Trent E.M., Wright P.K. Metal Cutting

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PREFACE

A new edition of Metal Cutting has been prepared. Every chapter is updated emphasizing

new information on machinability and tool materials. Today’s interests in “dry-machining”,

“high speed machining” and “computer modeling” are also featured in brand new chapters.

Chapters 1 through 5 now contain the recent economic trends in the machine tool and metal

cutting industry. There is more information on the essential features of metal cutting, and new

experimental results on the stresses and temperatures that occur during cutting.

Chapters 6 through 8 focus on the materials science aspects of cutting tool materials. Photo-

graphs of tool wear mechanisms and flow patterns in cutting are presented. New developments in

coatings for all types of tool material are described in detail. The new trends in diamond coated

tools are shown and Chapter 8 concludes with a cross-comparison of all tooling types.

Chapters 9 and 10 provide new information on “machinability” and the selection of coolants

and lubricants. These chapters deal with issues that are highly relevant for the day-to-day practitio-

ner of machining. The information includes recommended tooling selection for different work

materials, how to select “free cutting” grades of steel, and how to cut aerospace alloys. Specific

recommendations on “dry machining” are given at the end of Chapter 10. These recommendations

have a broad scope, not limited to cutting fluids alone. An improvement in the “dry-machining” of

steel can be achieved by the commercial introduction of special deoxidation treatments during

steel making. Calcium deoxidation modifies the non-metallic inclusions, the action of which at the

tool/work interface can greatly increase tool life without damage to material properties.

Chapters 11 through 15 are all new in this edition of Metal Cutting. They reflect two essential

aspects of 21st century manufacturing. The first trend is towards high speed machining of aero-

space and other difficult to machine alloys. The economics of this trend are first discussed in

Chapter 11. Next, the material behavior at high strain-rates is reviewed before going into details on

the physics of high-speed machining of aluminum, stainless steel and titanium alloys. The second

trend is the use of the computer to support analytical and computer modeling of cutting. A review

of models, techniques and recent findings is given in Chapter 12.

xii PREFACE

Chapter 13, the Conclusion, provides more information and ideas on the economic impor-

tance of machining. It will be shown that machining is a fundamental base for all 21st century

manufacturing methods and that there is a subtle but crucial link between precision machining

and the semiconductor and biotech industries.

Chapter 14 contains some review exercises for new students to the field.

Chapter 15 contains an extensive Bibliography to other books. These are complementary to

this text. Also, references to other books on forming and rapid prototyping are given, together

with some economic references.

A Web Site for this edition of Metal Cutting has been created which will continue to be

updated with links to other Web Sites and their URLs. Chapter 15 will therefore be an open-

ended resource and we invite colleagues, cutting tool manufacturers and others to add data,

information, interesting homework and assignments.

------------------------

It is especially interesting that the technology of metal cutting continues to have such an

enormous historical and economic range. While metal cutting has roots going back to the Indus-

trial Revolution, it keeps extending its frontiers in response to the everyday needs of a wide

range of contemporary industries. The economic importance of metal cutting using machine

tools cannot be underestimated. Today in industrialized countries, the cost of machining amounts

to more than 15% of the value of all manufactured products in those countries.

Many examples

of this economic importance are apparent at the time of writing, around the year 2000.

First, for standard consumer-products such as automobiles, aircraft and household appli-

ances, metal cutting remains a core production method. The increased international competition

in these basic, consumer-product-oriented industries has demanded greater efficiency and pro-

ductivity. Responding to this challenge, the advances in new tooling, high speed machining, and

modeling are discussed in Chapters 8 through 12. We are grateful to our colleagues at The Boe-

ing Company, Dr. Donald Sandstrom in particular, for the many new insights that are beginning

to emerge on high speed machining. The ideas on high speed machining and tool materials have

also been formed during a long correspondence and association with Dr. R. Komanduri at Okla-

homa State University. In addition, Dr. J.T. Black of Auburn University has contributed many

concepts, during a collaboration and friendship that spans several decades, and he has been par-

ticularly helpful in providing materials and the overall structure for Chapter 12 on modeling.

