Additive and Traditionally Manufactured Components

A Comparative Analysis of Mechanical Properties

Joshua Pelleg

• Publisher: Elsevier
• Year: 2020
• Print ISBN: 9780128219188
• eBook ISBN: 9780128219195
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Additive and Traditionally Manufactured Components: A Comparative Analysis of Mechanical Properties looks at the mechanical properties of materials produced by additive manufacturing (AM) and compares them with conventional methods. Since the production of objects by AM techniques can used in a broad array of materials, the alloys presented are the ones most commonly produced by AM - Al alloys, Ti alloys and steel. The book explores the six main types of techniques: Fused Deposition Method (FDM), Powder Bed Fusion (PBF), Inkjet Printing, Stereolithography (SLA), Direct Energy Deposition (DED) and Laminated Object Manufacturing (LOM), and follows with the techniques being utilized for fabrication.Testing of AM fabricated specimens, including tension, compression and hardness is included, along with a comparison of those results to specimens obtained by conventional fabrication methods. Topics covered include static deformation, time dependent deformation (creep), cyclic deformation (fatigue) and fracture in specimens. The book concludes with a review of the mechanical properties of nanoscale specimens obtained by AM.- Thoroughly explores AM processes that can be utilized for experimental design- Includes a review of dislocations observed in specimens obtained by AM- Compares the impact of both additive and traditional manufacturing techniques on the mechanical properties of materials

Chapter One

What is additive manufacturing?

Abstract

Additive manufacturing (AM) is also known as three-dimensional (3D) printing or 3D fabrication. In this process, the layers are repeatedly printed on top each other, being consolidated during the process until the object (shape and size) is complete. A classification of the various AM techniques is presented here as: (1) fused deposition method, (2) powder-bed fusion, (3) inkjet printing, (4) stereolithography, (5) direct energy deposition, and (6) laminated object manufacturing.

Keywords

3D printing; No post-processing; Computer-aided design (CAD)

Additive manufacturing (AM) also known as three-dimensional (3D) printing or 3D fabrication describes technologies to build objects by adding layer upon layer of material. Structures are made by this technique by the addition of layers, which combine to form the final product. The 3D fabrication method is universal to all material classes such as plastic, metallic, concrete, and biomaterials. The technology has been developing rapidly since its invention in the 1980s when the first technique was applied to print plastic objects. Early additive manufacturing (AM) equipment were developed at this time. One could consider truly without exaggeration that the AM technology is a manufacturing revolution characterizing the 20th century modifying all concepts and imagination of production on the industrial progress scale. The 3D printing mentioned previously is a general expression often used to indicate all types of additive manufacturing. The 3D printing is defined as a method for the fabrication of objects through the deposition of material using a print head, nozzle, or other printer technology. In the fabrication process, the computer and computer-added design (CAD) software are used to transfer the directions to the printer, which prints the objects in the desired shape and size one thin layer at a time. The layers are repeatedly printed on top of each other, being consolidated during the process until the object (shape and size) is complete. A variety of shapes can be produced in a wide range of sizes without the need of using additional operations such as drilling, extrusion, welding, etc., and thus intricate forms can be produced in one single operational step. A cycle of object processing takes a relatively short time and an important characteristic of a process is that changes can be made easily by the computer during fabrication. Such a flexibility without the need of additional mechanical operations results in considerable cost savings.

A classification of the various technologies is presented in this chapter, and the production details of these methods are described in the chapter on fabrication (Chapter 2). The main AM methods are as follows:

1. (1) Fused deposition method (FDM). Thermoplastic polymers are the material that are generally fabricated by this method.
2. (2) Powder-bed fusion (PBF). It is suitable for printing complex structures. The powders in each layer are fused together with a laser beam or a binder.
3. (3) Inkjet printing. It is one of the principal methods of ceramics manufacturing.
4. (4) Stereolithography (STL). UV (ultraviolet) light (or electron beam) is applied to initiate a chain reaction in a resin-like or monomer solution. It is effective for complex nanocomposite production.
5. (5) Direct energy deposition (DED). The sources of energy are laser electron beam and arc. It is used also in the automotive and aerospace industries.
6. (6) Laminated object manufacturing (LOM). It is useful for thermal bonding of ceramics and metallic materials.

In DED, energy is directed to a small region of the material to be deposited, which melts it and the requirement is that the laser energy (or other energy source) is powerful enough to melt the powder. The energy source (laser > electron beam > arc) and the deposition rate determine the quality of the DED process. Materials that can be fabricated are stainless steels, copper, aluminum and its alloys, titanium, nickel, cobalt, tin, etc. Thus, the number of alloys that are available for the various processes is not very limited in modern AM technology as it was at in earlier stages. Sometimes post-processing, secondary operations, and finishing are required to remove (or dissolve) supports that are used to support overhanging features during construction. Improvement is required to eliminate the necessity of finishing process. Thus, there is still a lot of work and research to be accomplished before AM technologies become standard in the manufacturing industry because not every commonly used manufacturing material can be handled.

AM processes take the information from a CAD file that is later converted to a stereolithography (STL) file. The increasing development and the successful results of AM since its early use predict that this technology has a significant place in future and current manufacturing techniques.

In practice, the terms 3D printing and AM may be used interchangeably.

Chapter Two

Fabrication

Abstract

A short description of the additive manufacturing processes is presented with the appropriate basic equations. All the methods are described in detail accompanied with appropriate illustrations and the appropriate relations of the processes. Melt properties, the liquefier, heat convection, pressure drop estimation, layer deposition and stability, road spreading and road cooling, and polymer bonding are all described for the fused deposition method and the equations used for this process evaluation. Similar details are presented to other processing techniques. In the case of the stereolithography properties of interest are the state of the resin, the maximum cure depth, the cured line width, and the laser scan velocity.

Keywords

Fused deposition method; Powder-bed fusion; Inkjet printing; Stereolithography; Direct energy deposition; Laminated object manufacturing

In this chapter, a short description of the processes mentioned in Chapter 1 is presented with some basic equations applicable to these processes.

2.1 Fused deposition method (FDM)

The FDM method is applied widely for producing plastic parts. It is one of the several additive ma...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• Preface
• About the author
• Chapter One: What is additive manufacturing?
• Chapter Two: Fabrication
• Chapter Three: Testing: Comparison of AM data with traditionally fabricated
• Chapter Four: Dislocations in AM and traditional manufacturing: A comparison
• Chapter Five: Deformation in AM and traditional manufacturing: A comparison
• Chapter Six: Dynamic deformation
• Chapter Seven: Time-dependent deformation creep in AM and traditional manufacturing
• Chapter Eight: Cyclic deformation (fatigue) in AM and traditional manufacturing: A comparison
• Chapter Nine: Fracture in AM and traditional manufactured components
• Chapter Ten: Comparison of deformation in AM and CP nanomaterials
• Chapter Eleven: Epilogue
• Index