In this presentation fully study about NC and CNC covered by M.M.RAFIK.

1. C.U. Shah College of
Engineering & Technology , Wadhwan
city.
Importance of NC
& CNC systems as
a part of CAM.Prepared by:
MEMAN MAHAMMADRAFIK J.
Enrolment No.: 120440119032
Roll No.: 39
Guided by:
Asstt. Prof. Y.A.
DARJI.
Mech.Engg.Dept.
C.C.E.T. Year:
2015-16

2.  Introduction.
 About NC Machine Tool.
 Elements of NC machine tool system.
 Classification of NC machine tool systems.
 Advantages & Disadvantages of NC machine
tools.
 About CNC Machine Tool.
 Elements of CNC machine tool system.
 Classification of CNC machine tool systems.
 Advantages & Disadvantages of CNC machine
tools.
 NC v/s CNC.

3.  The NC,
CNC and DNC
are machine
tools systems
which reduce the
non-productive
time in
machining
operation by
reducing time
elements like
workpiece

4.  NC-Numerical Control machine tools
are the machine tools which controls
the various operations during
machining by some specified letters
,numbers and symbols.
 The NC machine tool runs on the given
program to it without human operator.
 The NC program consists a set of
instructions for controlling the motion
of the drives in machine tool as well as
the motion of cutting tool.

5.  In NC machine tools , following
operations may be automatic:
I. Automatic starting and stopping of
the spindle;
II. Controlling the spindle speed;
III. Automatic positioning the cutting
tool by controlling the motion of
slides;
IV. Controlling the feed rate; and
V. Changing the cutting tools.

7. Punched Paper Tape Punched Plastic Tape
Magnetic Cassettes , Floppy discs, CD’s Keyboard

9. According to control loop feedback
systems:
Open-Loop type NC Machine
Close-Loop Type NC Machine

10. Point to Point
NC machine.
Straight cut
NC
machine.
Continuous path
control
NC machine.

11. Absolute
programming
NC Machine systems.
Incremental
programming
NC Machine
Systems.

12. NC Controller System.
CNC Controller System.

13. 1. Reduced lead time for production.
2. Increased Productivity.
3. Reduction of human error.
4. High degree of accuracy.
5. Less inspection required.
6. Greater machine tool safety.
7. Greater operator safety.

14. 1. High initial cost.
2. High maintenance cost.
3. High operational cost.
4. Limited life of tapes.
5. Time consuming punched tape
operation.

15.  In CNC-Computer Numerical Control
machine in which computer is used to
perform the most of basic NC machine
functions.
 In CNC machines the entire program is
entered and stored in computer
memory.
 The machining of each workpiece
controlled by the program which is
contained in computer.

17. 1. According to control loop feedback
systems:
a. Open-loop type CNC machines.
b. Close-loop type CNC machines.
2. According to type of tool motions:
a. Point to point CNC machines.
b. Straight cut CNC machines.
c. Continuous Path control CNC
machines.
3. According to Programming methods:
a. Absolute programming CNC machines.

18. Hybrid Controller
CNC system.
Straight Controller
CNC System.

19. 1. Easy to program input.
2. Multiple program storage.
3. Online part programming and editing
possible.
4. Greater flexibility of system.
5.Change in system of units possible.
6.Use of Advanced interpolation.
7. Automatic tool dimension adjustment.

20. 1. Higher investment cost.
2.Higher maintenance cost.
3. Required skilled operators.
4. For continuous production , proper
planning is needed.

21. 1. In NC , Computer
is not needed.
2.Part Program is
entered on the
Program tape.
3.Here each part
program requires
separate program
tape.
4.Modifying the
program is
1. In CNC,
Computer is
needed.
2. Part program is
entered and
stored in the
computer.
3. Here only one
computer is one
for different part
program.
4. Modification of

22.  AC machining is developed by Bendix
Research Laboratories, USA for US Air
Force.
 AC is a control system which measures
output process variables and uses
these to control the speed and feed of
the spindle.
 Some of the process variables used in
AC are: spindle deflection, force,
torque, cutting temperature, vibration
amplitude and power requirement.
 AC is mainly used to reduced the

23. Any
Questions…..???