1 Additive Manufacturing Process Classification, Applications, Trends, Opportunities, and Challenges 1

1.1 Additive Manufacturing: A Long-Term Game Changer 1

1.2 AM Standard Definition and Classification 4

1.3 Why Metal Additive Manufacturing? 5

1.4 Market Size: Current and Future Estimation 11

1.5 Applications of Metal AM 12

1.5.1 Medical and Dental 14

1.5.2 Aerospace and Defense 15

1.5.3 Communication 17

1.5.4 Energy and Resources 18

1.5.5 Automotive 19

1.5.6 Industrial Tooling and Other Applications 20

1.6 Economic/Environmental Benefits and Societal Impact 20

1.7 AM Trends, Challenges, and Opportunities 23

1.8 Looking Ahead 27

References 28

2 Basics of Metal Additive Manufacturing 31

2.1 Introduction 31

2.2 Main Metal Additive Manufacturing Processes 32

2.2.1 Powder Bed Fusion (PBF) 32

2.2.2 Directed Energy Deposition (DED) 41

2.2.3 Binder Jetting (BJ) 49

2.2.4 Emerging Metal AM Processes 55

2.3 Main Process Parameters for Metal DED, PBF, and BJ 62

2.3.1 Main Output Parameters 64

2.3.2 Combined Thermal Energy Source Parameters PBF and DED 65

2.3.3 Beam Scanning Strategies and Parameters for PBF and DED 68

2.3.4 Powder Properties for PBF, DED, and BJ 71

2.3.5 Wire Properties for DED 76

2.3.6 Layer Thickness for PBF, DED, and BJ 77

2.3.7 Ambient Parameters for PBF, DED, and BJ 79

2.3.8 Geometry-Specific Parameters (PBF) 80

2.3.9 Support Structures for PBF 82

2.3.10 Binder Properties for BJ 82

2.3.11 Binder Saturation for BJ 84

2.4 Materials 85

2.4.1 Ferrous Alloys 86

2.4.2 Titanium Alloys 86

2.4.3 Nickel Alloys 86

2.4.4 Aluminum Alloys 86

References 87

3 Main Sub-Systems for Metal AM Machines 91

3.1 Introduction 91

3.2 System Setup of AM Machines 92

3.2.1 Laser Powder Bed Fusion (LPBF) 92

3.2.2 Laser Directed Energy Deposition (LDED) with Blown Powder Known as Laser Powder-Fed (LPF) 92

3.2.3 Binder Jetting (BJ) 93

3.3 Laser Basics: Important Parameters needed to be known for AM 93

3.3.1 Laser Theory 93

3.3.2 Laser Components 100

3.3.3 Continuous Vs. Pulsed Laser 101

3.3.4 Laser Types 102

3.3.5 Laser Beam Properties 109

3.4 Electron Beam Basics 114

3.4.1 Comparisons and Contrasts between Laser and Electron Beams 114

3.4.2 Electron Beam Powder Bed Fusion Setup 114

3.4.3 Electron Beam Mechanism 116

3.4.4 Vacuum Chambers 119

3.5 Powder Feeders and Delivery Nozzles Technology 121

3.5.1 Classification of Powder Feeders 121

3.5.2 Powder Delivery Nozzles for DED 125

3.5.3 Powder Bed Delivery and Spreading Mechanisms 128

3.5.4 Wire Feed System 129

3.5.5 Positioning Devices and Scanners in Laser-Based AM 130

3.5.6 Print-Head in Binder Jetting 131

3.6 CAD File Formats 133

3.6.1 CAD/CAM Software 134

3.7 Summary 134

References 134

4 Directed Energy Deposition (DED): Physics and Modeling of Laser/Electron Beam Material Processing and DED 137

4.1 Introduction 137

4.2 Laser Material Interaction and the Associated Significant Parameters to Laser AM 140

4.2.1 Continuous Versus Pulsed/Modulated Lasers 141

4.2.2 Absorption, Reflection, and Transmission Factors 143

4.2.3 Dependencies of Absorption Factor to Wavelength and Temperature 144

4.2.4 Angle of Incidence 144

4.2.5 Surface Roughness Effects 147

4.2.6 Scattering Effects 147

4.3 E-beam Material Interaction 148

4.4 Power Density and Interaction Time for Various Heat Source-based Material Processing 149

4.5 Physical Phenomena and Governing Equations during DED 150

4.5.1 Absorption 150

4.5.2 Heat Conduction 151

4.5.3 Surface Convection and Radiation 152

4.5.4 Fluid Dynamics 153

4.5.5 Phase Transformation 156

4.5.6 Rapid Solidification 158

4.5.7 Thermal Stresses 158

4.5.8 Flow Field in DED with Injected Powder 159

4.6 Modeling of DED 161

4.6.1 Analytical Modeling: Basics, Simplified Equations, and Assumptions 161

