reduces the force needed for installation. When the rivet is driven in, the tubular portion expands outward to secure the rivet. Made from materials like steel, stainless steel, aluminum, brass, or copper, tubular rivets are selected based on their specific material properties and intended use.

Blind Rivets

Blind rivets, also known as pop rivets, feature a tubular body with a central mandrel. They are used when access to the back side of the materials being joined is not possible. The rivet is inserted into a hole, and the mandrel is pulled out with a special tool, causing the tube to deform and secure the rivet in place. Blind rivets can be self-drilling, self-tapping, or speed-fastening.

Drive Rivets

Drive rivets are a type of blind rivet with a shorter mandrel. They are installed by hammering, which causes the shank to expand and secure the connection on the inner surface of the material.

Split Rivets

Split rivets, or bifurcated rivets, are self-piercing fasteners with split legs attached to the head. The pre-split shaft is inserted into a hole and hammered, causing the legs to spread and create a secure connection.

Anchors

Anchors are specialized fasteners designed to secure metal components to materials such as concrete, epoxy, vinylester, and polyester resin. They can be installed either during the curing of the concrete or after it has hardened. Anchors are tailored to match the specific requirements of the item being secured and the application. Their main advantage is their ability to transfer both tensile strength and shear force to the substrate.

There are two main types of anchors: mechanical and chemical (bonded). Anchors must withstand both pullout and shear forces, where pullout forces act along the axis of the fastener and shear forces act perpendicular to it.

Mechanical anchors are inserted into pre-drilled holes, while chemical anchors use adhesives to secure them.

Some common types of anchors include:

Acoustical Wedge

Acoustical wedges are anchors specifically designed to secure wiring to concrete or masonry surfaces.

Double Expansion Shield

Double expansion shields are mechanical anchors that expand in two directions as they are screwed in, providing a secure hold in various materials.

Hammer Drive Pin

Hammer drive pin anchors are lightweight and are installed by driving the pin into the surface until it is flush with the material. They are commonly used for lighter-duty applications.

Screw-In Anchor

Screw-in anchors, made from materials such as plastic, metal, or composite fibers, feature a Phillips-style head and are installed by screwing them into a pre-drilled hole.

Inserts

Inserts, also known as threaded bushings, serve as reinforcement for fasteners by providing a durable threading surface within a pre-drilled hole. They are commonly used to repair stripped threads, offer threading for softer materials, or add threads where none exist. Inserts restore strength and stability to joints and connections.

Externally Threaded Inserts

Externally threaded inserts, or self-tapping inserts, are cylindrical metal bushings equipped with both external and internal threads. These inserts cut their own threads as they are screwed into a hole, providing a secure fit in a range of materials.

Internally Threaded Inserts

Internally threaded inserts feature threads on the inside and expand against the sides of a pre-drilled hole as they are inserted. This expansion creates a tight and stable grip, making them ideal for use in various materials.

Key Locking Inserts

Key locking inserts combine internal and external threads with a vertical key on top. When installed into a pre-drilled hole, a key is driven into the insert's threads to provide a mechanical lock, reinforcing weak parent materials.

Press-In Inserts

Press-in inserts are designed for use in hard plastics and require a specialized insertion tool. This tool applies high-frequency ultrasonic sound waves to the insert, melting the plastic and securing the insert in place as it is pressed into the hole.

Helical Screw Inserts

Helical screw thread inserts are made from diamond-shaped coiled wire. They are screwed into a threaded hole to repair or reinforce a damaged thread, offering a strong and durable connection.

Blind Threaded Stud Inserts

Blind threaded stud inserts feature a round, knurled body with a projecting machine screw threaded stud. These inserts are installed into a pre-drilled hole using a special tool. As the stud is tightened, the back of the insert's body expands to lock securely within the hole.

Retaining Rings

Retaining rings are metal fasteners used to secure a shaft or assembly in place. They come in numerous styles, configurations, designs, and sizes to accommodate various applications. Typically, they are permanent fasteners and are discarded when no longer needed.

Usually, a retaining ring is a circular metal piece that fits into a groove on a housing or shaft. Depending on the application, they can be installed either internally or externally, as illustrated in the diagram below.

Retaining rings offer significant convenience by eliminating the need for complex and costly machining processes. They simplify assembly operations by replacing bolts in gear assemblies, removing the requirement for drilling and tapping holes. This streamlining helps to simplify and expedite the installation process.

Chapter Four: What are the different types of washers?

