Additive manufacturing

The objective of this project is to address the limitations of conventional slicing and simulation software in the field of 3D printing. The project entails the creation of a comprehensive virtual environment utilising the Unity platform, thereby effectively integrating the capabilities of G-code generation programs with the precision of 3D models. By employing this innovative approach, the project has achieved a high degree of accuracy in simulating the movements of actual printing machinery and accurately representing material deposition processes. A key objective is the creation of a dynamic and interactive framework that can accommodate a wide range of inputs and sensory data in real time. This feature enhances the Virtual Twin technology, transforming it into a highly versatile tool for conducting simulations, improving printing efficiency, and facilitating advanced technical training. The significance of this project lies in its immediate practical applications and its potential to serve as a pioneering model for future developments within the 3D printing industry and beyond.

Keywords: 3D Model , 3D printing , Codification , Virtual Twin

This paper presents a method for designing a customized ergonomic office chair backrest aimed at improving user posture and long-term health. Given the importance of ergonomics in workplace settings, this study leverages 3D scanning and additive manufacturing to create personalized cushions that conform precisely to individual anatomical shapes, aligning with ergonomic standards. The process begins with high-resolution scans of both the user's back and a standard chair backrest, followed by cushion modeling in Blender to ensure exact fit and support. Additive manufacturing was selected for cushion fabrication, using a TPU material with an optimized internal structure to enhance comfort. Results indicate a notable improvement in posture alignment and comfort, verified through comparative scans before and after customization. The custom backrest also encourages proper posture through a postural retraining effect and provides a high level of hygiene due to its non-porous material.

Keywords: Additive manufacturing , Custom cushion , Ergonomic chair

In orthopedic surgery, bone tissues aid in the reconstruction of damaged or missing bone and ligaments, allowing patients to achieve optimal motor function recovery. A musculoskeletal tissue bank collects and certifies donated tissue for transplantation. However, sometimes suitable bone tissue is unavailable or incompatible geometrically with the required implant. Custom-made, biocompatible artificial bone tissue development could mitigate such challenges. Scaffolds, either biological or synthetic, promote bone regeneration within the body. Despite research on their chemical compositions and mechanical properties, limited attention is given to their geometric design and personalized shape. This study presents a method for designing bone scaffold geometry using additive manufacturing in a biocompatible material. The aim is to create a scaffold with variable density, from denser cortical to less dense medullary zones. CT images determine bone tissue density, compared to the density imposed on the scaffold. Additionally, the printability of the PEEK, the chosen material, is investigated.

Keywords: 3D Printing , Biomaterials , CAD , Lattice structures , PEEK

Geometric Dimensioning and Tolerancing (GD&T) are among the basic concepts of functional fitness and quality assurance in modern manufacturing. The historical development of GD&T took place primarily in the ambit of subtractive manufacturing; the advent of Additive Manufacturing (AM) now presents novel challenges due to the complexity of geometries, material variability, and process-induced variances. The present Perspective Paper briefly hints at key challenges for the future of GD&T in AM, with an eye to the necessary adaptation of tolerancing principles to AM-specific geometries, integration of Model-Based Definition (MBD) in digital threads, and development of new standards for surface texture and tolerance stack-up. New inspection techniques are also highlighted for the AM parts, which would become more prominent.

Keywords: additive manufacturing , geometric dimensioning and tolerancing , ISO , model-based definition , surface texture features

Build orientation significantly influences the overall performance of products realized with Fused Filament Fabrication (FFF) - based Additive Manufacturing (AM) technology. Based on an extensive experimental campaign, this study aims to investigate the simultaneous effect of build orientation on tensile strength, flatness, and surface roughness of PET-G (PolyEthylene Terephtalate Glycol) samples realized via FFF. A thorough analysis was conducted to clarify the connection between the rotation angles, which define the part orientation within the build volume, and the output variables. The results indicated a significant dependency of all the measured outputs on the out-of-plane rotation angle.