4.6.2 Numerical Models for DED 165

4.6.3 Experimental-based Models: Basics and Approaches 166

4.7 Case Studies on Common Modeling Platforms for DED 168

4.7.1 Lumped Analytical Model for Powder-Fed LDED 168

4.7.2 Comprehensive Analytical Model for Powder-Fed LDED (PF-LDED) 172

4.7.3 Numerical Modeling of LDED: Heat Transfer Model 184

4.7.4 Modeling of Wire-Fed E-beam DED (WF-EDED) 193

4.7.5 A Stochastic Model for Powder-Fed LDED 195

4.8 Summary 200

References 200

5 Powder Bed Fusion Processes: Physics and Modeling 203

5.1 Introduction and Notes to Readers 203

5.2 Physics of Laser Powder bed Fusion (LPBF) 204

5.2.1 Heat Transfer in LPBF: Governing Equations and Assumptions 205

5.2.2 Fluid Flow in the Melt Pool of LPBF: Governing Equations and Assumptions 215

5.2.3 Vaporization and Material Expulsion: Governing Equations and Assumptions 218

5.2.4 Thermal Residual Stresses: Governing Equations and Assumptions 219

5.2.5 Numerical Modeling of LPBF 220

5.2.6 Case Studies on Common LPBF Modeling Platforms 222

5.3 Physics and Modeling of Electron Beam Additive Manufacturing 228

5.3.1 Electron Beam Additive Manufacturing Parameters 228

5.3.2 Emissions in Electron Beam Sources 230

5.3.3 Mathematical Description of Free Electron Current 231

5.3.4 Modeling of Electron Beam Powder Bed Fusion (EB-PBF) 233

5.3.5 Case Studies 245

5.3.6 Summary 249

References 251

6 Binder Jetting and Material Jetting: Physics and Modeling 255

6.1 Introduction 255

6.2 Physics and Governing Equations 257

6.2.1 Droplet Formation 257

6.2.2 Droplet–Substrate Interaction 263

6.2.3 Binder Imbibition 265

6.3 Numerical Modeling 270

6.3.1 Level-Set Model 270

6.3.2 Lattice Boltzmann Method 274

6.4 Summary 277

References 277

7 Material Extrusion: Physics and Modeling 279

7.1 Introduction 279

7.2 Analytical Modeling of ME 281

7.2.1 Heat Transfer and Outlet Temperature 281

7.2.2 Flow Dynamics and Drop Pressure 283

7.2.3 Die Swell 288

7.2.4 Deposition and Healing 289

7.3 Numerical Modeling of ME 291

7.4 Summary 296

References 296

8 Material Design and Considerations for Metal Additive Manufacturing 297

8.1 Historical Background on Materials 297

8.2 Materials Science: Structure–Property Relationship 298

8.3 Manufacturing of Metallic Materials 299

8.4 Solidification of Metals: Equilibrium 301

8.5 Solidification in Additive Manufacturing: Non-Equilibrium 302

8.6 Equilibrium Solidification: Theory and Mechanism 304

8.6.1 Cooling Curve and Phase Diagram 304

8.7 Non-Equilibrium Solidification: Theory and Mechanism 307

8.8 Solute Redistribution and Microsegregation 308

8.9 Constitutional Supercooling 312

8.10 Nucleation and Growth Kinetics 314

8.10.1 Nucleation 315

8.10.2 Growth Behavior 319

8.11 Solidification Microstructure in Pure Metals and Alloys 321

8.12 Directional Solidification in AM 324

8.13 Factors Affecting Solidification in AM 325

8.13.1 Cooling Rate 325

8.13.2 Temperature Gradient and Solidification Rate 326

8.13.3 Process Parameters 329

8.13.4 Solidification Temperature Span 329

8.13.5 Gas Interactions 330

8.14 Solidification Defects 330

8.14.1 Porosity 330

8.14.2 Balling 332

8.14.3 Cracking 335

8.14.4 Lamellar Tearing 337

8.15 Post Solidification Phase Transformation 337

8.15.1 Ferrous Alloys/Steels 337

8.15.2 Al Alloys 338

8.15.3 Nickel Alloys/Superalloys 341

8.15.4 Titanium Alloys 350

8.16 Phases after Post-Process Heat Treatment 357

8.16.1 Ferrous Alloys 357

8.16.2 Al Alloys 357

8.16.3 Ni Alloys 357

8.16.4 Ti Alloys 358

8.17 Mechanical Properties 358

8.17.1 Hardness 359

8.17.2 Tensile Strength and Static Strength 363

8.17.3 Fatigue Behavior of AM-Manufactured Alloys 365

8.18 Summary 371

References 375

9 Additive Manufacturing of Metal Matrix Composites 383

