Choosing the Right Metal for Your Design:
A look at the differences between perforated metal, expanded metal and wire cloth
From function to
aesthetics, perforated metal, expanded metal and wire cloth have
many overlapping architectural applications. In recent years,
suppliers have been working with architects to incorporate these
materials into many new applications.
As the applications diversify, it's more important than ever for
architects to distinguish the strengths and weaknesses of each
material to achieve optimum performance and value.
This article will broadly compare the three materials against
specific applications, providing tips on material selection.
Defining Your Options
Perforated metal is a sheet of metal (or plastic) with a series of
holes punched into it. It comes in a virtually endless variety of
sizes, gauges, hole shapes and material types. Hole diameters range
from a few thousandths of an inch to more than 3 inches, punched in
material as thin as foil or as thick as 1-inch steel plate.
Expanded metal is made from a sheet of metal that has been slit
and stretched to form diamond-shaped openings in the sheet. The
diamond-shaped trusses form a sharp angle to the original plane of
the sheet adding strength and rigidity. Expanded metal is available
in standard, raised, flattened and decorative diamond patterns, and
comes in a range of gauges, opening sizes, materials and sheet
sizes. Wire cloth, also known as wire mesh, is metal wire that is
woven or welded to form a cloth.
Metal wire is made from various alloys including stainless steel,
brass and copper. Wire cloth can be woven or welded to create a
variety of opening sizes and wire diameters.
Price and Other Selection Issues
Because of raw materials costs, perforated metal typically carries
the highest up-front price of the three options. However, many
other attributes contribute to the overall value of a material in
any given application, including:
- Resistance to environmental elements
- Fabrication costs
- Application-specific needs such as acoustical capabilities and
Expanded metal, perforated metal and wire cloth all offer a unique
look that will enhance any design. Out of the three materials,
however, perforated metal offers the greatest visual variety.
Endless options in hole shapes, sizes, materials and geometric
patterns are available to achieve a specific look. Perforated metal
also is more easily painted than either expanded metal or wire
Wire cloth presents several options depending on the weave of the
metal wire, while expanded metal is the most limited in design due
to the stretching of the raw material. Both materials can only be
cut to shape and framed.
All three of the materials can be used as a pass-through to
support sound absorption in ceilings and walls. They can function
as protective or decorative coverings for special acoustical
Perforated metal, however, is the only material to offer more
extensive sound-managing capabilities. It can play an active role
in eliminating specific frequencies in sound-filtering systems,
such as enclosures surrounding large air-conditioning or compressor
In addition to sound filtering, all three materials can be used in
other ventilation and filtration applications, as well. The
openings in each permit passage of light, air, heat and gases.
In harsh environments, the estimated energy loss or pressure loss
is often an important design consideration. If pressure control is
important in your application, perforated metal provides the
greatest ability to control or equalize pressure due to its high
The structural strength of perforated metal is one of its key
attributes. It can be used as a stand-alone component in several
architectural designs such as sun screens and panels. The "open
area" is the sheet of perforated metal, which has its own strength
and physical properties.
With expanded metal or wire cloth, however, the "open area" can't
stand alone. Wire cloth and expanded metal are lightweight, less
rigid materials that need additional fabrication processes. They
must be fastened and secured to a structure.
In many cases, additional fabrication can significantly increase
the total cost of expanded metal and wire cloth, despite their
lower up-front price.
Wire cloth and expanded metal both require additional operations,
including a punch press to open the material, bending to form the
structure and three welding operations to fasten the open material
to the structure.
Perforated metal typically requires less fabrication.
Stainless-steel perforated parts often are finished in two
operations: punching in a single pass and forming with a press
The Right Material for Your Design
If any of the qualities discussed here is important in your
circumstances, perforated metal's ability to outperform the other
options may offset the higher initial price tag.
So, should you use perforated metal, expanded metal or wire cloth
in your design? It's important to discuss the particulars of your
application with engineers who have expert knowledge of the
properties of each material option. Doing so will help you choose
your best option, and ensure the material is specified for optimum
performance in your application.
Bob Farber is the president of the
Milwaukee-based Industrial Perforators Association. Discover more
about the IPA and perforated materials at www.iperf.org.