The common additive manufacturing techniques like fused filament fabrication (FFF) routinely produce physical, rigid structures. But using this production technique for manufacturing flexible structures with high-end materials such as thermoplastic polyurethane (TPU) is more difficult. Because of its difficulty, the fabrication of these structures requires higher-end machinery, time-intensive fabrication, and skilled users. Therefore, we focus on the malleable dynamics of a rigid thermoplastics with mid-range FFF technology to expand the design-space of shape-changing interfaces and propose a fabrication approach for it. As a result, the intended user, for example a creative designer, can also integrate shape-changing interfaces of rigid thermoplastics in their designs, much sooner than if constrained by an FFF printing platform. In a first phase, we experiment with different materials through an iterative design-based process. In a second phase, we perform an explorative design-case study to test the material’s flexibility and the fabrication approach. The research is concluded with an approach proposal, discussion and future work.

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The current COVID-19 pandemic has resulted in an immense and unforeseen increase in demand for personal protective equipment (PPE) for healthcare workers worldwide. Amongst other products, respirator masks are crucial to protect the users against transmission of the virus. Decontamination and reuse of the existing stock could be a solution to the shortage of new respirators. Based upon existing studies, it was found that (I) a solid quality control method is essential to test product reuse, (II) in-depth evaluation of the different parts of the filtering facepiece respirator (FFR) should be considered, and (III) communication of the reuse cycle is essential to take track of the amount of reuse, as this is limited to ensure quality. The goal of this paper is two-fold. First, we identify the impact of decontamination on the different parts of the FFRs and how the quality control should be performed. Two different types of FFRs are analysed within this paper, resulting in the recommendation of combining quantitative respirator mask fit testing with a thorough sensory evaluation of decontaminated FFRs to qualify them for reuse. Secondly, the possibilities of communication of this reuse to the eventual user are mapped through in-depth reasoning.

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Saxophonists have different expectations from the saxophone mouthpiece, as it significantly affects the playability and the sound of the instrument. A mass personalization paradigm provides unique products to cater to their needs, using the flexibility of additive manufacturing. The lack of quantitative knowledge on mouthpiece design hinders the personalization attempts. This study aims to lay out how design parameters affect mouthpiece characteristics. Twenty-seven 3D-printed mouthpieces with varying design parameters are used in conjunction with an artificial blowing machine, to determine the acoustical relevance of the various mouthpiece designs on four selected mouthpiece features. The influence of the design parameters is evaluated statistically and via a case study with five saxophonists. The analysis shows that seven out of nine parameters tested affect the mouthpiece characteristics by relatively different amounts. A user study demonstrates that saxophonists confirm the results in 7 of 10 cases, and they prefer personalized mouthpieces in 4 of 5 cases. The results present a key contribution to the understanding of mouthpiece design. The findings provide valuable insights for new mouthpiece design and mouthpiece personalization.

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With the worldwide spread of the COVID-19 virus in early 2020, shortages of surgical masks and filtering facepiece respirator (FFR) masks became a critical problem. European governments recommended that civilians should not use these masks so that the shortages in the hospitals would be minimised. In Europe, civilians were instead advised to wear community face coverings. In June 2020, the European Committee for Standardisation (CEN) published CWA 17553:2020 [1–3] which formalised minimum requirements, methods of testing and use of community face coverings. The CWA 17553 is presently only a recommendation, and not an official standard such as the EN14683 standard for surgical masks or the EN149 standard for filtering facepiece respirators. Because there are different performance requirements for these three different classes of masks, it makes comparing their performance challenging. In this work, we perform particulate filtration efficiency measurement, total inward leakage measurement and breathability measurement on a range of surgical masks, filtering facepiece respirators and community face coverings. This analysis provides a useful comparison between material performance and the effectiveness of a mask’s design which is manufactured from this material.

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Mass-Customization (MC) has been considered to answer diversifying customer needs and reshape the consumer product market. However, after about two decades of trials, MC has been largely far from success in practice. One of the major reasons for this is considered to be a lack of user engagement with customized products and the customization process itself. Therefore, this draws the attention from what is provided to the customer to how it is provided. The user involvement in MC is in the form of co-creation and often done through online tools, also known as product configurators. In practice, these product configurators for MC frequently fail in sales conversion. This study investigates the experience for customers throughout the co-creation process in an attempt to shed light on different aspects of this experience and provide a better understanding of all contributing factors.

