Additive Manufacturing Technologies

Frontmatter

Chapter 1. Introduction and Basic Principles

Abstract

The technology described in this book was originally referred to as Rapid Prototyping. The term Rapid Prototyping (or RP) is used to describe a process for rapidly creating a system or part representation before final release or commercialization. The emphasis is on creating something quickly for use as a prototype or basis model from which further models and eventually the final product will be derived. In product development, the term Rapid Prototyping describes technologies which create physical prototypes. This text is about technologies which can directly produce objects from digital data. These technologies were first developed for prototyping but are now used for many more purposes.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 2. Development of Additive Manufacturing Technology

Abstract

It is important to understand that AM was not developed in isolation from other technologies. It would not be possible for AM to exist were it not for innovations in areas like 3D graphics and Computer-Aided Design software. This chapter highlights some of the key moments that catalogue the development of Additive Manufacturing. It describes how the different technologies converged to a state where they could be integrated into AM machines. It will also discuss milestone AM technologies and how they have contributed to increase the range of AM applications. Furthermore, we will discuss how the application of Additive Manufacturing has evolved to include greater functionality and embrace a wider range of applications beyond the initial intent of prototyping.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 3. Generalized Additive Manufacturing Process Chain

Abstract

Although there are an increasing number of AM technologies and variants, they nearly all use a similar process chain. This eight-step process is introduced in this chapter, which aims to provide a framework for the rest of the book. Later chapters address specific process stages in much more detail, leading to ways of overcoming inherent problems within the AM process chain. Furthermore, we look at some application sectors and discuss how the demands of different industries are driving the development of AM.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 4. Vat Photopolymerization

Abstract

Photopolymerization processes make use of liquid polymers that react to radiation to become solid. This reaction is called photopolymerization, and liquids which photopolymerize are known as photopolymers. Photopolymers are widely applied in coating and printing industries, as well as for other purposes. Stereolithography was the first type of Vat Photopolymerization (VPP) process and was developed by Charles Hull as an extension to work he had done previously with photopolymers. In VPP, a container (vat) containing photopolymers is exposed to repeated patterns of radiation corresponding to cross-sections of the part being built. In the case of stereolithography, the radiation was provided by a UV laser. Subsequent variants of VPP processes have involved different radiation sources and several types of layering mechanisms. VPP processes were the first commercialized AM technologies, and they continue to be broadly used across many industries and applications.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 5. Powder Bed Fusion

Abstract

Powder Bed Fusion (PBF) was one of the earliest and remains one of the most versatile AM processes, being well-suited for polymers and metals and, to a lesser extent, ceramics and composites. There are an increasing number of machine variants for fusing powders using different energy sources. The most active area of development is for metal PBF processes using lasers. Laser-Based Powder Bed Fusion (LB-PBF) processes are of great interest across many industries as a means of direct manufacturing. This chapter will cover various approaches to PBF, issues surrounding the handling of powders, and the growing types of applications for these technologies.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 6. Material Extrusion

Abstract

Material Extrusion (MEX) machines have, by far, the largest install base of any AM technology. Inexpensive machines are sold to hobbyists at hardware stores, like Home Depot, and through multiple vendors on Amazon. Higher-end industrial machines are available through dozens of companies. While there are other techniques for creating an extrusion, heat is normally used to melt bulk material just before or during the process of being forced through a nozzle. In most systems, a round material filament is pushed by a set of pinch rollers, which creates the pressure to extrude. In this chapter, we will deal with AM technologies that use extrusion to form parts. We will cover the basic theory and attempt to give the reader a good understanding for why it is a leading AM technology.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 7. Material Jetting

Abstract

Printing technologies progressed rapidly as the adoption of personal computers spread through offices and homes. Inkjet printing, in particular, is a huge market, and billions of dollars have been invested to make inkjet print heads reliable, inexpensive, and widely available. As a result of advances in inkjet printing technologies, many application areas beyond photos and text have been explored, including electronics packaging, optics, and Additive Manufacturing. Some of these applications have literally taken the technology into a new dimension. The employment of printing technologies in the creation of three-dimensional products quickly became a promising manufacturing practice, both widely studied and increasingly widely used.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 8. Binder Jetting

