Decisive element is metal molding technology.
Previously, I said "Elements that ultimately determine the specifications of a perforated metal are plate (material) and holes." This is a viewpoint only in terms of material. In terms of processing method, a punch, a die (dedicated press mold) and press machine equipped with the punch and die are important elements.
Punching (perforation), which is the basic work for manufacturing perforated metal, requires short time and is capable of mass production compared with mechanical working such as cutting work for scraping a material and grinding work for polishing a material. Punching is simple work and can make regularly-arranged holes at low cost according to customer order. Simple holes such as round or square holes are possible but using special metal molds makes it possible to punch variously-shaped holes. In terms of processing, metal mold technique determines the quality of perforated metals.
Punching (perforation) work is a kind of shearing work
A press machine is used to process a material by applying a force to metal mold. Press work, in which a press machine is used, is roughly classified into "shearing," "bending," "squeezing," "forming" and "compression." Punching work corresponds to shearing among these. Shearing is a general term for processing method for destroying a material by a tool shaped according to purpose and then cutting and separating the material to intended shape and size. Punching work is essentially a kind of destructive processing, and therefore unlike machine processing, tool shape is not accurately reproduced. Thus, in order to manufacture highly precise products, metal mode design and processing method need to be carefully set.
More specifically, in punching work, a material put between punch and die is subject to a tensile force to separate (rupture) it. Technically speaking, the shape and size of punched product depend on the die, and opposite-side hole diameter depends on the punch. Compressive stress and tensile stress applied to a material when it is punched affect the product's sagging, shear and curve. These stresses also affect hole quality, which determines the quality of perforated metal. Therefore, balance between metal mold and press machine is important.
Press work superior in both quality and quantity
There are two mechanical methods of punching a hole, namely press work, which uses metal molds (punch and die), and cutting work, which uses a tool. Press work is characterized by high speed, uniform hole diameter and pitch and high-quality finish. Moreover, press work is relatively simple work, so it is suitable to mass production. On the other hand, it requires metal mold for each process, so it takes time in case of design modification.
On the other hand, cutting work is highly versatile and suitable to small-lot production. However, it has demerits in that its processing speed is slow and hole diameter and alignment tend to be unstable. Judging from these, press work is obviously superior for perforated metal production in terms of both quality and production volume. This has been proven by the historical fact that initial perforated metals were manufactured by press work.