1
3D Printing as a Multidisciplinary Field

Hamid Reza Vanaei1, 2, 3, Sofiane Khelladi3, and Abbas Tcharkhtchi4

1ESILV, Léonard de Vinci Pôle Universitaire, 92916 Paris La Défense, France

2Léonard de Vinci Pôle Universitaire Research Center, 92916 Paris La Défense, France

3Arts et Métiers Institute of Technology, CNAM, LIFSE, HESAM University, 75013 Paris, France

4Arts et Métiers Institute of Technology, CNRS, CNAM, PIMM, HESAM University, 75013 Paris, France

1.1 Introduction

The challenges related to effective bonding, diminished strength, and mechanical performance of 3D models created through fused filament fabrication (FFF) remain significant focal points within the realm of 3D‐printed structures. FFF, commonly known as 3D printing, is extensively utilized in crafting prototypes for various industries such as aerospace, medical, and automotive sectors. This technique involves feeding a thermoplastic polymer into a liquefier, which then extrudes a filament while traversing successive X–Y planes along the Z‐axis direction. This process results in the gradual construction of a 3D component layer by layer. As the deposition advances, the heated filament is placed upon previously deposited filaments that are in the cooling phase. This action triggers their reheating, establishing a specific period during which the interfaces of contacting filaments achieve temperatures beyond the glass transition temperature (Tg) for amorphous materials or the crystallization temperature (Tc) for semicrystalline materials. This temperature range is essential for effective bonding to occur. Consequently, each filament must attain a sufficient level of heat during deposition, while avoiding excessive heat that might lead to deformation due to the force of gravity and the weight of subsequently deposited filaments in subsequent layers.

Hence, numerous factors influence the quality of the produced component, such as the polymer's temperature profile, and, consequently, the bonding between layers. Consequently, comprehending the manner in which the process parameters impact the temperature changes in the filaments is of significant importance. Furthermore, given that rheological properties like viscosity are influenced by temperature variations, it is plausible to establish a connection between this dependency and the changing temperatures of the deposited filaments. This suggests the possibility of establishing a linked correlation between viscosity and temperature. Consequently, this concept gives rise to the notion of a time, temperature, transformation (TTT) diagram for the material, enabling the simultaneous exploration of both temperature variations and their impact on viscosity.

While 3D printing offers certain benefits, there is a need for enhancement and refinement to meet industry standards. This improvement entails enhancing mechanical attributes and the quality of bonding (with the goal of achieving superior component quality), as well as minimizing production costs and construction duration (with the aim of optimizing the overall process).

Given the abovementioned statements, the temperature evolution during 3D printing process thoroughly specified the quality and mechanical strength of fabricated structures. Experimental monitoring and analytical investigations are still challenging in 3D printing, and lack of practical knowledge corresponds to the problem of bonding in this process. Since the rheological characteristics are a function of temperature, together with the mentioned process variables, are widely affected by temperature evolution of filaments while printing. To sum up, investigation on temperature and temperature dependence viscosity of 3D printing materials while printing is still in its early stages, and it governs the bonding quality itself.

This chapter highlights the significance of 3D printing as a multidisciplinary field. It emphasizes the pivotal variables that exert control over the bonding quality of the end product. Additionally, the discussion delves into essential techniques for characterizing these factors and enhancing our perspective for the purpose of optimization through a combination of experimental and numerical methods.

1.2 Unveiling the Foundations: Grasping the Essential Features of 3D Printing

1.2.1 Historical Review

ME‐3DP emerged as one of the earliest innovations in the realm of 3D printing, with its inception traced back to the late 1980s through the appearance of its initial patent [1]. This pivotal development paved the way for the establishment of Stratasys, an entity that has since grown to attain a prominent status as one of the globe's largest and most influential enterprises in the 3D printing domain. Throughout the initial 20 years of ME‐3DP's existence, Stratasys maintained a notable presence, primarily wielding its fused deposition modeling (FDM®) apparatus. These integrated machines, recognized for their association with rapid prototyping, paralleled the functions of other contemporary 3D printing technologies during that era.

A significant transformation in both the technological and market landscapes of 3D printing emerged during the later part of the 2000s. This transformative shift was primarily instigated by two pivotal occurrences –first, the advent of the RepRap initiative, which championed open‐source principles, and second, the expiration of Stratasys' original patents. This confluence of events heralded a proliferation of participants in the market, primarily consisting of hardware startups, who embarked on the development of desktop 3D printers inspired by the RepRap model and bearing striking resemblances to Stratasys' machinery [2]. This period witnessed the rapid expansion of several of these entities, either propelling them to the forefront of the market or leading them to be acquired by established industry leaders. The consequence was the emergence of a burgeoning market characterized by an ever‐diversifying array of products. For instance, the current landscape features an extensive array of FFF (increasingly standardized as opposed to FDM) printers, spanning a price spectrum from modest hundreds of dollars to significant figures in the hundreds of thousands. Another pivotal transformation was the transition from self‐contained product architectures, emblematic of the early era of 3D printing firms, to an open ecosystem comprising specialized providers of machinery, materials, components, and software. This shift played a pivotal role in accelerating the democratization and innovation within the 3D printing field. It facilitated the technology's penetration into markets that had hitherto remained inaccessible due to various barriers. Presently, 3D printing stands as the most widely embraced 3D printing technology, quantified by both the staggering volume of machine shipments (exceeding one million annually on a global scale) and the extensive user base numbering in the millions.

For the 3D printers, a considerable proportion is comprised of FFF printers that, for the most part, retain operational similarities to the original Stratasys machines. Nevertheless, there have been successive innovations within the process over time, resulting in a significant broadening and enhancement of the technological landscape governing 3D printing methodologies (as indicated in Figure 1.1). Among the most prominent instances is the utilization of 3D printing for generating continuous fiber‐reinforced composite structures, a groundbreaking concept initially pioneered by the US‐based firm Markforged. Subsequently, this innovation garnered widespread attention both within industrial circles and scholarly discourse. This advancement empowers the creation of structures characterized by extraordinary stiffness and resilience, thereby enabling 3D printing to venture into novel domains of material attributes that had hitherto remained inaccessible.

Figure 1.1 Process variations in 3D printing.

1.2.2 Potential of 3D Printing from Lab to Industry

The evolution of 3D printing technology, from its origins in laboratories to its widespread adoption in various industries, has been nothing short of transformative. Initially developed as a rapid prototyping tool in the 1980s, 3D printing has now emerged as a powerful force that holds immense potential across a wide spectrum of applications. Its journey from lab experimentation to industrial integration highlights its capacity to revolutionize traditional manufacturing processes and redefine the boundaries of creativity and innovation.

In the early stages, 3D printing was primarily confined to research laboratories, where it was used for creating prototypes and conceptual models with relative ease and speed. This capability drastically cuts down development times and costs compared to traditional subtractive manufacturing methods. As the technology advanced, its potential began to extend beyond prototyping, leading to the production of intricate and customized components that were previously deemed unfeasible. As 3D printing techniques evolved, industries such as aerospace, automotive, healthcare, and consumer goods took notice of the technology's promise. In aerospace, for instance, the ability to create lightweight,...