Cutting Tool

 A cutting tool is a relatively hard material than the work material formed with a cutting edge at its end. The basic requirements of a cutting tool are:

Hardness

The material of the tool must be harder than the material to be cut. For high speed cutting operations like in machining, the tool must be able to withstand its hardness at elevated cutting temperatures.

Toughness

The tool must be tough enough to withstand shocks and vibrations.

Wear resistance

The tool must be wear resistant to retain the sharpness of the cutting edge for more tool life.

Tool geometry

The cutting edge of the tool must be formed in such a way that it must be able to penetrate into the work with ease and at the same time strong enough to withstand the forces. Usually experimentally proved optimum standard values are being chosen for various angles to form the cutting edges.

The figure illustrates the relation between the strength and sharpness of the two different cutting edge geometry.

In case 1, A tool with keen cutting edge can easily penetrate into the work but not strong enough to withstand the heavy cutting forces. So it is only suited for cutting soft materials.

In case 2, A tool with wide cutting edge is strong enough to withstand heavy cutting forces but difficult to penetrate into the work easily. These type of cutting edges are suited for hard materials.