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The purpose of this paper is to gain insight into whether additive manufacturing (AM) represents incremental, radical, disruptive innovation or an industrial revolution and its implications.

This study applies a desk research strategy. Data were collected through a variety of industry sources as well as academic publications.

It was found that AM represents different innovations in different settings, while it represents incremental innovation in one industry, it has led to radical changes in other industries. There are also indications that it has a disruptive nature and some of the developments appear to be of the industrial revolutionary type, i.e. they cause fundamental shifts in society. Some explanation for the observed differences can come from different performance objectives.

The spread of AM has been limited due to initial intellectual property protection. That means that while illustrations and examples were found for the different types of innovations, the level in which AM will ultimately penetrate manufacturing industries and society overall is not (yet) known. This calls for continued research for instance to study, in-depth, the adoption characteristics of AM in very specific settings.

Manufacturing is undergoing many changes as a consequence of the AM innovation. Many manufacturing industries have already been impacted through incremental changes as well as radical changes to entire industry dynamics. Manufacturers are advised to carefully monitor the continuous innovations in the technological capabilities of AM and their competitive and strategic consequences for adoption decisions.

AM has an impact on many aspects of society because it affects many industries and enables household manufacturing. It has also affected education, i.e. the current generation of students in terms of skill requirements, and leads to legal difficulties in terms of intellectual property.

This study contributes to the understanding of the AM innovation and the widespread implications for different manufacturing industries and society at large.

This study aims to present a vision-guided robotic system design for application in vat photopolymerization additive manufacturing (AM), enabling vat photopolymerization AM hybrid with injection molding process.

In the system, a robot equipped with a camera and a custom-made gripper as well as driven by a visual servoing (VS) controller is expected to perceive objective, handle variation, connect multi-process steps in soft tooling process and realize automation of vat photopolymerization AM. Meanwhile, the vat photopolymerization AM printer is customized in both hardware and software to interact with the robotic system.

By ArUco marker-based vision-guided robotic system, the printing platform can be manipulated in arbitrary initial position quickly and robustly, which constitutes the first step in exploring automation of vat photopolymerization AM hybrid with soft tooling process.

The vision-guided robotic system monitors and controls vat photopolymerization AM process, which has potential for vat photopolymerization AM hybrid with other mass production methods, for instance, injection molding.

This paper aims to investigate the influence of post-curing temperature, post-curing time and gamma ray irradiation dose upon the tensile and compressive mechanical properties of the medical graded vat photopolymerization parts.

Medical graded vat photopolymerization specimens, made from photopolymer resin, were fabricated using bottom-up vat photopolymerization machine. Tensile and compressive tests were conducted to assess the mechanical properties. The specimens were categorized into uncured and post-curing groups. Temperature post-processing and/or gamma irradiation exposure were for post-curing specimens. The post-curing parameters considered included temperature levels of 50°C, 60°C and 70°C, with 1, 2, 3 and 4 h periods. For the gamma irradiation, the exposure doses were 25, 50, 75 and 100 kGy.

Post-curing improved the mechanical properties of medical graded vat photopolymerization parts for both tensile and compressive specimens. Post-curing temperature greater than 50°C or a prolonged post-curing period of more than 1 h made insignificant changes or deterioration in mechanical properties. The optimal post-curing condition was therefore a 50°C post-curing temperature with 1 h post-curing time. Exposure to gamma ray improved the compressive mechanical properties, but deteriorated tensile mechanical properties. Higher gamma irradiation doses could decrease the mechanical properties and also make the part more brittle, especially for doses more than 25 kGy.

The obtained results would be beneficial to the medical device manufacturer who fabricated the invasive temporary contact personalized surgical instruments by vat photopolymerization technique. In addition, it also raised awareness in excessive gamma sterilization in the medical graded vat photopolymerization parts.

This paper aims to present an investigation of material-process interaction of VAT-photopolymerization processes. The aim of the research is to evaluate the effect of different printing factors on the tensile properties, such as elastic modulus, of 3D printed specimens.

To perform this study, Design of Experiments is used by the use of Taguchi’s techniques. The relationship between each factor and the elastic modulus, ultimate tensile stress and strain at break is obtained. Furthermore, the total print time is analyzed with respect to the obtained properties.

The study indicates that part orientation, exposure time to the UV light and layer thickness are the most important factors affecting the investigated properties. At the same time, it was found that the highest mechanical properties can be obtained with the shortest printing times. A comprehensive list of factors available on the slicing software and other factors, like the orientation of the part or its position, is investigated. Future studies including post curing and chemical characteristics based on the obtained results are necessary.

