Fundamentals of CNC Machining

Fundamentals of CNC Machining

A Practical Guide for Beginners

Compliments of NexGenCAM, Inc.

Fundamentals of CNC Machining

Desk Copy

Compliments of NexGenCAM

Copyright ?2012 HSMWorks, ApS

All Rights Reserved.

Reproduction or translation of any part of this work beyond that permitted by Sections 107 and 108 of the 1976 United States Copyright Act without the expressed written permission of the copyright owner is unlawful. Request for permission or further information should be addressed to HSMWorks, ApS

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Fundamentals of CNC Machining

Desk Copy

Document Number: 060711

ISBN-13: 978-0-615-50059-1 ISBN-10: 0615500595

Fundamentals of CNC Machining

Table of Contents

Chapter 1: Introduction& CNC Process Overview

Description ................................................................ 1-3 Prerequisites .......................................................... 1-3 Audience ................................................................ 1-3 Course Design ........................................................ 1-3

SRP vs. RP .................................................................. 1-4 Prototype vs. Production Machining......................... 1-4 Required Tools and Equipment ................................. 1-4 Lessons and Appendices ........................................... 1-5 InstructionalResources.............................................. 1-5 Recommended Use ................................................... 1-6 Overview of CAD/CAM Process................................. 1-6

Chapter 2: ShopSafety

Overview ................................................................... 2-3 SafetyAwareness ....................................................... 2-3 PersonalConduct& Shop Etiquette............................ 2-4 Shop Clothing ............................................................ 2-4

Proper Shop Attire Illustration............................... 2-5 General Safety Practices............................................ 2-6 CNC Safety Practices ................................................. 2-6 SafetyContract........................................................... 2-7

SafetyContractForm............................................... 2-8

Chapter3: CNC Tools

Overview ................................................................... 3-3 End Mills .................................................................... 3-3 Face Mill .................................................................... 3-4 Corner Radius Mill ..................................................... 3-5 Slot Mill/SlottingSaw ................................................. 3-5 Center-Spot Drill........................................................ 3-5 Twist Drill................................................................... 3-6 Tap............................................................................. 3-6 Reamer ...................................................................... 3-7 Counterbore .............................................................. 3-8 CuttingTool Fundamentals ........................................ 3-8

Rotational Direction............................................... 3-8 Chip Formation ...................................................... 3-8 Chip Load ............................................................... 3-9 Climb vs. ConventionalMilling ............................... 3-9 Cutting Speeds and Feeds Formulas ....................... 3-10 Speed Formula ..................................................... 3-11 Feed Formula ....................................................... 3-12 TapFeed Formula ................................................. 3-12 Speed/FeedExamples .............................................. 3-13 Milling Speed/FeedExample ................................ 3-13 Drill Speed/FeedExample..................................... 3-14

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Fundamentals of CNC Machining Chapter4: CoordinateSystems

Chapter5: CNC ProgrammingLanguage

Chapter6: CNC Operation

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Tap Speed/FeedExample ..................................... 3-15 Maximum Spindle Speed Example....................... 3-16 Cutting Data ............................................................ 3-17 Best Practices MachiningParameters .................. 3-18 Troubleshooting Speed/FeedProblems ............... 3-19

Overview ................................................................... 4-3 CartesianCoordinate System ..................................... 4-3

Number Line .......................................................... 4-3 3D CartesianCoordinate System ............................ 4-3 Quadrants .............................................................. 4-4 Units .......................................................................... 4-5 Vertical Machining Center (VMC) Motion................. 4-5 CNC Motion Control............................................... 4-6 CNC Machine Coordinates ..................................... 4-6 About Machine Home Position.............................. 4-7 WorkCoordinate System (WCS) ................................ 4-8 WCS Example-1 ...................................................... 4-9 WCS Example-2 .................................................... 4-10 WCS Example-3 .................................................... 4-11 Machine and Tool Offsets ....................................... 4-12 Machine Offset XY ............................................... 4-12 Machine Offset Z.................................................. 4-13 ToolLenght Offset (TLO)....................................... 4-13

Overview ................................................................... 5-3 CNC Language and Structure..................................... 5-3

Program Format..................................................... 5-4 CNC Editor ................................................................. 5-4 Alphabetic&SpecialCharacterAddress Codes ............ 5-5

AlphabeticAddress Code Definitions ..................... 5-5 G&M Codes ............................................................... 5-8

G-Codes.................................................................. 5-8 M-Codes................................................................. 5-8 Select G-Code Definitions (Expanded) ................... 5-9 Canned Cycles ......................................................... 5-10

Overview of CNC Setup and Operation ..................... 6-3

Machine and Tool Offsets ......................................... 6-5 Fixture Offset XY .................................................... 6-5 Fixture Offset Z ...................................................... 6-6 ToolLength Offset (TLO)......................................... 6-7

Haas Control Face...................................................... 6-8 Haas Keyboard ....................................................... 6-9

Start/Home Machine............................................... 6-10 Load Tools ............................................................... 6-11 Set ToolLength Offset (TLO) .................................... 6-13 Set Fixture Offset XY................................................ 6-17

