(RWTHedition) Fritz Klocke (auth )-Manufacturing Processes 1_ Cutting-Springer-Verlag Berlin Heidelberg (2011)

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RWTH edition
RWTH Aachen
Fritz Klocke
Manufacturing Processes 1
Cutting
Translated by Aaron Kuchle
123
Professor Dr.-Ing. Dr.-Ing. E.h. Dr. h.c. Dr. h.c. Fritz Klocke
Laboratory for Machine Tools and Production Engineering
RWTH Aachen University
Steinbachstr. 19
52074 Aachen
Germany
f.klocke@wzl.rwth-aachen.de
Translated by
Aaron Kuchle
Yeungnam University
Korean Language Institute
214-1 Dae-dong Gyeongsan Gyeongbuk 712-749
Korea
aaronkuchle@yahoo.com
ISSN 1865-0899 e-ISSN 1865-0902
ISBN 978-3-642-11978-1 e-ISBN 978-3-642-11979-8
DOI 10.1007/978-3-642-11979-8
Springer Heidelberg Dordrecht London New York
Library of Congress Control Number: 2011925556
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Springer is part of Springer Science+Business Media (www.springer.com)
Preamble About Compendium “Manufacturing
Processes”
Key factors for quality and economic efficiency of industrial production are the
choice of the manufacturing processes and their design. Manufacturing Technology
is an elemental part of the fundamental knowledge of machining engineers. Also
design engineers have to gain knowledge in this field, since they have high respon-
sibility for the manufacturing costs. However, the students as well as practising
experts who are willing to enhance their knowledge have the problem to collect
information. To the current day there is no extensive, but still clear description of
manufacturing processes focussing on the technology itself.
In order to counter this necessity the compendium at hand is supposed to present
an overall picture of the most common machining and non-machining manufac-
turing processes. Additional to the description of the techniques these volumes are
desired to deliver an insight in the underlying physical principles whenever it is
necessary for the understanding of the processes.
The apportionment of the compendium “Manufacturing Processes” into
Volume 1: Cutting
Volume 2: Grinding, Honing, Lapping
Volume 3: Electrical Erosion and Hybride Processes
Volume 4: Forming
Volume 5: Casting, Sintering, Rapid Prototyping
groups techniques with similar active principles together.
In front of the first volume is placed a technique-spanning section to the toler-
ances and questions of the workpiece measuring techniques used in manufacturing.
Within the individual volumes was tried to avoid an encyclopaedic listing of the
techniques. The book series are primarily intended for junior scientists in the fields
of manufacturing technology and construction. In addition, the practitioner will be
able to refurbish or extend his knowledge. The variety of manufacturing problems
v
vi Preamble About Compendium “Manufacturing Processes”
is as large as the multiplicity of the products, and alone with text book wise sayings
manufacturing questions are not to be solved. We wish that this book offers starting
points and ways to its readers, on which they can come up with successful solutions
by engineering thinking.
Aachen, Germany Fritz Klocke
September 2010
Preamble for Volume 1 “Cutting”
The available volume treats machining with geometrically defined cutting edges.
It approaches both the practical engineer and the student of engineering sciences.
This book is based on the lecture “Manufacturing Technologies I and II” and the
pertinent exercises, which are held at RWTH Aachen University. The arrangement
of the book results from the experiences, which were gained when lecturing in the
chronology of the course.
The structure of the book is oriented to a large extent at didactical criteria. The
first section deals with the metrology and the workpiece quality, followed by a chap-
ter about the fundamentals of cutting. Based on the common technological principle
of the cutting processes and their variants, the second section deals with the mech-
anisms occurring at the cutting edge and the resulting loads on the tools. The next
section deals with the demands on the cutting materials as well as their manufac-
turing processes and application. The text presents topics like the use of the finite
element method for cutting processes as well as cutting fluids. A detailed chapter
about the machinability of the most important work piece materials, such as steel
and cast iron, light metal alloy and high temperature resistant materials imparts a
broad knowledge of the alternating coactions of work piece material, the cutting
material and the process parameters.
The necessity for process control, used sensor systems and application possi-
bilities are regarded. Due to the increasing relevance and application in industrial
manufacturing plants, monitoring systems are discussed in their own chapter.
Finally, the different cutting processes and their kinematic characteristics are
presented in detail.
For their cooperation with the compilation of the available edition I would
like to thank my co-workers, Dr.-Ing. M. Abouridouane, Dr.-Ing. K. Gerschwiler,
Dipl.-Ing. M. Arft, Dipl.-Ing. C. Essig, Dipl.-Ing. P. Frank, Dipl.-Ing. A. Krämer,
Dipl.-Ing. D. Lung, Dipl.-Ing. H. Sangermann, Dipl.-Ing. R. Schlosser, Dipl.-Ing.
vii
viii Preamble for Volume 1 “Cutting”
P. Vogtel, as well as Dipl.-Ing. S. E. Cordes, who was additionally responsible for
the coordination of the work on this book.
Further I would like to thank the many former co-workers, who participated in
the past German editions and now have leading positions in industry and research
companies.
Aachen, Germany Fritz Klocke
September 2010
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Metrology and Workpiece Quality . . . . . . . . . . . . . . . . . . 3
2.1 Manufacturing Disturbances and Manufacturing History . . . . 3
2.2 Measuring and Testing . . . . . . . . . . . . . . . . . . . . . . 8
2.2.1 Measurement Errors . . . . . . . . . . . . . . . . . . 9
2.2.2 Macro- and Microgeometry of Components . . . . . . 10
2.3 Length Testing Devices . . . . . . . . . . . . . . . . . . . . . . 13
2.3.1 Material Measures . . . . . . . . . . . . . . . . . . . 13
2.3.2 Gauges . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.3.3 Indicating Measuring Instruments . . . . . . . . . . . 14
2.4 Surface Inspection . . . . . . . . . . . . . . . . . . . . . . . . 21
2.4.1 Surface Parameters . . . . . . . . . . . . . . . . . . . 22
2.4.2 Subjective Surface Inspection . . . . . . . . . . . . . 26
2.4.3 Surface Measurement . . . . . . . . . . . . . . . . . . 27
2.5 Inspection of the Workpiece Rim . . . . . . . . . . . . . . . . 30
2.5.1 Surface Layers . . . . . . . . . . . . . . . . . . . . . 31
2.5.2 Inspection of the Surface Rim Zone . . . . . . . . . . 33
3 Fundamentals of Cutting . . . . . . . . . . . . . . . . . . . . . . . . 39
3.1 The Cutting Part – Concepts and Terms . . . . . . . . . . . . . 39
3.2 Reference Systems . . . . . . . . . . . . . . . . . . . . . . . . 42
3.3 Basic Process Variants. . . . . . . . . . . . . . . . . . . . . . 45
3.4 Chip Formation . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.4.1 The Cutting Process . . . . . . . . . . . . . . . . . . 47
3.4.2 Different Types of Chip Formation . . . . . . . . . . . 49
3.5 Kinematic Surface Roughness . . . . . . . . . . . . . . . . . . 54
3.6 Mechanical and Thermal Strain on the Cutting Section . . . . . 55
3.6.1 Influence of the Geometry of the Cutting Section . . . 68
3.7 Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
3.7.1 Wear Mechanisms . . . . . . . . . . . . . . . . . . . 71
3.7.2 Causes of Wear . . . . . . . . . . . . . . . . . . . . . 74
3.7.3 Forms and Dimensions of Wear . . . . . . . . . . . . 85
ix
x Contents
3.8 Cutting Theory . . . . . . . . . . . . . . . . . . . . . . . . . . 87
3.8.1 Shear Plane Theory . . . . . . . . . . . . . . . . . . . 87
3.8.2 Application of Plasticity Theory to Cutting . . . . . . 92
4 Cutting Tool Materials and Tools . . . . . . . . . . . . . . . . . . . 95
4.1 Overview of Cutting Tool Materials . . . . . . . . . . . . . . . 95
4.1.1 Classification of Hard Cutting Tool Materials . . . . . 97
4.2 Tool Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
