Fasteners
The term "fasteners" encompasses a wide variety of screws, bolts, nuts and other kinds of tools used to join and secure materials together. There are more than 500,000 types of fasteners available on the market, and they are applied in all kinds of industrial, commercial and consumer products contexts.
Quick Links to Fasteners Information
The History of Fasteners
The history of fasteners dates back thousands of years. Because fasteners are such basic and integral parts of life, it’s hard to say exactly when and where the first fastener was used. We do know, however, that one of its best-known types, the screw, was likely invented by the Egyptians, and also used by the ancient Greeks.
Archytas of Tarentum invented screw threads for the western world around 400 BC, while another well-known Greek, the mathematician Archimedes, invented the screw principle around 234 BC. He used his principle to create and use wooden water screws, which helped greatly with farm irrigation and ship bilge water removal. Other early screws were found in presses used to extract olive oil and grape juice.
The screw got its first mention in Mechanica of Heron of Alexandria in the first century AD. Centuries later, in about 1750, Antoine Thiout changed what was possible by adding a screw drive to a lathe; this allowed tool carriages to be moved longitudinally semi-automatically.
Meanwhile, there is no clear consensus among experts as to when nuts and bolts, probably the most common type of fasteners, originated. No doubt, its roots were planted when the screw thread was invented.
The most prominent advancements in current-day bolt and screw processes were achieved during the last 150 years, and nuts and bolts have been firmly established as an important component of engineering and construction since the Industrial Revolution. The U.S. Standard Thread was formed in the early 1870s. Then came the Society of Automotive Engineers (SAE) standard, and screw thread designs continued to evolve. The self-drilling screw arrived on the scene in the late 1960s in the metal building industry. It was introduced as a "pinched point" (or cold forged) self-drill, offering the benefits of a decrease in the overall time and cost of installing the fastener.
There has been tremendous development in fastener designs in the past 20 years, as industries started using nickel-based alloys. This material can withstand high temperature environments like turbochargers and engines where steel does not perform well. There is ongoing research and development of lightweight metal bolts from metals like aluminum, magnesium and titanium. Modern-day fasteners have come a long way from their Greek lineage, sparking industrial development and human progression.
Design of Fasteners
- Production Process
- Depending on the material, fasteners are manufactured and produced in a number of different ways. For example, most plastic fasteners are injection molded, while metal fasteners are made via heating and casting. To thread fasteners, manufacturers put the pieces through a process called thread rolling, in which a hard metal die with a threaded profile is pressed onto a rotating workpiece. The force is increased, and the thread profile is transferred onto the fastener via cold working.
- Material Design
- Suppliers usually manufacture industrial fasteners from strong sheet metal, like stainless steel, titanium or alloy steel. Titanium is the leading aerospace fastener material, while stainless steel screws and other fasteners are very popular in automotive manufacturing. Light-duty fasteners, like those used to make children’s toys, are usually made from plastics, brass or bronze.
- Design Considerations
- Fastener manufacturers have many options when it comes to standard and custom design choices, as they can manufacture fasteners in all shapes and sizes, with or without threads. In addition, manufacturers have a choice of measurement system—In the US, fasteners usually follow the American system of measurement, but metric fasteners are more commonly used outside of the US.
- When making their decisions, professionals must consider how all of these variables, and others, will impact fastener performance. "Others" include: the weight of the materials being connected, head type (determines how the fasteners will sit against the materials in which they are installed, and affects required fastener length), environmental factors (temperature, moisture and ultraviolet radiation, chemicals to which the fasteners may be exposed, etc.), and all other application requirements. For example, does the fastener need to be tamper proof? Does it need to incorporate design elements?
Types of Fasteners
By and large, fasteners can be divided into groups of threaded and non-threaded fasteners.
- Threaded Fasteners
- Contain spiral ridges (threads) that aid in their attachment. Threaded fasteners include: nuts, bolts, screws, continuous-thread studs, tap-end studs, double-end studs, riveting fasteners, and clinching fasteners.
- Nut
- And bolts work together to form a common fastening mechanism. Nuts are metal blocks with complementary internal threads that grasp the upper shaft of the bolt and secure the workpiece together.
- Bolt
- Or bolt stud, is an external threaded fastener that consists of a partially threaded shaft, which penetrates the object connected. It is held in place by nuts.
- Screw
- Externally threaded fasteners that are made up of a spiral-shaped shaft and a head. To hold work pieces together, users drive the screw into them, which stays in place because of its head.
- Continuous-Thread Stud
- Threaded from end to end. They’re often used for flange bolting, in conjunction with two nuts.
