Computer numerical control (CNC) is the automation of machine tools by means of computers executing per-programmed sequences of machine control commands. This is in contrast to machines that are manually controlled by hand wheels or levers, or mechanically automated by cams alone.

1. Welcome To Our Presentation
PRESENTED BY
1. HAMID, MD. AKTER ID:15-28491-1
2. TOHA,ABU SALEH MD. ID: 15-28909-1
3. SAHA,APU ID:15-28640-1
4. SAHA,NITUN ID: 15-28485-1
5. ROUF,SADIA ID:15-28540-1
GROUP NO : 04
SEC: C
COURSE NAME: POWER STATIONS
COURSE INSTRUCTOR : RETHWAN FAIZ

2. Computer Numeric
Control
(CNC)

3. CONTENTS
HISTORY
CNC INTRODUCTION
Why Use CNC ?
HOW CNC WORKS?
ELEMENTS OF CNC
FEATURES OF CNC MACHINE
MOTION CONTROL OF CNC
MACHINE
BLOCK DIAGRAM OF CNC
MACHINE
CONFIGURATION OF THE CNC
SYSTEM
 HARDWARE
 SOFTWARE
 SERIAL COMMUNICATION IN A
DISTRIBUTED NUMERIC
CONTROL SYSTEM
 CNC MACHINES ADVANTAGE
AND DISADVANTAGE
CONCLUSION

4. History
• The first NC machines were built in the
1940s and 1950s by Prof. John T Parson.
• CNC machine came into existence after
evolution of computer around 1980.
• Modern CNC Machine are improving
further as the technology is changing with
a variety of functions according to
applications.

5. CNC
INTRODUCTION
 Numerical control is
a method of
automatically
operating a
manufacturing
machine based on
code, numbers, and
special characters.
 The program is
translated into the
appropriate

6. Why Use CNC Machines?
• Increase production
• Improve the quality and accuracy of manufactured
parts
• Stabilize manufacturing costs
• Unmanned Operation

7. How CNC Works?
• Controlled by G and M codes C# Programmed
• Number of values and co-ordinates.
• Each number or code is assigned to a particular operation.
• Typed in manually to CAD by machine operators.
• G&M codes are automatically generated by the computer
software.
Basic Block Diagram Of a CNC

8. ELEMENTS OF CNC MACHINE
• A CNC machine consist of following 6 major elements:
i. Input Device
ii. Machine Control Unit
iii. Machine Tool
iv. Driving System
v. Feedback Devices
vi. Display Unit

9. FEATURES OF CNC MACHINERY
• The tool moves automatically.
• Tools can operate in 1-5 axes.
• Machine control unit (MCU)
• Movement controlled
• Feedback
• Multiple Tool Can change automatically
.

10. Open loop systems & closed loop systems
.
In closed loop systems the position sensors are used to correct slide
movements and achieve higher accuracy and repeatability
In open loop systems the slide may overshoot or may not reach
desired position because of inertia, wear , tear and friction, hence
inaccurate machining
Motion Control of CNC:

11. Block diagram of CNC Machine

12. CONFIGURATION OF THE CNC SYSTEM

13. Hardware
• Metallic body
• Pic 18 controller.
• Stepper motors and electrical movable arm
• Driver circuit for steppers
• Serial communication interface.
• Encoder
• Safety
We used a limit switches in our body to ensure that
the machine will stop directly in case the motor try
to rotate a distance more that the length of the
axis.

14. Software
C# application with simple and easy to use
interface.
Main idea in C# application is to read a text
file which contain the G-Code and parse the
values of pixel of the image to the PIC, then
the microcontroller get the values and move
the motors according to the signed values
received.

15. Serial communication in a Distributed
Numerical Control system

16. CNC Machines- Advantages &
Disadvantages
• Advantages:
• Volume of production is very high
• Automatic tool settings
• Flexibility in job change, less scrap
• More safe, higher productivity, better quality
• Less paper work, faster prototype production, reduction in
lead times
• High Repeatability and Precision
• Disadvantages:
• Costly setup, skilled operators
•Computers, programming knowledge required
•Maintenance is difficult

17. Conclusion
.
• Large Factory use CNC machines to achieve their
manufacturing targets. For manufacturing works
of large scale it is very difficult to work with
manual machines as they are time consuming.
CNC machines have their wide scope because
they are easy to handle, the work becomes
easier and jobs are done with perfection.

18. References:
[1]
http://www.brighthubengineering.com/manufacturing-
technology/55787-what-is-the-cnc-machine-how-cnc-
machine-works/
[2] https://www.okuma.com/cnc-machine-tool-lineup
[3] http://hongyumold.en.made-in-china.com/
[4] https://wiki.mcneel.com/rhino/cncbasics
[5] https://www.mmsonline.com/articles/key-cnc-
concept-9the-key-sequences-of-operation

19. Any QUESTION?