Mechanical anchors are anchors that mechanically anchor themselves in
the base material using friction and some type of movement within the
mechanical anchor to achieve holding values. Mechanical anchors are
made up of more than one part, allowing the parts of the mechanical
anchor to move independently and create expansion of the mechanical
anchor. Once placed in the hole in the base material, the mechanical
anchor is expanded. This exerts pressure against the wall of the hole,
creating friction and holding power. Mechanical anchors are designed to
go into the hole in the base material, but will not come out.
Different Types of Mechanical Anchors
Mechanical anchors can be male or female type masonry anchors.
Some mechanical anchors can only be used in solid concrete while others
can be used in a variety of base materials, such as concrete, brick or
block. The way mechanical anchors are set in the base material also
varies. Mechanical anchors require a hammer, or setting tool, or a
wrench. All of these different types of mechanical anchors were
developed for use in applications that have specific requirements.
Wedge Anchors
The wedge anchor
is a mechanical anchor that requires a wrench to be used to set. It is
designed for use in solid concrete only. Turning the nut clockwise
expands a wedge clip at the working end of the wedge anchor. This pulls
the stud up, expanding or wedging the clip against the anchor body and
the inside wall of the hole in the concrete. The clip is designed with
nubs that protrude to keep the clip from spinning in the hole when the
nut is turned.
Sleeve Anchors
The sleeve anchor
is a four piece mechanical anchor that can be used in a variety of base
materials. The four-piece mechanical sleeve anchor comes preassembled
and consists of anchor body, anchor sleeve nut and washer. The anchor
body fits inside the anchor sleeve with the nut and washer attached at
the threaded end of the anchor body. Opposite of the threaded end of
the anchor body, it is necked outward in a cone shape. Once the
mechanical sleeve anchor is inserted into the hole in the base material,
the nut is turned clockwise. This pulls the anchor body up. The cone
shaped end then expands the anchor sleeve against the wall of the hole
in the base materials. The sleeve anchor is a very versatile anchor and
can be used in most base materials such as concrete, brick or block.
Machine Screw Anchors
Machine screw anchors
are female type masonry anchors that require a setting tool to be used
to mechanically expand the anchor in the base material. The machine
screw anchor is a two-piece anchor made up of an outer anchor sleeve and
the internally threaded cone shaped anchor body. It comes preassembled.
The machine screw anchor is inserted into the predrilled hole in the
base material, internal threaded cone first. The setting tool is then
place inside the anchor body. Striking the setting tool with a hammer
pushes the anchor sleeve down, expanding as it is pushed outward and
following the contours of the cone shaped anchor body. Machine screw
anchors work well in most base materials and can be used in concrete,
brick or block.
Hammer Drive Anchors
Hammer drive anchors
are a two-piece mechanical anchor made up of an anchor body and an
expansion nail that comes preassembled. Half the anchor body holds the
nail before expansion. The expansion half of the anchor body is split
along its length. The hole down the length of the inside of the anchor
body is slightly smaller in diameter at the working end of the anchor. A
hammer is used to strike the nail, pushing it down into the anchor body
and expanding the working end of the anchor body against the walls of
the hole in the base material. The hammer drive anchor is set once the
head of the nail is level with the head of the anchor body.
Single Expansion Anchors
The single expansion anchor
is female type anchor that can be used in concrete, brick or block base
material. It is made up of three pieces: one cone shaped internally
threaded nut and two halves of the anchor body, which are all
preassembled into a single unit. Place the single expansion screw into a
predrilled hole, cone shaped internally threaded part first, and then
insert a national coarse threaded screw or bolt. Turning clockwise will
pull the cone shaped nut up the anchor body, expanding them outward.
The single expansion mechanical anchor can be use in concrete, brick or
block.
Double Expansion Anchors
The double expansion anchor
is a female anchor that can be used in a variety of base materials such
as concrete, brick or block. It is made up of five parts: two halves of
an anchor body, two expander cones and one wire. The double expansion
anchor comes preassembled and is inserted into the base material with
the threaded expander cone first. Once set in the base material, a
machine threaded bolt or screw is inserted into the body of the double
expansion anchor. Turning the bolt clockwise pulls the threaded
expander cone up the bolt. This also allows the non-threaded expander
cone to move down the threads, expanding the anchor body along its
entire length. This double expansion cone system makes the double
expansion anchor a desirable anchor to use in base material of
questionable strength.
As with any anchoring project, it is important to keep safety in mind and follow instructions carefully. Always remember to wear safety goggles, handle all tools with extra care and follow all technical specifications. This article is meant to serve only as a basic explanation of concrete fasteners. Always refer to manufacturer's instructions or consult a contracting expert during any anchoring project.
Article Written By:
Bob Carlisle, President of Concrete Fasteners
Concrete Fasteners, Inc. has over 40 years of experience selling concrete fasteners. We can ship out one box or a whole pallet of concrete anchors. Our products are of the highest quality... "your satisfaction is guaranteed". We ship all orders the same day the order is received.