4.2.1 Cold Work Steels . . . . . . . . . . . . . . . . . . . . 100
4.2.2 High Speed Steels . . . . . . . . . . . . . . . . . . . 101
4.3 Cemented Carbides . . . . . . . . . . . . . . . . . . . . . . . . 110
4.3.1 Historical Development . . . . . . . . . . . . . . . . 111
4.3.2 Cemented Carbide Production . . . . . . . . . . . . . 112
4.3.3 Components of Cemented Carbides and Their
Properties . . . . . . . . . . . . . . . . . . . . . . . . 114
4.3.4 Microstructure . . . . . . . . . . . . . . . . . . . . . 116
4.3.5 Classification of Cemented Carbides . . . . . . . . . . 117
4.3.6 Uncoated Cemented Carbides and Cermets . . . . . . 123
4.3.7 Function Gradient Cemented Carbides . . . . . . . . . 123
4.3.8 Coated Cemented Carbides and Cermets . . . . . . . . 126
4.4 Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
4.4.1 Coating Methods . . . . . . . . . . . . . . . . . . . . 128
4.4.2 Specific Properties of Hard Material Coatings . . . . . 149
4.4.3 Substrate Pretreatment . . . . . . . . . . . . . . . . . 161
4.5 Ceramic Cutting Tool Materials . . . . . . . . . . . . . . . . . 161
4.5.1 Cutting Ceramics . . . . . . . . . . . . . . . . . . . . 162
4.5.2 Superhard Non-metallic Cutting Tool Materials . . . . 173
4.6 Tool Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
4.6.1 Solid Tools . . . . . . . . . . . . . . . . . . . . . . . 185
4.6.2 Tools with Inserts . . . . . . . . . . . . . . . . . . . . 187
4.7 Tool Preparation . . . . . . . . . . . . . . . . . . . . . . . . . 193
5 Finite Element Method (FEM) . . . . . . . . . . . . . . . . . . . . 197
5.1 Basic Concepts of FEM . . . . . . . . . . . . . . . . . . . . . 197
5.2 Lagrangian and Eulerian Considerations of the Continuum . . . 199
5.3 Explicit and Implicit Methods of Solution . . . . . . . . . . . . 199
5.4 Combined Thermal and Mechanical FEA . . . . . . . . . . . . 200
5.5 Nonlinearities . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
5.6 Material Laws . . . . . . . . . . . . . . . . . . . . . . . . . . 201
5.7 Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
5.8 Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
5.9 Phases of a Finite Element Analysis (FEA) . . . . . . . . . . . 205
5.10 The Use of FEM in Cutting Technology . . . . . . . . . . . . . 206
5.10.1 Continuous Chip Simulation . . . . . . . . . . . . . . 207
5.10.2 Segmented Chip Simulation . . . . . . . . . . . . . . 209
5.10.3 Simulation of the Cutting Process . . . . . . . . . . . 212
Contents xi
6 Cutting Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
6.1 The Functions of Cutting Fluids . . . . . . . . . . . . . . . . . 219
6.2 Types of Cutting Fluids . . . . . . . . . . . . . . . . . . . . . . 219
6.2.1 Non Water-Miscible Cutting Fluids . . . . . . . . . . 220
6.2.2 Water-Based Cutting Fluids . . . . . . . . . . . . . . 221
6.3 Guidelines on the Use of Coolant Emulsions . . . . . . . . . . 222
6.4 Effects of the Cutting Fluid on the Machining Process . . . . . 223
6.5 Selection of Cutting Fluids . . . . . . . . . . . . . . . . . . . . 226
6.6 Reducing or Avoiding the Use of Cutting Fluids . . . . . . . . . 227
6.6.1 Reducing Cutting Fluids . . . . . . . . . . . . . . . . 228
6.6.2 Minimum Quantity Cooling Lubrication (MQCL) . . . 229
6.6.3 Avoiding Cutting Fluids . . . . . . . . . . . . . . . . 233
7 Tool Life Behaviour . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
7.1 Determining Tool Life Parameters . . . . . . . . . . . . . . . . 239
7.2 Machinability . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
7.2.1 Tool Life . . . . . . . . . . . . . . . . . . . . . . . . 240
7.2.2 Resultant Force . . . . . . . . . . . . . . . . . . . . . 243
7.2.3 Surface Quality . . . . . . . . . . . . . . . . . . . . . 245
7.2.4 Chip Form . . . . . . . . . . . . . . . . . . . . . . . 248
7.2.5 Cutting Speed . . . . . . . . . . . . . . . . . . . . . . 248
7.3 The Machinability of Steel Materials . . . . . . . . . . . . . . 249
7.3.1 Metallographic Constituents . . . . . . . . . . . . . . 250
7.3.2 Carbon Content . . . . . . . . . . . . . . . . . . . . . 252
7.3.3 Alloying Elements . . . . . . . . . . . . . . . . . . . 254
7.3.4 Types of Heat Treatment . . . . . . . . . . . . . . . . 256
7.4 Machinability of Various Steel Materials . . . . . . . . . . . . 263
7.4.1 Machining Steels . . . . . . . . . . . . . . . . . . . . 263
7.4.2 Case-Hardened Steels . . . . . . . . . . . . . . . . . 266
7.4.3 Heat-Treatable Steels . . . . . . . . . . . . . . . . . . 267
7.4.4 Nitrided Steels . . . . . . . . . . . . . . . . . . . . . 268
7.4.5 Tool Steels . . . . . . . . . . . . . . . . . . . . . . . 269
7.4.6 Hardened Steels . . . . . . . . . . . . . . . . . . . . 271
7.4.7 Non-rusting Steels . . . . . . . . . . . . . . . . . . . 274
7.5 Machinability of Cast Iron . . . . . . . . . . . . . . . . . . . . 280
7.5.1 White Cast Iron . . . . . . . . . . . . . . . . . . . . . 280
7.5.2 Grey Cast Iron . . . . . . . . . . . . . . . . . . . . . 283
7.6 Machinability of Non-ferrous Metals . . . . . . . . . . . . . . 290
7.6.1 Aluminium Alloys . . . . . . . . . . . . . . . . . . . 290
7.6.2 Magnesium Alloys . . . . . . . . . . . . . . . . . . . 293
7.6.3 Titanium Alloys . . . . . . . . . . . . . . . . . . . . 296
7.6.4 Copper Alloys . . . . . . . . . . . . . . . . . . . . . 311
7.6.5 Nickel Alloys . . . . . . . . . . . . . . . . . . . . . . 314
7.7 Machinability of Non-metals . . . . . . . . . . . . . . . . . . . 327
7.7.1 Graphite . . . . . . . . . . . . . . . . . . . . . . . . . 327
7.7.2 Fibre-Reinforced Plastics . . . . . . . . . . . . . . . . 331
xii Contents
8 Process Design and Process Monitoring . . . . . . . . . . . . . . . 339
8.1 Finding Economical Cutting Parameters . . . . . . . . . . . . . 339
8.1.1 Cutting Parameter Limits . . . . . . . . . . . . . . . . 339
8.1.2 Optimizing the Cutting Parameters . . . . . . . . . . . 342
8.1.3 Calculating the Machine Hour-Rate . . . . . . . . . . 350
8.1.4 Planning Methods and Tools . . . . . . . . . . . . . . 351
8.2 Process Monitoring . . . . . . . . . . . . . . . . . . . . . . . . 352
8.2.1 Sensors for Process Monitoring . . . . . . . . . . . . 354
8.2.2 Signal Processing and Monitoring Strategies . . . . . 371
9 Processes with Rotational Primary Movement . . . . . . . . . . . . 383
9.1 Turning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383
9.1.1 Face Turning . . . . . . . . . . . . . . . . . . . . . . 385
9.1.2 Cylindrical Turning . . . . . . . . . . . . . . . . . . . 386
9.1.3 Helical Turning . . . . . . . . . . . . . .. . . . . . . 387
9.1.4 Profile Turning . . . . . . . . . . . . . . . . . . . . . 388
9.1.5 Form Turning . . . . . . . . . . . . . . . . . . . . . . 389
9.1.6 Further Process Variants . . . . . . . . . . . . . . . . 390
9.2 Milling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
9.2.1 Process Variants, Specific Characteristics and Tools . . 395
9.3 Drilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416
9.3.1 Profile Counterboring . . . . . . . . . . . . . . . . . . 416
9.3.2 Rotary Drilling . . . . . . . . . . . . . . . . . . . . . 418
9.4 Sawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439
9.4.1 Bandsawing . . . . . . . . . . . . . . . . . . . . . . . 439
9.4.2 Hacksawing . . . . . . . . . . . . . . . . . . . . . . . 442
9.4.3 Circular Sawing . . . . . . . . . . . . . . . . . . . . 442
10 Processes with Translatory Primary Movement . . . . . . . . . . . 445
10.1 Broaching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445
10.1.1 Face and Circular Broaching . . . . . . . . . . . . . . 446
10.1.2 Profile Broaching . . . . . . . . . . . . . . . . . . . . 449
10.1.3 Form Broaching . . . . . . . . . . . . . . . . . . . . 451
10.2 Shaving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 454
10.3 Planing and Shaping . . . . . . . . . . . . . . . . . . . . . . . 457
10.3.1 Face Shaping and Face Planing . . . . . . . . . . . . 458
10.3.2 Gear Shaping . . . . . . . . . . . . . . . . . . . . . . 459
10.3.3 Gear Planing . . . . . . . . . . . . . . . . . . . . . . 466
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469
Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497
Symbols and Abbreviations
Capital Letters
A mm2 Cross section
A % Stretch ratio