For higher cutting speeds and hence production rates, ceramic tools, sialon tools and alu-

mina-based tools containing zirconia or silicon carbide “whiskers” have been developed. Mean-

while, ultra-hard polycrystalline diamond, CVD coated diamond and cubic boron nitride have

extended their range of application for cutting very hard and abrasive materials. These trends are

considered in detail in Chapter 8. At the same time, high speed steel and cemented carbide con-

tinue as the tool materials for the bulk of industrial metal cutting operations. Developments of

these tools are reported in Chapters 6 and 7, and relate mostly to PVD and CVD coatings.

Second, metal cutting is more ubiquitous in industrial society than it may appear from the

above description of traditional manufacturing industries. All forgings, for example used in cars

and trucks, and many sheet metal products, for example used in steel furniture and filing cabi-

nets, are formed in dies that have been machined. In fact, most of today’s electronic products are

packaged in a plastic casing that has been injection-molded into a die. Cell phones, computers,

music-systems, the “Walkman” and all such products, thus depend on the metal cutting of dies.

PREFACE xiii

While the initial prototype of a new cell phone might well be created with one of the newer rapid

prototyping processes that emerged after 1987 - stereolithography (SLA), selective laser sinter-

ing (SLS), or fused deposition modeling (FDM) - the final plastic products, made in batch sizes

in the thousands or millions (see Chapter 13) will be injection-molded in a die that has been cut

in metal with great precision and surface finish constraints. The machining of such dies, usually

from highly alloyed steels, requires some of the most exacting precisions and surface qualities in

metal cutting technology. It prompts the need for new cutting tool designs; novel manufacturing

software that can predict and correct for tool deflections and deleterious burrs; and new CAD/

CAM procedures that incorporate the physics and knowledge-bases of machining into the basic

geometrical design of a component. In these regards we are grateful to the recent discussions and

contributions from our colleagues: at the University of California, Berkeley - Dr. David Dorn-

feld, Dr. Paul Sheng, Dr. Carlo Sequin, Dr. Frank Wang, Dr. Sung Ahn, Dr. Kyriakos

Komvopoulos, Dr. Bruce Kramer (concurrently with the National Science Foundation) and Dr.

Jami Shah (concurrently with Arizona State University); at the University of Illinois, Urbana-

Champaign - Dr. Richard DeVor, Dr. James Stori and Dr. Shiv Kapoor; at M.I.T. - Dr. Sanjay

Sarma; at Siemens - Dr. Steven Schofield; at the University of Kentucky - Dr. I. S. Jawahir; at

Ford/Visteon - Mr. Charles Szuluk, Dr. Shuh-Yuan Liou, Dr. Richard Furness and Dr. Shounak

Athavale; at the University of New South Wales - the late Dr. Peter Oxley.

Third, the worldwide semiconductor industry also depends on precision metal cutting as a

core production method for the semiconductor manufacturing equipment, which in turn fabri-

cates the semiconductors. The crucial link between the machine tool industry and the semicon-

ductor and electronics industry is a subtle one that is further expanded with some interesting

Tables in the Conclusion - Chapter 13. For the purposes of this Preface, the key point is: the

machine tool industry is a key building block for industrial society, since it provides the base

upon which other industries perform their production.

This third point can be amplified by considering some basic data in this paragraph, followed

by some historical comparisons in the next two paragraphs. At the time of writing, around the

year 2000, the line-widths (i.e. the length of the field-effect transistor gate) in a typical logic-

transistor of an Integrated Circuit (IC) is about 0.35 microns: during the months this book is

going to press, the gate length will reduce to 0.18 microns in many applications. Computer-aided

design tools, automated process technologies, advanced clean room systems, and rigorous testing

equipment have helped bring semiconductor fabrication to these sub-micron levels. These

demands for ever smaller and more powerful semiconductors produce a corresponding demand

for advanced manufacturing equipment. It includes advanced lithography equipment, specialized

ion-beam machines, chemical-mechanical polishing equipment to achieve ultra-flat surfaces,

lasers and high vacuum systems. The demands from the lithography process, which accounts for

about 35% of the cost of semiconductors, are perhaps the most demanding. As specific exam-

ples: highly precise, magnetically levitated stages are needed for these new generations of semi-

conductors; lenses are being replaced by mirrors which are held on ultra-precise adjustment

stages; the mirrors themselves must be ground and polished to perfection. All such sub-compo-

nents must be fabricated in a machine shop by metal cutting. Furthermore, the new levels of

ultra-precision demand an even greater understanding of the detailed processes going on at the

all-important cutting edge. During precision machining, with small undeformed chip-thick-

nesses, the flow patterns at the cutting edge govern the quality and integrity of the surface finish.

xiv PREFACE

The design of tool angles and the selection of the correct machining parameters have become

even more important than in previous decades.

