Handbook of MODERN GRINDING TECHNOLOGY OTHER OUTSTANDING VOLUMES IN THE CHAPMAN AND HALL ADVANCED INDUSTRIAL TECHNOLOGY SERIES V. Daniel Hunt: SMART ROBOTS: A Handbook of Intelligent Robotic Systems David F. Tver and Roger W. Bolz: ENCYCLOPEDIC DICTIONARY OF INDUSTRIAL TECHNOLOGY: Materials, Processes and Equipment Roger W.
Bolz: MANUFACTURING AUTOMATION MANAGEMENT: A Productivity Handbook Igor Aleksander: ARTIFICIAL VISION FOR ROBOTS D. Todd: WALKING MACHINES: An Introduction to Legged Robots Igor Aleksander: COMPUTING TECHNIQUES FOR ROBOTS Robert I. King: HANDBOOK OF HIGH SPEED MACHINING TECH- NOLOGY Douglas M. Considine and Glenn D.
Considine: STANDARD HAND- BOOK OF INDUSTRIAL AUTOMATION V. Daniel Hunt: ARTIFICIAL INTELLIGENCE AND EXPERT SYSTEMS SOURCEBOOK Handbook of MODERN GRINDING TECHNOLOGY Robert I. Hahn CHAPMAN AND HALL NEW YORK LONDON First published 1986 by Chapman and Hall 29 West 35th St. 10001 Published in Great Britain by Chapman and Hall Ltd 1 New Fetter Lane, London EC4P 4EE © 1986 Chapman and Hall All Rights Reserved.
No part of this book may be reprinted, or reproduced or utilized in any form or by any electronic, mechanical or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing 'from the publishers. Library of Congress Cataloging in Publication Data King, Robert I. (Robert Ira), 1924- Handbook of modern grinding technology. Grinding and polishing-Handbooks, manuals, etc.9'2 86-17626 ISBN-13: 978-1-4612-9167-1 e-ISBN-13: 978-1-4613-1965-8 DOl: 10.1007/978-1-4613-1965-8 Acknowledgments We, the authors, acknowledge the excellent assistance given by the fol- lowing organizations during the preparation of the text: Norton Company, 3M Company, Ohio State University, Pneumo Precision Company, and the Lockheed Missiles & Space Company.
This text would not have been possible without their help. The editors wish to give credit to both Kathleen Hahn, for her flawless typing and editing of the draft copies of this complex manuscript, and Donna King, for her support and suggestions during the development and integration of the text. Dedication This book on grinding is dedicated to all those who are searching for a way to improve the productivity of man and machine. Contents Acknowledgments v Dedication vii Preface xi 1 Part Processing by Grinding 3 Robert S.
Hahn 2 Principles of Grinding 30 Richard Lindsay 3 Types of Grinding Wheels 72 William Ault 4 Truing and Dressing of Grinding Wheels 88 William Ault 5 Grinding with Superabrasives 98 R. Mahar 6 Grinding Chatter and Vibrations 119 K. Srinivasan 7 Precision Grinding Cycles 170 Robert S. Hahn 8 Centerless Grinding 190 W.
Jessup 9 Vertical Spindle Surface Grinding 233 David H. Youden 10 Reciprocating Surface Grinding 251 Robert S. Hahn 11 Coated Abrasives 261 E. Duwell 12 Creep Feed Grinding 282 Stuart C.
Salmon IX x Contents 13 Honing 301 Hans Fischer 14 Adaptive Control in Grinding 337 Robert S. Hahn 15 Trouble Shooting Grinding Problems 347 Robert S. Hahn PREFACE The latest information indicates that the United States now spends in excess of $150 billion annually to perform its metal removal tasks using conventional machining technology. That estimate is increased from $115 billion 5 years ago.
It becomes clear that metal removal technology is a very important candidate for rigorous investigation looking toward improvement of productivity within the manufacturing system. To aid in that endeavor, an extensive program of research has developed within the industrial community with the express purpose of establish- ing a new scientific and applied base that will provide principles upon which new manufacturing decisions can be made. One of the metal removal techniques that has the potential for great economic advantages is high-rate metal removal with related tech- nologies. This text is concerned with the field of grinding as a subset of the general field of high-rate metal removal.
