CNC machines operate based on coded instructions to control machine tools. A CNC system includes a part program, program input device, machine control unit, drive system, machine tool, and feedback system. CNC machines can move tools in either a point-to-point or continuous path manner and use either open or closed loop control systems. Common types of CNC machines include vertical turning lathes, roll turning and center lathes, and deep hole boring machines. CNC machines are used for various manufacturing applications such as cutting, drilling, milling, welding, boring, and more.

1. BYNIDHI PRAWINA TIGGA
JV-B/10/1702

2. CONTENTS
 What are NC and CNC?
 CNC system elements
 Properties of CNC machines
 Point-to-point tool movements
 Continuous-Path tool movements
 Feedback system for controlling tool movements
 Types of CNC machines
 Application of CNC machines

3. What are
NC & CNC ?
Numerical control (NC) is a method of automatically
operating a manufacturing machine based on a code
letters, numbers and special characters.
The numerical data required to produce a part is
provided to a machine in the form of program, called
part program or CNC (computer numerical control).

4. The program is translated into the appropriate electrical
signals for input to motors that run the machine.
A CNC machine is an numerical control machine with
the added feature of an on board computer. The
computer is referred to as the machine control unit
(MCU).

5. CNC SYSTEM ELEMENTS
A typical CNC system
consists of the following
six elements
 Part program
 Program input device
 Machine control unit
 Drive system
 Machine tool
 Feedback system
Figure 1. Schematic illustration of the major
components of a numerical control
machine tool

6. Properties of CNC machines
 Based on Motion Type: Motion control -the
heart of CNC.
Point-to-Point or Continuous path.
 Based on Control Loops: Open loop or Closed
Loop.
 Based on Power Supply: Electric or Hydraulic
Or Pneumatic.
 Based on Positioning System: Incremental or
Absolute.

7. Point-to-Point Tool Movements
 Point-to-point control
systems cause the tool to
move to a point on the part
and execute an operation at
that point only.
 The tool is not in continuous
contact with the part
while it is moving.
 Examples: drilling, reaming,
punching, boring and
tapping.

8. Continuous-Path Tool Movements
 Continuous-path
controllers cause the tool
to Maintain continuous
contact with the part as the
tool cuts a contour shape.
 These operations include
milling along any lines at
any angle, milling arcs and
lathe turning.

9. Feedback Systems for Controlling
Tool Movement
 OPEN LOOP SYSTEM CONTROL
 CLOSED LOOP SYSTEM CONTROL

10. Open loop system

11. Closed loop system

12. Types of CNC Machines
 Vertical Turning Lathes(6-AXIS AND 2-AXIS)

13. •CNC Roll Turning & Centre Lathes

14. •CNC Deep Hole Boring Machine

15. APPLICATION of CNC
MACHINES
 Cutting
 Drilling
 Milling
 Welding
 Boring
 Bending
 Spinning
 Pinning
 Gluing
 Sewing
 Routing