Patent ID: 8621907

Claim:
A method for making a metallic casing, the method comprising: providing an apparatus comprising a first mold and a second mold, the first mold being opposite and movable relative to the second mold, the first mold defining a rectangular depression opposite to the second mold, the rectangular depression comprising a plurality of side surfaces connected to each other, each side surface having a sharp edge, the second mold comprising a plurality of cutting edges corresponding to the sharp edges, and one of the cutting edges having a secondary-cutting edge; placing a preform into the rectangular depression of the first mold, the preform comprising a base and a plurality of sidewalls extending from a periphery of the base, the plurality of sidewalls connected to each other, an end of each sidewall bending outward and forming an excess, the plurality of the excesses connected to each other, each connecting portion between a corresponding sidewall and a corresponding excess being located at a corresponding sharp edge; moving the first mold to the second mold so that each sharp edge is substantially coplanar with a corresponding cutting edge; moving the first mold to the second mold so that the cutting edges are beyond the corresponding sharp edges of the first mold to complete a partial cut procedure in a predetermined sequence, wherein in the partial cut procedure, the first cutting edge having the secondary-cutting edge partially cuts the corresponding connecting portion between the sidewall and the corresponding excess; moving the first mold to the second mold so that the secondary-cutting edge moves beyond the corresponding sharp edge, and completely cuts the excess off the side wall.