Multi Jet Fusion Research Articles

Lattice Structures-Mechanical Description with Respect to Additive Manufacturing.

Lattice structures, characterized by their repetitive, interlocking patterns, provide an efficient balance of strength, flexibility, and reduced weight, making them essential in fields such as aerospace and automotive engineering. These structures use minimal material while effectively distributing stress, providing high resilience, energy absorption, and impact resistance. Composed of unit cells, lattice structures are highly customizable, from simple 2D honeycomb designs to complex 3D TPMS forms, and they adapt well to additive manufacturing, which minimizes material waste and production costs. In compression tests, lattice structures maintain stiffness even when filled with powder, suggesting minimal effect from the filler material. This paper shows the principles of creating finite element simulations with 3D-printed specimens and with usage of the lattice structure. The comparing of simulation and real testing is also shown in this research. The efficiency in material and energy use underscores the ecological and economic benefits of lattice-based designs, positioning them as a sustainable choice across multiple industries. This research analyzes three selected structures-solid material, pure latices structure, and boxed lattice structure with internal powder. The experimental findings reveal that the simulation error is less than 8% compared to the real measurement. This error is caused by the simplified material model, which is considering the isotropic behavior of the used material PA12GB (not the anisotropic model). The used and analyzed production method was multi jet fusion.

Sustainable Transformation: A Case Study of an Engineering-to-Order Additive Manufacturing Firm

Purpose: Addressing sustainability challenges in additive manufacturing (AM) is critical due to high energy consumption and waste. Optimising AM operations is vital for sustainability. However, the existing literature lacks practical examples for AM companies on how to enhance sustainability. To address this gap, a case study within an AM firm was conducted. Design approach: Using the analytical hierarchy process (AHP), sustainability key performance indicators (KPIs) were identified, aligned with the firm’s strategic objectives. Sustainable value stream mapping (Sus-VSM) analysed the production process for sustainability performance. A sustainability strategy map (SSM) was created based on the five perspectives of the 4th generation balanced scorecard (BSC) approach and the results from the case study. Findings: The research identified optimisation areas in the multi-jet-fusion (MJF) process, crafted tailored sustainability KPIs, and developed a SSM to seamlessly integrate sustainability initiatives into the company’s vision. Value: This contribution provides a structured methodology for selecting KPIs and offers a holistic approach to implementing Sus-VSM within the AM industry. The manuscript emphasises the need to incorporate a fifth perspective into the BSC and proposes a framework for developing a SSM. This study aims to guide AM companies toward a more environmentally responsible and socially conscious approach to manufacturing.

The preparation and axial compressive properties of 3D-printed polymer lattice-reinforced cementitious composite columns

Research on the mechanical properties of 3D-printed lattice-reinforced cementitious materials is becoming increasingly widespread. The bending and compression performances of such materials have been studied from the perspectives of the lattice preparation materials, structural forms, gradient design, and cement-based material types. The extant research has primarily focused on the bending performance of lattice-reinforced specimens, while little research has been conducted on the compressive properties. In addition, the reinforcing effect of the lattice on cementitious materials under lateral constraints has not been considered. This article investigates the compressive performance of cement mortar reinforced by 3D-printed spiral lattices or skin structures with different volume reinforcement ratios (different grid constraint layers). Multi Jet Fusion (MJF) technology was used to print four types of spiral lattices, and six specimens, including a control group, were prepared. The experiment considered the performance differences of polymer-reinforced mortars with different volume reinforcement ratios, bonding performance, and skin reinforcement. The load, displacement, stress, strain and other data of the specimen were measured, and combined with the full field strain measured by DIC technology, the strength, energy absorption performance, ductility, elastic modulus, constraint effect, deformation mechanism, and failure mode of the specimen were comprehensively analyzed. The experimental results indicate that 3D-printed spiral or skin lattices can improve the ductility and energy absorption capacity of cementitious materials. However, the elastic modulus of the raw materials used to reinforce the structure is lower than that of cementitious materials, which will reduce the compressive strength and elastic modulus. In addition, the lateral deformation constraint effect of the lattice or skin structure on the cement mortar under axial compression is not significant. All cementitious specimens were found to exhibit the shear failure of the inclined section under axial compression. This article reveals that 3D printed spiral lattices can improve the deformation ability of cementitious composite materials under compression, providing new ideas for the ideal replacement of stirrups and the development of building energy conservation and emission reduction.

