Handbook of modern grinding technology

Handbook of

MODERN GRINDING

TECHNOLOGY

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SOURCEBOOK

Handbook of

MODERN GRINDING

TECHNOLOGY

Robert I. King

Robert S. Hahn

CHAPMAN AND HALL

NEW YORK LONDON

First published 1986

by Chapman and Hall

29 West 35th St., New York, N.Y. 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.

(Chapman and Hall advanced industrial technology series)

Bibliography: p.

Includes index.

1. Grinding and polishing-Handbooks, manuals, etc.

I. Hahn, Robert S. II. Title. III. Series.

TJ1280.K53 1986 621.9'2 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.

Acknowledgments v

Dedication vii

Preface xi

1 Part Processing by Grinding

2 Principles of Grinding 30

3 Types of Grinding Wheels

3

72

4 Truing and Dressing of Grinding Wheels

5 Grinding with Superabrasives 98

6 Grinding Chatter and Vibrations 119

7 Precision Grinding Cycles 170

8 Centerless Grinding 190

9 Vertical Spindle Surface Grinding 233

10 Reciprocating Surface Grinding 251

11 Coated Abrasives 261

12 Creep Feed Grinding 282

Contents

Robert S. Hahn

Richard Lindsay

William Ault

88 William Ault

R. L. Mahar

K. Srinivasan

Robert S. Hahn

W. F. Jessup

David H. Youden

Robert S. Hahn

E. J. Duwell

Stuart C. Salmon

IX

x Contents

13 Honing 301

14 Adaptive Control in Grinding 337

15 Trouble Shooting Grinding Problems 347

Hans Fischer

Robert S. Hahn

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.

Robert I. King

San Jose, California

Robert S. Hahn

Northboro, Massachusetts

February, 1986

Handbook of

MODERN GRINDING

TECHNOLOGY

Introduction

CHAPTER 1

Part Processing

by Grinding

Robert S. Hahn

Hahn Associates

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. 1.1. Each machine toollequip￾3

4 Handbook of Modern Grinding Technology

WORKPI ECE

DESCRIPTION

Geom.

Data

Equipment

Setup

No. 1

Fig. 1.1 The

manufacturing planning

process

Equipment

Setup

No. 2

Oper. No.

Data

Processor

eeds

peeds

o. of Cuts

MACHINE

TOOL

CONTROLLER

FINISHED

WORKPI rCE

Equipment \--_--'

Setup

No. 3

,

, L __ _

Oper. No.

Data

Processor

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. 1.2.

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. 1.2.

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

WORKPIECE

DESCRIPTION

- -'"

WORKPIECE

SPECIFICATIONS

DIMENSIONS

TOLERANCES

ROUNDNESS

SQUARE NESS

MACHINE TOOL

INFORMATION

PROCESSOR

MACHINE INPUT

VARIABLES

WHEELSPEED

WORKS PEED

ROUGH FEED

FINISH FEED

II.

SURFACE FINISH SPARKOUT TIME

SURFACE INTEGRITY DRESS DEPTH

SIZE POSITIONS

RAPID TRAV. POS.

DRESS INTERVAL

WORKPIECE

RANDOM VARIABLES

STOCK VARIATION

HARDNESS VARIATI N

ENVIRONMENTAL

VARIABLES

TEMPERATURE

Part Processing by Grinding 5

MACHINE

TOOL

MACHINE TOOL

CHARACTERISTICS

RIGIDITY

POWER

ERROR CHAR.

GRINDING PROCESS

VARIABLES

FINISHED

WORKPIECE

OUTPUT

VARIABLES

SIZE ERROR

TAPER ERROR

OUT OF ROUND

SUR. FIN. ER ROR

SUR. I NTEGRI TV

CYCLE TIME

METAL REMOVAL PARA. COS T / PART

THRESHOLD FORCE

BREAKDOWN FORCE

WHEELWEAR PARA.

Fig. 1.2 Abrasive

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. 1.3. 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

FEEDRATE

WHEELSPEED

WORKS PEED

DRESS DEPTH

DRESS LEAD

SPARKOUT TIME

~ GRINDING

MACHINE

STOCK VARIATIONS

HARDNESS VARIATIONS

SYSTEM RI GI DITY

STOCK RUNOUT

nterface Force

GRINDING

PROCESS

heel Sharpness

OUTPUTS

CONCENTRI CITY

ROUNDNESS

TAPER

SIZE TOLERANCE

SURFACE FINISH

SURFACE INTEGRITY

CYCLE TIME

CHATTER

COS~1 PIECE

Fig. 1.3 Input/output

variables for grinding

machines and the

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