Contents

Contents Chapter7: 2D MillingToolpaths

Chapter8: CNC Turning

Fundamentals of CNC Machining

Set Fixture Offset Z.................................................. 6-21 Load CNC Program .................................................. 6-24 Run CNC Program.................................................... 6-26 AdjustingDiameter (CDC) Offsets ............................ 6-27 Shut Down CNC ....................................................... 6-29

Overview ................................................................... 7-3 2D/3D/4X/5X Defined ............................................... 7-3

2D (Prismatic) Parts ............................................... 7-3 3D Parts.................................................................. 7-4 4-Axis Parts ............................................................ 7-4 Standard CAD Views vs. CAM Views ......................... 7-6 CAD Features vs. MachiningFeatures........................ 7-6 Toolpaths by Type and Use ....................................... 7-7 2D MachiningFeaturesExample ............................. 7-8 2D ToolpathTerminology........................................... 7-9 Facing ...................................................................... 7-10 2D Contouring ......................................................... 7-11 Cutter Diameter Compensation........................... 7-12 Pocketing................................................................. 7-13 Slot Milling .............................................................. 7-14 ChamferMilling........................................................ 7-15 Radius (Corner-Round) Milling ................................ 7-16 Center Drill .............................................................. 7-17 Drilling ..................................................................... 7-18 Tapping.................................................................... 7-19

Overview ................................................................... 8-3 Lathe Components................................................. 8-4 Spindle ................................................................... 8-5 Turret ..................................................................... 8-6

LatheCoordinate System ........................................... 8-8 Driven (Live) Tools..................................................... 8-9 ImaginaryTool Tip.................................................... 8-10 Part Datum .............................................................. 8-11 Tools and ToolHolders............................................. 8-12

Chip Breaker ........................................................ 8-12 Relief Angle .......................................................... 8-13 ToolCutting Angles............................................... 8-13 Rake Angle ........................................................... 8-14 Insert Designations.................................................. 8-15 LatheTool Types ...................................................... 8-17 Face/Turn Tools ................................................... 8-17 Groove Tool ......................................................... 8-18 Bore Tool.............................................................. 8-19 Thread Tool .......................................................... 8-20 CutoffTool ............................................................ 8-21 Cutting Speeds and Feeds ....................................... 8-22 Speed/FeedExample ............................................ 8-23 CuttingFeedExample............................................ 8-24 Lathe Setup and ProgrammingExample .................. 8-25 Setup .................................................................... 8-26

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Fundamentals of CNC Machining

Chapter9: 3D Toolpaths

Chapter10: Milling Setups

Face...................................................................... 8-27 Rough ................................................................... 8-28 Finish.................................................................... 8-29 Groove ................................................................. 8-30 Thread.................................................................. 8-31 Drill....................................................................... 8-32 Bore ..................................................................... 8-33 Cutoff ................................................................... 8-34

Overview ................................................................... 9-3 3D Cutter Compensation........................................... 9-3 Tolerances ................................................................. 9-4 3D Toolpath Setups ................................................... 9-6 3D Roughing .............................................................. 9-6 Parallel Finish ............................................................ 9-7

ScallopHeight ......................................................... 9-8 3D Scallop .................................................................. 9-9 REST Milling ............................................................. 9-10 PencilToolpaths ....................................................... 9-11 Conceptualizing 3D Toolpaths ................................. 9-12

Overview ................................................................. 10-3 Fixture Components................................................ 10-3 Subplates and Angle Plates ..................................... 10-3

Clamps .................................................................. 10-4 ShoulderBolts and Dowel Pins ................................ 10-5 Vise Accessories ...................................................... 10-5

Hard Jaws ............................................................. 10-6 Soft Jaws.................................................................. 10-6

Appendix A: CNC MillingWork-Holding Examples

Project 1 : Install Vise ................................................ A-2 Project 2 : Install Vise Jaws........................................ A-4 Project 3 : Square Block............................................. A-5 Project 4 : Contour Square Step .............................. A-13 Project 5 : Base........................................................ A-16 Project 6 : Housing .................................................. A-21 Project 7 : Fan Blades .............................................. A-23 Project 8 : Clamp ..................................................... A-29 Project 9 : Fixture Plate ........................................... A-31 Project 10 : French Curve ........................................ A-33 Project 11 : Honeycomb .......................................... A-38 Project 12 : Bracket ................................................. A-40 Project 13 : MicrowaveHousing .............................. A-49 Project 14 : Geneva Gear ........................................ A-57

Contents

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Contents Appendix B: AlternateTool Setting Methods

Appendix C: CNC Process Planning Form

Fundamentals of CNC Machining

List of Common Methods.......................................... B-1 UsingPaper ................................................................ B-2 1-2-3 Block on Finished Part Face ............................. B-3 1-2-3 Block and Dial Indicator ................................... B-4 Tool Probe ................................................................. B-4

CNC Process Planning Form ............................... C-1, C-2

Appendix D: G-M Code Reference

Appendix E: Glossary

Appendix F: Drill Chart

Milling G- Codes ........................................................ D-1 Milling M-Codes ........................................................ D-2 Lathe G-Codes ................................................... D-3, D-4 Lathe M-Codes .......................................................... D-4

Glossary .............................................................. E-1, E-2

Drill Chart ............................................................F-1, F-2 Inch Pipe Threads .......................................................F-4 MetricTaps .................................................................F-5

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