As a result of this research, it is outlined that using design for additive manufacturing for vat-photopolymerization, especially on DLP processes, 3D printing methods can be stablished. Furthermore, it outlines the possibility of tailoring mechanical properties of printed parts as a function of print parameters and print time. Considering the limited amount of information available in the open literature, the results presented in this paper are of great interest for researchers in the field of VAT-photopolymerization.

The purpose of this paper is to evaluate the influence of layer thickness and post-curing temperature on shape memory properties in components manufactured by stereolithography.

Layer thicknesses of 20 and 100 µm and 22 and 45°C for post-curing temperature were selected following the design of experiments approach. Tensile and bending tests were applied for quantitative evaluation of the shape memory effect (SME). Qualitative analysis was performed using complex geometries and computed tomography as a measurement tool. Additionally, the degree of photopolymerization and glass transition temperature (T_g) were evaluated.

The tensile test resulted in fixity and recovery ratio values close to 100%. In bending, they varied between 97%–111% for fixity and 88%–95% for recovery. The layer thickness was found to have a higher influence on the SME. In complex structures, SME was dependent on geometry and less sensitive to variation in process parameters. The post-curing temperature had a higher influence on the photopolymerization and T_g. Average T_g of 77.5°C was achieved at 45°C, compared to 73.1°C at 22°C.

In the current state of the art in the processing of shape memory polymers with vat photopolymerization typically, the chemical composition or the thermal and deformation patterns are studied. The effect of the processing parameters is, however, not explored. This paper aims to close the research gap and facilitate the process optimization towards high fixing and recovery characteristics.

Over the past few years, the number of related research to additive manufacturing (AM) has risen. The selective composite formation (SCF) can also be found among the new technologies that were developed. This technology was first introduced in 2013, and because of its innovative character, there are still many challenges to be overcome. Therefore, the main aim of this study is to present a finite element method which allows to investigate the processing of the material during the selective formation of a composite material based on cellulose and acrylic.

In the beginning, we introduced a brand new finite element method approach which is based on light transmittance network and photopolymerisation in transient state. This method is mainly characterised by internal light absorption, transversal reflectance, light transmittance coefficient and photopolymerisation kinetics. The authors defined experimentally the main model coefficients besides investigating the formation of composite material in six case studies. The main variables evaluated in those studies were the number of layers and the number of lines. By the end, the degree of polymer conversion and the preliminary evaluation of adherence between layers were identified in addition to the formation profile of composite material.

The presented method evidence that the SCF resulted in a profile of polymerisation which is different from profiles found in vat polymerisation processes. It was shown that the light diffraction increases polymerisation area to outside of laser limits and reduces the penetration depth. It was also exposed that the selective formation of composite material on the top layer interferes with the polymerisation of previous layers and might increase the polymerised area in about 25 per cent per layer. By the end, adherence between layers was evidenced because of a high-pass filter that limited polymer conversion to over 60 per cent. In this case, the adherence between the top layers was provided by the interface between layers, while the deeper layers resulted in a solid formed by composite.

This paper presents research results related to a very new AM technology and also proposes a new method to characterise this concept. Because of this new analytic approach, the process planning can be simulated and optimised, in addition to being a useful tool for other researches related to photocurable polymers and AM technologies.

The industrial application of continuous glass fabric-reinforced polymer composites (GFRPCs) is growing; however, the manufacturing boundedness of complex structures and the high cost of molds restrict their use. This research proposes a three-dimensional (3 D) printing process for GFRPCs that allows low-cost and rapid fabrication of complex composite parts.

The composite is manufactured using a digital light processing (DLP) based Vat-photopolymerization (VPP) process. For the composites, suitable resin material and glass fabrics are chosen based on their strength, stiffness, and printability. Jacob's working curve characterizes the curing parameters for adequate adhesion between the matrix and fabrics. The tensile and flexural properties were examined using UTM. The fabric distribution and compactness of the cured resin were analyzed in scanning electron microscopy.

The result showed that the object could print at a glass fabric content of 40 volume%. In DLP-based VPP printing technology, the adequate exposure time was found to be 30 seconds for making a GFRPC. The tensile strength and Young's modulus values were increased by 5.54 and 8.81 times, respectively than non-reinforced cured specimens. The flexural strength and modulus were also effectively increased to 2.8 and 3 times more than the neat specimens. In addition, the process is found to help fabricate the functional component.

The experimental procedure to fabricate GFRPC specimens through DLP-based AM is a spectacular experimental approach.