Additive manufacturing of flexible thermoplastic polyurethane (TPU): enhancing the material elongation through process optimisation

AbstractThermoplastic polyurethane (TPU) is used to produce elastomeric parts with superior wear/abrasion resistance, toughness, shock absorption properties, and flexibility, even at low temperatures. The production of this material through additive manufacturing (AM) techniques has been increasing because of the possibility of tuning the mechanical properties using structural design and build process parameters. Despite the data being limited, TPU produced by AM, mainly based on material extrusion, is much stiffer than the corresponding produced by conventional manufacturing, and, therefore, it shows a limited elongation. This study presents the mechanical characterization of TPU produced by the infrared light powder bed fusion (PBF-IrL) system (HP multi-jet fusion), which has recently been introduced. The properties are compared with TPU produced by open (3ntrA4) and closed (Markforged) material extrusion (MEX) systems. For the open FDM, the effects of the processing conditions are investigated to improve the material elongation and UTS with respect to the data reported in the literature for AM and conventional manufacturing. For this reason, an extensive and comprehensive review has been carried out. Compared to material extrusion, PBF-IrL TPU specimens showed higher Young’s modulus, but poorer A%. Considering the samples produced by MEX and compared to previous results in the literature, the properties obtained in this study are superior both in terms of UTS and A%.

Material Characterization of Silicones for Additive Manufacturing.

Three-dimensional printing is ideally suited to produce unique and complex shapes. In this study, the material properties of polysiloxanes, commonly named silicones, produced additively by two different methods, namely, multi-jet fusion (MJF) and material extrusion (ME) with liquid printing heads, are investigated. The chemical composition was compared via Fourier-transform infrared spectroscopy, evolved gas analysis mass spectrometry, pyrolysis gas chromatography coupled to mass spectrometry, and thermogravimetry (TGA). Density and low-temperature flexibility, mechanical properties and crosslink distance via freezing point depression were measured before and after post-treatment at elevated temperatures. The results show significant differences in the chemical composition, material properties, as well as surface quality of the tested products produced by the two manufacturing routes. Chemical analysis indicates that the investigated MJF materials contain acrylate moieties, possibly isobornyl acrylate linking branches. The hardness of the MJF samples is associated with crosslinking density. In the ashes after TGA, traces of phosphorus were found, which could originate from initiators or catalysts of the curing process. The ME materials contain fillers, most probably silica, that differ in their amount. It is possible that silica also plays a role in the processing to stabilize the extrusion strand. For the harder material, a higher crosslink density was found, which was supported also by the other tested properties. The MJF samples have smooth surfaces, while the ME samples show grooved surface structures typical for the material extrusion process. Post-treatment did not improve the material properties. In the MJF samples, significant color changes were observed.

Using a Model Created Using a 3D Printer to Mould a Grey Cast Iron Casting.

This article deals with the possibility of using 3D-printed models as an input for the production of a mould for cast iron castings. This new progressive process is significantly faster (with sufficient accuracy) compared to the current way of making models for moulds. The need to create a wooden model is removed by this process. The quality of this wooden model was highly dependent on the experience and qualifications of the worker. This article describes the manufacturing process of the model and mould in detail. The key dimensions of the final parts are compared with the model and, thus, the accuracy of the chosen procedure is verified. A 3D-printing technology known as Multi Jet Fusion (MJF) was used to produce the model. The material used for the production of the model is polyamide PA12 with 40% glass fibre filling. This material has sufficient structural and strength properties to be used for the given application. Taking into account the dimensions of the part and the printing space of the printer, it was necessary to structurally modify and divide the part. The inlet cone of a turbine is used as an example This cone is produced from grey cast iron as standard.

