A drop-in anchor is an internally threaded (female) displacement setting expansion anchor that is specifically designed for use in solid concrete with a minimum entry hole. It places a permanent, heavy-duty machine thread inside the concrete, allowing you to secure objects using standard machine bolts or threaded rods. Drop-in anchors are valued for their low cost, shallow concrete embedment, ease of use and strong load-bearing capacity. They are commonly employed by carpenters, electricians, plumbers, light installers, ceiling installers, fire protection specialists, steel fabricators, and general builders.
Drop-In Anchors are a crucial component in modern construction, offering reliable and efficient solutions for securing various structures and fixtures to concrete. Their versatility and strength make them suitable for a wide range of applications such as supporting cable trays, ductwork, pipes, and various other structural elements. The different types of drop-in anchors, including those approved under AS5216 make them highly suitable for a wide range of users in the construction industry. Understanding their types, applications, and correct usage is key for any professional engaged in construction and maintenance work.
Componentry
The anchor is made of three primary parts:
- the slotted metal tubular shell, with
- a pre-assembled internal tapered plug (cone), and
- internal (normally coarse) threads (metric, imperial, or Whitworth).
How it Works
- Drill a Hole: using a mortar bit 0.5mm to 1.0mm larger than the OD of the anchor, drill a hole ~ 5mm deeper than the length of the anchor
- Insert the anchor (insertion): Clean the hole and drop the anchor into the concrete – open end facing up, and tap it until it is flush with the surface.
- Set the anchor (expansion): Using a specialized setting tool or pin punch and a hammer, you strike the internal plug, driving it down. This forces the metal shell to expand outwards, gripping the concrete tightly.
- Using the anchor (fastening): Once expanded, you thread your bolt or threaded rod into the anchor to secure your fixture.
Types of Drop-In Anchors
Collar / Lip Variations
- Lip / Collared: Features a small rim at the top that prevents the anchor from falling too deep into the drilled hole, ensuring it mounts perfectly flush with the concrete surface.
- Lip-less / Flush: Sits entirely below the surface of the concrete, which allows you to easily patch or fill the hole if the anchor is ever abandoned.
Material Variations:
- Carbon steel (zinc-plated) is used for economy standard indoor/dry applications
- Stainless steel (304 or 316) is preferred for durability and mandatory for outdoor or corrosive environments.