Notching is a metal-cutting process used on sheetmetal or thin barstock, sometimes on angle sections or tube. A shearing or punching process is used in a press, so as to cut vertically down and perpendicular to the surface, working from the edge of a workpiece. Sometimes the goal is merely the notch itself, but usually this is a precursor to some other process: such as Bending a corner in sheet or joining two tubes at a tee joint, notching one to fit closely to the other.
The speed of notching is usually limited by manual handling when loading the workpieces into the press. Pieces some feet long may be manually loaded into a single-stroke press. Smaller pieces are still generally hand-fed, limiting speeds to perhaps 100 strokes / minute.