Abstract

Binder Jetting (BJT) methods were developed in the early 1990s, primarily at MIT. They developed what they called the 3D Printing (3DP) process in which a binder is printed onto a powder bed to form part cross-sections. This concept can be compared to Powder Bed Fusion (PBF), where a laser melts powder particles to define a part cross-section. A wide range of polymer, composite, metal, and ceramic materials have been demonstrated, but only a subset of these are commercially available. Some BJT machines contain nozzles that print color, enabling the fabrication of parts with many colors. Several companies licensed the 3DP technology from MIT and became successful machine developers, including ExOne and Z Corp (purchased by 3D Systems in 2011). A novel continuous printing technology was developed by Voxeljet that can, in principle, fabricate parts of unlimited length. A resurgence of interest in BJT has occurred with several companies adopting the process for metal part fabrication.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 9. Sheet Lamination

Abstract

Sheet Lamination (SHL) was one of the earliest commercialized AM techniques, but it has had only limited success in the marketplace. In SHL, sheets of materials are cut, stacked, and bonded (not always in that order) to form an object, and the material not used in the part cannot be easily reused and is typically discarded. Sheet material, however, can be some of the cheapest available and quite easy to handle. Metal variants exist as do paper, polymer, and ceramic variants. This process has been shown to be useful for the construction of very large, bulky objects. Although industrial applications for SHL are limited at the present time, continued research and technology development ensure these techniques will continue to serve niche applications for years to come.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 10. Directed Energy Deposition

Abstract

Directed Energy Deposition (DED) is a method for melting material as it is being deposited layer-by-layer. Material in wire or powder form is delivered along with the energy required to melt it. Although it has been shown that a number of material types can be processed this way, DED is almost exclusively applied to metals in both research and commercialized instantiations. DED presents unique advantages and disadvantages that make it particularly suited for repair and feature addition to an existing part. DED is gaining industrial interest because of its ability to create near-net-shape, large freeform structures more quickly and inexpensively than traditionally made near-net-shape castings and forgings.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 11. Direct Write Technologies

Abstract

Direct Write (DW) technologies are a collection of AM and related approaches for creation of very small components. Most of these approaches were covered in prior chapters. However, since feature creation at very small scales brings unique challenges and benefits, it is appropriate to address this topic separately. In particular, there are increasing uses of DW technologies combined with compatible AM techniques to create unique devices that include electrical, electronic, and other functionality all in an integrated component. Approaches to DW and its applications are thus explored in this chapter.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 12. Hybrid Additive Manufacturing

Abstract

As manufacturing systems have evolved from manual to powered to automated processes over the past 200 years, it is common to find examples of multiple manufacturing systems combined into a single, hybrid machine to increase manufacturing efficiencies for certain categories of parts. In additive manufacturing, this trend is also accelerating. The most common hybrid AM systems involve the inclusion of a material removal (e.g., machining or cutting) step into the AM process chain. But hybrid AM systems go far beyond this one instantiation to include multiple AM processes in a single machine, combinations of traditional and AM manufacturing in a single machine, and more. In this chapter we explore various types of hybrid AM approaches and the unique benefits these hybrid machines enable.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 13. The Impact of Low-Cost AM Systems

Abstract

Since 2010, Additive Manufacturing has gone from a niche prototyping technology primarily known to the manufacturing, design, and engineering communities to a technology that is widely known to the general population as “3D Printing.” Much of this growth in awareness is due to an increase in the adoption of the technology due to massive reductions in the cost of Material Extrusion (MEX) machines. By making it possible for individuals to afford AM machines for their own personal use, the potential for AM has become known to the masses. This chapter will discuss some of the issues surrounding low-cost AM technologies, including new machine developments due to patent expirations, the rise of the Maker movement, and some of the new business models that have resulted.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 14. Materials for Additive Manufacturing

Abstract

Good materials are crucial for effective AM, and different processes require these materials to be prepared in different ways. Some AM processes are capable of processing a wider range of materials than others. In this chapter we look at metals, ceramics, polymers, and composites and in particular how they change throughout AM processing. Ceramics have not been dealt with widely in other chapters so we cover a range of ways in which we can produce ceramic parts using AM. We also discuss problems that may occur when using different AM materials.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 15. Guidelines for Process Selection

