Fundamentals of CNC Machining PDF
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Fundamentals of CNC Machining A Practical Guide for Beginners Fundamentals of CNC Machining Desk Copy Compliments of Autodesk, Inc. Copyright 2014 Autodesk, Inc. 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 Autodesk, Inc. Disclaimer of Liability The entire risk as to its accuracy and quality is with the reader. In no event shall Autodesk, Inc. be liable for direct, indirect, or consequential damages resulting from any defect in this material. Trademarks All brands are the trademark of their respective owners. Printed in the United States of America Registered with the Library of Congress 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 Instructional Resources ............................................. 1-‐5 Recommended Use ................................................... 1-‐6 Overview of CAD/CAM Process ................................. 1-‐6 Chapter 2: Shop Safety Overview ................................................................... 2-‐3 Safety Awareness ...................................................... 2-‐3 Personal Conduct & Shop Etiquette .......................... 2-‐4 Shop Clothing ............................................................ 2-‐4 Proper Shop Attire Illustration ............................... 2-‐5 General Safety Practices ............................................ 2-‐6 CNC Safety Practices .................................................. 2-‐6 Safety Contract .......................................................... 2-‐7 Safety Contract Form ............................................. 2-‐8 Chapter 3: CNC Tools Overview ................................................................... 3-‐3 End Mills .................................................................... 3-‐3 Face Mill .................................................................... 3-‐4 Corner Radius Mill ..................................................... 3-‐5 Slot Mill/Slotting Saw ................................................ 3-‐5 Center-‐Spot Drill ........................................................ 3-‐5 Twist Drill ................................................................... 3-‐6 Tap ............................................................................. 3-‐6 Reamer ...................................................................... 3-‐7 Counterbore .............................................................. 3-‐8 Cutting Tool Fundamentals ....................................... 3-‐8 Rotational Direction ............................................... 3-‐8 Chip Formation ...................................................... 3-‐8 Chip Load ............................................................... 3-‐9 Climb vs. Conventional Milling ............................... 3-‐9 Cutting Speeds and Feeds Formulas ........................ 3-‐10 Speed Formula ..................................................... 3-‐11 Feed Formula ....................................................... 3-‐12 Tap Feed Formula ................................................ 3-‐12 Speed/Feed Examples ............................................. 3-‐13 Milling Speed/Feed Example ................................ 3-‐13 Drill Speed/Feed Example .................................... 3-‐14 i Fundamentals of CNC Machining Contents Tap Speed/Feed Example ..................................... 3-‐15 Maximum Spindle Speed Example ....................... 3-‐16 Cutting Data ............................................................. 3-‐17 Best Practices Machining Parameters .................. 3-‐18 Troubleshooting Speed/Feed Problems ............... 3-‐19 Chapter 4: Coordinate Systems Overview ................................................................... 4-‐3 Cartesian Coordinate System .................................... 4-‐3 Number Line .......................................................... 4-‐3 3D Cartesian Coordinate 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 Work Coordinate 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 Tool Lenght Offset (TLO) ...................................... 4-‐13 Chapter 5: CNC Programming Language Overview ................................................................... 5-‐3 CNC Language and Structure ..................................... 5-‐3 Program Format ..................................................... 5-‐4 CNC Editor ................................................................. 5-‐4 Alphabetic & Special Character Address Codes ......... 5-‐5 Alphabetic Address 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 Chapter 6: CNC Operation Overview of CNC Setup and Operation ..................... 6-‐3 Machine and Tool Offsets ......................................... 6-‐5 Fixture Offset XY .................................................... 6-‐5 Fixture Offset Z ...................................................... 6-‐6 Tool Length Offset (TLO) ........................................ 6-‐7 Haas Control Face ...................................................... 6-‐8 Haas Keyboard ....................................................... 6-‐9 Start/Home Machine ............................................... 6-‐10 Load Tools ............................................................... 6-‐11 Set Tool Length Offset (TLO) ................................... 6-‐13 Set Fixture Offset XY ................................................ 6-‐17 ii Contents Fundamentals of CNC Machining Set Fixture Offset Z .................................................. 6-‐21 Load CNC Program ................................................... 6-‐24 Run CNC Program .................................................... 6-‐26 Adjusting Diameter (CDC) Offsets ........................... 6-‐27 Shut Down CNC ....................................................... 6-‐29 Chapter 7: 2D Milling Toolpaths 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. Machining Features ....................... 7-‐6 Toolpaths by Type and Use ....................................... 7-‐7 2D Machining Features Example ............................ 7-‐8 2D Toolpath Terminology .......................................... 7-‐9 Facing ...................................................................... 7-‐10 2D Contouring ......................................................... 7-‐11 Cutter Diameter Compensation ........................... 7-‐12 Pocketing ................................................................. 7-‐13 Slot Milling ............................................................... 