Fasteners Types and Terms

  • Aerospace fasteners are screws and bolts used in the assembly of aircraft.
  • 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.
  • Metric fasteners follow the metric system instead of the English 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, 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 provide an alternative to traditional metal fasteners, although they have low resistance to UV radiation. Plastic fasteners are common components of children's toys, as well as appliances and automobiles.
  • 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 external 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.
  • Special 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.
  • Through-hardened fasteners have received heat treatments, resulting in consistent hardness throughout the entire fastener.

Bearing Surface - The supporting part of the fastener through which the fastener is loaded.
 
Blind Fastener - A fastener accessible on only one side.
 
Blind Side - The point on a blind fastener that can not 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 a fastener 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 a fastener resulting from the application of stress and heat.
 
Eccentricity - The degree of difference between the centers of the surface of a fastener 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 the fastener connects 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.
 
Shank - The part of the fastener body between the head and the threaded portion.
 
Spacers - Components designed to protect fragile materials at contact points between the material and the fastener.
 
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