Advances in Additive Manufacturing Processes

At present, the requirement for new product development and upgrading of the existing product have become inevitable in the manufacturing scenario. The manufacturing sectors are striving hard to sustain in the global market, hence they are continuously seeking rapid manufacturing technologies for developing new products as there is a demand for innovative designs with enhanced features. Conventional manufacturing technologies have certain shortcomings, such as long production times, and are inherent to material wastage due to the subtractive nature of the processes. To meet the demand, it is necessary to accelerate the product development process. The time spent on the design, manufacturing and testing of a product has to be shortened. To emphasize the part representation (or) to rapidly create a system, the prototyping part is ‘Rapid Prototyping’ (RP), and the technology is ‘Additive Manufacturing’ (AM); it is also popularly known as ‘3D Printing’. AM is a novel manufacturing technology as the products are fabricated by adding successive layers of material with the aid of a computer. A Computer Aided Design (CAD) model is created and exported as a Standard Triangle Language (STL) file that is readable by an AM machine. There are many techniques available, which can be categorized according to their raw material. This chapter comprehensively reviews the AM techniques, the applications and the various materials used to produce the AM component.

Selective Laser Sintering (SLS) is a laser-based additive manufacturing technique capable of printing both metallic and non-metallic three-dimensional physical parts rapidly in the layer-by-layer fashion directly from the CAD models. It is an effective method in rapid prototyping, which forms the layer of material by directing a high-density laser into the bed of metallic or non-metallic powders. SLS can be classified based on the laser medium used and the mechanism of printing. Based on the mechanism, it is classified into direct SLS and indirect SLS. The quality of parts in terms of surface finish, mechanical properties, metallurgical properties, and so on depends on SLS's operating parameters, such as laser parameters, feedstock properties, and geometrical parameters. The SLS printed parts can have properties similar to the wrought material.

The chapter presents a comprehensive report of technological developments in direct metal laser sintering (DMLS). The DMLS process is a powder bed fusion process capable of manufacturing three-dimensional complex metallic parts through the layer-by-layer deposition of metallic materials having a wide range of applications in different fields, such as medical, automotive, aerospace, and energy. The present chapter aims to provide an insight on the DMLS working principle, sintering mechanism, and process parameters (i.e., laser power, scan speed, layer thickness, etc.) that influence the quality of the built part. Also, a comprehensive discussion on process monitoring and control techniques, modeling, and optimization techniques has been presented. Further, an extensive argument is provided on the challenges faced in DMLS concerning various materials (titanium, aluminum, steel, etc.), the evolution of microstructure, and mechanical properties experimentally and numerically. The chapter concludes with a detailed discussion on various applications and future research directions.

Our work presents a comprehensive report on selective laser melting (SLM) techniques with a specific focus on the different material families compatible with the SLM process, the mechanical and microstructural characteristics, residual stress and defect analyses. The major process parameters that determine the geometric accuracy and post-treatment techniques that eradicate defects in SLM fabrication are also reviewed. Then, a keyword co-occurrence analysis is performed to determine the future research directions in the SLM. The results showed mechanical characteristaion of SLM, defect analysis of SLM, SLM fabrication of porous implants and bulk metallic glass production using SLM to be the four major domains in SLM literature.

Electron beam melting (EBM) is an effective and competent additive manufacturing process for fabricating three-dimensional metal parts. EBM process uses raw materials in the form of powders. EBM uses an electron beam as the heat source to carry out the bonding process between powders to consolidate them into a required solid part. It involves the use of data from a 3D computer-aided design (CAD) model to create successive layers of raw material. This process requires a vacuum chamber finding EBM as a suitable technique to process reactive materials like titanium alloys. Apart from titanium alloys, EBM also caters to a wide range of powder materials like alloys of cobalt, Inconel, copper, and steel. The parts fabricated using EBM are fully dense and exhibit good mechanical and morphological properties. The applications of EBM include automotive, tooling, aerospace, and biomedical implant industries.

Binder Jet additive manufacturing is a 3D printing technology that is used for a variety of materials irrespective of the properties and characteristics. A variety of materials that are used include ceramics, polymers and metals. The materials are formed layer by layer by the adhesive bonding between material and binder. Compared with recent developing modern manufacturing methods, binder jetting has the capability of producing quickly integrated complex features for obtaining isotropic properties. Green part manufacturing is processed to obtain the end part. Property obtained through this process is close to the traditional powder metallurgy sintering technique. This article discusses in detail the different materials used in binder jet additive manufacturing, different process challenges involved, binder and droplets, post-processing, characterization, the advantages and applications. Further, the powder characteristics and process parameters are explained.