In a typical additive manufacturing (AM) system, it is critical to make a trade-off between the resolution and the build area for applications in which varied dimensions, feature sizes and accuracies are desired. Conventional solutions to this challenge are based on curing of multiple areas with a single high resolution and stitching them to form a large layer. However, because of the lack of the capability in adjusting resolution dynamically, such stitching approaches will elongate the build time greatly in some cases. To address the challenge without sacrificing the build speed, this paper aims to design and develop a novel AM system with dynamic resolution control capability.

A laser projector is adopted in a vat photopolymerization system. The laser projection system has unique properties, including focus-free operation and capability to produce dynamic mask image irrespective of any surface (flat or curved). By translating the projector along the building direction, the pixel size can be adjusted dynamically within a certain range. Consequently, the build area and resolution could be tuned dynamically in the hardware testbed. Besides, a layered depth image (LDI) algorithm is used to construct mask images with varied resolutions. The curing characteristics under various resolution settings are quantified, and accordingly, a process planning approach for fabricating models with dynamically controlled resolutions is developed.

A laser projection-based stereolithography (SL) system could tune resolution dynamically during the building process. Such a dynamic resolution control approach completely addresses the build size-resolution dilemma in vat photopolymerization AM processes without sacrificing the build speed. Through fabricating layers with changing resolutions instead of a single resolution, various build areas and feature sizes could be produced precisely, with optimized build speed.

A focus-free laser projector is investigated and adopted in a SL system for the first time. The material curing characteristics with changing focal length and therefore changing light intensities are explored. The related digital mask image planning and process control methods are developed. In digital mask image planning, it is the first attempt to adopt the LDI algorithm, to identify proper resolution settings for fabricating a sliced layer precisely and quickly. In the process of characterizing material curing properties, parametric dependence of curing properties on focal length has been unveiled. This research contributes to the advancement of AM by addressing the historical dilemma of the resolution and build size, and optimizing the build speed meanwhile.

This paper aims to investigate the dimensional accuracy and surface roughness of printed masked stereolithography (m-SLA) parts. The fabricated specimens of photosensitive polymer resin have complex shapes and various features. The influence of four process parameters of m-SLA, including layer height, exposure time, light-off delay and print orientation, is studied on response characteristics.

The Box–Behnken design of response surface methodology is used to examine the effect of process parameters on the shrinkage of various geometrical dimensions like diameter, length, width, and height of different features in a complex shape. Additionally, a multi-response optimization has been carried out using the desirability function to minimize the surface roughness and printing time and maximize the dimensional accuracy.

The layer height and print orientation influence the surface roughness of parts. An increase in layer height results in increased surface roughness, and the orientation parallel to the z-axis of the machine gives the highest surface roughness. The dimensional accuracy of m-SLA parts is influenced by layer height, exposure time, and print orientation. Although not significant in dimensional accuracy and surface roughness, the light-off delay can affect printing time apart from other parameters like layer height and print orientation.

The effect of layer height and print orientation on dimensional accuracy, printing time, and surface roughness is investigated by researchers using simple shapes in other vat photopolymerization techniques. The present work is focused on studying the effect of these parameters and additional parameters like light-off delay in complicated geometrical parts in m-SLA.

Soft robotics is currently a rapidly growing new field of robotics whereby the robots are fundamentally soft and elastically deformable. Fabrication of soft robots is currently challenging and highly time- and labor-intensive. Recent advancements in three-dimensional (3D) printing of soft materials and multi-materials have become the key to enable direct manufacturing of soft robots with sophisticated designs and functions. Hence, this paper aims to review the current 3D printing processes and materials for soft robotics applications, as well as the potentials of 3D printing technologies on 3D printed soft robotics.

The paper reviews the polymer 3D printing techniques and materials that have been used for the development of soft robotics. Current challenges to adopting 3D printing for soft robotics are also discussed. Next, the potentials of 3D printing technologies and the future outlooks of 3D printed soft robotics are presented.

This paper reviews five different 3D printing techniques and commonly used materials. The advantages and disadvantages of each technique for the soft robotic application are evaluated. The typical designs and geometries used by each technique are also summarized. There is an increasing trend of printing shape memory polymers, as well as multiple materials simultaneously using direct ink writing and material jetting techniques to produce robotics with varying stiffness values that range from intrinsically soft and highly compliant to rigid polymers. Although the recent work is done is still limited to experimentation and prototyping of 3D printed soft robotics, additive manufacturing could ultimately be used for the end-use and production of soft robotics.

The paper provides the current trend of how 3D printing techniques and materials are used particularly in the soft robotics application. The potentials of 3D printing technology on the soft robotic applications and the future outlooks of 3D printed soft robotics are also presented.