Additive manufacturing (AM) is also known as 3D printing and classifies various advanced manufacturing processes that are used to manufacture three dimensional parts or components with a digital file in a sequential layer-by-layer. This chapter gives a clear insight into the various AM processes that are popular and under development. AM processes are broadly classified into seven categories based on the type of the technology used such as source of heat (ultraviolet light, laser) and type materials (resigns, polymers, metal and metal alloys) used to fabricate the parts. These AM processes have their own merits and demerits depending upon the end part application. Some of these AM processes require extensive post-processing in order to get the finished part. For this process, a separate machine is required to overcome this hurdle in AM; hybrid manufacturing comes into the picture with building and post-processing the part in the same machine. This chapter also discusses the fourth industrial revolution (I 4.0) from the perspective of additive manufacturing.
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The innovative thinking of designers develops the product where the manufacturers bring the same into reality by different manufacturing methods using suitable materials, to fill the needs of society. Design and manufacturing are the two important aspects of product development. Problem recognition, conceptualization, synthesis, analysis, design description, optimization and implementation are the steps involved in the design process. Further, proper selection of the material and the process used to manufacture the product play important roles in the life of the component. The manufacturing technology is as old as the invention of the wheel. Several techniques like casting, joining, forming, machining etc. help the manufacturers to bring out the product to meet the requirements. In the year 1920, the powder metallurgy is added to the manufacturing processes by the invention of the sintering process. Later, Computer Numerical Control (CNC) machines made the manufacturing processes easy. Just three decades ago, Additive Manufacturing has been invented, which is a revolution in the manufacturing sector.
The most common manufacturing methods used to fabricate components include casting, machining, forming, joining, sheet metal work and powder metallurgy. The selection of the process is done depending on the applications of the end product. The casting process uses molten material which is poured into a die, prepared to suit the size and shape of the component required. Any complex shape can be made with a casting process if the die is prepared. The dimensional accuracy and finishing of the component depend on the material and accuracy of the die. But the preparation of the die requires much skill, consumes a lot of money and time, sometimes years together. The material properties cannot be retained in the casting process since the material is melted to a liquid state and solidified in the die. The removal of the excess material from the base material is called machining process which is classified as turning, milling, drilling, grinding etc. The material removal in machining is in the form of chips, which shear from the base material. Generally, a hard-cutting tool is used to machine a soft workpiece. More difference in the hardness between the workpiece and tool results in a component with high accuracy and surface finish. With a lesser difference in hardness, it is difficult to machine and the cutting tool may show its traces on the finished components and the total process requires a lot of time. Forming is the process of shaping the components without adding or removing the material but by the application of force, sometimes maybe at elevated temperatures. Rolling, forging, extruding, wiredrawing, punching, blanking etc. are the different types of forming processes. Since the processes are carried out at heavy loads and sometimes at elevated temperatures, the residual stresses induced which affects the properties of the components a lot. The powder metallurgy is the science where solid components are fabricated with the metal powders pressed in a die with heavy loads with or without elevating the temperatures, sometimes in the presence of a binder. Generally, the components made from the powder metallurgy are used as bearings since they possess high porosity, which is essential for self-lubricating components. In sheet metal work, a thin sheet is cut and bent to form the desired components.
A Computer Numerical Control (CNC) machining processes is an autonomous and requires less human intervention, a program is written in the computer to perform one or more of the aforementioned tasks, generally machining, high precision components can be made with high accuracy but it suits well for the mass production. Thus, almost all conventional and computer-controlled processes have limitations to produce customized products. Additive Manufacturing (AM) is the technique which fabricates the components, layer by layer taking the inputs from the CAD data. Any complex shape can be made with AM technology. AM supports many plastics and metals and it is possible to fabricate near net shape components also.
Additive Manufacturing (AM)/ Three-Dimensional Printing (3DP) industry is comprised of a progression of innovations containing computerized methods that can rapidly manufacture any given three-dimensional component/ part with the end goal of testing the structure, fit, and capacity of a configuration (Billiet, et al. 2012). As a layer-based added substance producing system, AM gives an architect the ability to manufacture any possible geometry.