Description

Anchors are mechanical fasteners that attach an object to a support structure.

Types of Anchors

Some common types of anchors include:

• Concrete anchors - Concrete anchors or anchor bolts are screw-bolt fastening systems that are used to attach objects to concrete. Variations include L-anchors, concrete I-bolt anchors, concrete strike anchors, sleeve bolt anchors, and floor anchors.
• Expansion anchors - Expansion anchors (expansion shield anchors) are designed to accommodate mating screws or bolts that are exposed to vibration or side pressure loads. Variations include single expansion anchors and double expansion anchors.
• Lag screw anchors - Lag screw anchors or lag shield anchors are medium-duty fasteners with a ribbed outer surface that expands to fill the volume of pre-drilled holes as a mating lag screw is tightened.
• Machine anchors - Machine screw anchors are a caulking fastener system that allows for quick-setting in brick, concrete, or stone. A malleable-metal lead shield allows machine screw anchors to compensate for uneven or irregular hole / roundness conditions.
• Screw anchors -  Screw anchors (drop-in anchors) are used in concrete and solid block materials. Upon installation, four surfaces of the metal plug expand to form a permanent hold below the target material's surface, creating a secure threaded hole for the mating screw.
• Spring anchors -  Spring anchors are small or miniature-sized externally-threaded studs.
• Wall anchors - Wall anchors are light-duty fastening systems that are used in drywall, foundation repair, sump pump installation, and basement waterproofing. Wall anchors are sometimes called molly bolts or molly anchors, hollow wall anchors, wallboard anchors, sleeve screw anchors, or drywall anchors.
• Wedge anchors - Wedge anchors or wedge stud anchors are heavy-duty mechanical fasteners. They may include a mounting bracket, and provide greater shear strength than other light-duty and medium-duty expansion anchors. Wedge anchors are designed to withstand temperature fluctuations, and are used for permanent embedding in materials such as concrete. Uses include machinery mounts. Variations include seismic wedge anchors.
• Toggle bolts - Toggle bolts or wing anchors have a wing-like toggle (sometimes spring-loaded) designed to pass through a drilled hole. When the bolt is tightened, toggle bolts tightly grasp the inside surface of a target material such as drywall or wallboard. 

Specifications

Anchors also differ in terms of specifications and features. Fastener material strength, hole-size (diameter), length, and thread size are important parameters to consider. In terms of features, some anchors are removable or non-permanent. Others are designated as bulk-fed, typically for use with power tools.       
 

Standards

A-A-1922 - Shield, expansion (caulking anchors, single lead)

A-A-1923 - Shield, expansion (lag, machine and externally threaded wedge bolt anchors)

A-A-1924 - Shield, expansion (self drilling tubular expansion shell bold anchors)

A-A-1925 - Shield, expansion (nail anchors)

Resources

Image Credit:

Kee Safety Inc.|Nelson Stud Welding