It is interesting to make some historical comparisons from 200 years ago with the above

demands in semiconductors today. It is well known that the technical roots of the first Industrial

Revolution began with James Watt’s steam engine in 1769. Thereafter, a complex mix of techni-

cal, economic and political factors accelerated the Revolution over a fifty year period between

approximately 1770 and 1820. The period from 1820 to 1910 then saw the rise and consolidation

of many industries including the basic machine tool industry. But in particular, the machine tool

industry remained unique - it was always the essential base upon which these other industries

critically depended. Increased standardization, improved precision, more reliable cutting tools

and more powerful machines, provided a base for all other metal-product type industries. These

secondary industries - Samuel Colt’s gun-making, and Henry Ford’s automobile industry for

example - could only expand because of the availability of reliable machine tools, and this state-

ment remains critically true today for all industries.

One can thus conjecture a similar historical trend, given that society is now in the middle of

a second Industrial Revolution, often called the Information Age Revolution. Rather than begin-

ning with the steam engine in 1769, this new Age begins with the invention of the transistor in

1947. This is followed by a period of approximately fifty years of rapid growth in other transis-

tor technologies, integrated circuits (beginning in 1958), microprocessors (beginning in 1971) all

of which is fueled by the economic and political importance of computing and networking.

Research shows

that the semiconductor industry is now moving into an analogous and a very

necessary period of consolidation in equipment refinement and productivity gains. During this

period, the 21st century semiconductor equipment industries will be the equivalent of the 19th

century machine tool industries - they will be the important base upon which the rest of the

industry will depend upon for growth. This “new machine tool industry of the 21st century” is

redefined as “a combination of the semiconductor equipment manufacturers supported by the

classical base of machine tools, cutting tools and metal cutting theory.”

In summary, the metal cutting process is a basic building-block for consumer product manu-

facturing of all kinds. But it cannot be emphasized enough that metal cutting is fundamentally

related to all other manufacturing processes - not just the obviously metal-based production of

automobiles, airplanes, and humble products such as lawn mowers and washing machines. All

aspects of CAD/CAM, rapid prototyping, die making, and complex equipment making - espe-

cially for semiconductors - have metal cutting at their core.

Edward M. Trent and Paul K. Wright, 1999

1) Merchant, M.E., Machining Science and Technology, 2,157 (1998)

2) Leachman, R.C. and Hodges, D.A., IEEE Transactions on Semiconductor Manufacturing, 9,

(2) 158 (1996)

ACKNOWLEDGMENTS

We have been fortunate in having many able and congenial colleagues during the many years in

which we have been actively interested in the subject of metal cutting. Without their collaboration

and the contributions which they have made in skill and ideas this book would not have been writ-

ten. We would like here to acknowledge the part which they have played in developing our under-

standing of the metal cutting process. We also acknowledge that there are some differences of

opinion on precise issues of chip formation, seizure effects, how diffusion occurs at the chip-tool

interface, and how segmented chip forms are triggered at certain speeds with different work mate-

rials. These different views make the topic of metal cutting lively and engaging for students.

The metallurgical emphasis of this book has its “roots” at Sheffield University, England in the

Metallurgy Department where two people in particular - Dr. Edwin Gregory and Mr. G.A. de Belin

- were responsible for a very high level of teaching in the techniques of metallography.

These traditions were continued in the “Machining Research Group” in the Department of Met-

allurgy and Materials of the University of Birmingham, England, under the late Professor E.C.

Rollason and late Professor D. V. Wilson. In that work we acknowledge in particular the contribu-

tions of Mr. E. Lardner, Dr. D.R. Milner, and the late Professor G.W. Rowe.

Many of the specific photographs that are shown, come from the detailed experimental work

that was carried out by our colleague Edward Smart. His great devotion to the experimental

aspects of machining research, inspired many students in their careers. We miss his cheerful coun-

tenance and hope this book continues to keep his memory alive.

The most important element in the evidence presented here comes from such direct observation

using optical metallography. The field of useful observation is being greatly extended by electron

microscopy and by instruments such as the microprobe analyser. Computer modeling of machin-

ing is now key to the modern analysis. Nevertheless, a high level of optical metallography and

experimental work remains at the center of all investigations - in such work the behavior of tool

materials and work materials are directly observed.

xvi ACKNOWLEDGMENTS

The resources of Wickman-Wimet Ltd. under the former Research Director, Mr. A.E. Oliver,

are acknowledged.

