Material extrusion systems are the most common types of additive manufacturing systems, also known as three-dimensional (3D) printers. This article focuses on the general 3D printing processes as can be demonstrated and manipulated in desktop printers. The discussion includes details of the components involved in material extrusion as well as the melt extrusion solidification (during cooling) process, the underlying mechanism of road bonding, and the factors affecting good part quality. The discussion also covers support material, postprocessing, and road-quality considerations and the addition of infill in melt extrusion to the hollow spaces inside an object to give it structural strength. Information is also provided on different materials and associated material properties that affect the rate the printer is able to advance and retract material, thereby affecting the quality and rate at which a part is printed. The final section provides information on the mechanism of viscous extrusion 3D printing.

Traditional processing methods for the part production of Co-Cr alloys include casting, powder metallurgy, and metal forming. However, the steps involved during materials processing followed by metal forming and machining are time consuming and fraught with processing variables. Three-dimensional (3D) printing enables rapid evolution in design, personalization, and so on. This article presents a brief description of some common additive manufacturing (AM) processes for the production of cobalt alloy parts, and provides a comparison between AM and conventional processing methods. The discussion is centered on process-microstructure-properties correlation in additively manufactured cobalt alloys and applications of these alloys.

This article provides an overview of the implementation of wire embedding with ultrasonic energy and thermal embedding for polymer additive manufacturing, discussing the applications and advantages of the technique. The mechanical and electrical performance of the embedded wires is compared with that of other conductive ink processes in terms of electrical conductivity and mechanical strength.

This article presents a detailed account of the processes involved in vat-photopolymerization-based fabrication of ceramics, namely bioceramics, structural ceramics, piezoelectric ceramics, optical ceramics, and polymer-derived ceramics. Information and methods of material preparation, curing characteristics, green-part fabrication, property identification, process design and planning, and quality control and optimization are introduced. The article also provides information on postprocessing techniques, namely debinding and sintering, as well as on the phenomenon of shrinkage and compensation.

Material jetting (MJ) is a classification of additive manufacturing processes that involves the selective jetting and subsequent solidification of liquid droplets onto a substrate in a layerwise manner. This article focuses solely on MJ of polymers, providing a process overview and describing the functional characteristics that distinguish it from other AM technologies. It provides information on the properties and design considerations of both build and support materials. Process-related effects on final part properties and overall quality, as well as corresponding design considerations are also covered. The article also discusses the applications and future scope of polymer MJ systems.

The highly irregular morphologies of ceramic powder particles due to their process history present a challenge to binder jetting additive manufacturing (BJ-AM) ceramic powder feedstock processability, but knowledge of powder metallurgy of ceramics benefits the development and analysis of the BJ-AM ceramic processes. Understanding BJ-AM process principles and ceramics processing challenges requires reviewing a number of fundamental principles, which this article delineates. The discussion covers the processability considerations, a brief summary of some fundamental aspects of modeling of liquid permeation in the powder bed, and process capabilities and advantages of BJ-AM technology.

Tungsten, molybdenum, and cemented carbide parts can be produced using several additive manufacturing technologies. This article classifies the most relevant technologies into two groups based on the raw materials used: powder-bed methods, such as selective laser melting, electron beam melting, and binder jet three-dimensional (3-D) printing, and feedstock methods, such as fused-filament fabrication and thermoplastic 3-D printing. It discusses the characteristics, processing steps, properties, advantages, limitations, and applications of these technologies.

This article focuses on binder-jetting technologies in additive manufacturing (AM) that produce metal artifacts either directly or indirectly. The intent is to focus on the most strategic and widespread uses of the binder jetting technology and review some of the challenges and opportunities for that technology. The discussion includes a historical overview and covers the major steps involved and the advantages of using the binder jetting process. The major steps of the process covered include printing, curing, de-powdering, and sintering.

This article presents a brief history of additive manufacturing (AM). It begins by describing additive manufacturing prehistory, dating back to 1860, which is characterized by additive part creation without the use of a computer. The article then discusses the development of additive manufacturing processes occurring in the period from 1968 to 1984 and is followed by a section on modern additive manufacturing (1981 to the late 2000s). The article concludes by providing information on the growth of additive manufacturing since 2010 and the development of standards.

This article discusses the advantages, limitations, and applications of material jetting of ceramics, focusing on two primary methods of droplet formation: continuous stream and drop on demand (thermal and piezoelectric) ink jetting processes.

