Perforated Metals Handbook

Perforated Metal, Expanded Metal or Wire Cloth

When choosing between Perforated Metal, Expanded Metal or Wire Cloth, there is more than price to consider…

There are many applications where the product designer or architect needs to provide a component that has a perforated or otherwise open area to allow the passage of air or liquids or sound…or perhaps even solids as is the case in some food processing machinery. The choice of material for these situations usually comes down to one of three, perforated metal, expanded metal or wire cloth.

A basic criterion for selection is price, of course, but, there are other more important criteria to consider.

The intended function of the material is most important. There are some functions that only perforated metal can do.

Exhibit 1 compares the functional capabilities of the three materials. Some of the functional capabilities are what you would expect to find in such a list. Ventilation, filtering, sorting and the support for sound-absorbing material used in walls and ceilings to reduce noise are all familiar applications of these materials. You may be surprised at some of the less obvious capabilities of perforated metal, its capabilities in sound managing systems go beyond being “transparent” to sound to allow it to pass through to absorbing materials. Perforated materials also can play an active role in systems that eliminate specific sound frequencies such as those placed in jet engine nacelles and in enclosures that surround large air conditioning or compressor units. Perforated metal is also widely used to contain various kinds of radiation and still provide ventilation or visibility; your microwave oven is a good example.

Some of the functions listed in the chart can only be performed, and others might be better performed, by perforated metal. Important among its virtues is its great variability. Many hole shapes, sizes and patterns are available to offer designers and architects more choices and superior solutions to their design problems. But, there are many situations in which all three materials will perform equally as well. Is it then simply a matter of price?

wiretab (4K)

exh2 (22K)Material costs do not tell the whole story

There are fabricating considerations that can be more important to the ultimate costs of the choice. Consider Exhibit 2, for example. This stainless steel part was finished in two operations. Three panels of perforations were made with a single pass through the perforator’s press and then the part was formed in a press brake. The part is all in one piece.

Using expanded metal or wire cloth to provide the “open area” would require at least five operations, a punch press operation to open the “windows,” a bending operation to form the structure and finally three welding operations to fasten the open material to the structure. Instead of one piece, there are four work pieces involved. And certainly the welding operations will not provide the finished result you see in the perforated piece. The costs of these fabricating operations, both in dollars and in product quality, must be considered to make a valid comparison of the material