A long association with Kennametal Inc. is also acknowledged and we thank Dr. Yefim Val for

his many years of support and interest.

Similarly, Cincinnati Milacron was a great source of support for the work and we acknowledge

Mr. R. Messinger, Dr. R. Kegg and Mr. L. Burnett.

Thanks are due to the Association for Manufacturing Technology for material in Chapter 1 -

the associations with Mr. Charles Carter have been most valuable.

Collaboration with Sandia National Laboratories has been invaluable and we thank Mr. L. Tal-

lerico, Dr. R. Stoltz, Mr. A. Hazleton and Mr. A. West for their support.

Funding from the Ford Motor (and particularly the Visteon organization) is gratefully

acknowledged and we particularly thank Mr. Charles Szuluk for his long term interest in inte-

grated manufacturing.

We are also indebted to the following: the firms of Fagersta and Speed Steel (Sweden) for

advice and data on properties and performance of high speed steel tools; Dr J. Lumby and Lucas

Industries for information on, and permission to publish an electron micrograph of, sialon; Dr P.

Heath and DeBeers Industrial Diamonds for information on cubic boron nitride and polycrystal-

line diamond and permission to publish photomicrographs of structures and of tool wear.

Support from the National Science Foundation has been invaluable in developing some of the

fundamental ideas on stress analysis and tooling materials. Many colleagues have served at NSF

during the course of the research: Dr. C. Astill, Dr. B von Turkovich, Dr. W. Spurgeon, Dr. J.

Meyer, Dr. T. Woo, Dr. S. Settles, Dr. J. Lee, Dr. M. DeVries, Dr. W. DeVries, Dr. L. Martin-

Vega, Dr. C. Srinivasan, Dr. B. Chern, Dr. B. Kramer, and Dr. G. Hazelrigg have all played a role

in this work. Support from DARPA and ONR is also gratefully acknowledged as is the personal

interest of Dr. W. Isler, Dr. E. Mettala and Dr. J. Sheridan.

The authors are also grateful to their colleagues Dr. E. Amini, Dr. A. Bagchi, Dr. D.A. Dearn-

ley, Dr. B.W. Dines, Dr. R. M. Freeman, Dr. J. Hau-Bracamonte, Dr. R. Komanduri, Dr. Y. Naer-

heim, Dr. R. Milovic, Mr. M.E. Mueller, Dr. M. Samandi, Dr. D. Sandstrom, Dr. J.A. Stori, Mr.

K.F. Sullivan, Dr. J. Wallbank, and Dr. M. L. H. Wise for photomicrographs and graphs acknowl-

edged in the captions to the illustrations which they have contributed.

As well as the specific photomicrographs and graphs acknowledged in the captions, the ideas

in the book have evolved over many decades from close friendships, co-authorships, joint

projects and informal discussions at various conferences. In this regard, we acknowledge a long

association concerning manufacturing and metal cutting with the following colleagues:

•Professor T.H.C. Childs and Dr. P. Dearnley - part of the original group at Birmingham and

now at the University of Leeds;

•Professor D. Tabor, Dr. N. Gane, Dr. J. Williams, Dr. D. Doyle and Dr. J. G. Horne from the

“transparent sapphire tool group” at the Cavendish Laboratory, Cambridge University;

•Mr. L.S. Aiken, Mr. W. Beasley, Mr. P.D. Smith, Dr. J.L. Robinson, Dr. P.S. Jackson, Dr. A.W.

Wolfenden, Professor G. Arndt, Professor R.F. Meyer, and the late Professor J.H. Percy in New

Zealand;

•Professor P.L.B Oxley, Professor E.J.A. Armarego, Professor R.H. Brown and Dr. M.G.

Stevenson in Australia;

ACKNOWLEDGMENTS xvii

•Dr. A. Bagchi, Dr. A.J. Holzer, Dr. D.A. Bourne, Dr. C.C. Hayes, Dr. R.S. Rao, Dr. J.G. Chow,

Dr. S. C. Y. Lu, Dr. D.W. Yen, Dr. C. King, Mr. H. Kulluk, the late Dr. J.L. Swedlow, Dr. M.R.

