Fasteners

Construction fasteners, decking screws, furniture fasteners, self tapping screws, electronic equipment fasteners, appliance fasteners, automotive fasteners and specialty fasteners are just a few fastener varieties. Industrial fasteners are important parts of many industrial products and process equipment. Aerospace fasteners, which are an industrial fastener variety, are any non-threaded or threaded fasteners that are intended for use in aircraft assembly. Titanium is the leading aerospace fastener material, while stainless steel screws and other fasteners are very popular in automotive manufacturing. In the US, fasteners usually follow the American system of measurement, but metric fasteners are more commonly used outside of the US. Fasteners can be threaded, like screws, or unthreaded, like ring or pin fasteners. Fasteners can be manufactured in all shapes and sizes and in a wide variety of materials. While stainless steel fasteners are among the most common varieties, plastic fasteners can also be appropriate in some situations. The wide variety of fastener configurations and compositions open a world of possibilities to professionals throughout industry. This diversity can make choosing the right product a bit of a challenge.

In consideration of applying a given fastener variety, professionals must think of all of the variables that affect the way that fastener will perform in its application. Such variables include the size and shape of the fasteners, the weight of the materials being connected, the fastener's head type and many other considerations. There is a wide variety of head options for industrial fasteners; head type determines how the fasteners will sit against the materials in which they are installed. The type of head also affects the required length of the fasteners. Environmental conditions, such as temperature, moisture and ultraviolet radiation, are also important factors. Chemicals or other corrosive substances to which the fasteners may be exposed and decorative properties required of the fasteners must also be considered. Threaded fasteners, such as nuts, bolts and screws, contain spiral ridges called threads, which aid in the attachment of the threaded fasteners. Continuous-thread studs are used for flange bolting. Two nuts are applied and threaded from end to end. Tap-end studs have a short thread on one end for screwing into a tapped hole and a longer threaded end called a nut-end, which can be either chamfered or rounded. Double-end studs have equal-length threads on both ends with chamfered points and are used for flange bolting or other applications in which torching from both ends is necessary. Other threaded fasteners include sheet metal fasteners, riveting fasteners, and clinching fasteners.
 
Non-threaded fasteners, such as rivet fasteners, ring fasteners and pin fasteners, do not contain threads. These fasteners can be quickly assembled and removed from components and do not need extra fastening hardware. Bind fastener rivets or pop fastener rivets are inserted into a pre-drilled hole, and a rivet gun pulls on a headed-shaft that passes through the rivet. The shaft breaks or pops, leaving a bulge on the head of the rivet, which holds the two parts together. Dowel pins can be straight, tapered, rolled or grooved and provide perfect alignment, holding parts in absolute relation to one another. Most retaining rings need a groove to seal them into position and 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.

Fasteners are generally made either of plastic or metal, depending on their applications. Plastic fasteners are not very strong, so their use is generally restricted to light-duty applications. They can be used to affix upholstery in vehicles and furniture, they can be used to make children's toys and they are used in an extensive variety of consumer products. Metal fasteners are often made of steel, titanium, brass and bronze. Stainless steel fasteners are quite common in the automotive, electric, medical, marine, construction and aerospace industries because of their strength and resistance to corrosion and heat. Depending on the material, fasteners are manufactured and produced a number of different ways. Most plastic fasteners are injection molded. Metal fasteners are made by heating and casting. Threaded fasteners go through a process called thread rolling, in which a die made of harder metal than what the fastener is made of, with a threaded profile, is pressed onto a rotating work piece. The force is increased, and the thread profile is transferred onto the fastener via cold working. Carefully pairing a fastener with its application is essential to ensuring the effectiveness and longevity of the fastener and the materials in which it is installed.

Fasteners and Metric Fasteners Image Provided by Elgin Fastener Group	Fasteners and Metric Fasteners Image Provided by Ford Fasteners, Inc.

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Fastener Types

• Aerospace fasteners are screws and bolts used in the assembly of aircraft.
• Automotive fasteners are connecting tools used in the manufacture of automobiles.
• Decking screws are fasteners used primarily in the construction of wooden structures like outdoor decks.
• Breakstems are fasteners that are installed by pulling the end of the mandrel or stem, resulting in the breakage of the stem at the breaker groove and leaving the head of the stem within the fastener body.
  
• Case hardened fasteners have received heat treatments resulting in a fastener surface that is harder than the core.
• Industrial fasteners are screws, bolts, nuts and other connecting tools used in or produced by industrial processes.
• Metric fasteners follow the metric system instead of the American Customary system. Conversion charts are available from most fastener manufacturers.
  
• Mil spec fasteners comply with U.S. federal and military specifications for fastening mechanisms.
  
• Nuts and bolts work together to form a common fastening mechanism. A bolt is an external threaded fastener that consists of a partially threaded shaft, which penetrates the object connected and is held in place by nuts; nuts are metal blocks with complementary internal threads that grasp the upper shaft of the bolt and secure the work piece together.
  
• Panel fasteners function as latching mechanisms on doors and compartments and join panels on cabinets, workstations and appliances.
  
• Plastic fasteners are screws, nuts, bolts and other fasteners made of plastic materials. While plastic fasteners are not as strong as metal fasteners, they are still popular in applications like upholstering, consumer products manufacturing and many other examples.
  
• Rivets and pins are non-threaded fasteners commonly used on door hinges and pulleys, as well as furniture and electronic equipment. Pins are placed into aligned holes in the joined parts, forming a secure connection.
  
• Screws are externally threaded fasteners consisting of a spiral-shaped shaft and a head. The shaft fits into a work piece and is held in place by the head.
• Self tapping screws are threaded fasteners that can be screwed into surfaces that have not been tapped.
• Specialty fasteners are available through many fastener manufacturers. Specialty fasteners can be custom-made according to specific customer requirements.
  
• Stainless steel fasteners are strong, corrosion and heat resistant mechanisms that are useful in countless applications in the automotive, electronic, medical, marine and construction industries.
• Stainless steel screws are threaded fasteners made of stainless steel; these products are attractive because of their strength and corrosion resistance. 
• Threaded fasteners are screws, bolts and other connecting tools that are machined or rolled with ridges called threads.
• Through-hardened fasteners have received heat treatments, resulting in consistent hardness throughout the entire fastener.

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Fastener Terms

Bearing Surface - The supporting part of fasteners through which the fasteners are loaded.
 
Blind Fastener - Fasteners accessible on only one side.
 
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

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