Computer Aided Manufacturing
Course Outlines (2nd Term)
1st Term
Course Outlines (2nd Term cont.)
References
 Alan
Overby
,
“CNC
Machining
Handbook
Building,
Programming, and Implementation ”, Mc Graw Hil, 2011.
 Peter Smid,
“CNC Programming Handbook”, 2nd edition,
Industrial press, 2000.
 Steve Krar and
Arthur Gill, “Computer Numerical Control
Programming Basics”, 1999.
CAD/CAM (MEC 5431)
300 Marks
CW : 120 Marks
Semester
work: 90
Practical
Exam : 30
Final Exam :180
Marks
 Mid Term (20)
 Assignments (10)
1st term:
45
2nd term:
45
 Quizzes (10)
 Attendance (5)
CAD/CAM
Course Policies:
1. Homework Submission:
Homework solutions should be submitted on the due date.
2. Late homework policy:
On time, in the class (100%), same day after class (0%).
Lecture Rules
Today Lecture
9
1. Reading drawing
2. Programming
3. Input Program
4. Manufacturing
10
CAD Example
11
Process planning
simulation
12
Working Drawing
13
Program simulation
NC Words
General Format of a Block
Sequence Preparatory
Function
#
N
G
Dimension
Words
X Y Z
Example
Feed
Rate
I J K
Spindle
Speed
F
Tool
Number
S T
Misc.
Function
M
The following list presents the different types of NC
words:
N-Word: Sequence No.
This is used to identify the block
N010
N020
N025
N030
G-Code : Preparatory Word
Is used to prepare the controller for instructions
G20 – Inch input (in) – G70
G21 –Metric input (mm) – G71
G00 – Rapid positioning mode :
Move in a straight line at rapids speed. NOT used for cutting.
G01 – Linear Interpolation mode
Tool is moved along a straight-line path at programmed rate of
speed.
G02 – Circular motion clockwise (CW)
G03 – Circular motion counter clockwise (CWW)
Coordinate Systems
Absolute
(2,10)
2
Incremental
(10,10)
3
1
(-8,8)
2
(10,2)
(8,0)
3
1
(10,2)
Absolute & incremental coordinates
Absolute (G90) : All Points refers to Zero point
Incremental (G91) :
All Points refers to
Previous point
Practice
pt
Abs
Inc
X-Y-Z Word : Coordinates word
G Codes – Arcs
Method : Arc with R
(R is arc radius)
Absolute coordinates
N0 G90 ; Absolute coord
N5 G00 X1 Y2 ; start
N10 G02 X2 Y1 R1
X1Y2
R1
X2Y1
X1Y2
Relative coordinates
N0 G91; Relative coord
N05 G00 X1 Y2 ; start
N10 G02 X1 Y-1 R1
R1
X1Y-1
F-Word : Feed Rate :
The feed rate code to move the cutting tool or work piece to
the desired position.
S-Word : Spindle Speed (rpm)
T-Word: Tool number
T01, T02,….etc
26
Tool Magazine
CNC turret
27
Miscellaneous function
M-Code List: that used for decision command like
spindle on/off or coolant on/off
M02
End of Program
M03
Spindle on CW
M04
Spindle on CCW
M05
Spindle off
M06
Tool change
M07
Coolant 2 on
M08
Coolant 1 on
M09
Coolant off
M30
End of tape
Preparatory function
G-Code List: that used to guide the machine tool to
carry out machining processes
G00
G01
G02
G03
G17
G18
G19
G20
G21
G90
G91
Rapid Linear Interpolation PTP
Linear Interpolation
Clockwise Circular Interpolation
Counter Clockwise Circular Interpolation
X-Y Plane Selection
Z-X Plane Selection
Y-Z Plane Selection
Inch Mode
Metric Mode
Absolute Value Command
Incremental Value Command
Programming
Point N
P1
…
…
Pn
G
X
Y
Z
I
J
S
F
T
M
Profile milling
Profiling is to cut the WP using one side of the
cutting tool
Practice
Write a part programme to machine the following part and
list the tool used
50
30
20
80
Dim in mm
10
Solution
Y
P3
50
P2
30
Tool change Point
P0
P4
P5
20
P1
80
P6 X
10
Z
Solution
N010
G21
G90
N020
G00
X90
Y60
Z5
T01
X0
Y0
S1000 M03
M07
Z-15
F200
M05
M09
N030
N040
G01
N050
Y50
N060
X30
N070
Y20
N080
X80
N090
Y0
N100
X0
N110
Z5
N120
N130
G00
X90
Y60
M30
M06
Tool
Description
T01
End mill, 10mm
Dia.
36
36