Ac1 Transformation temperature (Start of austenite formation)
Ac3 Transformation temperature (End of austenite formation)
Aα mm2 Flank face
A′α mm2 Minor flank face
Aγ mm2 Rake face
A� mm2 Shear face
AFK Aramid Faser reinforced plastics
AIP Arc Ion Plating
AV mm Offset
BAZ Machining center
Cf min Axis intercept of the expanded TAYLOR equation,
f = 1 mm
Cv min Axis intercept of the expanded TAYLOR equation,
vc = 1 m/min
CBN Cubic boron nitride
CFK Carbon fibre reinforced plastics (CFRP)
CNC Computerised Numerical Control
CVD Chemical Vapour Deposition
CWT Continuous wavelet transform
D mm Tool diameter
DC Direct current
DLC Diamond-like carbon
DMS Strain gauge
DP Polycrystalline diamond
DWT Discrete wavelet transform
E Young’s modulus
EB-PVD Electron beam-PVD
xiii
xiv Symbols and Abbreviations
ECM Electro chemical machining
EDX Energy-dispersive X-ray spectroscopy
F N Resultant force
Fa N Active force
Fc N Cutting force
FD N Thrust force
Ff N Feed force
Fp N Passive force
F� N Shear force
FFT Fast Fourier transform
FVK Fibre-reinforced plastic (FRP)
GFK Glass-reinforced plastic (GRP)
H mm Stroke length
HB Brinell hardness
HC Diamond coated cemented carbide
HF Fine grain cemented carbide
HF-CVD Hot-Filament-Process-CVD
HM Cemented carbide
HRC Rockwell hardness
HSC High Speed Cutting
HSS High Speed Steel
HT-CVD High temperature-CVD
HV Vicker hardness
KA C Imputed amortizations
KE C Energy costs
KI C Maintenance costs
KF,min C/St. Minimal manufacturing costs per workpiece
KMH C/h Machine hour-rate
KML C Machine and labour cost hourly rate
KR C Room costs
KZ C Imputed interest
KB mm Crater width
KM mm Crater center distance
KSS Cutting fluid
KT mm Crater depth
L C/h Hourly wage
LARC Lateral Rotating Arc
MQCL Quantity Cooling Lubrication
MQC Minimum quantity cooling
MQS Minimum quantity lubrication
MQL Minimum quantity lubrication
MSIP Magnetron Sputter Ion Plating
MT-CVD Moderate Temperature-CVD
NC Numerical control
Symbols and Abbreviations xv
NE-Metalle Non-ferrous metals
PA-CVD Plasmaactivated-CVD
Pc W Cutting power
Pe W Effective power
Pf Assumed working plane
Pf W Feed power
Pn Tool cutting edge normal plane
Pne Effective cutting edge normal plane
Po Tool orthogonal plane
Pp Tool back plane
Pr Tool reference plane
Ps Cutting edge plane
PW W Effective power
PKD Polycrystalline diamond
PM Powder metallurgy
PM-HSS Powder Metallurgy High Speed Steel
PVD Physical Vapour Deposition
Q C Charge
R � Electrical resistance
Ra μm Average roughness
Re N/mm2 Elastic limit
REM Scanning electron microscope (SEM)
Rkin μm Surface quality
Rm N/mm2 Tensile strength
Rp0,2 N/mm2 0.2%–yield strength
Rt μm (Depth of) Surface roughness
Rz μm Averaged surface roughness
RF Radio Frequency
S Major cutting edge
S′ Minor cutting edge
SKV μm Rounded cutting edge
STFT Short-Time Fourier Analysis
SVα mm Displacement of the cutting edge in the direction of
the flank face
SVγ mm Displacement of the cutting edge in the direction of
the rake face
T min Tool life
T ◦C Temperature
Tm ◦C Melting temperature
Tr ◦C Room temperature
Tsp ◦C Temperature on the chip upper side
U V Voltage
U0 V Feeding voltage
VB mm Width of flank wear land
xvi Symbols and Abbreviations
VBmax mm Maximal width of flank wear land
VHM Cemented Carbide
Wc J Cutting work
We J Effective work
Wf J Feed work
WZ-D mm Tool diameter
WSP Insert
Z Atomic number
ZTU Time Temperature Transformation (TTT)
Small Letters
ae mm Width of cut
ap mm Depth of cut
apmax mm Maximum depth of cut
apok mm Optimal-cost depth of cut
a-C Hydrogenfree amorphous carbon film
a-C:H Hydrogenated amorphous carbon film
at.-% Atomic ratio
B mm Width of undeformed chip
bfα mm Width of chamfer
C m/min Speed of sound
cp Process capability index
cpk Rectified process capability index
dij pC/N Piezoelectric coefficient
dW/dt m/min Growth of wear
f mm Feed
fa mm Axial feed
fok mm Optimal-cost feed
fmax mm Maximal feed
fmin mm Minimal feed
fr mm Radial feed
fz mm Feed per tooth/cutting edge
f0 1/s Eigenfrequency
H mm Undeformed chip thickness
hch mm Chip thickness
hcu,max μm Maximal chip thickness
hmin mm Minimal chip thickness
K Strain sensitivity
kc1.1 N/mm2 Specific cutting force, b = h = 1 mm
kf1.1 N/mm2 Specific feed force, b = h = 1 mm
ki N/mm2 Specific resultant force
kp1.1 N/mm2 Specific passive force, b = h = 1 mm
Symbols and Abbreviations xvii
lc m Cutting path
lf m Feed path
mc Exponent of the specific cutting force
mn mm Normal module
pKSS bar Cutting fluid pressure
rε mm Corner radius
rß mm Rounded cutting edge radius
sd Coating thickness
T mm Pitch
T s Time
te,min min Minimal time per unit
tg min Basic time
tv min Additional time
te min Time per unit
ter min Recovery time
th min Main process time
tn min Auxiliary process time
tr min Setting-up time
ta-C Tetrahedral hydrogenated amorphous carbon film
vc m/min Cutting velocity
vch m/min Chip velocity
vf m/min Feed velocity
vfax mm/min Axiale feed velocity
ve m/min Effective velocity
x mm Profile offset
z Number of teeth
Greek Letters
α ◦ Tool clearance angle
αeff ◦ Effective tool clearance angle
αf ◦ First tool orthogonal clearance (Broaching)
αF
◦ Clearance angle at the pitch diameter (Gear shaping)
αo
◦ Tool clearance angle
αoe
◦ Working clearance angle
β ◦ Wedge angle
βo
◦ Wedge angle
βoe
◦ Working wedge angle
γ o
◦ Tool orthogonal rake angle
γ n
◦ Tool normal rake angle
γ ne
◦ Working rake angle
γ oe
◦ Wirk-Orthogonalspanwinkel
γ eff ◦ Effective rake angle
xviii Symbols and Abbreviations
ε Strain
ε¯ Shear strain
˙¯ε s–1 Shear strain speed
ε˙ 1/s Strain rate
εk Critical strain
εr
◦ Tool included angle
η ◦ Effective cutting speed angle
ϑ ◦C Temperature
κ r
◦ Tool cutting edge angle
κ re
◦ Working cutting edge angle
λs
◦ Tool cutting edge inclination
λse
◦ Working cutting edge inclination angle
μ Coefficient of friction
φ ◦ Phase
φ ◦ Shear angle
φf ◦ Slide angle
ϕ ◦ Feed motion angle
ρ kg/m3 Density
σN/mm2 Stress
σn N/mm2 Normal stress
ω rad/s Angular speed
Chapter 1
Introduction
From about 12,000 to 50,000 years ago, human beings could already adapt stone
tools with intentionally produced edges to specific machining tasks by varying the
geometry of the cutting edge, as is shown in early tool findings from the Palaeolithic
Age (Fig. 1.1).
The discovery of how to extract metals such as copper, tin and iron was a huge
milestone in the history of material and manufacturing technology. Since about
700 B.C., tools were almost exclusively made of iron. At the beginning of the 17th
century, constant improvements in iron smelting led to the preferred use of iron and
steel as construction materials instead of other metals known then and in place of
wood, which had predominated until then.
Inspired by the growth of the textile industry and the discovery of the steam
engine, there was increased exploration into manufacturing technology at the begin-
ning of the 19th century, leading by the second half of the 19th century to the
first systematic investigations into cutting methods and initiating a completely new
research area. At the end of the 19th century further research led to the discovery
of new cutting tool materials and, at the turn of the century, to the development of
high speed steel by F.W. TAYLOR, a significant contribution to the history of manu-
facturing technology [Tayl07]. In light of these developments, SCHLESINGER said:
“The dividends may lie on the cutting edge of steel, but the speed of these cutting
edges is a function of the machine moving them, so as wages increase, the cutting
machine is a trump card.” [Schl11].
Subsequent research followed in this direction, leading to the development of
cemented carbide in 1923 by SCHRÖTER [Schr23, DRP25] at the SOCIETY FOR
ELECTRIC LIGHTING as well as its use in machining by FRIEDR. KRUPP AG as
WIDIA cemented carbide. Following this was the invention of oxide-ceramic cutting
tool materials and their application in cutting after 1938 by OSENBERG as well
as WENTORF’s development and synthesis of the superhard cutting tool material
cBN (cubic-crystalline boron nitride) in 1956 [Went57]. The refinement of cutting
tools with wear-resistant cemented carbide coats starting in 1968 by the companies
Sandvik Coromant and Friedr. Krupp AG was a major contribution to improving
productivity and economy [Sche88].