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In order to support the decision-making process of industry on how to implement Augmented Reality (AR) in production, this article wants to provide guidance through a set of comparative user studies. The results are obtained from the feedback of 160 participants who performed the same repair task on a switch cabinet of an industrial robot. The studies compare several AR instruction applications on different display devices (head-mounted display, handheld tablet PC and projection-based spatial AR) with baseline conditions (paper instructions and phone support), both in a single-user and a collaborative setting. Next to insights on the performance of the individual device types for the single mode operation, the study is able to show significant indications on AR techniques are being especially helpful in a collaborative setting.

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This work presents a halftoning technique to manufacture 3D objects with the appearance of continuous grayscale imagery for Fused Deposition Modeling (FDM) printers. While droplet-based dithering is a common halftoning technique, this is not applicable to FDM printing, since FDM builds up objects by extruding material in semi-continuous paths. The line-based halftoning principle called 'hatching' is applied to the line patterns naturally occuring in FDM prints, which are built up in a layer-by-layer fashion. The proposed halftoning technique isn't limited by the challenges existing techniques face; existing FDM coloring techniques greatly influence the surface geometry and deteriorate with surface slopes deviating from vertical or greatly influence the basic parameters of the printing process and thereby the structural properties of the resulting product. Furthermore, the proposed technique has little effect on printing time. Experiments on a dual-nozzle FDM printer show promising results. Future work is required to calibrate the perceived tone.@en

Wire and Arc Additive Manufacturing (WAAM) is a metal 3D printing technique based on robotic welding. This technique yields potential in decreasing material consumption due to its high material efficiency and freedom of shape. Empirical measurements of WAAM, using a deposition rate of 1 kg/h, were performed on site of MX3D. The measured power consumption per kg stainless steel is 2.72 kW, of which 1.74 is consumed by the welder, 0.44 by the robotic arm, and 0.54 by the ventilation. The material loss was 1.1%. A 98% argon 2% CO2 welding gas was used with a flow of 12 l/min.

A cradle-to-gate Life Cycle Assessment (LCA) was performed. To give this assessment context, green sand casting and CNC milling were additionally assessed, through literature and databases. The purpose of this study is to develop insight into the environmental impact of WAAM. Results indicate that, in terms of total ReCiPe endpoints, the environmental impact of producing a kg of stainless steel 308 l product using WAAM is comparable to green sand casting. It equals CNC milling with a material utilization fraction of 0.75. Stainless steel is the main cause of environmental damage in all three techniques, emphasizing the importance of WAAM's mass reduction potential. When environmentally comparing the three techniques for fulfilling a certain function, optimized designs should be introduced for each manufacturing technique. Results can vary significantly based on product shape, function, materials, and process settings.@en

The project 'Factory-in-A-day' aims at reducing the installation time of a new hybrid robot-human production line, from weeks or months that current industrial systems now take, down to one day. The ability to rapidly install (and reconfigure) production lines where robots work alongside humans will strongly reduce operating cost and open a range of new opportunities for industry. In this paper, we explore a method of collaborative fabrication planning with the help of Augmented Reality as part of the concept Augmented Fabrication. In order to plan a new production line, two co-located workers at the factory wear a Microsoft Hololens head-mounted display and thus share a common visual context on the planed position of the robots and the production machines. They are assisted by an external remote expert connected via the Internet who is virtually co-located. We developed three different visualizations of the state of the local collaboration and plan to compare them in a user study.