Washers are a small, circular, metal disc in the shape of an annulus, halo, donut, or ring that is used to distribute the force of a screw, bolt, or nut. They can relieve friction, stop leakages, maintain tension, prevent corrosion, and serve as a spacer or separator. The wide and varied uses of washers has made them a necessity in a number of applications.

Washers come in a variety of materials, including zinc, copper, brass, iron, carbon steel, and stainless steel. Some applications require specialty washers made from non-metallic materials such as plastic, rubber, ceramics, and phenolic.

Washers can be categorized into three main types: plain, spring, and lock. Each category includes specialized forms designed to fulfill specific or unique functions.

Washers serve a multitude of functions, including:

1. Reduction of friction
2. Distribution of pressure
3. Blockage, cessation, or elimination of leakage
4. Separation of components
5. Enhancement and securing of connections from vibrations and shock

Plain

Plain washers are used to isolate the material being secured from bolts, screws, or nuts. They provide insulation and protect the substrate from damage. Additionally, plain washers help distribute the load by increasing the surface area in contact with the substrate. They can also compensate for oversized holes by covering the gap and ensuring a secure connection.

Flat Washer

Flat washers, also known as type A washers, are used for general purposes such as correcting hole sizes and distributing loads evenly.

Torque Washer

Torque washers are utilized in woodworking projects to prevent bolts from spinning when the nut is tightened, providing stability during assembly.

Fender Washer

Fender washers feature a small inner diameter and a larger outer diameter, designed to distribute force over a broad area, making them ideal for use with thin metals.

C Type Washer

C-type washers have a segment cut out, allowing them to be inserted even when a fastener is not fully disconnected. This design enables easy placement without removing the fastener completely.

Finishing Washer

Finishing washers are used with countersunk screws to hold them in place, providing a flush and neat finish.

Square Washer

Square washers, or blind rivet washers, have flat sides and are used in slots and channels. They are thicker and wider than round washers, providing excellent load distribution and stability.

Spring Washers

Spring washers function like a spring due to their slightly altered circular shape, which provides axial flexibility and elasticity. They help prevent loosening or loss of tension in fasteners due to shock, vibration, or movement.

Belleville Spring Washer

Belleville spring washers resemble a hollow cone with the top removed. They offer great flexibility and support axial forces with minimal deflection, making them suitable for applications with thermal expansion.

Crescent Spring Washer

Crescent spring washers are flat washers that are bent or curved to resemble a crescent. They can absorb small axial forces and are used in applications with limited movement.

Dome Spring Washer

Dome spring washers have a domed shape with a hole at the top. They are designed for high load capacity with minimal deflection and feature ground curves for a flatter load-bearing surface.

Wave Spring Washer

Wave spring washers are ideal for applications involving thermal expansion and contraction. Their design provides minimal axial space and a uniform wave pattern, offering optimal load rates and flexibility.

Locking Washers

Locking washers are used to secure bolts, nuts, and screws in place, preventing loosening due to friction, shock, rotation, or vibrations. They exert spring tension on the fastener to enhance stability and are placed beneath the fastener for added security.

External Teeth Washers

External teeth washers have teeth around their circumference that extend radially outward. As the fastener is tightened, these teeth bite into the substrate, securing the fastener firmly in place.

Internal Teeth Washers

Internal teeth washers have teeth on the inner diameter, extending toward the center. Similar to external teeth washers, these teeth dig into the substrate to lock the fastener securely.

Split Lock Washers

Split lock washers feature helical split rings that create spring force on the fastener, increasing friction and resistance to motion. The split ends of the washer interlock, providing a firm and secure fit when the fastener is tightened.

Tab Locking Washers

Tab locking washers have a flat design with one or more tabs extending from the inner side of the hole. These tabs fit around bolts or nuts, keeping them in place. Tab lock washers are particularly useful in high-temperature or high-vibration environments.

Chapter Five: How Fasteners are Made?

Several methods are employed to produce nuts, bolts, clips, screws, and other types of fasteners. The three most common methods are machining, cold forging, and hot forging. These techniques are widely used for forming and producing metal parts.

The selection of a production method depends on factors such as the type of fastener, the metal used, and the desired quantity. Some methods are more suitable for producing large quantities, while others are better for specific metal types and their characteristics, such as pliability and elasticity.

Machining

Machining is a process used to shape metals into parts and components through various cutting techniques. This includes operations such as cutting, drilling, turning, milling, and grinding to achieve the desired form. Unlike molding and casting, machining operates at room temperature or slightly above, with friction being the primary source of heat rather than an intentional heating process.