Ultrasonic Additive Manufacturing (UAM) is an innovative process technology that uses sound to combine layers of metal produced from foil stocks. The variation seen in UAM from other AM techniques is that metals are not melted but joined by ultrasonic welding instead. This technique uses high-frequency vibration to bond the surfaces of metal foils while the metal remains firm. The addition of foils by stacking one on the other by this welding technique leads to the creation of solid parts. This method creates high-density metallurgical bonds without melting the metals. This proves to be advantageous, as it avoids changes in grain size, phases, and precipitation reactions. It also aids in bonding dissimilar metals without creating any brittle intermetallic bonding. UAM provides a major application of embedding electronics in solid metal parts to fabricate microelectronics systems like micro-processors, telemetry, and sensors.

Direct Energy Deposition (DED) method of additive manufacturing (AM) is a new paragon for the production, repairing, and design of the complex components of different applications, such as automotive, aerospace, medical equipment, biomedical products, etc. The focused energy source and deposit material (wire or powder form) meet at a focal point where the material melts and is deposited layer by layer at the same time. The laser beam, electron beam, plasma, and electric arc sources are used as a focused energy source based on the type of materials. The demand for the DED process is increasing day by day due to its flexibility for using conductive/nonconductive materials in wire/powder forms. The desired shape and mechanical properties of the manufactured products can be optimized by administering the parameters of DED. A comprehensive review of the DED process is discussed in this chapter, where the deposition mechanisms, the energy sources, the effect of processing parameters, defects, and the mechanical properties, are highlighted in detail.

Wire arc additive manufacturing (WAAM) has confirmed its flexibility in meeting the mid- to large-scale component production requirements for the engineering and related sectors. Because of mechanical limitations such as under-matched mechanical properties, the existence of significant residual stresses and the necessary post-deposition activity of the formed component, WAAM currently cannot be used as a fully-fledged manufacturing process. The entire article offers an overview of the WAAM technology including one with a succinct description of the WAAM field history, situation, benefits and challenges. Emphasis has been given, particularly on the measures to limit porosity, tensile strength, microstructural inspections and other important advances in the field of WAAM. The main advantages of WAAM are the integration of the manufacturing process, the fair degree of design flexibility, as well as the resulting optimization ability. Owing to feasibility of large-scale composite materials of significantly higher deposition rates, considerable progress has been made in the setting of the WAAM process. An acceptable efficient heat treatment has been integrated to help reduce defects within the WAAM process and also to obtain the new options that are effective. The integration of materials and the production methods for manufacturing of defect-free and technically feasible deposited parts remains a vital step in the future.

Additive manufacturing is the method for fabricating the components effectively. The components fabricated by additive manufacturing process have wider applications in various domains. Fusion deposition modeling is one of the additive manufacturing methodologies that has been used for fabricating the components. Generating CAD model occupies the first and foremost step in this process, followed by printing of the designed model through fusion deposition extruders. The preparation of components through fused deposition makes it easier for the complex as well as most intricated shaped components, which is difficult in the case of existing conventional manufacturing practices. This liberty propels the effective utilization of additive manufacturing techniques in various fields ranging from the automotive to aerospace industries. This increasing demand turns the focus towards the selection of precise modeling techniques while selecting the process parameters in the fused deposition techniques. The present work mainly focused on the selection of best models for the fused deposition modeling and the comparative analysis between multiple regression analysis and ANFIS models for the selected parameters.

Additive manufacturing (AM), also sometimes referred to as 3D printing, is a rapidly growing manufacturing technology that has been in use for decades already. With the economic and efficiency advantages such as minimization of material waste, precision manufacturing of complex structures and reduced weight, AM has spanned into various industrial applications, including but not limited to aerospace, automotive, healthcare and many other industries that can leverage on the rapid prototyping capability associated with AM. The goal of this chapter is to elaborate on the industrial applications of AM, both current and potential, and to provide a deeper understanding of AM from a quality perspective. The market for AM is expected to grow up to $26.5 billion by the end of 2021. The cost of poor quality in relation to the potential market of AM is expected to be $5.3 billion (or 20% of AM market) in 2021, if the quality challenges are not taken care of. The chapter aims to uncover the advantages of AM over conventional manufacturing techniques and how this change works to the advantage of improved quality of the parts produced. An overview of current quality standards for AM, as defined by ISO and ASTM, is also provided in the chapter.