Laser Material Processing

by Steen, W. M.; Watkins, Kenneth

• ISBN13: 9781852336981
• ISBN10: 1852336986
• Edition: 3rd
• Format: Paperback
• Copyright: 2003-10-01
• Publisher: Springer Verlag

Summary

Lasers now play a major part in the processing of the disparate materials used in engineering and manufacturing. The range of procedures in which they are involved is ever increasing. With this growing prominence comes a need for clear and instructive textbooks to teach the next generation of laser users. The informal style of Laser Material Processing (3rd Edition) will guide you smoothly from the basics of laser physics to the detailed treatment of all the major materials processing techniques for which lasers are now essential. - Helps you to understand how the laser works and to decide which laser is best for your purposes - New chapters on bending and cleaning reflect the changes in the field since the last edition completing the range of practical knowledge about the processes possible with lasers already familiar to users of this well-known text. - Provides a firm grounding in the safety aspects of laser use. - Professor Steen's lively presentation is supported by a number of original cartoons by Patrick Wright and Noel Ford which will bring a smile to your face and ease the learning process. Laser Material Processing (3rd Edition) will be of use as university or industrial course material for senior undergraduate, graduate and non-degree technical training in optoelectronics, laser processing and advanced manufacturing. Practising engineers and technicians in these areas will also find the book an authoritative source of information on the rapidly expanding use of industrial lasers in material processing. "Written in a style that includes both technical detail and humor, Bill Steen's book on laser material processing is the standard by which others are judged. It is the text in my graduate-level course on the subject." C.E. Albright, The Ohio State University "I have used two previous editions for my class. The third edition has included some of the more recent applications. It is easy to read and explanations are lucid. I expect it will receive wide acceptance in class rooms world wide." J. Mazumder, University of Michigan "It is the great merit of this book to offer a compact survey on laser material processing. A useful and fascinating book, pleasant to read with many useful figures and examples of industrial applications. It is a textbook for advanced students in this field, but also a reference book for engineers." H. Weber, Technische Universit??t Berlin

Table of Contents

Prologue	1	(10)
1 Background and General Applications	11	(50)
1.1 How the Laser Works	11	(11)
1.1.1 Construction	11	(3)
1.1.2 Stimulated Emission Phenomenon	14	(8)
1.2 Types of Industrial Lasers	22	(12)
1.2.1 Carbon Dioxide Lasers	22	(6)
1.2.2 Carbon Monoxide Lasers	28	(1)
1.2.3 Solid State Lasers	28	(4)
1.2.4 Diode Lasers	32	(1)
1.2.5 Excimer Lasers	33	(1)
1.3 Comparison Between Lasers	34	(1)
1.4 Applications of Lasers	34	(24)
