workshop on computer numeric control machine programming.pptx
- 1. 30/07/2025 Dept. of MECHANICAL JNTUACEP 1 Workshop on Computer Numeric Control Machine Programming K.Pavan Kumar Reddy M. Tech (Ph. D) Asst Prof. (Adhoc) Department of Mechanical Engineering JNTUA College of Engineering (Autonomous) Pulivendula Kadapa (D), Andhra Pradesh
- 2. 30/07/2025 Dept. of MECHANICAL JNTUACEP Introduction to CNC 2 Numerical control (NC) is the automation of machine tools that are operated by precisely programmed commands encoded on a storage medium, as opposed to controlled manually. Most NC today is computer numerical control (CNC), in which computers play an integral part of the control. In modern CNC systems, end-to-end component design is highly automated using computer-aided design (CAD) and computer-aided manufacturing (CAM) programs.
- 3. 30/07/2025 Dept. of MECHANICAL JNTUACEP Operations in CNC 3 CNC Milling CNC Plasma Cutter CNC Electric Discharge Machining
- 4. 30/07/2025 Dept. of MECHANICAL JNTUACEP 4
- 5. 30/07/2025 Dept. of MECHANICAL JNTUACEP Advantages of CNC 5 CNC machines can be used continuously Batch production with high accuracy can be updated by improving the software Training in the use of CNCs is available through the use of ‘virtual software’. Intricate detail machining no need to make a prototype or a model One person can supervise many CNC machines simultaneously saves time
- 6. 30/07/2025 Dept. of MECHANICAL JNTUACEP Disadvantages 6 more expensive than manually operated machines The CNC machine operator only needs basic training and skills, enough to supervise several machines. In years gone by, engineers needed years of training to operate centre lathes, milling machines and other manually operated machines.This means many of the old skills are been lost. Investment in CNC machines can lead to unemployment
- 7. 30/07/2025 Dept. of MECHANICAL JNTUACEP Axes of CNC Machine Tool 7
- 8. 30/07/2025 Dept. of MECHANICAL JNTUACEP From 3-axis to 5-axis machining 8 • not sufficient for the complete finishing process for very deep part and having narrow cavities • results in a bad surface quality and long machining times in Case of harder material • dozens of views need to be defined • more tool movements • programming is quite difficult • sum of all views does not cover the whole geometry • overlapping views lead to surface quality problems • More number of lead-in and out movements
- 9. 30/07/2025 Dept. of MECHANICAL JNTUACEP Five Axis CNC 9
- 10. 30/07/2025 Dept. of MECHANICAL JNTUACEP ADVANTAGES OF 5 AXIS CNC 10 to machine complex shapes in a single setup reduces the machinist setup time and increases production rates By eliminating multiple set-ups, time and errors are reduced the feature-to-features accuracy is improved because the same zero or datum reference frame is used throughout the manufacturing process since simultaneous movement is allowed along the X andY axis, shorter and more rigid tools may be used higher spindle/cutting tool speeds may be achieved while reducing the load on the cutting tool Shorter and thicker cutters also reduce vibration when machining deep pockets or contoured features with three-axis machines.
- 11. 30/07/2025 Dept. of MECHANICAL JNTUACEP Application 11 complex three dimensional profiles for impellers, turbine blades, and plastic mold tools
- 12. 30/07/2025 Dept. of MECHANICAL JNTUACEP CONTENTS 1. History 2. CNC Introduction 3. how they look like? 4. Elements of CNC 5. Block diagram of CNC 6. How CNC Works? 7. Features of CNC Machines 8. CNC Programming Basics 9. Common Format of a Block 10. Programming Key Letters 11. Table of important G-codes 12. Table of important M-codes 13. Advantages 14. Challenges 15. Conclusion 16. References 12
- 13. 30/07/2025 Dept. of MECHANICAL JNTUACEP History The first NC machines were built in the 1940s and 1950s by Prof. JohnT 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. 13
- 14. 30/07/2025 Dept. of MECHANICAL JNTUACEP CNC Introduction A numerical control system in which the data handling, control sequences, and response to input is determined by an on-board computer system at the machine tool. 14
- 15. 30/07/2025 Dept. of MECHANICAL JNTUACEP CNC Machines- How do they look like? Slides Controller Servo Motors Display Console Controller Automated Tool changer Coolant control Chip collection and removal 15
- 16. 30/07/2025 Dept. of MECHANICAL JNTUACEP Elements of CNC Machine A CNC machine consist of following 6 major elements: i. Input Device ii. Machine Control Unit iii. MachineTool iv. Driving System v. Feedback Devices vi. Display Unit 16
- 17. 30/07/2025 Dept. of MECHANICAL JNTUACEP Block diagram of CNC Machine 17
- 18. 30/07/2025 Dept. of MECHANICAL JNTUACEP Open loop and Closed loop controls In open loop systems the slide may overshoot or may not reach desired position because of inertia, wear and tear and friction, hence inaccurate machining. In closed loop systems the position sensors are used to correct slide movements and achieve higher accuracy and repeatability 18
