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

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Presentation on theme: "1 CNC Lathe Machine Nurfaizey b. Abdul Hamid 26 February 2008."— Presentation transcript:

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

2 2 CONTENTS 1. Introduction to CNC 2. Operations and Capabilities 3. CNC Lathe Programmable Axes 4. CNC Lathe Programming 5. CNC Lathe Programming Example FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA

3 3 1. INTRODUCTION FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 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 4 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. FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA CNC Lathe Machine (www.okuma.co.jp)

5 5 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. FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA

6 6  Typical steps that have to taken by the operator to produce a component: 1.Choosing the right cutting tool for the operation 2.Place the cutting tool in the machine’s turret 3.Tighten the tools 4.Place the workpiece onto the work holding device 5.Tighten the workpiece 6.Set the zero point (datum) 7.Choosing the right speed 8.Check the turning direction of the spindle 9.Choosing the right feed rate 10. Start the spindle 11. Start the coolant motor 12. Start programme 13. Stop the coolant motor 14. Stop the spindle motor 15. Remove workpiece from the machine 16. Dimensional inspection of the component FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 2. OPERATION & CAPABILITIES

7 7 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). FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA The fundamental programmable axes of CNC lathe machine (R.R.Kibbe, 2006)

8 8 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. FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA Programme stage in manufacturing process 4. CNC PROGRAMMING

9 9 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 FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

10 10 Basic Programming - Program Configuration  Generally a program consists of: 1.Program Name 2.Sequence Name and Sequence label 3.Coordinates and commands 4.Remarks 5.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 FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

11 11 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 1.O1234-OK 2.OAB12-OK 3.O1AA2- Tak OK- after AA (sama) 4.O123=O0123  Program name can be omitted if there is only one main program in the file. FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

12 12 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 1.N1234-OK 2.NAT02-OK 3.N1AT2-tak OK (alphabet and numeric-berselang-seli) 4.N123 tak sama N0123 FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

13 13 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: 1.G00 commands the machine to move the cutter at a rapid speed to a specific point in the work. 2.M08 commands the machine to start spraying coolant through the nozzles. FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

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

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

16 16 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 μ m  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 FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

17 17  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 FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

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

19 19 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. FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

20 20  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: 1.T0101 commands the machine to select tool number 1 2.S2000 Sets the spindle speed to 2000 rpm 3.M03 Commands the spindle to rotate in clockwise direction speed determined by previous S code. In this case, 2000 rpm. 4.M05 Stops the spindle FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

21 21 Coolant on/off (M08, M09)  Example: T0101 S2000 M03 G00 X188 Z204 X185 X185M08 G01 X185 Z120 F0.5 X190 X190 Z100 Z100 X200 X200 G00 X300 Z300 M5M09M2 FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

22 22 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) FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

23 23 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) FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

24 24 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 FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

25 25 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 FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

26 26 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_ FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA 4. CNC PROGRAMMING –(cont’d)

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

28 28 THE END FAKULTI KEJURUTERAAN MEKANIKAL UNIVERSITI TEKNIKAL MALAYSIA MELAKA THANK YOU


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