Keywords: build orientation , flatness , Fused Filament Fabrication , roughness , tensile strength

The fabrication of three-dimensional (3D) scaffolds with imprinted physical, chemical and topographical cues is instrumental in tissue engineering strategies to instruct cell function and guide the regeneration of tissues. α-Amino acids based poly(ester amide)s (AAA-PEAs), combining the biocompatibility and biodegradability of polyesters with the superior mechanical properties of polyamides, have emerged as promising scaffolding materials. However, their processing via extrusion-based 3D printing remains challenging due to the lack of polymeric structures with suitable molecular weight and thermal stability. Here, we develop a new library of high molecular weight AAA-PEAs based on l-alanine (PEA-ala), l-alanine/glycine (PEA-ala-gly (75 : 25)) and l-alanine/glycine/jeffamine (PEA-ala-gly-jeff (50 : 25 : 25)) and investigate their performance as polymeric materials for 3D printing against commercially available poly(ϵ-caprolactone) (PCL). Thermogravimetric analysis reveals the stability of AAA-PEAs at high temperatures, enabling their processing via melt-extrusion printing. Despite differences in complex viscosity between PCL and AAA-PEAs, highlighted by oscillatory rheology measurements, the printability of AAA-PEAs does not seem to be compromised, resulting in 3D scaffolds with good shape-fidelity. Additional physicochemical characterisation of synthesised materials also confirm the possibility of fabricating two-dimensional (2D) films and 3D scaffolds with different mechanical properties, wettability and degradation profiles, depending on the AAA-PEA used. Biological tests carried out in vitro confirm the ability of synthesised materials to support the adhesion and function of metabolically active human bone marrow derived mesenchymal stem cells (hBM-MSCs).

The design of lightweight devices is a paramount goal in the industrial field. Great challenges involve the development of high-quality components manufactured by Fused Deposition Modeling (FDM). Accordingly, the aim of the study was to report preliminary features in the development of a strategy towards in situ monitoring and quality assessment of 3D printed parts. Block-shaped specimens were manufactured using FDM and polyethylene terephthalate glycol-modified (PETG) filament. Printing temperature, second deposition angle and printing speed were varied at three levels to evaluate their influence on the vibrations and on the flexural performance. The motions produced by a 3D printer were investigated, and suitable sensors were chosen and/or adapted as measuring systems. The vibrations produced during the FDM process were monitored by means of a customized sensor systems. The values for the three axes were produced in acceleration, and some examples of the amplitudes recorded over time were reported. Three-point bending tests were carried out on the 3D printed PETG. A potential correlation among the acceleration patterns and the mechanical properties (i.e.

Keywords: Design for additive manufacturing , Design of experiments , In situ monitoring , Mechanical measurements , Sensor measurements

The development of prototypes prior to the market launch of final products requires adapting production components to reduce costs and increase flexibility for potential modifications. While the manufacturing of rigid or structural components is well-established and widely practiced, the production of expanded materials presents significantly greater challenges due to the final product's reliance on the specific process employed. Changing the process to lower costs necessitates reproducing the same mechanical behaviour and appearance to ensure validation in terms of both style and function. This study focuses on replicating the behaviour of expanded polyurethane foam, commonly used in motorcycle seat padding, using thermoplastic polyurethane (TPU). The aim is to create a prototype or a customised version of the foam. The internal stochastic closed-cell structure is designed using slicing software, and test specimens are subsequently fabricated through Material Extrusion (MEX) additive manufacturing and subjected to compression testing. The results emphasise the critical influence of material hardness and infill density on the force-displacement curves. An experimental map, derived from three parameters (material hardness, elastic modulus, and foam density) illustrates the behaviour of the specimens, with iso-lines representing constant density.

Keywords: Additive manufacturing , Material extrusion (MEX) , Motorcycle saddle , Polymeric foams , Rapid prototyping , Stochastic infill

This study investigates an innovative surface finishing process for 3D-printed components using Material Extrusion (MEX). By applying controlled heating to the outer layer with a heated, semi-spherical tip, surface quality can be enhanced without adding material, effectively reducing imperfections caused by nozzle deposition. Using a prototype tool with distinct thermal properties, simulations were conducted to assess the optimal process parameters, including tool temperature, movement speed, and depth of influence within the material. Thermal simulations of the tool were performed to analyse temperature distribution and efficiency, identifying potential heat losses. Additionally, interactions between the tool tip and the material were simulated, highlighting temperature distribution at various depths. The simulations reliably model the tool's performance, providing a solid foundation for precise process parameter calibration while minimising reliance on experimental testing. Analyses conducted on PLA, PETG, ABS, PEEK, and PEKK demonstrated a clear correlation between speed and temperature in achieving optimal results.

