1.  Field of the Invention
The present invention relates, in general, to multi-function cutting tools and, more particularly, to a multi-function cutting tool, in which the side surfaces of a cutting insert are perpendicular to the lower surface of the cutting insert, so that the stiffness of the cutting insert can be increased, and the cutting insert can be securely fastened to a cutter body, thus making it possible to stably conduct a cutting operation despite the realization of high feed, high speed and high depth cutting. 
2.  Description of the Related Arts
Generally, cutting tools are used to cut iron, nonferrous metals, and nonmetallic workpieces.  Typically, cutting tools are attached by machines and cut workpieces to form them into desired shapes.  Such a cutting tool includes a cutting insert, which has a cutting edge, and a body, which supports the cutting insert. 
Meanwhile, as methods of cutting a metallic workpiece using the cutting tool, there are two representative methods.  First, there is a cutting method in which a workpiece, which is rotated, is brought into contact with the cutting edge of a cutting tool, which is stationary.  Second, there is a cutting method, in which a tool having a cutting edge, that is, a cutting insert, is fixed to a machine using a tool holder, and, in this state, the cutting insert is rotated and is brought into contact with a workpiece, which is stationary, thus forming the workpiece into a desired shape. 
Milling is a representative example of the second cutting method.  A milling cutter conducts a facing process, a shouldering process, a grooving process, a boring process, etc.  In the shoulder cutting process as the cutting depth increases, the length of the part of each cutting insert that is involved in the cutting is increased, so that the resistance applied to the entire cutting insert is also increased.  Various efforts have been conducted to efficiently disperse the resistance such that the cutting inserts can easily withstand a load, and thus increase the tool life of the cutting tool despite the realization of high feed, high speed and high depth cutting. 
However, in a conventional multi-function cutting tool, a cutting insert has a slanted relief face, so that the strength thereof is relatively low.  Furthermore, when the cutting insert is mounted to a cutter body, because the slanted clearance relief faces are in contact with the cutter body, the stability with which the cutting insert is mounted to the cutter body is reduced, thus reducing the tool life of the cutting tool.