CNC Presentation

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 electrical signals for input to motors that run the machine .

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 generat ed 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. • M achine control unit (MCU) • Movement controlled • Feedback • Multiple Tool Can change automatically .

10. O pen 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?