- Tap-End Stud
- A short thread on one end and a longer threaded end on the other. The short end is for screwing into tapped holes. The longer end, called a nut-end, can be either chamfered or rounded.
- Double-End Stud Fastener
- Have equal-length threads and chamfered points on both ends. They are used for flange bolting or other applications in which torching from both ends is necessary.
- Clinching Fastener
- Also known as a self-clinching fastener, clinch fastener or captive fastener. This term refers to any fastener that, when pushed into a ductile metal workpiece, displaces the material around the mounting hole, and causes it to cold flow into a specially designed annular recess in the fastener shank or pilot.
- Non-Threaded Fasteners
- Do not contain threads. These fasteners can be quickly assembled and removed from components and do not need extra fastening hardware. Examples include: rivet fasteners, pin fasteners, blind fastener rivets, dowel pins and retaining rings.
- Rivet Fastener
- Permanent mechanical fastener. On its own, it consists of a smooth cylindrical shaft and a head on one end. After a user installs the rivet by placing it in a punched or drilled hole, the other end of the shaft, known as the tail, deforms. When this happens, it expands about one and a half times in order to hold the rivet in place.
- Rivets often work in conjunction with pins, placed into aligned holes in the joined parts, to form secure connections on hinges and pulleys.
- Pin Fastener
- A steel pin, which is usually cylindrical. Use them to fasten or hold machine parts in proper alignment.
- Blind Fastener
- Also known as a blind rivet nut or a pop fastener rivet, is a tubular fastener, mainly used when users can access a joint only from one side. This fastener type is not good for critical structure applications.
- To install, insert the fastener into a pre-drilled hole, then use a rivet gun to pull on a headed-shaft. It will pass through the rivet, then break or pop. This popping action leaves a bulge on the head of the rivet, which holds the two parts together.
- Dowel Pin
- Solid cylindrical rods cut into small lengths, used for many different applications. Examples include: axles in toys, shelf supports and hanging piece supports. They provide perfect alignment, holding parts in absolute relation to one another. They may be straight, tapered, rolled or grooved.
- Retaining Ring
- Holds assemblies or parts onto shafts or in housings/bores. Most retaining rings need a groove to seal them into position, so they are stamped both internally and externally. While some of them may be self-locking, both kinds are used to keep parts from slipping or sliding apart.
- Snap Fastener
- Also known as press studs, poppers or snaps, are used in place of buttons to fasten items like clothing. They consist of two plastic or metal interlocking discs, and with force, they snap into place.
- Self-Tapping Screw
- A screw that can tap its own hole as it is driven in a workpiece. Companies most often manufacture self-tapping screws for dentists, surgeons and DIYers.
- Cap Screw
- A machine part fastener. It consists of a fully threaded shaft, held by threads tapped in the hole in which it is screwed.
- Decking Screw
- A specialty fastener, used primarily in the construction of outdoor decks and other wooden structures.
- Aerospace Fasteners
- Which are an industrial fastener variety, are any threaded or non-threaded fasteners that are intended for use in aircraft assembly.
- Stainless Steel Fastener
- Quite common in the automotive, electrical and electronic, medical, marine, construction and aerospace industries because of their strength and resistance to corrosion and heat.
Fastener Applications
Fasteners are everywhere, and they are used in almost every piece of equipment we use in our day-to-day life. From use in airplanes to kitchen appliances, fasteners are a quiet component of our world.
Some of the many industries that rely on them include: automotive manufacturing, aerospace, furniture, household appliances, building and construction, security, military and defense, electronics and HVAC.
Fastener Installation
In general, fasteners are installed using tools like hammers, screwdrivers and drills, including power drills. The choice of which you use depends entirely on the type of fastener you’re using and your application.
Standards and Specifications for Fasteners
It’s important that you purchase fasteners that meet the standard requirements of your country/region and industry/application. If the quality of fasteners is substandard, they can loosen or break, which will ultimately result in the device or machine failing.
The United States government has standards related to fastener characteristics like thread quality (coarse thread vs. fine thread), fastener length, etc., to help them distinguish between bolts and screws. Another important group is SAE International, a U.S. based and globally active standards association. SAE assigns grades to fasteners according to their characteristics. ISO and ASTM also offer screw grade designations. All of these help customers identify which fasteners are right for their application. Also, certification from associations like ISO and ASTM let you know that your fastener is quality-assured.
Things to Consider When Purchasing Fasteners
Choosing the right fastener for your product is a challenge. Follow the tips below to have an easier time making decisions.
- Fastener Material
- Figure out what material you need by considering the end-use of the product with which you intend to use your fastener. For example, if your fastener is keeping shut an enclosure with vibrating parts, choose a durable metal. If the product will not be opened and does not vibrate, you can probably get away with an inexpensive alternative like a plastic fastener.