In order to fulfill the constantly increasing requirements made on workpiece
quality and to make machining processes more economical, all the influencing
1F. Klocke, Manufacturing Processes 1, RWTH edition,
DOI 10.1007/978-3-642-11979-8_1, C© Springer-Verlag Berlin Heidelberg 2011
2 1 Introduction
Saw
Drill
End scraper
Gravettian point Notched point
Stemmed-base
hafted scraper
Side scraperRound scraperDouble tines
Fig. 1.1 Flint tools, acc. to KERND’L [Kern72]
parameters relevant for productivity and workpiece quality must be considered:
cutting edge geometry, process kinematics, cutting parameters, materials, cutting
tool materials and their coatings, wear behaviour as well as auxiliary materials. In
this pursuit, the following quotation by SCHLESINGER can act as a guideline: “The
machine tool must be designed with a view to the place it is used”.
As an introduction to the subject matter, the compendium will be preceded by a
general chapter providing a survey of the most important attributes of workpieces
and their test methods.
Chapter 2
Metrology and Workpiece Quality
2.1 Manufacturing Disturbances and Manufacturing History
The basic task of manufacturing is to provide workpieces with specified quality
characteristics in the required quantity in the most time- and cost-efficient way
possible. Every manufacturing process is affected by variable disturbances, which
can be both external and internal (occurring within the process itself). For this rea-
son, the functionally determinative properties of the components are provided with
tolerances. If a characteristic value lies outside of the permissible tolerance, it is
defective. Thus important functional characteristics must be tested either already
during manufacturing or at the end of manufacturing. Important disturbance factors
which must be taken into consideration as possible causes of defects are: distur-
bances caused by static forces, such as deflections effected by the workpiece weight
or clamping errors; disturbances caused by dynamic forces which lead to either
self-starting or forced oscillations; disturbances caused by thermal influences, such
as process heat or internal sources of heat in the machine tool; and disturbances
caused by tool wear (Fig. 2.1). This group also includes disturbances resulting from
the engagement kinematics between the tool and the workpiece, such as generated
cut deviations occurring during hobbing or diffraction effects on optical surfaces
caused by systematically applied tool marks.
Functionally determinative quality characteristics can be defined through macro-
geometrical properties. Macro-geometrical properties include, for example, the
accuracy of dimension, form and position of geometrical elements. Micro-
geometrical parameters include, for example, characteristic surface values, such
as roughness, mean roughness value and polishing depth. However, the functional
integrity of the process requires that certain properties are tolerated although they
lie below the surface in the peripheral surface zone. These may include hardness
values, residual stresses or certain structural properties.
The fluctuations of characteristics occurring in every manufacturing process can
basically be derived from the influence of either systematically or randomly occur-
ring disturbances. Systematic errors are caused by the system. They are reproducible
under identical boundary conditions and change the characteristic in a single direc-
tion; they cause manufacturing trends. Systematically acting disturbances cause
deviations in characteristics. If the causes of systematic errors are known, they can
3F. Klocke, Manufacturing Processes 1, RWTH edition,
DOI 10.1007/978-3-642-11979-8_2, C© Springer-Verlag Berlin Heidelberg 2011
4 2 Metrology and Workpiece Quality
Prozess
Statical disturbances
• Clamping fault
• Deflection
•
Thermal disturbances
• Internal heat sources
• Strain
• Process heat
• Environmental effect
•
Tool wear
• Displacement of cutting edge
• Flank wear
• Flank roughness
• Grinding wheel wear 
•
Dynamic disturbances
• Self-starting oscillation
• Forced oscillation
e.g. triggered over basement
•
• • •
• • •
• • •
• • •
Fig. 2.1 Variable disturbances in manufacturing
be corrected and compensated. Examples of systematic errors are geometric errors
of machine guiding elements and the development of cutting edge offset through
the continuous wear of turning tools used in turning processes. Changes of the cut-
ting force caused by sudden cutting depth fluctuations and the workpiece deflections
associated with them may also be of systematic nature (Fig. 2.2).
Randomly occurring disturbances lead to changes to characteristics, the effects
of which cannot be predicted in a strictly deterministic way. They influence the
result in both a positive and a negative direction. Thereby, the work result becomes
unstable. The influence of random disturbances on the work result can, however,
be statistically recorded. Examples of this include fluctuations in the structure of a
material, random temperature fluctuations or sudden self-starting oscillations (rat-
tling oscillations). Within real processes, it is not always easy to clearly decide
between systematic and random influences.
An important parameter describing the effect of random disturbances on a quality
characteristic (i.e. on the variation of a quality characteristic) is process capabilityor the process capability index (Fig. 2.3).
These process capability indices can only be applied if the variation of the
characteristics are normally distributed. In practice, it is frequently required that
cp ≥ 1.33. The process capability index is always taken as the dominant process
2.1 Manufacturing Disturbances and Manufacturing History 5
N
om
in
al
 d
ia
m
et
er
Pa
ss
iv
e 
fo
rc
e 
F P
 
 
/ N
 
D
im
en
si
on
al
 e
rr
or
/ µ
m
Feed direction
Cutting path
600
400
200
10
5
0
Workpiece material
Cutting tool material
Cutting speed 
Feed
Ck55 N
HW P10
Cutting part geometry:
κr = 70°
εr = 90°
rε = 0.8 mm
Cutting path
800
1000
v = 160 m/min
= 0.25 mm
vc
f
γ0 = 6°
α0 = 5°
lS = 0°
Fig. 2.2 Influence of passive force on dimensional accuracy
design criterion when large numbers of pieces must be manufactured with the high-
est possible level of productivity. Variation in manufacturing batches occur, when
it can not be guaranteed that all active elements work securely during the process
being at its performance limits. If, for example, cutting edges are randomly failed
during a cutting process because of cutting edge fractures or layer failures, this
can have an immediate, significant on the process capability. Another example of
critical process conditions is when the quantities of heat entering the workpiece
at high process performances cause thermal strain to induce an increased variation
of geometrical characteristics. These examples reveal that measuring and testing
procedures in manufacturing are necessary both to guarantee the quality of the
manufactured part and to start and develop processes.
In general, several manufacturing steps are necessary to manufacture a part.
Manufacturing progresses result from a manufacturing chain or a manufacturing
sequence. With every manufacturing step, characteristic changes (geometry, surface,
peripheral surface zone) are left behind on the part. Thus a manufacturing history
develops (Fig. 2.4). The output properties of the part following a certain manufac-
turing step in turn become the input factors for the processing steps which follow.
There can also be a significant interaction between the current step in the process
and previous changes.
6 2 Metrology and Workpiece Quality
s 3s
Process capability indices
cp = 0,71
cpk = 0,71
cp = 2,50
cpk = 1,00
cp = 1,67
cpk = 1,33
cp = 5,00
cpk = 5,00
LTL 10
15
20UTL
NV
x - LTL
x x
Mean value of the random sample UTL: Upper tolerance limit 
Estimation of the spread of the totality LTL: Lower tolerance limit
Mean deviation of the random sample NV: Nominal Value
σ :
s :
x :
Minimum proximity to process limit
Half process spread
=cpk =
Tolerance band
Process spread
=cp =
UTL - LTL
2 ( 3·σ )
xx
_
_
_
_
_
_
_
_
_
_
_
_
_
_
^
^
_
_
|x - NV|min
3 σ^
^
=
6s
T
_
Fig. 2.3 Process capability indices
Lu
Ll
Lu
Ll
Machining
center
Grinding
machine tool
k1a c2b knx
Turning
milling Hardening
Hard
machining Assembling
Forging,
cold
extrusion 
Enveloping cut
deviation Texture
Lu
Ll
Anisotropism
Lu
Ll
Lu,l Upper and
lower limit
c1a k2b cnX
k, c Damping and
stiffness
Machining
center
Geometry
Fig. 2.4 Manufacturing history (Source: Getrag Ford)
2.1 Manufacturing Disturbances and Manufacturing History 7
Box part: Automobile-gearbox made of Mg-alloy 
AZ 91hp
Standard tolerance IT 4
Requested cpk = 1.67
Manufacturing process: Primary shaping, machining
Manufacturing dispersion: Affected by residual stress, chucking 
0.008
0.01
Fig. 2.5 Representative case study – box part
The hole in a transmission part shown in Fig. 2.5 could not be manufactured in
a procedurally secure way with the required process capability index and specified.
There can also be a significant interaction between the current step in the process
and previous changes. The hole in a transmission part shown in Fig. 2.5 could not
Work piece:
Blisk
(Blade integrated Disk)
made of TiAl6V4
Tool:
End milling cutter
(D = 8 mm)
Manufacturing process: Forming, 5-axis-milling
Manufacturing dispersion: Process instability, chatter marks, long 
and slander tools 
Source: MTU
stabil
instabil
stability boundD
ep
th
 o
f c
ut
/m
m
Speed / min–1
Fig. 2.6 Stability bounds when milling a BLISK
8 2 Metrology and Workpiece Quality
Manufacturing process: Forming, turning, drilling, broaching
Manufacturing dispersion: Process anomaly,
tool life decrease of the part
Source: Rolls-Royce
Work piece: Turbine disk
made of 
Inconel718
Tool: VHM-drill 
(D = 8 mm)1000 10000 100000 1000000
Numbers of change of load
K
t xσ
ap
pl
. / 
M
Pa
50 µm
Without anomaly 
Smeared material
Low thermal influencing
High thermal influencing
Fig. 2.7 Surface damages when drilling with a worn drill
be manufactured in a procedurally secure way with the required process capability
index and the demanded productivity. This is due to released residual stresses which
arised in the previous die-casting process.
