Machine tools are generally power-driven metal cutting or forming machines used to shape metals by:
The removal of chips known as metal cutting
By the Pressing, drawing, or shearing of metals known as metal forming
By the controlled electrical machining process.
Generally, machine tools has the capacity of; holding and supporting the workpiece, holding and supporting the cutting tool, imparting a suitable movement (rotating or reciprocating) to the cutting tool or the work, and feeding the cutting tool or the work so that the desired cutting action and accuracy will be achieved, etc.
Therefore, machine tools can be said to be power-driven machines not portable by hand, used to shape or form metals or materials by cutting, impacting, forming, deplating, or a combination of these processes. Equipment and small tools supplement the work of the machine tool by means of the transfer mechanism, fixtures and jigs usually employed in moving or positioning the workpiece for operation by the machine tool. Small tools include contact tools such as forming, forging and drawing die and consumate tools such as drills, taps, reamers, lathe tools, and other tools for materials forming and removal.
The major categories of machine tools are:
CHIP PRODUCING MACHINES; this category form metals to sizes and shape by cutting away the unwanted sections. They alter the shape of steel products by milling, casting, forging or rolling in a steel mill. A good example of chip production in this category of machines is the operation of center lathe during threading operation in a solid steel shaft.
NON-CHIP PRODUCING MACHINES;
Just as the name sounds, this category of machine tools does not produce chips, rather they form metals to size and shape by the action of tensile or compressive force. The operation can be achieved by either pressing, drawing, forging, or shearing of the metal to obtain the required shape. These type of machine tolls can alter the shape of steel sheet products and also produce parts which need little or no machining by compressing granular or powdered metallic materials. A good example of such machine tool is the metal pressing machines used in the making stainless steel plates and water basins since they only press the steel sheets into shape.
NEW GENERATION MACHINES: this category goes beyond the action of the two categories mentioned previously, the category was developed to perform operations which would be very difficult or impossible to perform by the previous two categories. A good example is the Electro-discharge and Electro-chemical machines, for example, use either electrical or chemical energy to form metal to size and shape.
From the above mentioned details of machine tools, it is impossible to operate a metal processing industry without having any of the category of machine in your procession.