3D printing of bio-inspired porous polymeric solar steam generators for efficient and sustainable desalination

Freshwater scarcity is a pressing issue worldwide, and solar steam generators (SSGs) have emerged as a promising device for seawater desalination, harnessing renewable solar energy to facilitate sustainable water evaporation. The facile fabrication approach for SSG with complex topologies to achieve high water evaporation efficiency remains a challenge. Herein, a MIL-101 (Fe)-derived C@Fe3O4 ink was employed to multi-jet fusion (MJF) printing of polymeric porous SSGs with specific topologies. The optimized porous structure endows the printed SSGs with capillary force, greatly promoting water transport. The tree-like topology enables high water evaporation rates under various simulated solar radiation conditions. A finite element model was built to fully understand the light-to-thermal energy conversion and water evaporation processes. Moreover, the MJF-printed SSGs exhibit self-cleaning properties and can automatically remove accumulated salt on their surfaces, enabling sustainable desalination. During prolonged testing, the water evaporation rate of the SSGs remained relatively stable and reached as high as 1.55 kg m−2 h−1. Additionally, the desalinated water met the standards for direct drinking water. This study presents a state-of-the-art technology for producing efficient SSGs for desalination and introduces a novel method for MJF printing of functional nanocomposites.

Output Enhancement of a 3D‐Printed Triboelectric Nanogenerator Using Laser Surface 3D Patterning

This study investigates the performance of contact separation and sliding modes of triboelectric Nanogenerators (TENGs) using COMSOL Multiphysics simulation environment. The output performance of a plain surface TENG is compared with square, rectangular, and pyramid‐patterned TENGs. The pyramid pattern emerges as the most efficient geometry, demonstrating a solid output of 95.8 V (Voc) and 0.99 μA (Isc). Advanced 3D printing techniques (3DP) including powder‐based multijet fusion and resin‐based polyjet fusion are utilized to print polyamide 12 (PA12) and VeroClear, respectively. The laser surface patterning technique is used to make precise micropatterns on the surfaces of the VeroClear and PA12 layers, resulting in a consistent and effective surface morphology that enhances the surface area of triboelectric layers, and outperforms traditional approaches of patterning in consistency and efficacy. The validation of simulation results is made where the pyramid pattern is emerged as the most efficient geometry experimentally. Performance is maintained with minimal degradation after 102 cycles, and a 22 μF–63 V capacitor is successfully used to store the generated charge. This study not only sets the path for pre‐experimental analysis using simulation environment but also provides a clear demonstration of advanced manufacturing techniques for printing and patterning 3D‐printed triboelectric materials.

The effect of axial–torsion coupling on the compressive collapse behavior of Kresling tubes

The coupled axial compressive and torsional response of thin-walled tubes, having Kresling geometric units in series, with hollow hexagonal cross-sections of similar wall thickness, is studied. The tubes are fabricated using multi-jet fusion technology with Polyamide-12 (PA12) material. Each tube is compressed under displacement-controlled quasi-static loading with roller boundary conditions to eliminate any reaction torque being induced in the tube. The tube’s deformation response is characterized by an initial load rise followed by a drop in the load past a load maximum. This load drop is caused by localized collapse within a single Kresling unit. The collapse mechanism is accompanied by relative rotation between the ends of the Kresling unit, indicating the presence of compression-twist coupling. After local densification in the collapsed Kresling unit is attained, the load rises and attains a peak followed by a second load drop causing the other Kresling unit to collapse. Finite Element (FE) simulations show that the nonlinearity of the material response influences the onset of the collapse of the Kresling unit. Results from the present study will be helpful in tailoring the geometry of the Kresling unit cells to attain desired energy absorption or to “tune” the end-displacement vs. rotation response of the structure.

Parametric Production of Prostheses Using the Additive Polymer Manufacturing Technology Multi Jet Fusion.