Cutkosky and Dr. F. B. Prinz (both now at Stanford), Professor S. Finger, Professor M.

Nagurka, Professor P. Khosla, Dr. L. Weiss, Professor R. Sturges, Professor W. Sirignano and

Professor R. Reddy, from the research carried out at Carnegie Mellon University;

•Professor J.T. Schwartz, Professor K. Perlin, Mr. F.B. Hansen, Mr. L. Pavlakos, Dr. J. Hong, Dr.

X. Tan and Mr. I. Greenfeld of the Courant Institute at New York University;

•Professor B.F. von Turkovich at the University of Vermont; Professors R. Komanduri and J.

Mize, now at Oklahoma State University; Professor M.C. Shaw, at Arizona State University;

Dr. O. Richmond, Dr. M. Devenpeck and Dr. E. Appleby at Alcoa Research Laboratories; Pro-

fessor J.T. Black at Auburn University; Professor S. Kalpakjian at the Illinois Institute of

Technology; Professor H. Voelcker at Cornell University; Professor F. Ling at the University

of Texas, Austin; Professors N.P. Suh and D. Hardt at M.I.T.; Professors T. Kurfess, S. Liang,

S. Melkote and J. Colton at Georgia Tech.; Professors S.K. Gupta and D. Nau at the University

of Maryland; Professor W. Regli at Drexel; Professor S. Ramalingam at Minnesota; Dr. R.

Woods at Kaiser Aluminum; Professor D. Williams at Loughborough University, England;

Professor Nabil Gindy, Dr. T. Ratchev and colleagues at Nottingham University; Professor M.

Elbestawi and his group at McMaster University; Professor Y. Altintas at the University of

British Columbia; Professors Y. Koren, G. Ulsoy and J. Stein at the University of Michigan;

Professors K. Weinmann and J. Sutherland at Michigan Technological University; Professor

K.P. Rajurkar at the University of Nebraska; Professor J. Tlusty at the University of Florida;

Professors A. Lavine and D. Wang at UCLA; Professors I. Jawahir, A. T. Male and O. Dillon

at the University of Kentucky; Professor Tony Woo at the University of Washington; Profes-

sor S. Settles now at the University of Southern California; Professor W. DeVries at Iowa State

University; Professors M. DeVries and R. Gadh at the University of Wisconsin; and the many

colleagues at Berkeley, Illinois, M.I.T., Boeing and Ford/Visteon mentioned in the Preface.

The resources of the University of California, Berkeley are acknowledged and thanks are due

to Professor David Hodges, Professor Paul Gray, Professor Dan Mote, Professor David Bogy,

Professor Robert Cole, Professor Shankar Sastry and Professor Robert Brodersen for their col-

laborations and support.

Professors Erich Thomsen, Joseph Frisch and the late Shiro Kobayashi were the founders of

manufacturing related research at Berkeley and we thank them for their support and interest in

this work.

For their detailed assistance in the preparation of this edition we thank Bonita Korpi, William

Chui, Eric Mellers and Zachary Katz. Thanks are also due to V. Sundararajan, C. Smith, G. Sun,

S. Roundy, J. Kim, J. Brock, J. Plancarte, R. Inouye, D. Chapman, R. Hillaire, K. Urabe, N. An,

M. McKenzie, L. Marchetti, J. Smith and S. McMains.

The authors wish to thank the following organizations for permission to reproduce the illustra-

tions listed.

•The Metals Society - Figures 3.7, 3.9, 3.11, 3.22, 5.11, 5.12, 5.14, 6.6, 6.11, 6.12, 6.13, 6.14,

6.15, 6.21, 6.22, 6.26, 7.9, 7.15, 7.17, 7.20, 7.24, 7.32, 9.2, 9.9b, 9.18, 9.27, 9.33, 9.36, 9.43,

10.11, 10.12, 10.15, 10.17.

•International Journal for Production Research - Figures 5.13 to 5.18 , 9.37, 9.38, 9.39.

xviii ACKNOWLEDGMENTS

•International Journal for Machine Tool Design and Research - Figures 9.13, 10.1, 10.2, 10.3,

10.4, 10.5.

•American Society for Metals - Figures 6.27, 9.25

•American Society of Mechanical Engineers - Figures 5.7, 5.8.

