Metal Cutting Metal Cutting Fourth Edition Edward M Trent Department of Metallurgy and Materials University of Birmingham, England Paul K Wright Department of Mechanical Engineering University of California at Berkeley, U.S Boston Oxford Auckland Johannesburg Melbourne New Delhi Copyright © 2000 by Butterworth–Heinemann A member of the Reed Elsevier group All rights reserved No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher Recognizing the importance of preserving what has been written, Butterworth–Heinemann prints its books on acid-free paper whenever possible Butterworth–Heinemann supports the efforts of American Forests and the Global ReLeaf program in its campaign for the betterment of trees, forests, and our environment Library of Congress Cataloging-in-Publication Data Trent, E M (Edward Moor) Metal cutting / Edward M Trent, Paul K Wright.– 4th ed p cm Includes bibliographical references and index ISBN 0-7506-7069-X Metal-cutting Metal-cutting tools I Wright, Paul Kenneth II Title TJ1185.T73 2000 671.5’3—dc21 99-052104 The publisher offers special discounts on bulk orders of this book For information, please contact: Manager of Special Sales Butterworth–Heinemann 225 Wildwood Avenue Woburn, MA 01801–2041 Tel: 781-904-2500 Fax: 781-904-2620 For information on all Butterworth–Heinemann publications available, contact our World Wide Web home page at: http://www.bh.com 10 Printed in the United States of America TABLE OF CONTENTS Foreword Preface Acknowledgements Chapter Introduction: Historical and Economic Context The Metal Cutting (or Machining) Process A Short History of Machining Machining and the Global Economy Summary and Conclusion References Chapter Metal Cutting Operations and Terminology Introduction Turning Boring Operations Drilling Facing Forming and Parting Off Milling Shaping and Planing Broaching Conclusion References Bibliography (Also see Chapter 15) Chapter The Essential Features of Metal Cutting Introduction ix xi xv 1 9 12 13 14 14 14 16 18 19 19 19 21 21 vi The Chip Techniques for Study of Chip Formation Chip Shape Chip Formation The Chip/tool Interface Chip Flow Under Conditions of Seizure The Built-up Edge Machined Surfaces Summary and Conclusion References Chapter Forces and Stresses in Metal Cutting Introduction Stress on the Shear Plane Forces in the Flow Zone The Shear Plane and Minimum Energy Theory Forces in Cutting Metals and Alloys Stresses in the Tool Stress Distribution Conclusion References Chapter Heat in Metal Cutting Introduction Heat In the Primary Shear Zone Heat at the Tool/work Interface Heat Flow at the Tool Clearance Face Heat in Areas of Sliding Methods of Tool Temperature Measurement Measured Temperature Distribution in Tools Relationship of Tool Temperature to Speed Relationship of Tool Temperature to Tool Design Conclusion References Chapter Cutting Tool Materials I: High Speed Steels Introduction and Short History Carbon Steel Tools High Speed Steels Structure and Composition Properties of High Speed Steels Tool Life and Performance of High Speed Steel Tools Tool-life Testing Conditions of Use 23 24 25 26 29 40 41 47 47 55 57 57 58 60 62 74 79 80 95 95 97 97 98 102 112 113 114 121 126 128 130 130 132 132 133 138 140 144 149 163 166 vii Further Development Conclusion References Chapter Cutting Tool Materials II: Cemented Carbides Cemented Carbides: an Introduction Structures and Properties Tungsten Carbide-Cobalt Alloys (WC-Co) Tool Life and Performance of Tungsten Carbide-Cobalt Tools Tungsten-Titanium-Tantalum Carbide Bonded with Cobalt Performance of (WC+TiC+TaC) -Co Tools Perspective: “Straight” WC-Co Grades versus the “Steel-Cutting” Grades Performance of “TiC Only” Based Tools Performance of Laminated and Coated Tools Practical Techniques of Using Cemented Carbides for Cutting Conclusion on Carbide Tools References Chapter Cutting Tool Materials III: Ceramics, CBN Diamond Introduction Alumina (Ceramic) Tools Alumina-Based Composites (Al2O3 + TiC) Sialon Cubic Boron Nitride (CBN) Diamond, Synthetic Diamond, and Diamond Coated Cutting Tools General Survey of All Tool Materials References Chapter Machinability Introduction Magnesium Aluminum and Aluminum Alloys Copper, Brass and Other Copper Alloys Commercially Pure Iron Steels: Alloy Steels and Heat-Treatments Free-Cutting Steels Austenitic Stainless Steels Cast Iron Nickel and Nickel Alloys Titanium and Titanium Alloys Zirconium Conclusions on Machinability References 167 173 173 175 175 176 177 186 202 205 209 210 211 215 224 225 227 227 227 229 231 236 239 245 249 251 251 252 254 258 269 269 278 290 293 296 303 307 307 309 viii Chapter 10 Coolants and Lubricants Introduction Coolants Lubricants Conclusions on Coolants and Lubricants References Chapter 11 High Speed Machining Introduction to High Speed Machining Economics of High Speed Machining Brief Historical Perspective Material Properties at High Strain Rates Influence of Increasing Speed on Chip Formation Stainless Steel AISI 4340 Aerospace Aluminum and Titanium Conclusions and Recommendations References Chapter 12 Modeling of Metal Cutting Introduction to Modeling Empirical Models Review of Analytical Models Mechanistic Models Finite Element Analysis Based Models Artificial Intelligence Based Modeling Conclusions References Chapter 13 Management of Technology Retrospective and Perspective Conclusions on New Tool Materials