9.1 Introduction 383

9.2 Conventional Manufacturing Techniques for Metal Matrix Composites (MMCs) 384

9.3 Additive Manufacturing of Metal Matrix Composites (MMCs) 385

9.4 AM Challenges and Opportunities 386

9.5 Preparation of Composite Materials: Mechanical Mixing 387

9.6 Different Categories of MMCs 389

9.7 Additive Manufacturing of Ferrous Matrix Composites 390

9.7.1 316 SS-TiC Composite 390

9.7.2 316 SS–TiB2 Composite 392

9.7.3 H13–TiB2 Composite 392

9.7.4 H13–TiC Composite 393

9.7.5 Ferrous–WC Composite 393

9.7.6 Ferrous–VC Composites 394

9.8 Additive Manufacturing of Titanium-Matrix Composites (TMCs) 395

9.8.1 Ti–TiC Composite 396

9.8.2 Ti–TiB Composites 396

9.8.3 Ti–Hydroxyapatite (Ti–HA) Composites 399

9.8.4 Ti-6Al-4V-Metallic Glass (MG) Composites 400

9.8.5 Ti-6Al-4V + B4C Pre-alloyed Composites 401

9.8.6 Ti-6Al-4V +Mo Composite 402

9.8.7 Structure and Properties of Different TMCs 403

9.9 Additive Manufacturing of Aluminum Matrix Composites 403

9.9.1 Al–Fe2O3 Composite 405

9.9.2 AlSi10Mg–SiC Composite 405

9.9.3 AlSi10Mg–TiC Composite 406

9.9.4 2024Al–TiB2 Composite 406

9.9.5 AlSi10Mg–TiB2 Composite 407

9.9.6 AA7075–TiB2 Composite 407

9.10 Additive Manufacturing of Nickel Matrix Composites 407

9.10.1 Inconel 625–TiC Composites 408

9.10.2 Inconel 625–TiB2 Composite 409

9.11 Factors Affecting Composite Property 409

9.11.1 Mixing of Matrix and Reinforcing Elements 409

9.11.2 Size of Reinforcing Elements 410

9.11.3 Decomposition Temperature 411

9.11.4 Viscosity and Pore Formation 411

9.11.5 Volume of Reinforcing Elements and Pore Formation 412

9.11.6 Buoyancy Effects and Surface Tension Forces 412

9.12 Summary 414

References 417

10 Design for Metal Additive Manufacturing 421

10.1 Design Frameworks for Additive Manufacturing 421

10.1.1 Integrated Topological and Functional Optimization DfAM 422

10.1.2 Additive Manufacturing-Enabled Design Framework 422

10.1.3 Product Design Framework for AM with Integration of Topology Optimization 424

10.1.4 Multifunctional Optimization Methodology for DfAM 427

10.1.5 AM Process Model for Product Family Design 427

10.2 Design Rules and Guidelines 427

10.2.1 Laser Powder Bed Fusion (LPBF) 427

10.2.2 Electron Beam Powder Bed Fusion (EB-PBF) 431

10.2.3 Binder Jetting 433

10.2.4 Technologies Compared 434

10.3 Topology Optimization for Additive Manufacturing 434

10.3.1 Structural Optimization 435

10.3.2 Topology Optimization 436

10.3.3 Design-Dependent Topology Optimization 444

10.3.4 Efforts in AM-Constrained Topology Optimization 450

10.4 Lattice Structure Design 458

10.4.1 Unit Cell 458

10.4.2 Lattice Framework 459

10.4.3 Uniform Lattice 460

10.4.4 Conformal Lattices 462

10.4.5 Irregular/Randomized Lattices 462

10.4.6 Design Workflows for Lattice Structures 463

10.5 Design for Support Structures 473

10.5.1 Principles that Should Guide Support Structure Design 474

10.5.2 Build Orientation Optimization 474

10.5.3 Support Structure Optimization 476

10.6 Design Case Studies 483

10.6.1 Redesign of an Aerospace Bracket to be Made by LPBF 484

10.6.2 Design and Development of a Structural Member in a Suspension Assembly Using EB Powder Bed Fusion 487

10.6.3 Binder Jetting of the Framework of a Partial Metal Denture 488

10.6.4 Redesign of a Crank and Connecting Rod 490

10.6.5 Redesign of a Mechanical Assembly 492

10.6.6 Solid-Lattice Hip Prosthesis Design 498

10.7 Summary 501

References 501

11 Monitoring and Quality Assurance for Metal Additive Manufacturing 507

11.1 Why are Closed-Loop and Quality Assurance Platforms Essential? 507

11.2 In-Situ Sensing Devices and Setups 509

11.2.1 Types of Sensors Used in Metal AM 509

11.2.2 Mounting Strategies for In-line Monitoring Sensors in Metal AM Setups 521