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In recent years, mass-customization and on-demand production have spread to larger ground. To accommodate these developments, manufacturing systems are being transformed to allow more flexibility and agility. One of the technologies that allow flexibility and agility is Collaborative Robots. The design and implementation of Intelligent Manufacturing Systems is a complex activity that requires bridging between disciplines. With the introduction of Collaborative Robots, new disciplines are added to this activity, that need to be linked to existing design methods and procedures. Currently, the lack of these links is a bottleneck for Small and Medium sized Enterprises. These have limited resources for implementation. In this article, we introduce a Human-Robot Coproduction Design Methodology, with the aim of raising the capacity of Intelligent Manufacturing System designers for reasoning on collaboration between humans and robots in manufacturing. The methodology comprises four procedural steps: analysis, modeling, simulation, and evaluation, with specific methods, tools and instruments. The methodology has been evaluated in a laboratory environment by performing a pilot study with designers. While the current implementation of the methodology and its instrumentation is limited, it has been shown that the methodology enables quick design iterations during the conceptual design phase of Human-Robot Coproduction, thanks to procedures that have been tailored for this novel form of organizing and structuring production processes in Intelligent Manufacturing Systems.

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Digitization and the growing capabilities of data networks enable companies to perform tasks via remote support, which previously required service personnel to travel. But which mixed reality method leads to better results regarding human factors, grounding and performance criteria? This paper reports on a collaborative user study, in which a local worker is guided by a remote expert with the help of different augmented reality methods. The performed task is an controller exchange in a switch cabinet of an industrial robot, a task rather typical for failure detection within the field. Our study was conducted in collaboration with a technician school of which 50 technician apprentices participated in our study. Our results show clear advantages of using augmented reality (AR) to enable remote support. It further gives significant indications for using a projection based AR method.@en

This paper introduces a novel method for designing personalized orthopedic casts which are aware of thermal-comfort while satisfying mechanical requirements. Our pipeline starts from thermal images taken by an infrared camera, by which the distribution of thermal-comfort sensitivity is generated on the surface of a 3D scanned model. We formulate a hollowed Voronoi tessellation pattern to represent the covered region for a web-like cast design. The pattern is further optimized according to the thermal-comfort sensitivity calculated from thermal images. Working together with a thickness variation method, we generate a solid model for a personalized cast maximizing both thermal comfort and mechanical stiffness. To demonstrate the effectiveness of our approach, 3D printed models of personalized casts are tested on body parts of different individuals.@en

To make most out of manufacturing of the future, we need to engage stakeholders though technologies that blend the digital and physical. Through so-called Augmented Fabrication, computational precision and digital manufacturing are combined with user skills/intuition. One of such approaches is the use of co-located design in the built environment: through wearable AR systems such as the Microsoft Hololens, multiple stakeholders can conceive and consider several interventions to improve functions of a city.@en

Within the European Factory-in-a-day project, the aim is to improve communication between automation integrator and factory owner, in their analysis of feasibility and appropriateness of automating a manual task. A visualisation tool with preconfigured workflows and working principles, with specific focus on efficient human-robot coproduction workflows can improve this process. This paper describes the Workflow Simulation Tool, which is part of the Human-Robot Coproduction Methodology, currently in development. The tool encompasses a portable tablet PC, which runs a visual modelling environment combined with a handheld 3D scanning solution. The tool also features pre-modelled template layouts, implementation of a checklist of persistent notes and portable visual documentation. The tool's appropriateness was iteratively validated in collaboration with automation integrators. This evaluation showed that offering an interactive visual simulation enriches the dialogue during conceptual design and helps in revealing requirements that otherwise only appear during or after implementation.

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We present a novel, low-cost haptic feedback device for spatial design tasks that provides proprioceptive and tactile feedback. It uses the Manus VR datagloves and a custom VR CAD environment. Here, tactile feedback is provided to the index finger through a vibrating motor, which helps users in identifying points on a grid. This grid allows for alignment during the creation and manipulation of geometric shapes. Models can be adjusted by pinching at a vertex of the shape with index finger and thumb, and moving this to a different point on the grid. Here, proprioceptive feedback is provided by a solenoid locking mechanism. The system was evaluated through preliminary user testing. Results indicate that the device leads to more natural and intuitive interactions for both the point grid and vertex adjustment, but that the ergonomics needs to be improved. Future challenges involve further integration of the physical device and datagloves and refined, multi-finger feedback@en