Related processes (not cov- ered in this text) include such topics as turning, drilling, and milling. In the final evaluation, the correct decision in the determination of a grind- ing process must necessarily include an understanding of the other methods of metal removal. The term grinding, as used herein, includes polishing, buffing, lapping, and honing as well as conventional defini- tion: ". removing either metallic or other materials by the use of a solid grinding wheel." The injection of new high-rate metal removal techniques into conven- tional production procedures, which have remained basically un- changed for a century, presents a formidable systems problem both technically and managerially.
The proper solution requires a sophisti- cated, difficult process whereby management-worker relationships are reassessed, age-old machine designs reevaluated, .and a new vista of product-process planning and design admitted. The key to maximum xi xii Preface productivity is a "systems approach," even though a significant im- provement in process can be made with the piecemeal application of good solid practice. This text was structured with those concepts in mind. However, the reader should also consider complementing sub- jects, such as machine dynamics, factory flow/loading, management psychology/strategy, and manufacturing economics.
The "bottom line" is to increase the overall effectiveness of the factory from whatever de- vise that is reasonable, that is, to obtain the greatest return on the dollar invested. As an example, consider the technical problem of increasing the speed of the grinding wheel. To realize the benefits of that increase, the table or spindle feedrate must be increased. That in turn has an impact on the basic machine design and the response of the control system.
As the various speeds are increased, new dynamic ranges are encountered that could induce undesirable resonances in the machine and part being fab- ricated, requiring dampening consideration. The proper incorporation of an optimum grinding process into the factory requires the integration of all of the above technical considerations plus many others-a difficult systems solution requiring professional attention. Finally, when making any major change in factory operations, the reader should consider the managerial style used. Keep in mind that the processes suggested in this text could deviate considerably from those that may exist in any particular factory environment.
The use of new techniques would be ill advised if the operating employees are not sup- portive for any reason. Employee involvement and understanding dur- ing process change is necessary for success, and fear of the unknown is unacceptable. King San Jose, California Robert S. Hahn Northboro, Massachusetts February, 1986 Handbook of MODERN GRINDING TECHNOLOGY CHAPTER 1 Part Processing by Grinding Robert S.
Hahn Hahn Associates Introduction The problem of manufacturing high-quality parts at low cost confronts many companies. The cost of processing information required in the manufacturing process is substantial. With the introduction of computer-aided manufacturing, computer-aided process planning, and flexible manufacturing systems, the need for accurate, reliable process and equipment data is great. This chapter describes some of the factors involved in process planning, illustrates the detailed knowledge re- quired to perform typical precision grinding operations, and describes computer-generated grinding cycles and multioperation grinding.
The Grinding Process-Planning Problem The process-planning problem starts with the part print or data base prescribing the part dimensions, the tolerances, requirements for con- centricity, roundness, cylindricity or flatness, squareness, surface finish, surface integrity, cycle time, and production requirements. Those "soft- ware data" or geometric part-print data must be processed to select the appropriate machine tool(s), grinding cycle parameters, and inspection equipment to produce "hard finished parts" satisfying all of the im- posed specifications, as illustrated in Fig. Each machine toollequip- 3 4 Handbook of Modern Grinding Technology WORKPI ECE FINISHED DESCRIPTION WORKPI rCE Geom. Data Equipment Equipment Equipment \ - - _ - - ' Setup Setup Setup ,, No.
Data Data Processor Processor eeds peeds o. of Cuts MACHINE Fig.1 The TOOL manufacturing planning CONTROLLER process ment must be set up. Then, on each setup, for example, Setup No.2, 1 or more operations may be performed. Each operation, in turn, requires a data processor, which converts the geometric part-print specs into feeds and speeds.
Those data must then be fed to the machine tool (grinder) controller. In the case of a typical grinding machine, the rela- tionships between the machine characteristics, the grinding-process characteristics, and the machine input variables are indicated in Fig. Accordingly, the task for the machine tool information processor (per- formed by humans or computer) is to generate the proper feeds and speeds for the grinding-machine controller based upon a knowledge of the machine-tool characteristics, Grinding-Process Characteristics, and Workpiece random variables, as illustrated in Fig. Grinding-Process Variables In planning grinding operations it is necessary to define the various in- puts and outputs and to develop relationships between them.