1.4.1 Powerful Light	36	(1)
1.4.2 Alignment	36	(2)
1.4.3 Measurement of Length	38	(2)
1.4.4 Pollution Detection	40	(1)
1.4.5 Velocity Measurement	41	(4)
1.4.6 Holography	45	(1)
1.4.7 Speckle Interferometry	46	(1)
1.4.8 Inspection	47	(1)
1.4.9 Analytic Technique	48	(1)
1.4.10 Recording	49	(2)
1.4.11 Communications	51	(1)
1.4.12 Heat Source	52	(1)
1.4.13 Medical	52	(4)
1.4.14 Printing	56	(1)
1.4.15 Isotope Separation	56	(1)
1.4.16 Atomic Fusion	56	(2)
1.5 Market for Laser Applications	58	(3)
2 Basic Laser Optics	61	(46)
2.1 The Nature of Electromagnetic Radiation	61	(3)
2.2 Interaction of Electromagnetic Radiation with Matter	64	(5)
2.2.1 Nonlinear Effects	67	(2)
2.3 Reflection or Absorption	69	(5)
2.3.1 Effect of Wavelength	71	(1)
2.3.2 Effect of Temperature	71	(1)
2.3.3 Effect of Surface Films	72	(1)
2.3.4 Effect of Angle of Incidence	72	(2)
2.3.5 Effect of Materials and Surface Roughness	74	(1)
2.4 Refraction	74	(3)
2.4.1 Scattering	76	(1)
2.5 Interference	77	(1)
2.6 Diffraction	78	(1)
2.7 Laser Beam Characteristics	78	(5)
2.7.1 Wavelength	78	(1)
2.7.2 Coherence	79	(1)
2.7.3 Mode and Beam Diameter	79	(2)
2.7.4 Polarisation	81	(2)
2.8 Focusing with a Single Lens	83	(12)
2.8.1 Final Spot Size	84	(10)
2.8.2 Depth of Focus	94	(1)
2.9 Optical Components	95	(12)
2.9.1 Lens Doublets	95	(1)
2.9.2 Depolarisers	95	(1)
2.9.3 Collimators	96	(1)
2.9.4 Metal Optics	97	(1)
2.9.5 Diffractive Optical Elements - Holographic Lenses	98	(2)
2.9.6 Laser Scanning Systems	100	(1)
2.9.7 Fibre Delivery Systems	100	(7)
3 Laser Cutting	107	(50)
3.1 Introduction	107	(1)
3.2 The Process - How It Is done	108	(3)
3.3 Methods of Cutting	111	(14)
3.3.1 Vaporisation Cutting/Drilling	111	(3)
3.3.2 Fusion Cutting - Melt and Blow	114	(7)
3.3.3 Reactive Fusion Cutting	121	(1)
3.3.4 Controlled Fracture	122	(1)
3.3.5 Scribing	123	(1)
3.3.6 Cold Cutting	123	(1)
3.3.7 Laser Assisted Oxygen Cutting - The LASOX Process	124	(1)
3.4 Theoretical Models of Cutting	125	(1)
3.5 Practical Performance	126	(14)
3.5.1 Beam Properties	126	(5)
3.5.2 Transport Properties	131	(2)
3.5.3 Gas Properties	133	(5)
3.5.4 Material Properties	138	(1)
3.5.5 Practical Tips	139	(1)
3.6 Examples of Applications	140	(9)
3.6.1 Die Board Cutting	141	(1)
3.6.2 Cutting of Quartz Tubes	141	(1)
3.6.3 Profile Cutting	141	(1)
3.6.4 Cloth Cutting	142	(1)
3.6.5 Aerospace Materials	142	(1)
3.6.6 Cutting Fibre Glass	142	(1)
3.6.7 Cutting Kevlar	142	(1)
3.6.8 Prototype Car Production	142	(1)
3.6.9 Cutting Alumina and Dielectric Boards	143	(1)
3.6.10 Furniture Industry	143	(1)
3.6.11 Perforated Irrigation Pipes	144	(1)
3.6.12 Perforating Cigarette Paper	144	(1)
3.6.13 Flexographic Print Rolls	144	(1)
3.6.14 Cutting Radioactive Materials	144	(1)
3.6.15 Electronics Applications	145	(1)
3.6.16 Hole Drilling	145	(2)
3.6.17 Scrap Recovery	147	(1)
3.6.18 Laser Machining	148	(1)
3.6.19 Ship Building	148	(1)
3.6.20 The Laser Punch Press	148	(1)
3.6.21 Manufacture of Bikes and Tubular Structures	149	(1)
3.6.22 Cutting and Welding of Railcars	149	(1)
3.7 Costed Example	149	(1)
3.8 Process Variations	149	(2)