Figure 2.6 shows a part manufactured by milling with long, slender end mills.
The milling process is only stable for certain combinations for cutting speed
and depth of cut. When these areas are exceeded, rattling oscillations occur. These
characteristic stability areas must be known; otherwise the process cannot be carried
out at the performance limit.
However, not only impermissible macro-geometrically or micro-geometrically
recognizable changes may limit the process, but also impermissible changes in the
peripheral surface zone. Figure 2.7 shows a turbine disk which was exposed to
high mechanical and thermal stresses caused by machining the drill holes. These
stresses damaged the peripheral surface zone in a way that significantly diminished
the fatigue strength of the part.
2.2 Measuring and Testing
Quality characteristics must be tested during the manufacturing due to the boundary
manufacturing conditions mentioned above. This can be done by means either of
samples or of a 100% test. A 100% characteristic check is prescribed for many
safety-related parts. Though, a 100% test does not assure freedom of errors.
2.2 Measuring and Testing 9
Testing means determining whether the test sample exhibits the required char-
acteristics, such as dimension, form and surface quality. This determination can be
made in different ways, thus the distinction between subjective testing and objective
testing.
Subjective testing is performed by means of the sensory perception of the tester,
e.g. visual and tactile tests. Examples of this are the evaluation of burr formations
on the edges of parts and of shadings on polished surfaces.
In objective testing, the tester is supported by testing equipment. There are two
further methods which fall under this category; measuring and gauging.
Measurement is the comparison of a characteristic with a measurement standard.
The result is a measured value. Gauging is the comparison of the test object with
a dimension or a form. The result is information regarding whether the specified
requirements were satisfied or not (go or not-go).
Testing equipment is subdivided into measuring instruments, gauges and aids.
Measuring instruments and gauges are distinguished by material measures cor-
responding to the measurand. Material measures can be of mechanical, electric,
optical and electronic nature. Mechanical material measures may be, for example,
distances between surfaces or angular positions of surfaces. Indicating measuring
instruments have movable markers, divisions or counters. When using these devices,
the measuredvalue reading can be either direct analogue or digital. In contrast to
this, the gauge body corresponds merely to the dimension or the dimension and form
of the required characteristic. Intermediate values cannot be defined.
Table 2.1 provides a survey of the attainable accuracy values when using different
manufacturing processes.
Table 2.1 Survey of manufacturing qualities
16
Primary shaping
Die forming (warm)
Extrusion (cold)
Turning 
Drilling
Reaming
Milling
Grinding
1 2 3 4 5 6 7 98 10 11 12 13 14 15
Standard tolerance IT
Deep drawing
Erosion
2.2.1 Measurement Errors
As a matter of principle, every measurement result is subject to error. Possible
reasons for measurement errors are shown in the ISHIKAWA diagram in Fig. 2.8.
The causes of measurement errors may lie in the measuring method, the measuring
10 2 Metrology and Workpiece Quality
Measurement
Measuring method Preparation Environment
Temperature
Humidity 
Air pressure
Vibration 
Extraneous light
Interference field
Measuring personMeasuring deviceMeasured object
Preliminary
arrangements
Cleanliness
Protocol
Calibration
Unconsidered
disturbances
Aptitude 
Abbé principle error
Testing
deviation
Aim of the
measurement 
Measuring uncertainty
Aptitude
Measuring forces 
Assembling
Aptitude 
Routine 
Evaluation
Visual acuity
Mistake
Attention
error
Fig. 2.8 Causes for measuring errors by the measuring procedure
instrument, the measured object, the person measuring, the preparation involved and
the environment.
In order to achieve a high measurement accuracy, it is necessary to take the
abovementioned influences into consideration and, where applicable, to minimize
them, compensate them, or at least to estimate them in terms of their magnitude.
It can principally be distinguished between systematic and random disturbances in
measurement procedures, as well [DIN1319a].
2.2.2 Macro- and Microgeometry of Components
2.2.2.1 Structural Deviations
With regards to components, the distinction is often made between macro-
geometrical parameters and the surface quality. Macro-geometrical parameters refer
to deviations of dimension, form and position. The surface quality is defined by
roughness parameters. The transitions between these categories are not always
clearly definable. DIN 4760 offers a general system for organizing structural devi-
ations (Fig. 2.9). Therefore it is necessary to define the term “surfaces” at the
beginning. The real surface (primary surface; see DIN EN ISO 4287) is the sur-
face actually present on the part. The actual surface is the metrologically registered
surface. It may differ from the real surface, since every measuring method can only
approximate the real surface. A geometrically ideal surface is assumed in designs
2.2 Measuring and Testing 11
Superposition of structural deviations
1st up to 4th Order
5th Order: textural structure
6th Order: lattice structures of the material
4th Order: scores, scales (roughness)
3rd Order: grooves (roughness)
2nd Order: waviness
1st Order: form deviations 
Structural deviations
(in superelevated representation)
Not easily representable
Fig. 2.9 Structural deviations, acc. to DIN 4760
and forms the basis of tolerances. In Fig. 2.9 six orders of structural deviations are
defined on the basis of these observations.
Structural deviations of the 1st order (see also the following sections) are fre-
quently the result of systematic errors. With regards to waviness, i.e. the structural
deviations of the 2nd order, one cannot clearly define whether they are caused by
systematic or random influences. The unbalance of a rotating tool and any peri-
odical oscillations caused by it are forced, while sudden rattling oscillations are
self-starting. In general, fundamentally different actions must be implemented in
order to exclude any systematic or random causes of error. Structural deviations
of the 3rd order also occur regularly. They are to be attributed to the penetration
between tool and workpiece and are often determined by means of penetration
calculations. Examples of these are kinematic roughness associated with turning,
surface marks created in peripheral milling and generated cut deviations created
in hobbing. In such cases, the structural deviations can be influenced in a targeted
way by means of generation kinematics and tool design. The higher orders of struc-
tural deviation are primarily random in their occurrence. Examples of structural
deviations of the 4th order include chip formation processes and removal processes.
Roughness of the 5th order is rendered visible by structural properties on the surface.
This can play a significant role in the high-precision machining of metallic optical
mirrors. Thus in high-precision turning of multicrystalline metals, grain boundaries
may become visible because the individual crystals exhibit varying orientations and
therefore varying stiffnesses. In this case, anisotropism of the grains becomes visible
on the surface.
12 2 Metrology and Workpiece Quality
In general, all the structural deviations on a real surface are superposed. Filters
are employed to separate roughness and waviness in a measurement process [DIN
EN ISO 4287]. The following sections will treat macrogeometrical deviations of
structure, form and position, as well as the corresponding measurement technology.
Section 2.4 and the following sections describe the metrological recording of higher-
order structural deviations.
2.2.2.2 Form Deviations
Form deviations refer to deviations from a specified ideal geometrical property,
such as straightness, evenness, roundness or cylindric form [DIN EN ISO1101,
VDI2601].
The following will introduce some examples of form errors and their causes
(Fig. 2.10).
• A cause for deviations from the cylindric form of a workpiece can be the incorrect
alignment of the workpiece on the machine tool with respect to the tool.
• Another cause for form deviations is the continuous alteration over time of the
tool geometry caused by wear.
• Thermal displacements of the workpieces, tools and machine tools can also lead
to form deviations.
• Deviations from cylinder form can also arise when the workpiece deflects
because of a radial strain. This can happen, for example, e.g. when turning long,
slender parts when the workpiece is not supported.
• Roundness errors can develop through the incorrect clamping of the workpieces
on the machine tool.
2.2.2.3 Position Deviations
Position deviations are deviations of the position of a geometrical element with
respect to a reference, such as an edge, circulation line or axis of the predetermined
position. In general, the position of two surfaces or axes in relation to each other is
indicated by simple length or angle specifications.
Fig. 2.10 Deviations from
circularity and cylinder form
2.3 Length Testing Devices 13
Fig. 2.11 Deviations from
concentricity, straightness
and parallelism
Position deviations as shown in Fig. 2.11 may arise, for example, through
incorrect clamping or defective clamping devices.
2.3 Length Testing Devices
2.3.1 Material Measures
A material measure in length measurement technology represents lengths or angles
by means of fixed distances or angles between surfaces or lines. Setting standards
are material measures. The material measures used most frequently are gauges.
The most important and most precise material measures in length measurement
technology are parallel gauge blocks. They consist of two plane-parallel measuring
surfaces made of hardened steel or cemented carbide. Parallel gauge blocks are used
in prismatic and cylindric forms. Gauge blocks are composed of grades. A standard
set contains 5 grades each containing 9 blocks, from which almost any dimensions
can be assembled (see Fig.2.12). The measuring surfaces are superfinished and even
enough to allow, after careful cleaning of the measuring surfaces, individual gauge
blocks to be joined together so that they adhere.
