Plain sheet metals such as Stainless Steel, Brass, Bronze and Copper should only be cut with a metal shear. Such a cut will result in a minimal burr on the underside (the unfinished side) of the sheet, while “drawing” the cut on the finished side into very slight rounded edge: the “down-cut” edge. Thin gauge aluminum and metal laminates are generally cut by metal saws and hand tools. Deburring is done with routers and files.
A dull shear will cause significant burrs and pulling on the metal edge. It may also cause chipping and peeling of decorative finishes at the the sheet edge.