# A Review on Recent Trends and Applications of IoT in Additive Manufacturing
## 1 Introduction
ISO ASTM 52,900, which explains several techniques related to AM, has categorized seven core technologies of AM as Binder Jetting (BJT), Directed Energy Deposition (DED), Material Extrusion (ME), Material Jetting (MJT), Power Bed Fusion (PBF), Sheet Lamination (SHL), Vat Photo Polymerisation (VPP). There are several sub-inclusive AM processes, such as Selective Laser Sintering (SLS), Stereolithography (SLA), Fused Deposition Modelling (FDM), Laminated Object Manufacturing (LOM), Poly Jet 3D Printing (PJP), Inkjet 3D Printing (IJP), Colour Jet-Printing (CJP), Three-Dimensional Printing (3 DP), Multi-Jet-Printing (MJP), Electron Beam Melting (EBM), and Laser Metal Deposition (LMD), that have been heavily researched and developed, and put into commercial use by industries [11; 12; 13; 14; 15; 16; 17; 18; 19]. With the advancement of all these technologies, AM is evolving as the disruptive technology in the field of smart manufacturing systems and also plays a vital part in providing extensive contributions to Industry 4.0. AM offers design innovation, material waste reduction, part flexibility, inventory stock reduction, energy savings, customization, reduction of errors, and creative freedom without the cost and time constraints of traditional manufacturing [20]. However, there are some areas, such as limited material selection, part size restrictions, part cost, post-processing, dimensional control, and no custom alloying, that restrict its full-scale implementations, which have to be overcome by integrating other technologies or by following several research works [21]. Every gadget/machinery has internet access, making it easier to manage from anywhere on the Internet, with or without passwords. IoT Beacon technology allows us to remotely control and monitor pricey equipment with secure passwords. Beacon is hardware that combines Bluetooth Low Energy standard and a low-power battery to communicate messages and information directly to a smartphone, tablet, device, or other equipment to monitor persons around the machine [1; 22]. This makes AM technology more flexible and easier to process. The International Telecommunication Union recommends that the network architecture of IoT consists of the sensing layer, the access layer, the network layer, the middleware layer, and the application layers [23; 24]. These layers feature in capturing, transferring, integrating, managing, and controlling real-time network information for intelligent integrated processing. IoT possesses the capacity to assist devices in sensing the environment in which they are located, and by doing so, it has made it feasible to efficiently regulate and oversee industrial activities remotely [25; 26]. The network architecture and overview of various applications of IoT are shown in Figure 1.  
We have seen that the IoT devices can be created to be specific to almost every industry and vertical organization, including healthcare, industrial automation, smart homes and buildings, and automotive and wearable technologies, which we are naming as trendy gadgets and habituating towards the comforts offered by their usage. But the thirst for technological advancements that lead to cloning or integrating IoT with other processes is happening very rapidly in several sectors. In this list, the influence of AM technology on the conceptualization of future Internet of Things breakthroughs has been enormous. The necessity for an accurate and realistic prototype is a crucial aspect of new product development. Traditional means of obtaining a prototype that fits these requirements are rather costly. With additive manufacturing, however, these advancements may be produced at a fraction of the cost and in a shorter period than with conventional methods, while also being more exact. As a result, 3D printing is becoming an integral part of producing new goods for the Internet of Things. Internet of Things-enabled AM assists in sustainable manufacturing and leads to the evolution of industrial production systems which brings some expected benefits.