Conclusions on Machinability Conclusions on Modeling Machining and the Global Economy References Chapter 14 Exercises For Students Review Questions Interactive Further Work on the Shear Plane Bibliography and Selected Web-sites Index 311 311 313 322 334 337 339 339 340 341 343 348 352 359 360 363 368 371 371 373 374 375 382 397 404 406 411 411 412 414 416 417 422 425 425 434 435 439 FOREWORD Dr Edward M Trent who died recently (March, 1999) aged 85, was born in England, but was taken to the U.S.A as a baby when his parents emigrated to Pittsburgh and then to Philadelphia Returning to England, he was a bright scholar at Lansdowne High School and was accepted as a student by Sheffield University in England just before his seventeenth birthday, where he studied metallurgy After his first degree (B.Sc.), he went on to gain his M.Sc and Ph.D and was awarded medals in 1933 and 1934 for excellence in Metallurgy His special research subject was the machining process, and he continued in this work with Wickman/Wimet in Coventry until 1969 Sheffield University recognized the importance of his research, and awarded him the degree of D.Met in 1965 Prior to the 1950’s, little was known about the factors governing the life of metal cutting tools In a key paper, Edward Trent proposed that the failure of tungsten carbide tools to cut iron alloys at high speeds was due to the diffusion of tungsten and carbon atoms into the workpiece, producing a crater in the cutting tool, and resulting in a short life of the tool Sceptics disagreed, but when tools were covered with an insoluble coating, his ideas were confirmed With the practical knowledge he had gained in industry, and his exceptional skill as a metallographer, Edward Trent joined the Industrial Metallurgy Department at Birmingham University, England in 1969 and was a faculty member there until 1979 Just before his retirement, he was awarded the Hadfield Medal by the Iron and Steel Institute in recognition of his contribution to metallurgy Edward Trent was thus a leading figure in the materials science aspects of deformation and metal cutting As early as 1941, he published interesting photomicrographs of thermoplastic shear bands in high tensile steel ropes that were crushed by hammer blows One of these is reproduced in Figure 5.6 of this text Such studies of adiabatic shear zones naturally led him onward to the metal cutting problem It is an interesting coincidence that also in the late 1930s and early 1940s, another leader in materials science, Hans Ernst, curious about the mechanism by which a cutting tool removes metal from a workpiece, carried out some of the first detailed microscopy of the process of chip formation He employed such methods as studying the action of chip formation through the x FOREWORD microscope during cutting, taking high-speed motion pictures of such, and making photomicrographs of sections through chips still attached to workpieces As a result of such studies, he arrived at the concept of the “shear plane” in chip formation, i.e the very narrow shear zone between the body of the workpiece and the body of the chip that is being removed by the cutting tool, which could be geometrically approximated as a plane From such studies as those by Ernst, Trent and others, an understanding emerged of the geometrical nature of such shear zones, and of the role played by them in the plastic flows involved in the chip formation process in metal cutting That understanding laid the groundwork for the development, from the mid-1950s on, of analytical, physics-based models of the chip formation process by researchers such as Merchant, Shaw and others These fundamental studies of chip formation and tool wear, and the metal cutting technology resulting from it, are still the base of our understanding of the metal cutting process today As the manufacturing industry builds on the astounding potential of digital computer technology, born in the 1950s, and expands to Internet based collaboration, the resulting global enterprises still depend on the “local” detailed fundamental metal cutting technology if they are to obtain increasingly precise products at a high quality level and with rapid throughput However, one of the most important strengths that the computer technology has brought to bear on this situation is the fact that it provides powerful capability to integrate the machining performance with the performance of all of the other components of the overall system of manufacturing Accomplishment of such integration in industry has enabled the process of performing machining operations to have full online access to all of the total database of each enterprise’s full system of manufacturing Such capability greatly enhances both the accuracy and the speed of computer-based engineering of machining operations Furthermore, it enables each element of that system (product design, process and operations planning, production planning and control, etc.), anywhere in the global enterprise to interact fully with the process of performing machining and with its technology base These are enablements that endow machining technology with capability not only to play a major role in the functioning and productivity of an enterprise but also to enable the enterprise as a whole to utilize it fully as the powerful tool that it is M Eugene Merchant and Paul K Wright, June 1999