•Proceedings of the Royal Society - Figures 4.24 to 4.30

•The following photomicrographs were taken in the laboratories of Wickman Wimet Ltd. who

granted permission for their reproduction: Figures 3.7, 3.9, 3.10, 3.11, 7.2, 7.6, 7.8, 7.9, 7.10,

7.14, 7.15, 7.19, 7.20, 7.21, 7.25, 7.26, 7.27, 7.32, 9.2, 9.26, 9.31, 9.32, 9.36, 9.42, 10.11,

10.12, 10.17.

Our wives, Enid and Terry, and our families have contributed in innumerable ways to the writ-

ing of the book, but especially by spending many hours discussing the presentation and overall

scope. We are very grateful to them for this assistance and for their patience during the months

that we have been preoccupied with the work.

CHAPTER 1 INTRODUCTION:

HISTORICAL AND

ECONOMIC

CONTEXT

1.1 THE METAL CUTTING (or MACHINING) PROCESS

It would serve no useful purpose to attempt a precise definition of metal cutting or machining.

In this book the term is intended to include operations in which a thin layer of metal, the chip or

swarf, is removed by a wedge-shaped tool from a larger body. There is no hard and fast line sepa-

rating chip-forming operations from others such as the shearing of sheet metal, the punching of

holes or the cropping of lengths from a bar. These also can be considered as metal cutting, but the

action of the tools and the process of separation into two parts are so different from those encoun-

tered in chip-forming operations, that the subject requires a different treatment.

There is a great similarity between the operations of cutting and grinding. Our ancestors ground

stone tools before metals were discovered and later used the same process for sharpening metal

tools and weapons. The grinding wheel does much the same job as the file, which can be classified

as a cutting tool, but has a much larger number of cutting edges, randomly shaped and oriented.

Each edge removes a much smaller fragment of metal than is normal in cutting, and it is largely

because of this difference in size that conclusions drawn from investigations into metal cutting

must be applied with reservations to the operation of grinding.

1,2

In the engineering industry, the term machining is used to cover chip-forming operations, and

this definition appears in many dictionaries. Most machining today is carried out to shape metals

and alloys (many plastic products are also machined), but the lathe was first used to turn wood and

bone. The term metal cutting is used here because research has shown certain characteristic fea-

tures of the behavior of metals during cutting which dominate the process and, without further

work, it is not possible to extend the principles described here to the cutting of other materials.

While metal cutting is commonly associated with big industries (automotive, aerospace, home

appliance, etc.) that manufacture big products, the machining of metals and alloys plays a crucial

role in a range of manufacturing activities, including the ultraprecision machining of extremely

delicate components (Figure 1.1).

2 INTRODUCTION: HISTORICAL AND ECONOMIC CONTEXT

FIGURE 1.1 Three relatively distinct manufacturing paradigms (Adapted from Wirtz, 1991)

1.2 A SHORT HISTORY OF MACHINING

Before the middle of the 18th century, wood was the main material used in engineering struc-

tures. To shape wooden parts, craftsmen used machine tools - the lathe among them - which

were typically constructed of wood as well. The boring of cannons and the production of metal

screws and small instrument parts were the exceptions: these processes required metal tools. It

was the steam engine, with its large metal cylinders and other parts of unprecedented dimen-

sional accuracy, which led to the first major developments in metal cutting in the 1760s.

The materials which constituted the first steam engines were not very difficult to machine.

Gray cast iron, wrought iron, brass and bronze were readily cut using hardened carbon steel

tools. The methods of heat treatment of tool steel had been evolved by centuries of craftsmen,

and reasonably reliable tools were available, although rapid failure of the tools could be avoided

only by cutting very slowly. It required 27.5 working days to bore and face one of Watt’s large

cylinders.

At the inception of the steam engine, no machine tool industry existed. The century from

1760 to 1860 saw the establishment of enterprises devoted to the production of machine tools.

Maudslay, Whitworth, and Eli Whitney, among many other great engineers, generated, in metal-

lic components, the cylindrical and flat surfaces, threads, grooves, slots and holes of the many

shapes required by developing industries.

The lathe, planer, shaper, milling machine, drilling

machine and power saws all developed into rigid machines capable, in the hands of good crafts-

people, of turning out large numbers of very accurate parts that had never before been possible.

Dimension

Tolerance

Precision Machining

Very precise small components,

ex.: magnetic read/write heads

Normal Machining

Conventional products,

ex.: many automotive components

Ultraprecision Machining

Quantum electronic and

similar scale devices

μm