7-‐14 Chamfer Milling ....................................................... 7-‐15 Radius (Corner-‐Round) Milling ................................ 7-‐16 Center Drill .............................................................. 7-‐17 Drilling ..................................................................... 7-‐18 Tapping .................................................................... 7-‐19 Chapter 8: CNC Turning Overview ................................................................... 8-‐3 Lathe Components ................................................. 8-‐4 Spindle ................................................................... 8-‐5 Turret ..................................................................... 8-‐6 Lathe Coordinate System .......................................... 8-‐8 Driven (Live) Tools ..................................................... 8-‐9 Imaginary Tool Tip ................................................... 8-‐10 Part Datum .............................................................. 8-‐11 Tools and Tool Holders ............................................ 8-‐12 Chip Breaker ......................................................... 8-‐12 Relief Angle .......................................................... 8-‐13 Tool Cutting Angles .............................................. 8-‐13 Rake Angle ........................................................... 8-‐14 Insert Designations .................................................. 8-‐15 Lathe Tool Types ...................................................... 8-‐17 Face/Turn Tools ................................................... 8-‐17 Groove Tool .......................................................... 8-‐18 Bore Tool .............................................................. 8-‐19 Thread Tool .......................................................... 8-‐20 Cutoff Tool ........................................................... 8-‐21 Cutting Speeds and Feeds ....................................... 8-‐22 Speed/Feed Example ........................................... 8-‐23 Cutting Feed Example .......................................... 8-‐24 Lathe Setup and Programming Example ................. 8-‐25 Setup .................................................................... 8-‐26 iii Fundamentals of CNC Machining Contents Face ...................................................................... 8-‐27 Rough ................................................................... 8-‐28 Finish .................................................................... 8-‐29 Groove ................................................................. 8-‐30 Thread .................................................................. 8-‐31 Drill ....................................................................... 8-‐32 Bore ...................................................................... 8-‐33 Cutoff ................................................................... 8-‐34 Chapter 9: 3D Toolpaths Overview ................................................................... 9-‐3 3D Cutter Compensation ........................................... 9-‐3 Tolerances ................................................................. 9-‐4 3D Toolpath Setups ................................................... 9-‐6 3D Roughing .............................................................. 9-‐6 Parallel Finish ............................................................ 9-‐7 Scallop Height ........................................................ 9-‐8 3D Scallop .................................................................. 9-‐9 REST Milling ............................................................. 9-‐10 Pencil Toolpaths ...................................................... 9-‐11 Conceptualizing 3D Toolpaths ................................. 9-‐12 Chapter 10: Milling Setups Overview ................................................................. 10-‐3 Fixture Components ................................................ 10-‐3 Subplates and Angle Plates ................................... 10-‐3 Clamps .................................................................. 10-‐4 Shoulder Bolts and Dowel Pins ................................ 10-‐5 Vise Accessories ...................................................... 10-‐5 Hard Jaws ............................................................. 10-‐6 Soft Jaws .............................................................. 10-‐6 Appendix A: CNC Milling Work-‐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 : Microwave Housing .............................. A-‐49 Project 14 : Geneva Gear ......................................... A-‐57 iv Contents Fundamentals of CNC Machining Appendix B: Alternate Tool Setting Methods List of Common Methods .......................................... B-‐1 Using Paper ............................................................... 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 Appendix C: CNC Process Planning Form CNC Process Planning Form ................................ C-‐1, C-‐2 Appendix D: G-‐M Code Reference Milling G-‐ Codes ........................................................ D-‐1 Milling M-‐Codes ........................................................ D-‐2 Lathe G-‐Codes ................................................... D-‐3, D-‐4 Lathe M-‐Codes .......................................................... D-‐4 Appendix E: Glossary Glossary .............................................................. E-‐1, E-‐2 Appendix F: Drill Chart Drill Chart ........................................................... F-‐1, F-‐2 Inch Pipe Threads ...................................................... F-‐4 Metric Taps ................................................................ F-‐5 v Fundamentals of CNC Machining Contents vi Fundamentals of CNC Machining Lesson 1 Introduction & CNC Process Overview Upon successful completion of this lesson, you will be able to: • Describe overall course goal, prerequisites, audience and course design. • Describe the difference between Subtractive Rapid Prototyping (SRP) and Rapid Prototyping (RP) and the advantages and disadvantages of each. • List the tools and equipment required for this course. • List the major lesson topics covered by this course. • List the major student resources available and the information found in course appendices. • Describe the recommended use of course materials to maximize the learning experience. • Describe in general the overall CAD/CAM/CNC process. 1-‐1
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