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A Definition: Numerical Control is a system in which actions are controlled by the direct insertion of numerical data at some point. The system must automatically interpret at least some portion of the data 3

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Types of Numerical Control : 

Types of Numerical Control Conventional Numerical Control (NC) Direct Numerical Control (DNC) Computer Numerical Control (CNC) 5

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Conventional Numerical Control (NC) Data is sent to the machine tool by means of punch cards or tapes. The reader at the machine performs no calculations or interpolations. 6

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Direct Numeric Control (DNC) Is a method where a single computer controls many numerical control machine tools. These machine tools may or may not be of a similar nature 7

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Computer Numerical Control (CNC) The idea of computer numerical control is to position a computer right at the machine tool. Most, if not all machine tools that are numericaly controlled are CNC machine tools. 8

Computer Numerical Control (CNC) : 

Computer Numerical Control (CNC) 9

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Advantages Reduces time for delivery of part Reduces scrap rate of material Reduces tooling costs Reduces layout time Increases machine and tool life Reduces storage problems Less setup time Reduces actual machining time Allows rapid design changes in part Less jigs and fixtures are needed 10

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NC Programming Fundamentals or how to put the “GO” in your G-codes 11

NC Part Programming : 

NC Part Programming Linear tool motion (Milling) relative to the part 12

Example: A Milling Operation : 

Example: A Milling Operation X Z Y (0,0,0) NC CODE (Word Address Format) N50 G00 X15 Y12.5 Z0 N55 M03 N60 G01 Z-2.5 F500 M08 N65 G01 X50 N70 G01 Y45 N75 G01 X15 N80 G01 Y12.5 N85 G00 Z0 M09 N90 G79 M04 SPINDLE STARTED ! SPINDLE STOP ! 13

Basics of NC Part Programming : 

Basics of NC Part Programming it is always assumed that the tool moves relative to the work piece no matter what the real situation is. The position of the tool is described by using a Cartesian coordinate system. If (0,0,0) position can be described by the operator, then it is called floating zero. 14

Preparatory Functions (G Codes) : 

Preparatory Functions (G Codes) G-codes Tool motion Rapid traverse G00 Positioning command Moves the tool at a rapid feed rate to a specific XYZ coordinate Takes the shortest route to reach the specified point Format G00 Xx Yy Zz 15

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G-codes Linear Interpolation Moves the tool from its current position to a specific XYZ coordinate at a specified feed rate Format G01 Xx Yy Zz ff 16

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G-codes Linear Interpolation 17

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G-codes Circular Interpolations Moves a tool around a circular arc to a specific XYZ coordinate Requires 5 pieces of information Plane selection Arc start point Rotation direction Arc end point Arc center or arc radius 18

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G-codes Circular Interpolations G02 circular interpolation clockwise around an arc G03 circular interpolation counter clockwise around an arc 19

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G-codes How You Tell Directions The direction for G02 can be determined by rotating from the positive axes towards the negative axes. The direction for a G03 is exactly opposite 20

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G-codes Still Going in Circles basic methods Radius method (G02,G03) Xx Yy Rr Ff (on the XY plane) 21

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G-codes Radius Method Requires two entry parameters in the command the XYZ end point of the arc and the radius R G02/G03 Xx Yy Zz Rr 22

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G-codes 23 G90 M3 S2000 ; G90 -absolute coordinate ; M3 - spindle ON ; S - RPM G0 X0 Y0 Z10 ;G0- rapid movement X10 Y5 Z2 G1 Z-2 F100 ;G1- linear movement ;F- feed X80 F200 X10 Y40 Y5 x80 Y40 x45 y45 x10 y40 x80 x80 y5 g0 z10 x0y0 M30 ; Spindle off X5 y10 X80 y10 X80 y40 X45 y45 X5 y40

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G-codes 24

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25 Quiz

Homework #1 - Due date: March 10th : 

Homework #1 - Due date: March 10th 26 Z=-2 Tool Diameter = 0.5 mm

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CNC Pro-Light 1000 Machine 27

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G-codes 28

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29 Spindle On/Off Vice Open/Close E-stop

1- Machine Home : 

1- Machine Home 30

2- Reference Point : 

2- Reference Point 31

3. Set position : 

3. Set position 32

4- Run : 

4- Run 33