Mechanics of Metal Cutting

Unit - 1

MECHANICS OF METAL CUTTING

Mechanics of chip formation, forces in machining, Types of chip, cutting tools - – single point cutting tool nomenclature, orthogonal and oblique metal cutting, thermal aspects, cutting tool materials, tool wear, tool life, surface finish, cutting fluids and Machinability.

INTRODUCTION TO METAL CUTTING

In any engineering industry, components are made into various shapes and sizes by using metals. These shapes and sizes are formed either by using non-cutting or chipless operations such as forging, blanking, rolling, pressing, etc. or by using metal cutting or chip forming operations such as turning, milling, drilling, shaping etc. In metal cutting operations, the required shape is obtained by a suitable metal removing process. During machining, the excess material is gradually removed from the parent metal by using the suitable tools in the form of chips. Depending on the type of operations, suitable tools are used to cut the metal.

In recent years, increasing the importance of machining operations is gaining new dimensions in the present industrial scenario. The increasing competition demands all the efforts to be directed towards the economical manufacture of machined components: The following are the basic objectives of the economical and efficient machining practice:

1. Quick metal removal

2. High-class surface finish

3. Economy in tool cost

4. Less power consumption

5. Economy in the cost of replacement and sharpening of tools

6. The minimum idle time of machine tools.

During the metal removal process, the various forces act on the cutting tool and workpiece. In addition to these forces, the heat is generated due to friction between tool and workpiece. This heat generation affects the hardness of both work and tool. Finally, the grain structure of both tool and work is slightly refined. If it continues, the tool will damage. To avoid this, a complete study of the theory of metal cutting is required with its geometry, materials used and cutting fluids.