Keywords: Additive manufacturing , Finite element method , Heat propagation , Material extrusion , Thermal analysis , Thermoplastic polymers

The engineering process is a critical area in the design and development of devices for scientific, industrial and technological applications. This process involves the conceptualization, design, prototyping and production of equipment suitable for specific operations or functions. The main objectives of equipment engineering are to optimize the performance, efficiency of functionality, safety and reliability of devices, as well as to reduce costs and production time. The application of advanced engineering methodologies, such as Computer-Aided Design (CAD), systems analysis and advanced manufacturing techniques such as Additive Manufacturing (AM), allows the creation of high specialized and high performance equipment to satisfy the specific needs of modern industries. In the framework of advanced technologies such as nuclear fusion, equipment engineering plays a key role in solving complex challenges and developing innovative solutions involving various aspects of engineering knowledge.

Keywords: Additive Manufacturing , CAD , Design Methods , Engineering Design , Prototyping

To ensure the geometric accuracy of wire arc additive manufacturing (WAAM) components, it is essential to analyze how process parameters influence the weld bead dimensions and shape. This paper presents a formal and repeatable procedure to entirely characterize the geometry of beads by enhanced full-coverage optical scanning with focus on multi-layered thin-walled closed specimens realized by the cold metal transfer (CMT) welding process. A series of circular specimens have been manufactured according to a DOE plan of process parameters, scanned with a GOM fringe projection 3D optical scanner, geometrically processed in the Rhinoceros 3D CAD environment, and analyzed by statistical indices according to the ANOVA approach. Average dimensions, lateral surface waviness, interaction between successive layers, and the torch switch-on/off zone of closed layer paths have been assessed. Numerical correlations between bead sizes and deposition parameters have been established. The obtained results also reveal shape and dimensional variability, highlighting the challenges in controlling geometry accuracy.

Keywords: 3D optical scanning , Bead geometry analysis , Cold metal transfer , Design methods , Geometry processing algorithm , Wire arc additive manufacturing

This study investigates the influence of various printing parameters on the tensile, compressive, and bending stiffness of fused deposition modeling (FDM)-printed polylactic acid (PLA) parts through a comprehensive full factorial design of experiment. Key factors, including infill percentage, infill pattern, number of outer shells, and part orientation, were systematically varied to quantify their impact on mechanical performance. A total of 36 parameter combinations, selected based on a literature review and experimental feasibility, were tested using standardized specimens: beams for bending, cylinders for compression, and dogbones for tensile testing. Mechanical tests were performed according to ISO 5893:2019, employing a 1 kN load cell to determine stiffness and elastic modulus. The results indicate that the number of outer shells and infill density are the most influential parameters, whereas infill pattern and part orientation have a minor effect, depending on the loading condition. This study provides a novel and robust evaluation of the interactions between key printing parameters, offering new insights into optimizing the mechanical properties of FDM-printed parts.

Keywords: FDM , mechanical properties , PLA , printing settings

Manufacturing and testing electric propulsion systems can be very expensive both in economic and time terms. One of the main limiting factors is the manufacturing of ceramic components, such as alumina. However, the advent of 3D printing has made it possible to produce complex-shaped components made of technical ceramics at low cost and in reduced time. This paper illustrates the advancements made by the University of Pisa in Fused Filament Fabrication of alumina components for electric propulsion purposes. Rapid prototyping can help not only in manufacturing thrusters in a faster and cheaper way but also in producing more complex geometries, resulting in more efficient thrusters. The alumina produced through this method has achieved near-full density and a flexural strength of 430 MPa. Components manufactured with this technique successfully passed vibration and pyroshock tests.