Fig. 2.12 Gauge blocks (Source: Mahr)
2.3.2 Gauges
A gauge measures dimensions or forms generally according to limit dimensions
[DIN2257]. It can be distinguished between inspection gauges, limit gauges and
form gauges (Fig. 2.13).
14 2 Metrology and Workpiece Quality
21,5
G
o
G
u
Fig. 2.13 Types of gauges: inspection gauges, form gauges, limit gauges
Square profile
Go side
Not go side
Multitooth profile 
Go side
Not go side
Go side
Not go side
Shaft
Go
side
Not go side
Drill hole
Fig. 2.14 Different types of limit gauges
Inspection gauges are parts of a gauge set for which the measure is assembled
from the combination of gauges. Examples are the combination of parallel gauge
blocks and the setting of feeler gauges.
Form gauges allow for the testing of profiles using the light-slit method. They
include angles, radius gauges and thread gauges.
Limit gauges function according to Taylor’s principle: The go gauge must be
designed in such a way that the dimension and form of the workpiece can be
inspected when combined with the gauge. Not-go gauges are only used to inspect
single dimensions.
Limit gauges used most frequently are calliper gauges, limit plug gauges, gaug-
ing rings and thread gauges (Fig. 2.14). Gauges are the simplest testing equipment
used in industrial manufacturing.
2.3.3 Indicating Measuring Instruments
Indicating measuring instruments consist of a material measure and a display mech-
anism. The indicating range is the range of measured values that can be displayed
on a measuring instrument. The measuring range is the part of the indicating range
for which display deviations lie within specified or agreed limits. The suppression
range of a measuring instrument is the range which must be exceeded in order that
2.3 Length Testing Devices 15
the instrument can begin to display values. The hysteresis of a measuring instrument
equals the difference of the display values determined by measuring from different
directions. The hysteresis of a measuring instrument is often not constant, which
means that only a certain lower limit is indicated. The reversal error is principally
a systematic error. It can be compensated. The sensitivity of a measuring instru-
ment is the ratio of an observable change on the measuring instrument display to the
causative parameter. Using length measuring instruments, the sensitivity is defined
as the ratio of the range of the indicating element (e.g. the indicator) and the range
of the measuring element (e.g. the spindle or measuring arm). Conversion between
the measurement range and the display may be based on different physical prin-
ciples. The most frequently used conversion elements are mechanical, electrical,
pneumatic, optical and electronic conversion elements.
2.3.3.1 Instruments with Mechanical Converters
Instruments with mechanical converters utilize mechanical or optical indicating
elements. In length measurement technology, the most often used measuring instru-
ments function on the basis of mechanical converters, e.g. threads, racks, gearwheels
and blade segments (Fig. 2.15).
With mechanical callipers with sliding glideways as the conversion element, the
material measure is mounted on the bar on which the display, i.e. the slider, is
moved. Mechanical callipers have two different scales which can be read off against
each other by the observer. The scale on the slider is called a vernier (Fig. 2.15).
In the case of micrometers, highly precise threads are used as converters and as
a material measure. The system comprises a measuring spindle running in a sleeve,
whose forward face is designed as the measuring surface and whose back end car-
ries a ground thread as material measure. Typical thread pitches are 0.5 and 1 mm.
As seen with callipers, two different scales are read off against each other. One scale
is mounted on the sleeve, the other on the scale drum. In order to avoid influencing
Fixed measuring jaw
Moveable
measuring jaw
Clamp
Bar
Vernier
Linear scale
Measuring
ambos
Measuring
spindle
Scale sleeve
Thimble
Coupler
Fig. 2.15 Setup of callipers and micrometers
16 2 Metrology and Workpiece Quality
Arm with
blade
segment
Rack
Pinion
Prestressed
spring
Plug gauge
Fig. 2.16 Setup of dial gauges and dial comparator
the measurements through large fluctuations in the measuring force, the latter is lim-
ited to 5–10 N by means of a coupler (ratchet coupling). Micrometers are designed
both as outside micrometers for external dimensions and as inside micrometers for
internal dimensions (Fig. 2.15).
Dial gauges are length measuring instruments equipped with racks and gear-
wheels as conversion elements which allow a larger view of the path of the plug
gauge. The material measure lies in the gear mechanism, the conversion element
which leads to measurement reversal errors due to anisotropic friction and potential
tolerance. Needle positions greater than 360◦ are possible (Fig. 2.16).
Dial comparators are the most precise mechanical length measuring instruments.
They are equipped, unlike dial gauges, with a gear mechanism as lever arm system,
gear segment and pinion as conversion elements. Thereby, the movement of the plug
gauge is transmitted to the needle. The design only allows needle positions smaller
than 360◦ (Fig. 2.16).
In principle, all the instruments with mechanical conversion elements described
here can be equipped with frictionless optical indicator elements in order to improve
precision. Given constant conversion behaviour, the more precise indications the
measuring instrument should display, the longer the indicator must be. However,
since there is only a limited amount of space in the instruments and, above all,
since the inertia of the indicator can lead to distorted measurement results when the
measurement range is small, optical indicator elements are used. The principle is
basically this: a beam of light is directed to the material measure and, according to
the position of the material measure, this beam is reflected in a different direction.
The optical indicator then displays the measurement range of the material measure
without friction and inertia.
Further potential for increasing precision can be exploited by means of a fine
graduation of the scale which can no longer be observed with the naked eye, thus
necessitating optical magnifying aids in the form of microscopes. By means of the
microscope, a mechanism consisting of an objective and an ocular, a magnifica-
tion of a real image by the objective can be viewed with the ocular. In this way, a
remagnified virtual image of the object is created. The total magnification through
2.3 Length Testing Devices 17
a microscope is the product of the objective and ocular magnifications. The scale
graduation can be applied in the ocular directly or by means of an ocular plate.
Microscopes including measuring oculars are called measuring microscopes.
2.3.3.2 Instruments with Electrical Converters
These instruments are used to determine changes in the measurand caused by alter-
ations of electrical properties, such as resistance, inductance and capacity. The turns
of a coil, the distance between plates of a condensator and the resistance of an
electrical conductor can all serve as material measure. Inductance, for example, is
altered by changing the immersion depth of an iron core; the capacity of a plate
capacitor is a function of the plate distance (Fig. 2.17).
C
˙
s 
UB
UA
=
UA = Bridge-output voltage
UB = Bridge-supply voltage
C = Capacity
s = Measurement range
o
= Electric constant
r = Dielectric constantA = Surface area 
d = Distance
Position encoder
Sensor
Position encoder
Output to
measuring
amplifier 
L1
L2
s
R4
UA
UB
R3
d
C = r˙ 
Ao
˙
ε
ε
ε ε
Fig. 2.17 Capacitive and inductive measuring principles
18 2 Metrology and Workpiece Quality
Inductive position encoder
Fig. 2.18 Inductive working sensor in real execution
An alteration of the ohmic resistance can be effected by changing the conductor
length and/or by a cross-sectional variation [Hoff04, Grot05]. Figure 2.18 shows a
real execution for multi-point measuring with inductive working sensors.
2.3.3.3 Instruments with Optical Converters
These length measuring instruments exploit the wave property of light. The wave-
length of light is used as the material measure. Figure 2.19 shows the functional
principle of a laser interferometer.
Mirror
Laser
Detector
Wedge prism of
the measuring
beam
Measuring path
Polarizing
beam splitter 
Displacement
Wedge prism
of the reference beam 
R
ef
er
en
ce
 p
at
h
Interference of
measuring und
reference beam
Fig. 2.19 Longimetry with laser interferometer
2.3 Length Testing Devices 19
ϕ2
ϕ3
λ3
λ1
λ2
Time
Am
pl
.
l
Am
pl
.
Time
Am
pl
.
Time
TimeA
m
pl
.
Interference of two coherent
light waves out of phase
(destructive interference) 
Monochromatic light
Am
pl
.
Time
Interference of two coherent
light waves with the same
 phase length
(Addition of illuminance) 
λ: Wavelength
ϕ : Phase difference
Light mixture of different
wavelengths 
Monochromatic and 
coherent light
λ ≠ const. ϕ ≠ 0 λ = const. λ = const.ϕ ≠ 0 ϕ = 0
ϕ2
ϕ3 λ
λ
Fig. 2.20 Optical measuring principle, interference
A light source emits coherent, monochromatic light whose beam is split into a
reference beam and a measuring beam at a polarizing beam splitter. These beams are
reflected on a respective wedge prism and combined again through superposition.
Finally, the combined beam is detected and evaluated. If the wedge prism of the
measuring beam is shifted, interferences occur because of the difference of the opti-
cal paths of the two partial beams after combining them. These are fluctuations in
light intensity via eliminating and amplifying light. Integral multiples of the wave-
lengths lead to an amplification, phase differences of 180 degrees to an elimination
of light (Fig. 2.20).
The number of interference lines is directly related to the path being measured.
Since the wavelength of the light is a function of temperature and also air pressure
and humidity, these influences are compensated within the device. The advantages
of such systems lie in their large measuring range and especially in their contactless
measurements.