In order Part Processing by Grinding 5 WORKPIECE FINISHED DESCRIPTION WORKPIECE MACHINE TOOL MACHINE INFORMATION PROCESSOR II. TOOL -'" - WORKPIECE MACHINE INPUT MACHINE TOOL OUTPUT SPECIFICATIONS VARIABLES CHARACTERISTICS VARIABLES DIMENSIONS WHEELSPEED RIGIDITY SIZE ERROR TOLERANCES WORKS PEED POWER TAPER ERROR ROUNDNESS ROUGH FEED ERROR CHAR. OUT OF ROUND SQUARE NESS FINISH FEED SUR. ER ROR SURFACE FINISH SPARKOUT TIME GRINDING PROCESS SUR.
I NTEGRI TV SURFACE INTEGRITY DRESS DEPTH VARIABLES CYCLE TIME SIZE POSITIONS METAL REMOVAL PARA. COS T/ PART RAPID TRAV. THRESHOLD FORCE DRESS INTERVAL BREAKDOWN FORCE WHEELWEAR PARA. WORKPIECE RANDOM VARIABLES STOCK VARIATION HARDNESS VARIATI N ENVIRONMENTAL VARIABLES Fig.2 Abrasive TEMPERATURE processing variables to do that, it is important to distinguish between input variables to the grinding machine and inputs to the grinding process, which occurs at the wheelwork interface.
Typical inputs to grinding machines are: feed- rate or down feed, wheel- and workspeed, depth of dress, and sparkout time, as illustrated to Fig. The input to the grinding process is the normal force developed at the wheelwork interface. The grinding proc- ess is quite analogous to the filing process as carried out by a machinist who places a bar of steel in a vise and files the end of the bar. The input to the filing process is the normal force exerted by the machinist pushing the file down against the work.
The tangential force as well as the amount of chips removed and the resulting surface finish are outputs of the filing process. It is clear that the machinist cannot apply directly, a tangential force per se. Similarly, the normal force is the input to the grinding process while the tangential force, power, stock-removal rate, wheelwear rate, and surface finish are the output variables of the grind- ing process (see Chapter 2 for details). 6 Handbook of Modern Grinding Technology GRINDING PROCESS RELATIONSHIPS INPUTS OUTPUTS FEEDRATE CONCENTRI CITY WHEELSPEED ROUNDNESS WORKS PEED TAPER DRESS DEPTH SIZE TOLERANCE DRESS LEAD SURFACE FINISH SPARKOUT TIME SURFACE INTEGRITY CYCLE TIME CHATTER ~ GRINDING nterface Force GRINDING COS~1 PIECE MACHINE PROCESS heel Sharpness STOCK VARIATIONS HARDNESS VARIATIONS Fig.3 Input/output SYSTEM RI GI DITY variables for grinding machines and the STOCK RUNOUT grinding process On conventional grinding machines the feedrate is controlled.
As the grinding wheel engages the workpiece, forces are induced between wheel and work-the higher the force, the faster the stock removal. The induced force also governs the surface finish, the deflection in the ma- chine, and the onset of thermal damage. Therefore, the induced force is one of the important variables that are uncontrolled in conventional feedrate-grinding machines. The ability of the cutting surface of the grinding wheel to remove stock, called the wheel sharpness, is the second extremely important variable in the grinding process.
In feedrate grinding, as the wheel sharpness drops (the wheel becomes dull or glazed), the induced force rises, resulting in increased deflection and, sometimes, thermal damage. The size-holding ability of feedrate "sizematic" grinders is directly re- lated to their ability to maintain the same force between wheel and work at the instant of retraction. If the induced force fluctuates in value at the termination point in the grinding cycle, the system deflection will also fluctuate and a size error will result unless in-process gaging is used. Even with in-process gaging, taper and surface finish fluctuations will Part Processing by Grinding 7 occur.
Variations in the induced force are caused by stock variations, wheel sharpness variations, workpiece hardness, and microstructure variations.