- 19. 30/07/2025 Dept. of MECHANICAL JNTUACEP How CNC Works Controlled by G and M codes. These are number 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. 19
- 20. 30/07/2025 Dept. of MECHANICAL JNTUACEP Features of CNC Machinery The tool or material moves automatically. Tools can operate in 1-5 axes. Larger machines have a machine control unit (MCU) which manages operations. Movement is controlled by motors (actuators). Feedback is provided by sensors (transducers) Tool magazines are used to change tools automatically. 20
- 21. 30/07/2025 Dept. of MECHANICAL JNTUACEP CNC Programming Basics CNC instructions are called part program commands. When running, a part program is interpreted one command line at a time until all lines are completed. Commands, which are also referred to as blocks, are made up of words which each begin with a letter address and end with a numerical value. 21
- 22. 30/07/2025 Dept. of MECHANICAL JNTUACEP CNC programming Important things to know: Coordinate System Units, incremental or absolute positioning Coordinates: X,Y,Z, RX,RY,RZ Feed rate and spindle speed Coolant Control: On/Off, Flood, Mist Tool Control:Tool and tool parameters Programming consists of a series of instructions in form of letter codes •Preparatory Codes: G codes- Initial machining setup and establishing operating conditions N codes- specify program line number to executed by the MCU •Axis Codes: X,Y,Z Used to specify motion of the slide along X,Y, Z direction •Feed and Speed Codes: F and S Specify feed and spindle speed •Tool codes:T – specify tool number •Miscellaneous codes – M codes For coolant control and other activities 22
- 23. 30/07/2025 Dept. of MECHANICAL JNTUACEP Common Format of a Block Sequence # Preparatory Function Dimension Words Feed Rate Spindle Function Tool Function Misc. Function N50 G90 G01 X1.40Y2.25 F10 S1500 T01 M03 IndividualWords 23
- 24. 30/07/2025 Dept. of MECHANICAL JNTUACEP Programming Key Letters O - Program number (Used for program identification) N - Sequence number (Used for line identification) G - Preparatory function X - X axis designation Y -Y axis designation Z - Z axis designation R - Radius designation F – Feed rate designation S - Spindle speed designation H -Tool length offset designation D -Tool radius offset designation T -Tool Designation M - Miscellaneous function 24
- 25. 30/07/2025 Dept. of MECHANICAL JNTUACEP Table of Important G codes G00 RapidTransverse G01 Linear Interpolation G02 Circular Interpolation, CW G03 Circular Interpolation, CCW G17 XY Plane,G18 XZ Plane,G19YZ Plane G20/G70 Inch units G21/G71 Metric Units G40 Cutter compensation cancel G41 Cutter compensation left G42 Cutter compensation right G43Tool length compensation (plus) G43Tool length compensation (plus) G44Tool length compensation (minus) G49Tool length compensation cancel G80 Cancel canned cycles G81 Drilling cycle G82 Counter boring cycle G83 Deep hole drilling cycle G90 Absolute positioning G91 Incremental positioning 25
- 26. 30/07/2025 Dept. of MECHANICAL JNTUACEP Table of Important M codes M00 Program stop M01 Optional program stop M02 Program end M03 Spindle on clockwise M04 Spindle on counterclockwise M05 Spindle stop M06Tool change M08 Coolant on M09 Coolant off M10 Clamps on M11 Clamps off M30 Program stop, reset to start 26
- 27. 30/07/2025 Dept. of MECHANICAL JNTUACEP Advantages of CNC i. - Easier to program; ii. - Easy storage of existing programs; iii. - Easy to change a program iv. -Avoids human errors v. - CNC machines are safe to operate vi. - Complex geometry is produced as cheaply as simple ones vii. - Usually generates closer tolerances than manual machines 27
- 28. 30/07/2025 Dept. of MECHANICAL JNTUACEP i. Costly setup, skilled operators ii. Computers, programming knowledge required iii. Maintenance is difficult Challenges 28
- 29. 30/07/2025 Dept. of MECHANICAL JNTUACEP Conclusion The advantage of a CNC system are that the operation of a conventional machine is removed and the part production is made automatic. It reduces the labor work and hence highly efficient in the manufacturing process. BHEL generally uses CNC machines to achieve its 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. 29
- 30. 30/07/2025 Dept. of MECHANICAL JNTUACEP Thank You 30
Editor's Notes
- #7: A axis of motion is defined as an axis where relative motion between cutting tool and workpiece occurs. The primary axes of motion are referred to as the X, Y, and Z axes and form the machine tool XYZ coordinate system. In CNC machine tool, each axis of motion is equipped with a driving device to replace the handwheel of the conventional machine tool. Figure shows the coordinate system and the axes of motion of a typical machine tool. Conventionally machine tools are designated by the number of axes of motion they can provide to control the tool position and orientation. In these CNC machine tools, the tool is controlled along the three axes (X, Y, and Z) simultaneously, but the tool orientation doesn’t change with the tool motion .