Keywords: Additive manufacturing , Alumina , Electric propulsion , Fused filament fabrication , Hall thrusters , Hollow cathode

Gait training is essential in rehabilitation as it promotes mobility, prevents falls, and increases independence in daily activities. However, accurate gait assessment in the context of telemedicine remains a challenge. Wearable inertial devices offer value by providing a minimally invasive means to accurately capture movement. This study aims to improve telemedicine-based gait analysis by introducing a method utilizing a class II-B medical device equipped with a chest-worn inertial sensor. To enhance the quality of acceleration signals, we designed and 3D printed an 18-face polyhedron for stationary calibration. We validated this method by comparing its performance to a marker-based motion capture system in a cohort of young healthy adults. The results showed an 82% reduction in the root mean square error (RMSE) of acceleration signals. Furthermore, the study showed statistical and practical significant improvements in spatial gait characteristics. Specifically, there was a 14% reduction in root mean square error for gait velocity, a 59% reduction in RMSE for step length, and a 53% reduction in RMSE for stride length.

Keywords: 3D Printing , Gait Analysis , Motion Capture , Telerehabilitation , Wearable Devices

Lattice structures are defined by the organised repetition of a unit cell. These complex designs are widely used in engineering due to their lightweight nature and tailored mechanical properties. This study presents a novel 1D numerical method for modelling the standard Body-Centered Cubic (BCC) unit cell, a commonly used lattice structure geometry due to its geometry simplicity. Mechanical analyses were carried out using Ansys 2023 R2. A customised ANSYS Parametric Design Language (APDL) routine was developed to assign specific area and inertia properties to each beam element, independent from the nominal value of the strut diameter. The equivalent engineering constants were evaluated through uniaxial compression and in-plane shear tests. A neural network optimisation technique was then employed to optimise the 1D model's parameters and improve its accuracy. The neural network was trained using high-fidelity 3D FEM results as the reference data, enabling the identification of the most suitable parametric values for various strut diameters. The proposed 1D method aims to address the computational complexity associated with traditional 3D FEM analyses while maintaining accurate predictions of the mechanical response. By representing the lattice struts as beam elements in the 1D model, the computational cost can be significantly reduced, making it more feasible to analyse large-scale lattice structures or perform extensive parametric studies involving different design configurations and loading scenarios. This formulation has been tested by comparing numerical results coming from standard 3D and 1D elements on a variable span 3-point bending test.

Keywords: FEM , Lattice Structures , Neural Network

The significance of sustainability has steadily increased over the last decade, driving industries to explore innovative approaches that mitigate environmental impact while maintaining operational efficiency. Additive Manufacturing (AM) has emerged as a promising solution, offering design flexibility and potential for resource efficiency and localized production. However, accurately assessing the environmental impact within AM process workflows remains challenging, particularly within a life cycle assessment (LCA) context. This paper aims to address this gap by introducing a method to estimate energy consumption in Material Extrusion (MEX) AM and integrate it in the main workflow of the process. The study analyzes two different 3D printers and quantifies the energy contributions of different machine components across various operational conditions. Additionally, it describes regression models with high performance in predicting energy consumption based on key printing parameters such as printing time, nozzle temperature, and building plate temperature. This research contributes to advancing our understanding of energy efficiency in AM processes and supports the integration of sustainability considerations into additive manufacturing workflows. The findings have implications for optimizing energy usage, minimizing environmental impact, and enhancing the overall sustainability of AM operations.

Keywords: Additive manufacturing (AM) , Energy consumption , Life cycle assessment (LCA) , Material extrusion (MEX) , Sustainability

Polyether ether ketone (PEEK) is a thermoplastic polymer renowned for its exceptional thermal resistance, mechanical strength, durability, chemical resistance, and low density. PEEK can be additively manufactured using various techniques, including Power Bed Fusion (PBF) and Material Extrusion (MEX). Among these, MEX stands out for its ease of operation and cost-effectiveness. Optimizing printing parameters and thermal post-processing are crucial for enhancing the mechanical and thermal properties of printed parts. In this study, the effect of an infiltration process by a high-performance thermosetting epoxy resin on the flexural properties of PEEK has been investigated. Moreover, a comparison with respect to as-printed specimens has been carried out. Results revealed that infiltrated PEEK exhibits a 27,4% higher flexural strength, with an average value of 93,84 MPa, and a 12,5% higher flexural modulus, averaging at 3311,44 MPa. Furthermore, the strength-to-weight ratio and stiffness-to-weight ratio both experienced improvements in specimens subjected to infiltration. Notably, as-printed PEEK displayed increased susceptibility to delamination under flexural stress, demonstrating a more brittle fracture behavior compared to infiltrated specimens. In summary, the findings indicate that the developed infiltration post-processing method shows potential for improving the mechanical properties of additively manufactured PEEK.