11.3 Commercially Available Sensors 522

11.3.1 LPBF Commercial Sensors 522

11.3.2 LDED Commercial Sensors 525

11.4 Signal/Data Conditioning, Methodologies, and Classic Controllers for Monitoring, Control, and Quality Assurance in Metal AM Processes 526

11.4.1 Signal/Data Conditioning and Controllers for Melt Pool Geometrical Analysis 526

11.4.2 Signal/Data Conditioning and Methodologies for Temperature Monitoring and Analysis 531

11.4.3 Signal/Data Conditioning and Methodologies for the Detection of Porosity 532

11.4.4 Signal/Data Conditioning and Methodologies for Detection of Crack and Delamination 537

11.4.5 Signal/Data Conditioning and Methodologies for Detection of Plasma Plume and Spatters 538

11.5 Machine Learning for Data Analytics and Quality Assurance in Metal AM 539

11.5.1 Supervised Learning 539

11.5.2 Unsupervised Learning 549

11.6 Case Study 553

11.6.1 Design of Experiments 554

11.6.2 In-Situ Sensors and Quality Assurance Algorithm 555

11.6.3 Correlation Between CT Scan and Analyzed Data 560

11.7 Summary 563

References 565

12 Safety 577

12.1 Introduction 577

12.2 Overview of Hazards 578

12.3 AM Process Hazards 578

12.4 Laser Safety in Additive Manufacturing 579

12.4.1 Laser Categorization 579

12.4.2 Laser Hazards 581

12.4.3 Eye Protection 584

12.4.4 Laser Protective Eyewear Requirements 584

12.5 Electron Beam Safety 585

12.6 Powder Hazards 585

12.6.1 Combustibility 586

12.7 Human Health Hazards 587

12.8 Comprehensive Steps to AM Safety Management 587

12.8.1 Engineering Controls 587

12.8.2 Personal Protective Equipment 588

12.8.3 AM Guidelines and Standards 588

Additive Manufacturing (AM)—also commonly referred to as 3D printing—builds three-dimensional objects by adding materials layer by layer. Recent years have seen unprecedented investment in additive manufacturing research and development by governments and corporations worldwide. This technology has the potential to replace many conventional manufacturing processes, enable the development of new industry practices, and transform the entire manufacturing enterprise.

Metal Additive Manufacturing provides an up-to-date review of all essential physics of metal additive manufacturing techniques with emphasis on both laser-based and non-laser-based additive manufacturing processes. This comprehensive volume covers fundamental processes and equipment, governing physics and modelling, design and topology optimization, and more. The text adresses introductory, intermediate, and advanced topics ranging from basic additive manufacturing process classification to practical and material design aspects of additive manufacturability. Written by a panel of expert authors in the field, this authoritative resource:

Provides a thorough analysis of AM processes and their theoretical foundations
Explains the classification, advantages, and applications of AM processes
Describes the equipment required for different AM processes for metallic structures, including laser technologies, positioning devices, feeder and spreader mechanisms, and CAD software
Discusses the opportunities, challenges, and current and emerging trends within the field
Covers practical considerations, including design for AM, safety, quality assurance, automation, and real-time control of AM processes
Includes illustrative cases studies and numerous figures and tables
Featuring material drawn from the lead author’s research and professional experience on laser additive manufacturing, Metal Additive Manufacturing is an important source for manufacturing professionals, research and development engineers in the additive industry, and students and researchers involved in mechanical, mechatronics, automatic control, and materials engineering and science.