Sheet metal is currently defined in the Internet, there are many versions, I think the best one is: sheet metal against metal sheet (usually 6mm or less) an integrated cold working process, including the scissors, red / cut / composite, folding, welding , riveting, stitching, molding (such as auto body), etc.. Of its salient features is the same thickness of the same parts.
    Generally speaking, the basic equipment includes Sheet Metal Works Shear (Shear Machine), CNC punching machine (CNC Punching Machine) / laser, plasma, water jet cutting machine (Laser, Plasma, Waterjet Cutting Machine) / Composite Machines (Combination Machine), Bending Machine (Bending Machine) and a variety of auxiliary equipment such as: open-book machine, leveling machine, deburring machines, spot welding and so on.
Typically, the sheet metal factory three most important step is to cut, red / cutting, folding.