Keywords: 3D-printed PEEK , Flexural properties , Thermosetting epoxy resin , Vacuum infiltration

Lattice structures have developed as a vital component in advanced engineering applications due to their superior strength-to-weight ratios and adjustable mechanical properties. This paper focuses on examining the correlation between the isotropic features of lattices at the material level and their structural performance. The research used near-isotropic Crossing-cylinder (CC)-Body Centered Cubic (BCC) cells in various orientations and sizes. Both experimental analysis and finite element analysis were used to examine the compressive strength of the structure in each orientation. The results reveal that cell orientation is important for determining failure modes and mechanical performance at the structural level. At 0°, the lattice has higher compressive strength and energy absorption due to effective load transfer via CC-aligned struts. In contrast, higher orientations (e.g., 15°, 30°, and 45°) are dominated by collapse-type failures, indicating anisotropic behavior in an otherwise isotropic design. Smaller cell sizes have more strength at lower orientations due to their higher relative density, but larger cells perform better at higher orientations. © 2025, Universitas Muhammadiyah Magelang.

Keywords: Compressive strength , Failure modes , Isotropic , Lattice structures

Lattice Spring Models (LSMs) are fast and stable simulation methods based on networks of discrete deformable elements, well-suited for large deformations or topological changes in real-time applications. Considering that the identification of spring network topologies and elastic constants lacks standardization, defining a robust design workflow for LSMs would promote their wider adoption, enabling efficient and green simulations. In this work, the essential requirements to obtain optimal spring distributions for physically consistent LSM were outlined. Intrinsic rigidity, homogeneity, isotropy, and boundary conformity were identified as fundamental conditions for achieving realistic behaviors of deformable lattices. To generate optimal spring networks, the possibilities offered by high-quality unstructured triangular and tetrahedral meshes were explored, since they satisfy all the outlined design requirements. Several topological metrics were defined and applied to clusters of spring network samples, with the aim of comparing different lattice topologies. By discussing the obtained results, a series of useful considerations were pointed out, and many best practices to generate optimal mesh-derived lattice configurations were clearly identified. The optimal LSMs were validated on several case studies, including comparisons to dual FEM models, analyses on anisotropic spring networks, and fracture simulations, thus giving highly encouraging results.

Keywords: Lattice spring model , Modeling , Simulation , Tessellation , Topology metrics , Triangular and tetrahedral mesh

Although complex designs are acknowledged to be more suitable for fabrication with additive manufacturing, there is no formalized definition of what makes a geometry sufficiently complex and accordingly appropriate for additive manufacturing. This lack of a standardized definition represents a challenge for engineers and designers. In this context, the objective of this study is to evaluate the role of part geometry in manufacturing decisions and to understand the criteria influencing the selection of a manufacturing process. This research used semi-structured interviews with 11 experts and a survey with 37 novices to gather data. Through ten questions, participants were requested to evaluate ten shapes of parts without further information and speculate on their suitability for additive manufacturing. It emerged that some of the experts stressed batch volume, material, part size, mechanical properties, cost, and material waste as fundamental criteria for selecting a manufacturing process, while novices did not consider material waste and cost as critical aspects. Part geometry was overall given secondary importance unless the part included specific features such as thin walls, lattice structures, and optimized topologies, where the selection leant towards additive manufacturing for both experts and novices. The latter preferred additive manufacturing (70% of the answers) more frequently than the former (54%). Overall, this study highlights the differences in decision-making criteria between experience levels and underlines the need for a formalized framework to evaluate geometric suitability for AM.

Keywords: Design for additive manufacturing , Experts , Geometric complexity , Manufacturing process selection , Novices , Semi-structured interview