This study aims to develop a procedure for the production of 3D-printed forearm prostheses (especially hard outer sockets). The production procedure is designed in the form of a parametric workflow (CAD model), which significantly speeds up the designing process of the prosthesis. This procedure is not fixedly dependent on the software (SW) equipment and is fully transferable into another SW environment. The use of these prostheses will significantly increase the comfort of their patients' lives. It is possible to produce prostheses faster and in larger amounts and variants by the usage of additive technology. The input for the own production of the prosthesis is a model of the internal soft socket of the patient. This soft socket (soft bed) is made by a qualified prosthetist. A 3D-scanned CAD model is obtained afterward using the scanning method by an automatic laser projector. An editable, parametric external socket (modifiable in any CAD format) is generated from the obtained 3D scan using a special algorithmic model. This socket, after the necessary individual modifications, is transferred to 3D printing technology and produced using powder technology Multi Jet Fusion (HP MJF). The result of the designed and tested procedure is a quickly editable 3D-printed outer socket (main part of prosthesis), which is able to fully replace the current long-fiber composite solution. Production of current solutions is relatively time-consuming, and only one piece is produced in a given time. The newly designed technology eliminates this. This study summarized the possibilities of speeding up the production of forearm prostheses (but not only these) by creating a parametric CAD model that is applicable to different patients.

Fracture assessment of polyamide 12 (PA12) specimens fabricated via Multi Jet FusionTM in the presence of geometrical discontinuities

This study aims to study the fracture resistance of additively manufactured polyamide 12 (PA12), specifically when subjected to notches and cracks, and how it varies with the printing direction using Multi Jet Fusion (MJF). The methodology involved conducting tensile tests on V-notched samples, with a focus on different combinations of opening angle (0°-120°) and tip radius (0.2–2 mm). The findings revealed that the sensitivity to the notch opening angle decreased with an increase in the notch tip radius. Furthermore, the fracture resistance for different mode mixities was examined using semi-circular bend (SCB) specimens, with the crack angle varied between 0° and 53°. The results demonstrated two distinct fracture behaviours, namely brittle and ductile, depending on the crack angle. Theoretical analyses revealed that with appropriate tuning, average strain energy density (ASED) can predict the load capacity of notched and cracked PA12 parts manufactured with MJF, within an error range of ± 20 %.

PA12 Surface Treatment and Its Effect on Compatibility with Nutritional Culture Medium to Maintain Cell Vitality and Proliferation.

This research investigates the suitability of printed polyamide 12 (PA12) and its dyed version to support cells in bioengineering applications. For this purpose, human gingival fibroblasts (hGF06) were cultured on PA-12 scaffolds that were 3D-printed by Multi Jet Fusion (MJF). The study examined the direct cultivation of cells on MJF-printed cell culture scaffolds and the effect of leachate of PA-12 printed by MJF on the cultured cells. The article presents research on the surface treatment of PA12 material used in 3D printing and the effect of automatic staining on cell vitality and proliferation in vitro. The study presents a unique device designed exclusively for staining prints made of the biocompatible material PA12 and demonstrates the compatibility of 3D-printed polyamide 12 parts stained in the novel device with a nutrient culture medium and cells. This novel PA12 surface treatment for biomedical purposes does not affect the compatibility with the culture medium, which is essential for cell viability and proliferation. Fluorescence microscopy revealed that mitochondrial fitness and cell survival were not affected by prolonged incubation with clear or dyed PA12 3D-printed parts.

Additive Manufacturing: A Comprehensive Review.

Additive manufacturing has revolutionized manufacturing across a spectrum of industries by enabling the production of complex geometries with unparalleled customization and reduced waste. Beginning as a rapid prototyping tool, additive manufacturing has matured into a comprehensive manufacturing solution, embracing a wide range of materials, such as polymers, metals, ceramics, and composites. This paper delves into the workflow of additive manufacturing, encompassing design, modeling, slicing, printing, and post-processing. Various additive manufacturing technologies are explored, including material extrusion, VAT polymerization, material jetting, binder jetting, selective laser sintering, selective laser melting, direct metal laser sintering, electron beam melting, multi-jet fusion, direct energy deposition, carbon fiber reinforced, laminated object manufacturing, and more, discussing their principles, advantages, disadvantages, material compatibilities, applications, and developing trends. Additionally, the future of additive manufacturing is projected, highlighting potential advancements in 3D bioprinting, 3D food printing, large-scale 3D printing, 4D printing, and AI-based additive manufacturing. This comprehensive survey aims to underscore the transformative impact of additive manufacturing on global manufacturing, emphasizing ongoing challenges and the promising horizon of innovations that could further elevate its role in the manufacturing revolution.

