A perforated metal is a punched wire mesh.
Perforated metals are used in various scenes ranging from familiar daily necessities to industrial field. As its name indicates, a wire mesh is a product made by interknitting metal wire rods in a net-like fashion. A wire mesh may conjure up the image of gridiron for baking rice cake or a fence installed at site boundary. Wire mesh can be manufactured not only by manual weaving but also by the mechanical perforation (punching) of material, which has become widespread since about 50 years ago as a manufacturing method and as mechanization progressed. In other words, a punched (perforated) metal is manufactured not by weaving but by perforating a material such as metal by press work.
In olden days, most of manufacturers that handled perforated metals also produced daily necessities such as bamboo basket, filter and window screen. During the high economic growth period since 1955, demand for perforated metals by construction and manufacture industries increased. Perforated metals played a significant role particularly for the development of heavy chemical industry and became indispensable as industrial filters for plants and ship building. Currently, perforated metals are used in infrastructure-promoting sites such as water treatment plant, petrochemical plant, mine and steel plant as well as wide-ranging industries such as medicinal chemical manufacture, food factory and recycling plant.
They are mainly used as screens and filters for sorting out liquids (water and oil), solids (powders) and gases (and air). Therefore, a perforated metal plays an important process through which substances having a necessary size are sorted out. In addition to filtering function required of perforated metal as wire mesh, perforated metals are increasingly used in scenes where high quality design is required.
Metal perforation produces holes, not cavities.
As indicated by the above-mentioned description "substances having a necessary size are sorted out," a perforated metal has holes, not cavities. Holes and cavities differ in that the former penetrate the metal whereas the latter do not. Therefore, those penetrating 5-yen and 50-yen coins are holes, and a space in a limestone cave is a cavity. Because one of the major roles of a perforated metal is to sort out a liquid, solid and gas, it must have holes, not cavities.
Those that penetrate needle, sliding screen paper and socks are also holes. Those that are dug through mines to obtain minerals are called pits. An example is a coal pit made to obtain coal. This may sound like a language dictionary, but I have dared to talk about it to emphasize the importance of the holes of perforated metals, which were originally developed from wire meshes.
Does the term "punching metal" make sense in English-speaking countries?
I have talked about perforated metal's holes, which determine the function of a perforated metal. Now I talk about the term "punching metal," which is commonly used in Japan. Although it sounds like English, it is not, and in fact it is a Japanese English. Therefore, the term does not make sense to people in English-speaking countries. For example, the term "note personal computer," which is commonly used in Japan, never makes sense in English-speaking countries, and "laptop computer" is correct.
Similarly, the term "punching metal," which sounds like purely English, makes sense only in Japan. In English-speaking countries, "perforated metal" is used instead. It also means value-added metal. The expression "value-added" suggests that perforated metals ranging from daily necessities to industrial ones deeply relate to our daily lives.
For reference, a perforated metal is described as "穿孔金属板" in China. This sounds like the direct translation of the equivalent Japanese term "パンチングメタル (perforated metal)." The term "穿孔," which means punching (perforation), conjures up the vivid image of perforated metal.