3.8.1 Arc Augmented Laser Cutting	149	(1)
3.8.2 Hot Machining	150	(1)
3.9 Future Developments	151	(1)
3.9.1 Higher Powered Lasers	151	(1)
3.9.2 Additional Energy Sources	151	(1)
3.9.3 Improved Coupling	151	(1)
3.9.4 Smaller Spot Size	151	(1)
3.9.5 Increased Drag	152	(1)
3.9.6 Increased Fluidity	152	(1)
3.10 Worked Example of Power Requirement	152	(5)
4 Laser Welding	157	(44)
4.1 Introduction	157	(3)
4.2 Process Arrangement	160	(2)
4.3 Process Mechanisms - Keyholes and Plasmas	162	(4)
4.4 Operating Characteristics	166	(22)
4.4.1 Power	166	(4)
4.4.2 Spot Size and Mode	170	(2)
4.4.3 Polarisation	172	(1)
4.4.4 Wavelength	172	(2)
4.4.5 Speed	174	(1)
4.4.6 Focal Position	175	(1)
4.4.7 Joint Geometries	176	(6)
4.4.8 Gas Shroud and Gas Pressure	182	(3)
4.4.9 Effect of Gas Pressure - Due to Velocity and Environment	185	(1)
4.4.10 Effect of Material Properties	186	(1)
4.4.11 Gravity	187	(1)
4.5 Process Variations	188	(3)
4.5.1 Arc Augmented Laser Welding	188	(2)
4.5.2 Twin Beam Laser Welding	190	(1)
4.5.3 Walking and Spinning Beams	191	(1)
4.6 Applications	191	(4)
4.6.1 Tailored Blanks	193	(2)
4.7 Costed Example	195	(6)
5 Heat Flow Theory	201	(26)
5.1 Introduction	201	(4)
5.2 Analytic Models in One-dimensional Heat Flow	205	(2)
5.3 Analytic Models for a Stationary Point Source	207	(3)
5.3.1 The Instantaneous Point Source	207	(2)
5.3.2 The Continuous Point Source	209	(1)
5.3.3 Sources Other than Point Sources	210	(1)
5.4 Analytic Models for a Moving Point Source	210	(2)
5.5 Alternative Surface Heating Models	212	(1)
5.5.1 The Ashby-Shercliffe Model: The Moving Hypersurface Line Source	212	(1)
5.5.2 The Davis et al. Model: The Moving Gaussian Source	212	(1)
5.6 Analytic Keyhole Models - Line Source Solution	213	(3)
5.7 Analytic Moving Point-Line Source Solution	216	(1)
5.8 Finite-difference Models	217	(2)
5.9 Semi-quantitative Models	219	(3)
5.10 Flow Models	222	(1)
5.11 Stress Models	223	(1)
5.12 Conclusions	223	(1)
5.13 List of Symbols	223	(4)
6 Laser Surface Treatment	227	(52)
6.1 Introduction	227	(2)
6.2 Laser Heat Treatment	229	(13)
6.2.1 Heat Flow	232	(5)
6.2.2 Mass Flow by Diffusion	237	(1)
6.2.3 Mechanism of Transformation Process	237	(2)
6.2.4 Properties of Transformed Steels	239	(3)
6.3 Laser Surface Melting	242	(9)
6.3.1 Solidification Mechanisms	246	(5)
6.4 Laser Surface Alloying	251	(2)
6.4.1 Process Variations	251	(1)
6.4.2 Applications	252	(1)
6.5 Laser Cladding	253	(9)
6.5.1 Laser Cladding with Preplaced Powder	254	(1)
6.5.2 Blown Powder Laser Cladding	255	(7)
6.6 Particle Injection	262	(1)
6.7 Surface Texturing	263	(1)
6.8 Enhanced Electroplating	263	(4)
6.9 Laser Chemical Vapour Deposition	267	(1)
6.10 Laser Physical Vapour Deposition	267	(1)
6.11 Non-contact Bending	268	(1)
6.12 Magnetic Domain Control	268	(1)
6.13 Laser Cleaning and Paint Stripping	269	(1)
6.14 Surface Roughening	269	(1)
6.15 Scabbling	269	(1)
6.16 Micro-machining	270	(1)
6.17 Laser Marking	271	(1)
6.18 Shock Hardening	271	(2)
6.19 Conclusions	273	(6)
7 Rapid Prototyping and Low-volume Manufacture	279	(22)
7.1 Introduction	279	(1)
