A Lathe Machine (Source:MIT-NMIS)
The machines commonly used to perform material removal operations are known as machine tools. The principle of a machine tool is to generate required surface by providing requisite motion between the cutting tool and the workpiece. The most commonly used machine tool applications are turning, milling, shaping, drilling, grinding etc. Thus, the basic purpose and principle of machine tools are:
To provide the relative motion between the cutting tool and the workpiece.
To provide the stiffness required for the cutting operation.
To control the vibrations caused during cutting.
As a source of power for the cutting operation.
To facilitate accuracy and surface finish.
Etc.
In Conventional Machine Tools:
The basic structure of a machine tool consists of base and tower arrangement. Here, depending on the machining process, the tool is fixed on the tower and the workpiece is held on the base or vice-versa.
The relative motion is achieved by movements parallel to the three spatial axes. This is achieved by means of linear guideways and bearings, axial movements along the screws, rack and pinion arrangements etc.
The machine is built of heavy steel and iron parts. The base of the machine usually is of cast iron. The structure is fixed over a concrete base. This arrangement is instrumental in stiffness and vibration control. The tool holding devices, joints and links also control vibration.
The power is generally transmitted by systems comprising of gears, axles, screws etc.
The accuracy and surface finish are dependent on the the accuracy of relative motion, stiffness and vibration control.
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