2.3.3.4 Instruments with Pneumatic Converters
These instruments use pressure and flow rates as material measures (Figs. 2.21
and 2.22).
This measuring principle can be used for both tactile and contactless measure-
ment (Fig. 2.22).
There are two types of such measuring instruments: high-pressure and low-
pressure instruments. High-pressure instruments work with an operating pressure
greater than 0.5 bar, low-pressure instruments with an operating pressure lower than
20 2 Metrology and Workpiece Quality
1 2 3
4
s
Volume measuring
method
1. Air filter
2. Pressure control
3. Flowmeter
4. Measuring nozzle
1 2
h
6
3 4
5
s
Velocity measuring
method
1. Air filter
2. Pressure control
3. Venturi-nozzle
4. Flow of valve
5. Measuring nozzle
6. Differential pressure
 manometer
Fig. 2.21 Measuring principle of pneumatic distance measurement
Air inlet
Valve
Follower
Work piece
Guide body
Measuring
nozzles
Drill hole
Tactile measurement Contactless measurement
Fig. 2.22 Pneumatic sensor
0.1 bar. The pressure range between 0.1 and 0.5 bar is outside the operating range
of the instrument [DIN2271a].
Figure 2.23 shows the functional principle of contactless pneumatic measure-
ment. The left side shows an external measurement, the right side an internal
measurement. If the measuring rod is designed in a way that both measuring nozzles
2.4 Surface Inspection 21
Measuring
nozzle ∅dm
h
Annulus
pa pa
ps
Work piece surface Measuring
nozzle 
Test sample
Fig. 2.23 Functional principles and examples for pneumatic measurement
work within the linear range of the characteristic diagram, then an exact centring in
the hole is unnecessary, since the air currents of the two nozzles are added and the
sum represent the measure for the total gap width. Since the type of hole measure-
ment described is a two-point measurement, deviations from hole roundness and
diameter can be determined by turning the rod or the workpiece.
The measuring rods are often specially adjusted to the measurement of a spe-
cific workpiece. Therefore, for economical reasons, pneumatic measurement is used
predominately in serial production, especially if a 100% test is required.
The advantages of contactless pneumatic measurement lie in the self-cleansing
effect of the measuring device (i.e. the workpieces do not generally have to be
cleansed of oil, dirt or micro-chips) and in the quickness of the measuring process.
2.3.3.5 Electronic Measuring Instruments
These devices work with photoelectric sensors, by which light-dark fields of a gauge
are converted into electric signals. The material measure is realised through the
light-dark fields. Impulse gauges and code gauges are preferably used as path mea-
surement systems. To be precise, it is a mechanical guidance system whose positions
are detected and indicated optoelectronically. This path measurement system is also
executed with callipers, dial gauges and dial comparators. It is also realized in
coordinate measuring devices and machine tools. To control measuring axes and
to evaluate data, an exact control system and effective software are required which
can influence the quality of the measuring result and the applicability of the data
[Pfei01]. The measurement of freeform surfaces and tooth-flank topographies on
spur gears and bevel gears with coordinate measuring devices is currently state of
the art (Fig. 2.24).
2.4 Surface Inspection
The task of characterizing a technical surface consists in attaining a complete
topological record of its three-dimensional geometry and describing it. Often, in
order to simplify the measuring process, only parameters for surface roughness
along a single measured length are registered (one-dimensional parameters). This
22 2 Metrology and Workpiece Quality
Fig. 2.24 3-D coordinate measuring machines
procedure is frequently followed in practice and is sufficient in many cases. For cer-
tain applications, e.g. in optics or for characterizing grinding wheel surfaces, more
comprehensive, multi-dimensional surface descriptions must be used. However, the
following will exclusively treat one-dimensional parameters.
2.4.1 Surface Parameters
In most of the procedures used in industrial surface inspection technology, only
structural deviations of the second or higher orders are analyzed and measured on
surface sections. These sections must be statistically representative for the entire
surface [DIN2257]. The surface can be detected by means of surface sections or
the bearing surface (Fig. 2.25) [DIN4760]. Profile sections are sections which are
oriented to the surface normally, tangentially or at other angles.
First, a profile section will be used to illustrate some of the basic terms of surface
inspection technology (Fig. 2.26). With respect to a profile, the distinction is made
between the test length Lt of the surface section being metrologically detected and
Tangential cross sectionProfile
α
Profile
Cross section parallel to
the tangentialcross section Diagonal crosssection
Vertical cross sections
Fig. 2.25 Registration of structural deviations by surface cuts
2.4 Surface Inspection 23
Ra
Z (x)
Measured length L
Zt
1
L1 L2 L3 L4 L5 L6
Zp
1
Zv
1
Zv
2
Zp
6
x
Fig. 2.26 Fundamental terms of surface inspection technology
the measured length L, which is used for evaluation (L < Lt) [Grot05]. The detected
profile (actual profile) of a surface depends on the measuring procedure and the filter
used, thus it only represents an approximate image of the actual surface. The refer-
ence profile shifted within the measured length perpendicularly to the geometrically
ideal profile is defined as the middle profile. This is oriented in such a way that the
surface areas above and below the middle profile line are equally large (Fig. 2.26).
By using different measuring procedures and depending on which filter is used,
different profiles can be determined [DIN EN ISO 4287]. These are the P-Profile
(primary profile), the R-Profile (roughness profile) and the W-Profile (waviness
profile) (Fig. 2.27).
Grenzwellenlänge: λ = 0,75 mm
1 
µm
250 µm
1 
µm
250 µm
1 
µm
250 µm
W-Profil (Welligkeit)
R-Profil (Rauheit)
Without wave filter
High-pass filter
Low-pass filter
W-Profile (waviness)
R-Profile (roughness)
Cutoff wavelength: λ = 0,75 mm
250 µm
1 
µm
250 µm
1 
µm
250 µm
1 
µm
P-Profile (waviness and roughness)
Manufacturing technology: Short-stroke honing
Average roughness: Ra = 0.75
Scanning system: HAT 25/6
Scanning path: 10 mm
Fig. 2.27 Separation of waviness and roughness by wave filter
24 2 Metrology and Workpiece Quality
The examples given below refer to the R-Profile (roughness) (Fig. 2.26).
According to DIN EN ISO 4287, the following roughness parameters can be
distinguished:
• The height of the highest profile point Rp: value of the y-coordinate Z(x) of the
highest profile point of the middle profile line within the sampling length Li.
• The depth of the deepest profile valley Rv: value of the y-coordinate Z(x) of
the deepest point of the profile of the middle profile line within the sampling
length Li.
• The total height of the profile Rt: the sum of the highest profile point and the
depth of the deepest profile valley within the measured length L.
• The greatest height of the profile Rz: the sum of the height of the highest pro-
file point Rp and the depth of the deepest profile valley Rv within a sampling
length Li.
• The mean roughness value Ra: the arithmetic mean of the values of the
y-coordinates Z(x) within a sampling length Li.
Ra = 1L
L∫
0
|Z(x)| dx (2.1)
Horizontal parameters (distance parameters) are also designated as bearing
lengths. They are determined by means of tangential sections. Forming a ratio
of of the summed single bearing lengths and dividing by the measured length
yields the relative bearing length (material ratio) in a specified section depth c.
By creating sections at different depths c, the bearing ratio curve – also called the
ABBOTT-FIRESTONE curve – can be determined (Fig. 2.28).
The bearing ratio of the roughness profile Rmr(c) is calculated as follows:
Rmr(c) =
∑
Xi
L
(2.2)
Measuring length L
c
10060200
Rmr (c ) / %
x1 x2 x3 x4
x5 x6 x7 x8 x9 x10 x
Z(x)
Fig. 2.28 Bearing ratio curve of the profile, acc. to DIN EN ISO 4287
2.4 Surface Inspection 25
The bearing ratio can be calculated on the basis of the primary profile (Pm), the
roughness profile (Rm) and the waviness profile (Wm).
Using the average roughness, Table 2.2 provides an overview of the surface
roughness values which can be achieved with different manufacturing processes.
With respect to general specifications on achievable surface values, one must
consider the fact that it is not necessarily possible to deduce the manufacturing pro-
cess when using one-dimensional parameters for describing the surface [Abou76].
Due to the characteristic engagement conditions between the workpiece and the tool
one would also have to specify, for each surface parameter, which manufacturing
process is to be used to create that parameter. This problem is somewhat alleviated
if multiple one-dimensional surface parameters are used instead of just one when
describing the manufactured surface or if surface reference standards are available
(Figs. 2.29 and 2.30).
Table 2.2 Achievable average roughness
10
00
Primary shaping
0.
1
0.
25
0.
4
1 2
.5 4 1610 25 40
0
25
0
Achievable average roughness Rz / µm 
0.
04
16
0
30
0
63
0
Die forming
Extrusion
Turning
Drilling
Reaming
MillingMilling
Grinding
Erosion
Rough and finish turned
Planed
Honed
Grinded
Fig. 2.29 Surface quality for several manufacturing operations
26 2 Metrology and Workpiece Quality
Flat
lapping
Reaming
Flat
grinding
Horizontal
milling
Face
milling 
Cylindrical
turning
R
ou
gh
ne
ss
 R
t (µ
m)
Ar
ith
m
. a
ve
ra
ge
ro
u
gh
ne
ss
 R
a 
(µm
)
10
3.