In machining, a round or hexagonal metal piece, known as the workpiece, is transformed through threading and shanking to meet specific geometric requirements. The process can be performed on a Computer Numerical Control (CNC) machine, which enhances efficiency by allowing multiple processes to be executed simultaneously.

The advantages of machining include high precision, exceptional tolerances, and the capability to create complex geometries. However, it is a time-consuming process best suited for short runs or minimal quantities.

Cold Forming

Cold forming, or cold roll forming, is a widely used method for producing fasteners due to its efficiency and minimal waste generation. Performed at or near room temperature, this method enables the rapid and cost-effective production of large quantities of fasteners.

The process begins with a coil of wire that is straightened and sheared to the required length. These pieces are then fed into a rolling machine, where they are shaped and detailed with high precision. The pressure applied during cold forming preserves the metal&#;s original grain structure, which enhances the tensile strength of the final product.

Cold forming encompasses several techniques, including upsetting or heading, extrusion, and rolling. In the upsetting process, the workpiece is deformed at one end to increase the cross-sectional area. Extrusion involves applying compressive force to cause deformation heat, which can be applied at different angles. Cold roll forming applies pressure to shape the workpiece into the desired form.

Hot Forging

Hot forging is employed for producing fasteners when machining or cold forming are not suitable. A critical aspect of hot forging is the heating of the workpiece to its recrystallization temperature, which can reach up to °C (°F). This high temperature enables the metal to retain its deformed shape as it cools.

During the forging process, the metal&#;s grain structure is refined and homogenized, resulting in improved strength, ductility, and toughness. Hot forging is noted for its efficiency, as it generates minimal scrap and waste compared to other metal forming methods.

Stamping is a cold forming process that molds metal sheets using a stamping press, similar to blanking and piercing. It can be performed in a single step or involve multiple stages, depending on the complexity of the part being created. One of the most commonly produced items through stamping is washers in various types and configurations.

Stamping is versatile and can accommodate any production run, from high-volume processes that use metal coils fed into the stamping press to smaller-scale manufacturing needs.

Metals Used to Make Fasteners

When selecting the appropriate metal or fastener for an application, several factors must be considered, including the intended location, environmental conditions, and exposure to moisture and heat. While heavier metals might appear suitable, they can underperform or fail if not matched to the specific conditions of the environment.

Steel

Steel is the most commonly used metal for manufacturing fasteners. It can be used in its plain form or with surface treatments like galvanization.

Steel fasteners are typically made from various grades of steel, including Grades 2, 5, 8, as well as alloyed steel.

• Grade 2: Most common and least expensive
• Grade 5: Hardened to increase strength and used in automotive applications
• Grade 8: Hardest of the three and used in demanding and stressful applications

Alloyed Steel

Alloyed steel fasteners are known for their exceptional strength and are typically heat-treated for enhanced durability. They usually come with a dull black finish to provide additional protection.

Stainless Steel

Stainless steel is highly suitable for fasteners due to its resistance to corrosion and rust, maintaining these properties even if scratched during installation. It comes in various grades, each offering distinct characteristics and advantages.

• 18-8 Stainless Steel: The most common stainless steel.
• 316 Stainless Steel: Exceptionally resistant to corrosion and ideal for salt water and chlorine environments.
• 410 Stainless Steel: Harder than 18-8 but less resistant to corrosion.

Aluminum

Aluminum is typically alloyed with other metals when used for producing fasteners. For example, rivets are often made from series aluminum. These added alloys enhance aluminum's strength and increase its melting point.

Brass

Brass is an alloy of zinc and copper, known for its softness, corrosion resistance, and electrical conductivity. It is often chosen for its aesthetic appeal.

Bronze

Bronze, an alloy of copper, tin, and a small amount of silicon, offers superior corrosion resistance and strength. It is suitable for use as a non-permanent fastener due to its ability to be re-fastened.

Conclusion

• A fastener is a non-permanent or permanent mechanical tool that rigidly joins, or affixes two surfaces or objects together.
• There are an endless number of shapes, sizes, lengths, and varieties of fasteners that range from the common nail to huge bolts to hold heavy duty manufacturing equipment in place.
• The group of permanent fasteners do not have threads and can be quickly installed without the need of extra fastening components.
• Washers relieve friction, stop leakages, maintain tension, prevent corrosion, and serve as a spacer or separator.
• The three methods used to produce fasteners are machining, cold forging, and hot forging; these are commonly used methods for forming and producing metal parts.

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