Before sheet metal can be formed into any part or product, it must itself be formed. To reach its rectangular sheet form, raw metal is heated until malleable and laid out as long, molten slabs. After this, the slabs of metal are fed through a set of large, powerful rollers, which compress them into large, broad planes, or sheets. Two of the most common metal materials used to create sheet metal are stainless steel and aluminum. Stainless steel is valued as sheet metal because it provides strength, durability, corrosion resistance, and easy cleaning. These qualities prove valuable in harsh environments and to the manufacturing, food processing, and storage industries.
Aluminum is popular because it offers compressive strength, tensile strength, and lightness. Aluminum sheet metal products have applications in aerospace, automotive manufacturing and other transportation industries, and the packaging, construction, food and beverage, music, household, and electronics industries, among others. Other metals used to create sheet metal include brass, copper, nickel, titanium and, for specialty applications, gold, silver, and platinum.
After the sheet metal has been created, it is sent on to another manufacturing plant, where it undergoes design and fabrication. Sheet metal design is the process of identifying any and all potential stress points, weak areas, and other potential problems a finished product may face, and formulating and carrying out a comprehensive plan of action to ensure that the product does not fall victim to any of these potential issues.
Sheet metal fabrication may be performed manually or with the guidance of a computer operated (CNC) machine. When deciding what processes to undertake to fabricate a metal part or parts, manufacturers factor into their design plan specifications like required strength, part size, part quantity, and additional material requirements.
As noted earlier, some of the basic sheet metal fabrication processes include bending, drawing, flanging, stretching, punching, shearing, and spinning. Bending is typically carried out on a standard die set, where the most common bends produced include C-shapes, V-shapes and channel shapes. During bending, metal is bent or deformed along a straight line. Drawing, as well as deep drawing, are stamping processes that transform flat sheet metal into any number of three-dimensional forms. In flanging, another stamping process, material is bent along a curved line.
Stretching is yet another stamping process. Stretching involves clamping flat sheet metal around its edges and then stretching it to create products like smooth auto body parts. Punching perforates sheet metal when, after the metal has been placed between a punch and a die mounted in a press, the press pushes the punch into the die with enough force to create a hole. In addition, sometimes, the punch and die “nest” together to create a depression instead of a hole in the metal.
Punching should not be confused with perforating, which is a process that produces multiple small holes on a flat surface. Shearing is a cutting method that uses large shears to slice into sheet metal. Next, spinning uses rigid tools or rollers to hold a heated sheet in place against a rotating form, or mandrel, where it stretches it until it forms a tubular part.
Most often, this process is used to fabricate satellite dishes, metal kitchen funnels, rocket motor casings, and missile nose cones. Some other sheet metal fabrication processes include wheeling, water jet cutting, rolling, roll forming, press brake forming, photochemical machining, laser cutting, ironing, incremental sheet forming, hemming and sealing, hydroforming, expanding, curling, and decambering.
As technology has advanced, sheet metal fabrication has become more precise and more efficient. Sheet metal products may be produced on automated lines with robotic machinery that turn and move them as necessary. CNC machinery has also revolutionized metalworking by allowing for more accuracy and uniformity. With sheet metal fabrication, the possibilities really are endless.