7.2 Range of Processes	280	(1)
7.2.1 Styles of Manufacture	280	(1)
7.2.2 Classification of Rapid Prototyping Techniques by Material	281	(1)
7.3 CAD File Manipulation	281	(2)
7.3.1 General Software Manipulation	281	(2)
7.4 Layered Manufacturing Issues	283	(2)
7.4.1 General	283	(1)
7.4.2 Stair Stepping	283	(1)
7.4.3 Layer Thickness Selection	284	(1)
7.4.4 Accuracy	284	(1)
7.4.5 Part Orientation	284	(1)
7.4.6 Support Structures	284	(1)
7.5 Individual Processes	285	(10)
7.5.1 Stereolithography	285	(3)
7.5.2 Selective Laser Sintering	288	(2)
7.5.3 Laminated Object Manufacture	290	(2)
7.5.4 Laser Direct Casting	292	(3)
7.6 Rapid Manufacturing Technologies	295	(2)
7.6.1 Silicone Rubber Moulding	295	(1)
7.6.2 Investment Casting	295	(1)
7.6.3 Sand Casting	296	(1)
7.6.4 Laser Direct Casting	296	(1)
7.6.5 Rapid Prototyping Tooling	297	(1)
7.7 Applications	297	(1)
7.8 Conclusions	297	(4)
8 Laser Bending or Forming	301	(26)
8.1 Introduction	301	(1)
8.2 The Process Mechanisms	302	(3)
8.2.1 The Thermal Gradient Mechanism	302	(1)
8.2.2 Point Source Mechanism	303	(1)
8.2.3 The Buckling Mechanism	304	(1)
8.2.4 Upsetting Mechanism	305	(1)
8.3 Theoretical Models	305	(10)
8.3.1 Models for Thermal Gradient Mechanism	306	(5)
8.3.2 Buckling Mechanism Model	311	(3)
8.3.3 Upsetting Mechanism Model	314	(1)
8.4 Operating Characteristics	315	(5)
8.4.1 Effect of Power	315	(1)
8.4.2 Effect of Speed - "Line Energy"	316	(1)
8.4.3 Effect of Material	317	(1)
8.4.4 Effect of Thickness - Thickening at the Bend	317	(1)
8.4.5 Effect of Plate Dimensions - Edge Effects	318	(1)
8.4.6 Effect of Number of Passes	319	(1)
8.5 Applications	320	(3)
8.6 Conclusions	323	(1)
8.7 Glossary	323	(4)
9 Laser Cleaning	327	(24)
9.1 Introduction	327	(2)
9.2 Mechanisms of Laser Cleaning	329	(17)
9.2.1 Selective Vaporisation	329	(4)
9.2.2 Spallation	333	(2)
9.2.3 Transient Surface Heating	335	(2)
9.2.4 Evaporation Pressure	337	(3)
9.2.5 Photon Pressure	340	(1)
9.2.6 Ablation (Bond Breaking)	340	(1)
9.2.7 Dry and Steam Laser Cleaning	341	(3)
9.2.8 Angular Laser Cleaning	344	(1)
9.2.9 Laser Shock Cleaning	345	(1)
9.3 An Overview of the Laser Cleaning Process	346	(1)
9.4 Practical Applications	347	(4)
10 Laser Automation and In-process Sensing	351	(36)
10.1 Automation Principles	351	(3)
10.2 In-process Monitoring	354	(24)
10.2.1 Monitoring Beam Characteristics	354	(8)
10.2.2 Monitoring Work Table Characteristics	362	(4)
10.2.3 Monitoring Process Characteristics	366	(12)
10.3 In-process Control	378	(1)
10.3.1 In-process Power Control	378	(1)
10.3.2 In-process Temperature Control	379	(1)
10.4 "Intelligent" In-process Control	379	(3)
10.5 Conclusions	382	(5)
11 Laser Safety	387	(10)
11.1 The Dangers	387	(1)
11.2 The Standards	387	(1)
11.3 The Safety Limits	388	(3)
11.3.1 Damage to the Eye	388	(3)
11.3.2 Damage to the Skin	391	(1)
11.4 Laser Classification	391	(1)
11.5 Typical Class 4 Safety Arrangements	391	(1)
11.6 Where Are the Risks in a Properly Set Up Facility?	391	(1)
11.7 Electrical Hazards	392	(2)
11.8 Fume Hazards	394	(1)
11.9 Conclusions	394	(3)
Epilogue	397	(4)
Index	401