- Fastener Intended Use
- Before choosing the fastener for your design, another important aspect to consider is to understand your specific needs. Your product design will dictate the primary function, size and material of the fastener. Failing to consider this can lead to the fastener not doing the job properly, ultimately affecting the performance of your product. In addition, you need to pay attention to the threads of the fastener. If your design calls for a multiple thread fastener, a single threaded one will not do. Never use metal that is too heavy for your application, and never ask your provider to meet critical tolerances that your product does not need. The same goes for the size of the fastener.
- Choose Finish According to Function
- Settle on a finish for your fastener after your provider studies your requirement. You need to choose the finish hardness according to your product design; make sure that the metal grade and gauge thickness is the same as your application. Moreover, when ordering, communicate to your supplier what job the fastener is supposed to perform, and ask about fastener limitations.
- Cost Cutting and Savings
- Cost is always a concern for everything we do. This is especially true to manufacturers, since the primary motive of a business is to earn profit. Since fasteners are a basic need in a lot of industries, businesses generally look to cut corners to save cost. Avoid this. Cutting cost on fasteners may help you gain a few dollars in the short-term, but in the end, it can have a devastating impact on your reputation, as low-quality fasteners may fail which will ultimately lead to failure of your product, dealing a blow to your brand.
- Choose the Right Manufacturer
- One of the most important pieces of advice we can offer you is to choose the right manufacturer. Who is the right manufacturer and how do you find them? The right manufacturer is the one that doesn’t just look at their bottom line, but instead works to give you the highest quality fastener possible. They will respect your deadlines, budget and specifications. Start your search for your perfect supplier by scrolling to the top of this page and checking out the list of reliable companies we’ve compiled for you.
Proper Care for Fasteners
The most frequent culprit of fastener damage is rust, corrosion and wear. If you’re using a metal fastener, you can prolong its life by keeping it lubricated or by having your fastener manufacturer add a protective coating. Also, shield them from prolonged moisture exposure as much as possible. A plastic fastener is less susceptible to damage from corrosion, but it could still sustain damage from impact or heat. So, make sure to only use your fastener for its intended application and keep it confined to environments that its material can stand.
Accessories for Fasteners
Accessories that you may need for your application include: washers, spacers, screw protectors, plugs and sticky circles and squares.
Fastener Terms
- Bearing Surface
- The supporting part of fasteners through which the fasteners are loaded.
- Blind Fastener
- Fasteners accessible on only one side.
- Automotive Fastener
- They play an important role in car equipment safety, and they must be strong enough to fare well under the harsh, stressful conditions that are always involved in the operation of an automobile.
- Blind Side
- The point on blind fasteners that cannot be accessed.
- Body
- Referring to blind fasteners, it is the part of the rivet that expands into the material. In reference to threaded fasteners, it is the part of the fastener that is not threaded and is located under the head.
- Button Head
- A head of a threaded fastener that has a low, rounded top surface and a bearing surface, which is large and flat.
- Clench
- The ability of fasteners to hold together previously separated materials.
- Complete Hole Fill
- A feature of fasteners that allows them to fill irregular, slotted, oversized or misaligned holes.
- Concentricity
- The condition in which two fastener surfaces share the same center.
- Countersunk Head
- A head that, when installed, will sit flush to the surface.
- Creep
- The permanent deformation of fasteners resulting from the application of stress and heat.
- Eccentricity
- The degree of difference between the centers of the surface of fasteners at different points.
- Fatigue Strength
- A fracture resistance ability of a fastener during subjection to stress variations.
- Fillister Head
- A head with a rounded top, cylindrical-shaped sides and a bearing surface that is flat.
- Grip
- The thickness of the assembled materials or parts for which the fastener was designed to secure.
- Joint
- The materials that fasteners have connected together.
- Lead Thread
- A measurement indicating the length between the beginning of a thread and the point at which the thread reaches its fullest size.
- Major Diameter
- The widest point of a screw thread.
- Minor Diameter
- The narrowest point of a screw thread.
- Pitch
- The distance between two threads on fasteners.
- Shank
- The part of fasteners bodies between the head and the threaded portion.
- Spacers
- Components designed to protect fragile materials at contact points between the material and the fasteners.
- Thread Cutting
- The process of creating threads by cutting into the metal blank, as opposed to rolling.
- Thread Rolling
- A cold forming process involving the creation of threads through the plastic deformation of a metal blank. The process, which produces rolled threads that have higher strength and abrasion resistance than threads constructed through cutting, involves the application of pressure, which stretches the metal past its elastic limit into the required profile.