1. CNC Lathe Machine
Nurfaizey b. Abdul Hamid
26 February 2008

2. Operations and Capabilities CNC Lathe Programmable Axes
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
CONTENTS
Introduction to CNC
Operations and Capabilities
CNC Lathe Programmable Axes
CNC Lathe Programming
CNC Lathe Programming Example

3. Introduction to Computer Numerical Control (CNC)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
1. INTRODUCTION
Introduction to Computer Numerical Control (CNC)
CNC is defined as ‘Control of machine tools and other manufacturing equipment using computer programs’ (R.R.Kibbe, 2006).
Since the earliest days of production manufacturing involving the precision of duplication of parts, manufacturing engineers and industrial technologists have sought ways to increase dimensional accuracy and to increase the speed of production.
After the development of computers, CNC had been used to control machines in order to get high degree of repeatable precision.
The precision dimensional requirements that are the mainstay of the machining processes, such as drilling, turning and milling, have made CNC ideal to control the machines.
Today, CNC is not only limited to machining processes. It also appears in many other types of manufacturing processes.
CNC is also used for robotic spot welding, wire welding, robotic assembly, pipe and tube bending, laser and plasma arc cutting, wood routers, flame and abrasive water jet cutting, electro-discharge machining (EDM), spray painting and etc.

4. 1. INTRODUCTION – (cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
1. INTRODUCTION – (cont’d)
The Advantages of Computer Numerical Control (CNC)
Higher production rate
High degree of repeatable precision
Lower reject rate
Reduce tooling cost
Less handling by operators
Able to produce complex shapes
CNC Lathe Machines
A CNC lathe machine does the same operations as the conventional lathe machine. It is used to produce component with circular cross section using turning operations and related tasks such as drilling, boring, tapping and reaming.
The main difference is the use of CNC to control the operation of the machine.
Using computer programs, CNC lathe machines are able to produce components with all the advantages associated with CNC.
CNC Lathe Machine (

5. 2. OPERATION & CAPABILITIES
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
2. OPERATION & CAPABILITIES
The Operations of CNC Lathe Machine
Plane turning (Melarik lurus)
Taper turning (Melarik tirus)
Facing (Merata permukaan)
Parting off (Memotong)
Threading (Membenang)
Knurling (Membunga)
Drilling/reaming (Membuat lubang)
Boring (Membesarkan lubang)
Polishing (Menggilap)
CNC Lathe Machine Capabilities
Can operate in long period without operator’s supervision.
Can operate using numerical control program to produce various components.
Programs can be created, stored, and can be used whenever needed to manufacture the component.

6. 2. OPERATION & CAPABILITIES
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
2. OPERATION & CAPABILITIES
Typical steps that have to taken by the operator to produce a component:
Choosing the right cutting tool for the operation
Place the cutting tool in the machine’s turret
Tighten the tools
Place the workpiece onto the work holding device
Tighten the workpiece
Set the zero point (datum)
Choosing the right speed
Check the turning direction of the spindle
Choosing the right feed rate
Start the spindle
Start the coolant motor
Start programme
Stop the coolant motor
Stop the spindle motor
Remove workpiece from the machine
Dimensional inspection of the component

7. The fundamental programmable axes of CNC lathe machine
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
3. CNC PROGRAMMABLE AXES
The Programmable Axes on CNC Lathe Machine
Every CNC machine tool is designed to position the workpiece and cutting tools to perform cutting operations.
Each machine has a definite three dimensional volume of space in which tools and workpieces may be moved about and positioned.
On CNC lathe machines, the spindle axis is Z and the cross slide is X (figure below).
The fundamental programmable axes of CNC lathe machine
(R.R.Kibbe, 2006)

8. Programme stage in manufacturing process
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4. CNC PROGRAMMING
CNC Lathe - Basic Programming Concept
The purpose of NC programming is to write a sequence of events to be done, a set of cutting tool to be used and a set of machine control functions to be used to apply the tools and position the workpiece properly.
The program stage in manufacturing process is as shown below.
Programme stage in manufacturing process

9. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
CNC Program Standard Code
Most modern CNC programming is done in the word address format
Preparatory function codes or G codes. Usually noted in uppercase (G)
Programmable axes dimensional information for positioning tools and workpieces (X, Y, Z, a, b, c)
Miscellaneous function codes or M codes. Usually noted in uppercase (M)
Various other letter codes such as I, J, K, F, S and R

10. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Basic Programming - Program Configuration
Generally a program consists of:
Program Name
Sequence Name and Sequence label
Coordinates and commands
Remarks
End of program block
This information is presented using ALPHABATIC CHARACTERS and NUMERIC CHARACTERS. Each line of characters is called a BLOCK.
O________ (Can be omitted if only one program in the file)
N________ G_X_Z_S_T_M_ : M2

11. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Program Name (Program Number)
Program name designation
O_ _ _ _
Up to 4 characters can be used
The characters can be numeric
Alphabetic character must be a head of numeric character.
Example: Program name
O OK
OAB12 -OK
O1AA2 - Tak OK- after AA (sama)
O123 = O0123
Program name can be omitted if there is only one main program in the file.

12. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Sequence Name and Label
A sequence name is defined as a name assigned to a block. Numeric or alphabetic characters following after “N” are designated for a sequence name.
N_____
Sequence name must be placed at the beginning of a block. However it is not essential to include sequence name in program
Sequence name may be specified in any order.
Example: Program name
N OK
NAT02 -OK
N1AT2 -tak OK (alphabet and numeric-berselang-seli)
N123 tak sama N0123

13. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Commands
Machine carries out its tasks by following the commands written in a program. These commands are presented by groups of codes, so called G code and M code. Each code commands the machine to do specific action.
For example:
G00 commands the machine to move the cutter at a rapid speed to a specific point in the work.
M08 commands the machine to start spraying coolant through the nozzles.

14. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)

15. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)

16. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Coordinates
In order to let the machine know where it should move the tool, the coordinate point have to be specified. The coordinate value is represented by X, Z, A, C, I and K-axis. However, only X and Z-axis is being concerned in this class.
X±_____.___ Z ±_____.___
In default parameter setting, the unit system is in millimeters
X90.1 is effectively 90.1 mm or 90100μm
Also by default, the unit system allow 3 significant digits after the decimal point. X0.001
Decimal point is not essential if integer value is assigned.
X90 is effective as X90. or X90.0
Example: X Z100
X Z90

17. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Other code address include F, S, T, P, Q……
Where:
F = Feed rate (cutting)
S = Spindle speed (Rotation – counterclockwise)
T = Tool number and tool offset number

18. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Tool Selection
Selection of a cutting tool is made by 4 digit figures following a
character T
T_ _ _ _ Example: T 02 02
When Tool nose radius compensation function is used, selection of a cutting tool is made by 6 digit figures. T
Tool Offset Number
Tool Number
Tool Offset Number
Tool Number
Tool nose radius compensation

19. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Controlling The spindle (S, M03, M04, M05)
Logically the spindle must be rotating before the cutting process commences. These codes are used to control the direction and its speed.

20. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Example:
T0101
S2000 M03
G00 X188 Z204
X188
G01 X185 Z120 F0.5
X190
Z100
X200
G00 X300 Z300
M5 (Spindle stop)
M2 (End of program)
In the above example:
T0101 commands the machine to select tool number 1
S2000 Sets the spindle speed to 2000 rpm
M03 Commands the spindle to rotate in clockwise direction speed determined by previous S code. In this case, 2000 rpm.
M05 Stops the spindle

21. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Coolant on/off (M08, M09)
Example:
T0101
S2000 M03
G00 X188 Z204
X185
M08
G01 X185 Z120 F0.5
X190
Z100
X200
G00 X300 Z300 M5
M09 M2

22. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Program Stop and Program End (M00, M01, M02)
M00 Program Stop. The machining cycle stops when this code is encountered during program execution. Pressing CYCLE START at this point will resume the operation.
M01 Optional Stop. M01 performs the same functions as M00, except, it is only effective when the OPTIONAL STOP button on the control panel is switched on. Pressing CYCLE START at this point will be resume the operation.
M02 End of program. It must be included to indicate end of a program. This code also resets the control.
Example: T
S2000 M03
G00 X188 Z204
X185
M00 (Operation cycle stop here)
M08 (Operation cycle continues here when CYCLE START button is
pressed)

23. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
G01 X185 Z120 F0.5
X190
Z100
X200
M01 (Operation cycle Stop if OPTIONAL STOP button is switched on)
G00 X300 Z300
M5 (Spindle stop)
M09 (Coolant off)
M2 (End of program)

24. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Positioning (G00)
G00 commands the machine to position the cutter to a coordinate point at rapid feed rate
G00 X_ _ _ _ . _ _ _ Z _ _ _ _ . _ _ _
X and Z designate the stopping point
Example T
S2000 M03
G00 X188 Z204
X185 M5 M2

25. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Straight line cutting
This code commands the machine to move the cutter from current position to the position specified by X and Z. Along a straight line a feed rate specified by F.
G01 X_ _ _ _ . _ _ _ Z _ _ _ _ . _ _ _ F_ . _ _ _
Example straight line cutting
T0101
S2000 M03
G00 X188 Z204
X185
M08
G01 X185 Z120 F0.5
X190
Z100
X200
G00 X300 Z300 M5
M09 M2

26. 4. CNC PROGRAMMING –(cont’d)
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
4. CNC PROGRAMMING –(cont’d)
Dwell (G04) & maximum spindle speed (G50)
Program will pause for F_second
G04 F_
Specify the max spindle speed (S_ _ _ _) allowed in the program
G50 S_

27. 5. PROGRAMMING EXAMPLE * Refer to handout
FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
5. PROGRAMMING EXAMPLE
* Refer to handout

28. FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA
THE END
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