The document explains the fundamentals of CNC (Computer Numerical Control) machines, detailing their programming structure and key functions for controlling the cutting and shaping of materials. It describes various programming commands, their meanings, and includes a programming example with interpretations for clarity. Additionally, it highlights the advantages of CNC technology, such as improved tolerances, reduced setup times, and enhanced machine utilization.

1. CNC Machine
(Computer Numerical Control M/c)

3. MEANING OF ‘CNC’
CNC means Computer Numerical Control. This means a
computer converts the design into numbers which the
computer uses to control the cutting and shaping of the
material.

4. BASIC OF CNC MACHINE

6. BASED ON MOTION

7. BASED ON CONTROL LOOPS
Open Loop
Closed Loop

8. BASED ON COORDINATE SYSTEM
a) Absolute System b) Incremental System

9. 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

10. FEATURES OF PROGRAMMING
N3 G2 X+1.4 Y+1.4 Z+1.4 I1.4 J1.4 K1.4 F3.2 S4 T4 M2
sequence
no
preparatory function
destination coordinates dist to center of circle
feed rate
spindle speed
tool
Other function
Sequence and format of words:

11. Raw Material Finished Part
Programming Example-1

12. Programming Example
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
N003 G01 X-8 Y0 Z0 XYF150
N004 G01 X-8 Y0 Z-0.5 XYF150
N005 G01 X70 Y0 Z-0.5 XYF 75
N006 G01 X70 Y60 Z-0.5 XYF 75
N007 G01 X30 Y60 Z-0.5 XYF 75
N008 G01 X0 Y40 Z-0.5 XYF 75
N009 G01 X0 Y0 Z-0.5 XYF 75
N010 G81 R3 E9 N7 Z-0.5
N011 M05
N012 M02
x
y

13. Program Interpretation
G55 X200 Y80
Setting the datum to the lower left corner of
the work piece

14. Program Interpretation
G55 X200 Y80
Program 1
Program Identification Number

15. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N001 Sequence Number
M06 Tool Change (End Mill with Diameter=12mm)
T1 Tool Number

16. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
Start rotating the spindle clockwise
with 400 rpm

17. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
N003 G01 X-8 Y0 Z0 XYF 150
Go to Safe Position with feed
150mm/min

18. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
N003 G01 X-8 Y0 Z0 XYF 150
N004 G01 X-8 Y0 Z-0.5 XYF 150
Lower the end mill to determine the
depth of cut

19. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
N003 G01 X-8 Y0 Z0 XYF 150
N004 G01 X-8 Y0 Z-0.5 XYF
150
N005 G01 X70 Y0 Z-0.5 XYF 75
Move from the lower left
corner of the work piece
to the right lower one
cutting with
feed=75mm/min

20. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
N003 G01 X-8 Y0 Z0 XYF 150
N004 G01 X-8 Y0 Z-0.5 XYF
150
N005 G01 X70 Y0 Z-0.5 XYF 75
N006 G01 X70 Y60 Z-0.5 XYF
75
Move from the lower left
corner of the work piece to
the right lower one cutting
with feed=75mm/min

21. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
N003 G01 X-8 Y0 Z0 XYF 150
N004 G01 X-8 Y0 Z-0.5 XYF
150
N005 G01 X70 Y0 Z-0.5 XYF 75
N006 G01 X70 Y60 Z-0.5 XYF
75
N007 G01 X30 Y60 Z-0.5 XYF
75
Cutting the horizontally
up to X=30

22. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
N003 G01 X-8 Y0 Z0 XYF 150
N004 G01 X-8 Y0 Z-0.5 XYF 150
N005 G01 X70 Y0 Z-0.5 XYF 75
N006 G01 X70 Y60 Z-0.5 XYF 75
N007 G01 X30 Y60 Z-0.5 XYF 75
N008 G01 X0 Y40 Z-0.5 XYF 75
Cutting to X=0 & Y=40

23. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
N003 G01 X-8 Y0 Z0 XYF150
N004 G01 X-8 Y0 Z-0.5 XYF150
N005 G01 X70 Y0 Z-0.5 XYF75
N006 G01 X70 Y60 Z-0.5 XYF75
N007 G01 X30 Y60 Z-0.5 XYF75
N008 G01 X0 Y40 Z-0.5 XYF75
N009 G01 X0 Y0 Z-0.5 XYF75
Complete the countering

24. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
N003 G01 X-8 Y0 Z0 XYF150
N004 G01 X-8 Y0 Z-0.5 XYF150
N005 G01 X70 Y0 Z-0.5 XYF75
N006 G01 X70 Y60 Z-0.5 XYF75
N007 G01 X30 Y60 Z-0.5 XYF75
N008 G01 X0 Y40 Z-0.5 XYF75
N009 G01 X0 Y0 Z-0.5 XYF75
N010 G81 R3 E9 N7 Z-0.5
Repeat 7 times blocks from N003 to N009
with incremental offset of Z=-0.5

25. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
N003 G01 X-8 Y0 Z0 XYF150
N004 G01 X-8 Y0 Z-0.5 XYF150
N005 G01 X70 Y0 Z-0.5 XYF75
N006 G01 X70 Y60 Z-0.5 XYF75
N007 G01 X30 Y60 Z-0.5 XYF75
N008 G01 X0 Y40 Z-0.5 XYF75
N009 G01 X0 Y0 Z-0.5 XYF75
N010 G81 R3 E9 N7 Z-0.5
N011 M05
Spindle Off

26. Program Interpretation
G55 X200 Y80
Program 1
N001 M06 T1
N002 M03 S400
N003 G01 X-8 Y0 Z0 XYF150
N004 G01 X-8 Y0 Z-0.5 XYF150
N005 G01 X70 Y0 Z-0.5 XYF75
N006 G01 X70 Y60 Z-0.5 XYF75
N007 G01 X30 Y60 Z-0.5 XYF75
N008 G01 X0 Y40 Z-0.5 XYF75
N009 G01 X0 Y0 Z-0.5 XYF75
N010 G81 R3 E9 N7 Z-0.5
N011 M05
N012 M02
End Program

27. ATC
(Automatic Tool Changer)

28. CNC Tooling
SINGLE ARM MECHANISM

29. CNC Tooling
PIVOT INSERTION MECHANISM

30. CNC Tooling
AUTOMATIC TOOL CHANGER
(ATC)

31. ADVANTAGES
OF CNC
Easier to
program
Easy
storage of
existing
programs
Easy to
change a
program
Avoids
human
errors
Safer to
operate
Complex
geometry is
produced
cheaply

32. ADVANTAGES
OF CNC
Closer
tolerances
than
manual
machines
Reduced
set-up time
Reduced
lead times
Reduced
inventory
Better
machine
utilization
Job
advancement
opportunities

33. Thank you