Digital Manufacturing: From Rapid Prototyping to Rapid Manufacturing
Digital manufacturing involves the direct fabrication of objects without setting pre‐tools or workpiece requirements. Although the terms RP and AM are used synonymously, there was a distinct difference among them. RP refers to the process associated with the development of a prototype model, i.e. here the model processing is restricted till the pre‐production step that could not be used as functional working objects. Thus, the progressive transformation of RP leads to the AM processes that involve the actual production of functional workpieces from prototype models. Thus, AM allows RP to evolve into rapid manufacturing (RM) with more flexibility, work freedom, and exploitation of applications in developing a layered physical object. 3D printing was found to have vast potential applications of prototyping in several industrial sectors such as pharmaceuticals, automotive, space engineering, civil constructions, art, aviation, archaeology, cosmetics, and fashion industries (Rahman et al. 2018). Nevertheless, the most attractive application of 3D printing in food manufacturing is designing foods in a customized manner that leads to the development of the food fabrication process commonly referred to as food 3D printing. 3D printing of foods has a quite huge market potential as it aids in the mass customization, personalized diets, and sustainability practices than the traditional food manufacturing technologies (Derossi et al. 2019). Thus, 3D printing of foods referred to as food layer manufacturing (FLM) involves the sequential process of fabricating three‐dimensional edible constructs in a layer‐by‐layer manner with the capability of binding the adjacent layers through phase transitions or by chemical reactions (Nachal et al. 2019). A typical 3D printing process follows a series of well‐defined steps (Figure 1.2). First, it starts with scanning of real‐time objects or the creation of a 3D model using computer‐aided design (CAD) software. The shape and surface characteristics are stored in a unique STL file format that is native to 3D printing technology. Later the digital representation of the stored 3D object is transformed to the sliced information using a slicing software that translates the 3D model into computer‐generated codes (G and M codes). Based on which the movement arms and motors of 3D printers are controlled (Bechtold 2016). Thus, the whole printing process is controlled digitally using computers with minimal human interactions.
Figure 1.2 Workflow of 3D printing process.
1.3 Milestones in 3D Printing Technology
Although 3D printing received a wide attention in recent years, the technology dated back to several decades. Printing technology that uses two laser beams to fabricate the 3D objects was patented by Wyn Swainson of Denmark in the 1970s (Bechtold 2016). Later in the 1980s, another patent on 3D printing was filed by Dr. Hideo Kodama of Japan. However, this patent got rejected as the deadline for filing was passed out. After that, the next patent was awarded to Charles Chuck Hull in 1986 for his efforts in developing a stereolithography (SLA) apparatus (Beltagui et al. 2020). Hull co‐founded 3D Systems, one of the leading companies in the 3D industry. Later the company introduces the first commercialized 3D printer based on SLA in 1988. Further, they have developed a new file format that was specific to 3D printing technology named STL that was understandable to 3D printers which aid in the printing of 3D objects. While in 1988 DTM Inc., developed the first 3D printer based on selective laser sintering (SLS) technique (Saptarshi and Zhou 2019). Another 3D printing technology named fused deposition modelling (FDM) which was the most commonly adopted 3D printing technique was developed by Scott and Lisa Crump in the 1980s. They received a patent on this FDM technology and co‐founded Stratasys, another major player among the 3D industries (Su and Al’Aref 2018).
During the 1990s with the advancements of technology researchers of Stanford and Mellon proposed several other 3D techniques applied for micro‐level casting and spraying of materials. In 1993, MIT filed a patent on inkjet technology that employs liquid‐based ink for the construction of 3D objects commonly used in inkjet printers (Prasad and Smyth 2016). Later this technique was transferred and licensed to Z corporation for the development and marketing of 3D printers. Apart from materials manufacturing at the industrial level, 3D printing allows to produce consumer end products. In 2005, the RepRap project (3D printing open‐source project) was started by Adrian Bowyer at the University of Bath for the development of 3D printers at a low cost that could be affordable to the consumers (Bechtold 2016).
1.4 Different Historical Eras in 3D Printing
Since the incipient of 3D printing technology, 3D printing has shaped and transformed into different forms. Various technological advancements in the development of these AM processes are summarized in the subsequent sections.
1.4.1 Ancient Age
As stated earlier, the 3D printing process was first demonstrated and documented by Kodama of MIT where he developed a method for fabrication of 3D models out of plastics through photo‐hardening of photopolymers cured by ultraviolet (UV) light (Kodama 1981). Later in 1984, three researchers named Mehute, Witte, and Andre filed a patent on the STL process which was unsuccessful with the lack of business potential (Sokolov et al. 2018). After that, the STL technology was commercialized by 3D systems corporations which resulted in a viable manufacturing process for 3D printing. Meanwhile, the other 3D printing FDM technology has become popular as it paved for the production of consumer‐oriented 3D printed products (Sanchez Ramirez et al. 2019). This technology involved extruding hot‐melted plastics through the nozzle die thereby resulting in the deposition of layers to form 3D objects. These printers were quite large as like ‘1970s 5 MB hard disk’ which were then gradually reduced in size with advancements in 3D printing technology.
1.4.2 Middle Age
Around the 1990s, 3D printing received a vast attention due to its advantageous features that drive researchers of different universities to start working on this emerging area. In the 1990s, EOS GmbH developed a ‘stereos’ system, the first commercial industrial 3D printer (Calignano et al. 2019). Then Stratasys filed a patent on FDM technology that leads to the development of domestic 3D printers. In the late 1990s, new technologies were introduced by many aspiring 3D printing companies such as dot‐on‐dot printing techniques that use polymer jet for the fabrication of 3D objects. One such technique is MIT’s inkjet printing that uses polymer solution in a drop‐on‐demand (DoD) manner (Prasad and Smyth 2016). Similarly, the Fraunhofer Institute of Germany introduced selective laser melting (SLM) in 1995 which employs laser light as a curing medium. Meanwhile, the Z corporation worked in collaboration with MIT for the development and production of FDM printers on a commercial scale. Another advancement of printing technology that made its application in the biological field is in regenerative medicine that supports the growth of human organs as the Wake Forest Institute made a successful attempt in the development of tissue scaffolds (Su and Al’Aref 2018). This medieval period remains to be a golden age that promoted various advancements in 3D technologies and 3D printers.
1.4.3 Modern Age
During the start of the twenty‐first century, 3D printing had moved and expanded its wing from the commercial scale and entered into the domestic level. In 2000, the workers of Object Geometries created the first inkjet 3D printer which was then commercialized by Z corporation that paves a way for the development of multi‐colour 3D printer which remains one of the milestones in the evolutionary history of 3D printers (Yang et al. 2018). Later in 2001, the desktop 3D printers were becoming common and in 2002 Wake Forest Institute worked in the development of miniature 3D printed kidney that mimics the functions of the human