0
0.
55
0.
05
0.
1
0.
2
0.
4
0.
8
1.
6
2.
5
8.
0
4.
0
16
32
50N
7
N
6
N
5
N
4
N
3
N
2
N
10
N
9
N
8
N
7
N
6
N
5
R
ou
gh
ne
ss
 m
ar
kl
IS
O
 R
 1
30
2–
19
71
Su
rfa
ce
 m
ar
k
D
IN
 1
40
Ar
ith
m
. a
ve
ra
ge
ro
u
gh
ne
ss
 R
a 
(µm
) 1
2.
5
6.
3
3.
2
0.
8
0.
4
R
ou
gh
ne
ss
 R
t (µ
m)
6,
0
1.
0
1.
6
1.
6
Fig. 2.30 Surface reference standard (Source: Rupert)
2.4.2 Subjective Surface Inspection
In some cases, a visual inspection can determine whether the processed surface
meets the specified requirements. A testing device frequently used in the work-
shop is the straight edge, which is used to check the evenness of a surface using
the light-slit method. In workshop operations, spotting straight edges or spotting
plates are used to detect form deviations or contact patterns on the workpiece surface
(Fig. 2.31).
Impression methods using lacquers have been developed for surfaces which are
difficult to access (e.g. drill holes, internal surfaces). The lacquer is applied onto the
Spotting straight edge
Spotting medium
Work piece
Grey gleaming
areas
(bearing points) 
Light areas 
(lowest points) 
Black areas 
(spotting medium) 
Spotting plate
Fig. 2.31 Surface inspection by spotting
2.4 Surface Inspection 27
test surface and pulled off after drying. The contact patterns attained on the lacquer
film thus attained can then be evaluated.
A frequent use of spotting is detecting contact patterns in quality testing and in
the assembly of gear teeth (especially bevel gear teeth). Applying spotting paste
and then rolling the teeth under light strain causes the bearing points on the tooth
flanks to become visible. These bearing points can then be compared to the reference
contact pattern. Nowadays in individual cases machine-tool guiding elements also
become scraped, therefore, spotting is used to judge the surface.
2.4.3 Surface Measurement
All the physical principles mentioned in the context of length measurement technol-
ogy are also fundamentally applicable to surface measurements. Since mechanical
and optical measuring methods have proven to be the most effective in this field, the
following discussion will limit itself to these methods.
2.4.3.1 Mechanical Measuring Methods
Devices for surface measurement which function on the basis of a mechanical
functional principle are generally referred to as stylus instruments. Mechanical mea-
suring methods are classified as either scanning methods or sensing methods. In the
scanning method, a contact stylus descends upon the surfaceto be tested at a speci-
fied frequency. The surface is guided under the needle with a constant feed rate. The
path of the contact stylus can be visualized mechanically, optically, electrically or
electronically. The contact stylus can either be raised to a fixed level (the WOXEN
principle) or raised by a fixed amount from the respective point of impact to the
surface (differential tactile procedure) (Fig. 2.32).
In the differential tactile procedure, the impact energy of the contact stylus is
lower in comparison to the WOXEN principle and exhibits marginal dispersion. As a
result, the penetration depth of the needle remains constant, the measuring accuracy
being thus higher than in the case of the WOXEN principle. In the case of instruments
functioning according to the sensing method, the contact stylus is guided continu-
ously over the surface. The needle rises and falls in line with the profile pattern
Scanning method Sensing method
Woxen principle Differential tactile procedure Differential tactile procedure
Fig. 2.32 Mechanical measuring methods
28 2 Metrology and Workpiece Quality
Caliper
Caliper slide
Table
Plane of reference
system 
Caliper slide
Caliper
Skid
Oscillating scanning
system 
Caliper
Scanning
arm 
Skid
Semi-rigid
System 
Fig. 2.33 Different surface scanning systems
(Fig. 2.32). The lifting motion is indicated relative to a reference point defined in the
device or to a reference level. Here too, mechanical, electric, optical and electronic
converters are used.
Sensing profile methods are the most widespread in practice. Independently of
the design type of the contact stylus instruments used, three system designs are
distinguished (Fig. 2.33).
Plane of Reference System
In this system, the scanning unit is guided on a reference surface (plane, cylinder)
which corresponds to the ideally geometrical surface of the test sample and is ori-
ented along the surface to be measured (Fig. 2.33). Aside from errors arising due to
the calliper geometry, this scanning system provides a faithful transmission of the
roughness and waviness values of the test sample. When measuring small or very
large surfaces, however, the handling of this scanning system can frequently become
unwieldy. An alternative is the reference surface contact system. Here, the work-
piece is conveyed on very precisely guided slides in a horizontal direction beneath
the firmly anchored scanning system. Besides roughness, the macrostructure of a
surface can also be detected in certain areas.
Semi-Rigid System
In semi-rigid systems, the scanning unit, which contains the contact stylus, is guided
on the skid gliding on the surface to be measured (Fig. 2.33). This system has the
advantage that it requires little space and is thus suitable for measuring small or
hard-to-access surfaces. A disadvantage is that the system requires an orientation to
the surface to be measured which can cause parts of the profile to be transmitted in
a distorted manner.
Oscillating Scanning System
Two glide skids guide the scanning unit of the oscillating scanning system
(Fig. 2.33). The latter is oriented towards the surface to be measured and is thus
2.4 Surface Inspection 29
comfortable to operate. However, it requires more space than the single skid system
and can therefore not be used for small or hard-to-access surfaces. The distortions
caused by long-wave profile sections are smaller than those in half-rigid systems,
because the skids are flat and farther apart. Nevertheless the waviness must be
filtered out in many cases [Henz68].
Usually, the magnification gauges for x- and y-coordinates are selected in a highly
varying way in profile records. This is necessary because the measuring lengths
(abscissa) lie in the mm region and roughness parameters are represented on the
ordinate which lie in the μm region. The optical impression of the profile record is
thus strongly distorted in comparison to reality. The contact styluses used in con-
tact stylus instruments often have an apex radius of 2 μm. They function with a
bearing strength of 0.5 N, which can result in considerable surface pressures (up
to 6000 N/mm2), which possibly cause alteration of the test surface. On the other
hand, excessively large contact stylus radii distort the result; they act like mechan-
ical filters. Thus the optimal conditions must be determined on the basis of the
material of the test sample and documented in their entirety in the measurement
report.
2.4.3.2 Optical Measuring Methods
White-Light Interferometer
This technology differs from length measuring technology both in that it employs
white light, i.e. light with the entire wavelength spectrum, and in that it does not just
use one beam, as with laser interferometers, but rather an entire bundle. A reflected-
light microscope is used to display an image of a section of the test object on a
detector (e.g. CCD camera). By using different interference lenses, a beam splitter
can be used to superimpose a highly accurate reference surface with the image of
the test object on the same scale. The interferences which are then created can be
detected and evaluated (Fig. 2.34).
The topography of the test object creates a spatial modulation of the light
intensity in the interference image. Depending on the surface to be measured,
two different measuring modes are used: one to characterize very flat surfaces
with an average roughness value Ra < 1 nm and one for all other surfaces. Steps
and roughnesses of up to several millimetres high can be displayed using this
technology.
Fringe Projection
The fringe projection method functions according to the triangulation procedure, in
which equidistant stripe patterns are observed and evaluated at a certain angle, i.e.
the triangulation angle. The stripe patterns on the test object are detected and evalu-
ated from a certain position, with the projected stripes following the arbitrary form
of the test surface. These stripes appear from the observer’s standpoint to be “inter-
ferences”, though they only appear this way because the location of the projection
30 2 Metrology and Workpiece Quality
Lenses
Light
Detector
Displacement
Interference of
measuring and reference
beam 
Te
st
 o
bje
ct
z
x
Reference mirror
D
is
pl
ac
em
en
t
Fig. 2.34 Principle of a white-light interferometer (two-beam interferometer)
surface points varies in relation to that of the projector. The stripe patterns then are
evaluated interferometrically on the basis of fluctuations in light intensity. The most
important geometrical values on which this method is based are:
• the real distance of the projected stripes
• the stripe distance registered from the position of observation
• the triangulation angle
Fringe projection is used, for example, to judge surfaces bent over a large area,
such as those found in deep-drawing tools and on deep-drawn parts. The advantages
of this method are a high measurement speed and a spatial or laminar scanning.
A disadvantage is that the test objects may not be transparent or reflective.
2.5 Inspection of the Workpiece Rim
The functional behaviour and applicability of a component depend not only on its
macrogeometry and surface roughness, but also from the physical properties of the
material both on the interior and near the surface. While the inspection of material
properties properly belongs to the field of materials science and materials testing
and thus cannot be treated here in further detail, the following will discuss some
of the properties of technical surfaces and of layers near the surface (i.e. the rim
zone) and methods used to measure rim zone properties. Technical surfaces can be
categorized according to types of load into the following groups:
2.5 Inspection of the Workpiece Rim 31
• external surfaces