CNC MACHINE TOOLS AND MANUFACTURING SYSTEMS

The basic components of a numerical controlled machine tools are the program of instructions ( called the part program or G-code), the numerical or machine controller, servo drives and eedback devices  for each axis of motion.  The controller commands the servo drives to move the machine axes to drive the tool along the tool path specified in the part program. Both linear and rotary motions can be directed and controlled simultaneously.

Types of CNC Machines
There are two general classes of CNC machine tools.
CNC lathes or turning centers,  perform turning, boring, facing, threading, profiling, and cutoff operations.
CNC machining centers perform  milling, boring, drilling, and tapping.


CNC Lathes


In CNC lathes, multiple tools are held in a turret, which rotates and brings the specific tool to cut. The turret is commonly mounted on a slant bed slide, which sheds chips into the bottom of the machine. All CNC lathes have a headstock with spindle, and most have a tailstock. 

CNC automatics are similar to turning centers but include more axes, have provision for rotating tooling, and multiple slides and spindles.  These machines are multifunctional machines or mill-turn machines.   On CNC automatics, a job can be divided into segments and tools can work on
different areas of a workpiece simultaneously. Cycle times can thus be made shorter compared to CNC lathes.  CNC lathes and automatics are modern equivalents of cam-driven screw and bar machines, which they have largely displaced.

CNC Machining Centers

Machining centers are  classified by spindle orientation as vertical or horizontal and the number of axes controlled. On a vertical spindle machine, the workpiece is mounted on a horizontal bed;
on a horizontal spindle machine, the workpiece is usually mounted on a vertical fixture or table.  Vertical machines are preferred for large workpieces, flat parts, and especially for contoured surfaces in dies so that the thrust force is absorbed directly by the bed of the machine.