This article is a detailed account of the advantages, disadvantages, and applications of microdispensing processes used in electronics manufacturing industries. The discussion covers various approaches to control material flow, namely time pressure, auger, positive displacement, and progressive cavity pump dispensing. The concept of valving to control starting and stopping is also discussed. The applications include printing solders in microelectronic packaging, printing to pads, printing conductive patterns for antennas, printing active circuits, printing on flexible surfaces, and structural printing.

This article describes two rapid tooling technologies, namely, direct rapid tooling and indirect rapid tooling, for forging-die applications. Commonly used direct rapid tooling technologies include selective laser sintering, three-dimensional printing, and laser-engineered net shape process. The indirect rapid tooling technologies include 3D Keltool process, hot isostatic pressing, rapid solidification process tooling, precision spray forming, and radially constricted consolidation process.

Aerosol jet printing (AJP) can digitally fabricate intricate patterns on conformal surfaces with applications that include flexible electronics and antennas on complex geometries. Given the potential performance and economic benefits, aerosol jetting was studied and compared with the well-known and competing inkjet printing (IJP). More than 35 of the most relevant, highly cited articles were reviewed, focusing on applications requiring fine features on complex surfaces. The following performance indicators were considered for the comparison of AJP and IJP, because these aspects were the most commonly mentioned within the included articles and were identified as being the most relevant for a comprehensive performance assessment: printing process, line width, overspray, complex surface compatibility, diversity of printable materials, and deposition rate. This article is an account of the results of this comparison study in terms of printing capabilities, ink requirements, and economic aspects.

This article is a review of the material extrusion-based ceramic additive manufacturing (MECAM) processes. The discussion begins with details of extrusion with filament and paste, covering the most popular variants of paste extrusion-based MECAM techniques that can be differentiated based on paste type and the method of shape retention of the deposited layer: extrusion freeforming, robocasting ceramic on-demand extrusion, and freeze-form extrusion fabrication. The article then focuses on post-processing considerations and the mechanical properties of sintered ceramic parts. It concludes with information on innovation opportunities in ceramic additive manufacturing, such as incorporating UV-curing and gelation in the process and producing geometrically complex structures from shapeable green bodies.

Vat polymerization (VP) is an additive manufacturing (AM), or three-dimensional (3-D) printing process in which 3-D objects are produced by hardening a liquid polymer into the desired shape. With the introduction of new materials and improvements in material properties, VP offers a good alternative for AM for low-volume production. This overview of the VP process begins with an introduction to two main processes of VP, namely stereolithography apparatus and digital light processing, and then moves on to discuss the characteristics of the feedstocks used as well as their selection criteria. The article then covers safety issues associated with feedstock handling and the manufacturing constraints related to part orientation and design, providing some key tips for VP support structures. This is followed by a discussion on postprocessing/finishing of VP parts. A brief concluding section considers some special topics related to AM process.

This article discusses the basic operating principles, industrial applications, and advantages as well as the parameters influencing the process of laser-induced forward transfer (LIFT) of solid materials, liquid materials, laser-absorbing layers, intact structures, and metallic 3D microstructures in additive manufacturing.

This article introduces the design and manufacturing implications of additive manufacturing (AM) on part characteristics as well as on design opportunities and on manufacturing practices, supply chains, and even business models. In addition, it describes how they relate to the fundamental nature of AM processes and discusses the characteristics and purposes of AM processes and the parts they fabricate.

The additive manufacturing technologies in the casting of precious metals are divided into two groups: indirect metal methods and direct metal methods. Besides providing a process overview of both of these methods, the focus of this article is on the characteristics, process steps, applications, and advantages of direct metal methods, namely laser melting, material extrusion, binder jetting, material jetting, and vat photopolymerization methods.

Additive manufacturing is a collection of manufacturing processes, each of which builds a part additively based on a digital solid model. The solid model-to-additive manufacturing interface and material deposition are entirely computer-controlled. The traditional additive manufacturing applications have been used for low production runs of parts with complex shapes and geometric features. Additive manufacturing is also used for topology optimization and it impacts the process and supply chain. This article discusses processes, including vat photopolymerization, material jetting, powder bed fusion, directed energy deposition, material extrusion, binder jetting, and sheet lamination.