Readiness of subtractive and additive manufacturing and their sustainable amalgamation from the perspective of Industry 4.0: a comprehensive review

Abstract

The successful realization of Industry 4.0 depends much on how coherently the cyber and physical realms are conjoined in cyber-physical systems. In the context of the fourth industrial revolution, research efforts have mostly been channeled toward the cyber domain, whereas the physical domain has received significantly lesser consideration. A physical domain generally comprises material shaping equipment, work material, tools, working medium, sensors, automation technology, and connectivity mechanisms. The article provides a comprehensive review of the published literature to establish the states of readiness of the two most important manufacturing technologies: subtractive and additive and their sustainable merger from the perspective of Industry 4.0. Rich potentials in the four characteristics at the process level: speed, sustainability, agility, and customer centricity and three at the system level: connectivity, data collection, and automation are required for a manufacturing system (physical domain) to be Industry 4.0 compatible. The review establishes that the subtractive manufacturing domain is nearly compatible regarding speed and agility but needs improvements in respect of sustainability and customer centricity. Additive manufacturing, on the other hand, appears strong on agility and customer-centricity fronts but needs amelioration regarding production speed and sustainability. In respect of the system level characteristics, both technologies seem to be compatible regarding automation, whereas significant improvements are required in connectivity and data sensing and collection. For the sake of raising compatibility levels of the manufacturing systems, subtractive-additive amalgamation is scrutinized. The amalgamation, especially in a done-in-one configuration, has, reportedly, succeeded to retain the favorable traits of the two manufacturing technologies, thus, bringing the merger much closer to the Industry 4.0 requirements. Proper process planning and optimal work distribution between the subtractive and additive modes are critical for operating an amalgamated system at high levels of the key characteristics.