Abstract

AM processes, like all material processing, are constrained by material properties, speed, cost, and accuracy. The performance capabilities of AM materials and machines may lag behind conventional manufacturing technology (e.g., injection molding) for mass production of identical geometries, but it can outperform traditional manufacturing for small- and medium-lot production. Speed and cost, in terms of time to market, are where AM technology contributes, particularly for complex or customized geometries. The variation between different AM processes and materials is immense. As a result, it can be overwhelming to decide which AM process and material to use. In this chapter we introduce methods for applying decision theory to AM to aid in process–material combination selection for a desired component.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 16. Post-Processing

Abstract

Throughout this book we have discussed geometric accuracy, surface finish, and property limitations of AM. When a part comes out of an AM machine, there may still be a number of processes to be carried out before it can be considered ready for use. This may include subtractive manufacturing, material treatments, or coatings. This chapter discussed processes applied to parts once the AM stage has been completed, generally referred to as “post-processing.”

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 17. Software for Additive Manufacturing

Abstract

This chapter deals with software that is commonly used for Additive Manufacturing. In particular, we will discuss the STL file format that is used by most machines for model input data. These files are manipulated in a number of machine-specific ways to create slice data and for support generation. Basic principles of STL files are covered here including some discussion on common errors and other software that can assist with STL files. We consider some of the limitations of the STL format and how it may be replaced by something more suitable like the Additive Manufacturing File format. A proliferation of software tools for AM are emerging and becoming a major productivity aid for AM users. This includes software for build preparation, machine scheduling, process modeling, automated design, and more. As such, the reader is encouraged to search the latest literature, in addition to this chapter, to better understand this dynamic aspect of the AM industry.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 18. Direct Digital Manufacturing

Abstract

From the mid-1980s to the present, the percentage of parts made from Additive Manufacturing that are used as final, production parts has consistently increased. For the first decade of AM, commercial focus was on prototyping. During the second decade of AM, a significant amount of work went into illustrating the benefits of AM for producing tooling (the subject of a subsequent chapter). Starting in the mid-2000s and continuing to the present, the focus has shifted to utilizing AM for production of end-use components, which we call “Direct Digital Manufacturing” (DDM). DDM has continued to gain momentum, and today the majority of parts made using AM are for DDM and rapid tooling, rather than for use as prototypes. An overview of the types of applications that DDM is enabling as well as benefits and drawbacks of DDM compared to traditional part manufacturing operations is overviewed in this chapter.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 19. Design for Additive Manufacturing

Abstract

The benefits and drawbacks of Additive Manufacturing Technologies enable designers to think beyond traditional design for manufacture and assembly constraints. AM has unique geometric, material, and customization benefits not provided by other production techniques. Likewise, AM has need for supports, typically produces anisotropic properties, and may require considerable post-processing. These and other benefits and drawbacks of AM have led to an increased emphasis on training designers to Design for Additive Manufacturing. In this chapter, we will revisit some of the concepts from prior chapters and introduce new concepts and ways of thinking to help designers take advantage of AM without falling into design pitfalls.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 20. Rapid Tooling

Abstract

This chapter discusses how Additive Manufacturing can be used to develop tooling solutions. Although AM is not well-suited to high-volume production for many types of geometries and materials, it does have unique benefit when producing tools for traditional volume manufacturing operations. This can be from the perspective of using AM to create patterns for parts where the materials or properties needed in those parts are not currently available using AM or for longer run tooling where AM may be able to simplify the process chain or improve the performance of the tool. Commonly referred to as rapid tooling, we discuss here how AM can contribute to tool-making for product manufacturing processes.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 21. Industrial Drivers for AM Adoption

Abstract

Additive Manufacturing is in its fourth decade of commercial technological development. Over that time, we have experienced a number of significant changes that have led to improvements in accuracy, better mechanical properties, a broader range of applications, and reductions in costs of machines and the parts made by them. In this chapter, we explore the evolution of the field and how these developments have impacted a variety of applications over time. We note also that different applications benefit from different aspects of AM, highlighting the versatility of this technology.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Chapter 22. Business and Societal Implications of AM

Abstract

The unique attributes of Additive Manufacturing offer opportunities for new types of business enterprises. These opportunities include new types of products, organizations, and employment. In this chapter we focus our discussion on how Additive Manufacturing disrupts conventional thinking and enables a new type of entrepreneurship, called “digiproneurship.” AM has already transformed the way people design, manufacture, and distribute software, hardware, products, and services; and this transformation will continue to accelerate as AM matures.

Ian Gibson, David Rosen, Brent Stucker, Mahyar Khorasani

Backmatter