The relentless civil war in Syria is having disastrous effects on the people of Syria and their rich cultural heritage. Initiatives are taken across the world to preserve the archaeological materials or at least the scientific information they contain. Our project focuses on casts of Assyrian clay tablets (ca. 1200 BC) with cuneiform script from the site of Tell Sabi Abyad (northern Syria) excavated by archaeologists from the National Museum of Antiquities and Leiden University between 1996 and 2006. After the excavations, the archaeologists made silicone rubber casts of the objects for detailed studies in Europe. Cuneiform, i.e., wedge-shaped writing was invented in the later fourth millennium BCE and remained in use in the Middle East until the 2nd century CE. Dated to the 12th century BCE, the Tell Sabi Abyad texts are an important historical source on the organization of the Middle Assyrian Empire. They provide unique insights in the daily scores of Assyrian officials managing a rural settlement on the western outskirts of their empire, levying taxes, and pacifying local tribes. In 2012 the original tablets were stolen from the archaeological museum of Raqqa when Raqqa became the capital of ISIS. The original objects gone, the moulds are the closest we can get to the originals. Assyriologists stress the importance of continued access to the objects to facilitate ongoing interpretation and re-translation. The short life expectancy (30 years) of the moulds necessitates measures for long-term preservation. We are developing a new method for safeguarding information from the lost artefacts: making high-resolution three-dimensional scans of the plastic moulds and subsequently physical replicas of the original objects by 3D printing. Leiden Assyriologists have confirmed the validity of a pilot reproduction. Nevertheless, several issues have aroused during this trial. First, the moulds are not free of imperfections and irregularities. For example, they contain air bubbles that have to be filtered out from the digital model of the surface of the clay tablet, especially when bubbles are lodged inside wedges. Second, the surface mesh size has to be optimized to preserve all information contained in the tablets without rendering the 3D printing too time consuming. Third, attention has to be paid to the colour, lustre and illumination of the 3D prints to facilitate deciphering. Preliminary results aiming to render the digital models and physical replicas even more real than the first reproduction are exposed. The use of the replicas by multiple stake holders (field archaeologists, assyriologists, museums, game industry) is envisaged.@en

This work presents halftoning techniques to manufacture 3D objects with the appearance of full grayscale imagery for Fused Deposition Modeling (FDM) printers. While droplet-based dithering is a common halftoning technique, this is not applicable to FDM printing, since FDM builds up objects by extruding material in semi-continuous paths. A set of three methods is presented which apply a linear halftoning principle called 'hatching' to horizontal, vertical and diagonal surfaces. These methods are better suited to FDM compared to other halftoning methods: their applicability stands irrespective of the geometry and surface slope and the perceived tone is less sensitive to the viewing angle. Furthermore, the methods have little effect on printing time. Experiments on a dual-nozzle FDM printer show promising results. Future work is required to optimize the interaction between the presented methods.

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This work wants to investigate which visualization method is able to support remote teleanalysis of industrial plants best regarding comprehension, usability and situation awareness. The application goal is the remote optimization of an industrial plant and the examined scenario was generated out of a large data set of a real production entity. The plant consists of an industrial manipulator, a molding machine and a montage system. Prior studies on the same plant with video based visualization explored by remote experts showed a large potential for optimization, but indicated a higher demand for situation awareness. In order to test the influence of the visualization method, a user study has been carried out with 60 student participants with six different visualization methods, including various VR and AR implementations. Overall, our used AR environment performed significantly better than the used VR and video implementations, but the VR implementation surpasses AR regarding situation awareness.@en

During the big Tour de France time trial on the 15th of July 2016, Tom Dumoulin was cycling in a new suit, developed jointly by Team Giant-Alpecin and TU Delft. [TUDelft 2016] The drag of different suits was optimized in the Delft wind tunnel. However, as one can't place a professional cyclist in a wind tunnel for weeks on end. For this, a 3D printed mannequin with the exact same physical measurements was made. An essential benefit using an exact replica in the wind tunnel is that it remains perfectly still, making the measurements of the airflows around the body much quicker and more accurate. Additive manufacturing was not chosen as easiest option, it lead to a collection of research opportunities. The process includes scanning, 3D segmenting, printing strategy and printing, assembling and testing. The complete process wasdone in less then 2,5 months.

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