This document provides an overview of computer numerical control (CNC) machines. It discusses the basic functions and components of CNC machines, including automatic and precise motion control along linear and rotary axes driven by motors and computer programs. The document also covers important G and M codes used in CNC programming to control functions like feed rate, spindle speed, tool changes, and coolant. Sample CNC programming for a basic contouring operation is presented to illustrate how coordinates and machining parameters are defined.

1. Computer Numerical Control

2. Types of Automation Manufacturing Automation Hard/ Rigid/ Mechanized Automation Soft/ Flexible/ Programmable Automation Copy milling machines Automats Special purpose machines CNC Machines Robots Automatically Guided Vehicles (AGVs) Reconfigurable conveyors Unlimited muscle power Speed Accuracy Unmanned operation Flexibility Simplified generic tooling even for the most complex jobs Advantages of Soft Automation

3. Introduction to CNC Conventionally, an operator decides and adjusts various machines parameters like feed , depth of cut etc depending on type of job , and controls the slide movements by hand. In a CNC Machine functions and slide movements are controlled by motors using computer programs. The most basic function of any CNC machine is automatic, precise, and consistent motion control. The two most common axis types are linear (driven along a straight path) and rotary (driven along a circular path).

4. Introduction to CNC Conventionally, an operator decides and adjusts various machines parameters like feed , depth of cut etc depending on type of job , and controls the slide movements by hand. In a CNC Machine functions and slide movements are controlled by motors using computer programs. The most basic function of any CNC machine is automatic, precise, and consistent motion control. The two most common axis types are linear (driven along a straight path) and rotary (driven along a circular path).

5. Why CNC is Accurate?

6. Defining Axes

7. Defining Axes Lathe Vertical Machining Center

8. Important G Codes G00 Rapid Transverse G01 Linear Interpolation G02 Circular Interpolation, CW G03 Circular Interpolation, CCW G17 XY Plane,G18 XZ Plane,G19 YZ Plane G20/G70 Inch units G21/G71 Metric Units G40 Cutter compensation cancel G41 Cutter compensation left G42 Cutter compensation right G43 Tool length compensation (plus) G43 Tool length compensation (plus) G44 Tool length compensation (minus) G49 Tool 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

9. Important M Codes M00 Program stop M01 Optional program stop M02 Program end M03 Spindle on clockwise M04 Spindle on counterclockwise M05 Spindle stop M06 Tool change M08 Coolant on M09 Coolant off M10 Clamps on M11 Clamps off M30 Program stop, reset to start

10. Modal and Non-Modal Commands Modal commands: Commands issued in the NC program that will stay in effect until it is changed by some other command, like, feed rate selection, coolant selection, etc. Nonmodal commands: Commands that are effective only when issued and whose effects are lost for subsequent commands, like, a dwell command which instructs the tool to remain in a given configuration for a given amount of time.

11. Open Loop and Closed Loop System

12. Tape Preparation

13. Programming : Absolute and Incremental 5 – Parity check 6 – Zero 7- Minus 8 – End of info EIA ASCII

14. Features of a CNC Systems The tool or material moves. Tools can operate in 1-5 axes. Larger machines have a machine control unit (MCU) which manages operations. Movement is controlled by a motors (actuators). Feedback is provided by sensors (transducers) Tool magazines are used to change tools automatically.

15. Types of Interpolations Point to Point - No contouring capability Straight cut control - one axis motion at a time is controlled for machining Contouring - multiple axis’s controlled simultaneously

16. Sample Programming Preparatory Information: units, incremental orabsolute positioning Coordinates: X,Y,Z, RX,RY,RZ Machining Parameters: Feed rate and spindlespeed Coolant Control: On/Off, Flood, Mist Tool Control: Tool and tool parameters Cycle Functions: Type of action required Miscellaneous Control: Spindle on/off, directionof rotation, stops forpart movement This information is conveyed to the machine through a set of instructions arranged in a desired sequence – Program

17. Sample Programming Manual Part Programming: Manual programming of the machines Computer Aided Programming (CAP): Programming done by a computer Manual Data Input (MDI): A manual program is entered into the machine’s controller via its own keyboard

18. Sample Programming Tool size = 0.25 inch, Feed rate = 6 inch per minute, Cutting speed = 300 rpm, Tool start position: 2.0, 2.0 Programming in inches Motion of tool: p0  p1  p2  p3  p4  p5  p1  p0

19. Sample Programming Set up the programming parameters Programming in inches Use absolute coordinates Feed in ipm N010 G70 G90 G94 G97 M04 Spindle speed in rpm Spindle CCW

20. Sample Programming Set up the machining conditions Machine moves in XY-plane Use full-circle interpolation Feed rate Spindle speed N020 G17 G75 F6.0 S300 T1001 M08 Tool no. Flood coolant ON

21. Sample Programming Move tool from p0 to p1 in straight line Linear interpolation target coordinates N030 G01 X3.875 Y3.698

22. Sample Programming Cut profile from p1 to p2 Linear interpolation target coordinates N040 G01 X3.875 Y9.125 or N040 G01 Y9.125 X-coordinate does not change  no need to program it

23. Sample Programming Cut profile from p2 to p3 Linear interpolation target coordinates N050 G01 X5.634 Y9.125

24. Sample Programming Cut along circle from p3 to p4 circular interpolation, CCW motion target coordinates N060 G03 X7.366 Y9.125 I0.866 J-0.125 coordinates of center of circle (always in incremental )

25. Sample Programming Complete Programming N010 G70 G90 G94 G97 M04 N020 G17 G75 F6.0 S300 T1001 M08 N030 G01 X3.875 Y3.698 N040 G01 X3.875 Y9.125 N050 G01 X5.634 Y9.125 N060 G03 X7.366 Y9.125 I0.866 J-0.125 N070 G01 X9.302 N080 G01 X3.875 Y3.698 N090 G01 X2.0 Y2.0 M30

26. Adaptive Control Adaptive control with constraints Adaptive control with optimization

27. Advantage of NC Increased productivity Reduced tool/fixture storage and cost Faster setup time Reduced parts inventory Flexibility that speeds changes in design Better accuracy of parts Reduction in parts handling Better uniformity of parts Better quality control Improvement in manufacturing control

28. Disadvantages Increase in electrical maintenance High initial investment Higher per-hour operating cost than traditional machine tools Retraining of existing personnel NC is a general term used for Numerical Control. CNC refers specifically to COMPUTER NUMERICAL CONTROL. CNC machines are all NC machines but not all NC machines are CNC machine.

30. Turning, boring, milling, grinding etc.

31. Sheet metal manufacture

32. Turret punch press, pipe bending, flow forming etc.

33. Non-traditional machining

34. Wire-EDM, water-jet cutting, electron beam machining, laser beam machining, plasma cutting etc.

35. Coordinate Measuring Machines

36. Drafting machines

37. Robots

38. Rapid Prototyping (RP) machinesNC is a control technique; not a process

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