In pursuit of a high-performance mechanical metamaterial: Simple-cubic-octahedral plate lattice

A comprehensive review by authors on well-known lattice cell topologies composed of metals and polymers having sizes ranging from micro to nano-length scale revealed the simple-cubic (SC) plate lattice exhibits the highest elastic modulus and yield strength. In this study, a novel simple-cubic-octahedral (SCO) plate lattice is proposed by reinforcing octahedral plates with SC-plate lattice. Finite element simulations demonstrated that the SCO-plate lattice exhibited the highest elastic modulus and yield strength among the strut, surface and plate lattices investigated previously. Furthermore, the SCO-plate lattice displayed a high degree of isotropy. Also, the proposed lattice absorbed significantly higher energy compared to the SC-plate lattice for a relative density of 40%. A new semi-analytical framework is also presented to evaluate the elastic modulus of the SCO-plate lattice. The homogenization scheme in Abaqus was used to evaluate the effective properties, resulting in a significant reduction in computational time. The effects of geometrical parameters on the mechanical properties of the SCO-plate lattice were also studied using a design of experiment approach. The quasi-static compression tests were performed on 3D-printed lattices fabricated using a multi-jet fusion technique to validate the numerical simulations. The proposed plate lattice can be an excellent choice for lightweight applications.

The Effects of Manufacturing Techniques on the Mechanical Performance of an Auxetic Structure Manufactured by Fused Filament Fabrication and Multijet Fusion Processes

Additive manufacturing is increasingly becoming potential for short‐run part production. The aim of this work is to explore the mechanical properties of a hybrid auxetic structure fabricated by multijet fusion (MJF) and fused filament fabrication (FFF). The experimental measurements indicate that robust specimens with high‐dimensional accuracy are successfully achieved using MJF process. In the case of the FFF process, the walls–walls and walls–cylinders areas (connecting areas) suffer large pores, indicating poor printing quality. The 3D printed specimens via FFF process reveal smooth plateau stress, while plateau stress with high peaks is observed when the MJF specimens are compressed along the Y‐axis. Moreover, specimens manufactured by the MJF process reveal the highest specific energy absorption (SEA) per unit volume and per unit mass. The calculated values of SEA are 2.1 and 2.5 J g−1 (for specimens fabricated by MJF) in which they significantly outperform the SEA (0.495 and 0.480 J g−1) of those manufactured by the FFF process. Furthermore, the trend of auxetic features (negative Poisson's ratio) has not been affected by the manufacturing processes. This study sheds light on the influence of fabrication methods on the mechanical properties of cellular materials especially their ability to absorb energy.

Enhanced heat transfer in 3D printed ball-end grinding tool with blade-shaped structure

Complex curved components in aero-engines often require demand small-sized compliance ball-end (BE) grinding tools to achieve smooth machining in interference-prone-area. Nevertheless, heat accumulation during the grinding of difficult-to-process materials challenges the weak stability of flexible materials, thereby limited tool life and grinding performance. In this study, a novel rotary-enhanced heat transfer structure (REHT) based on aero-engine blades was introduced into the BE. The blade-shaped structure tools were fabricated using multi jet fusion (MJF). Numerical simulations were conducted to investigate the effects of blade type, rotating direction, rotating speed, and forced cold air velocity on the heat transfer mechanism of BE. The grinding performance of these tools, along with conventional structures, was comparatively investigated through robot-assisted grinding of titanium plates. The results indicated that the REHT improved the heat transfer capability of the tool by introducing high momentum fluids into the tool cavity and increasing the flow rate of the grinding interface. The REHT structure reduced the grinding temperature by over 19.84%, extending tool life by more than 40%. Furthermore, compliant grinding tools with REHT exhibited higher cumulative material removal alongside lower and more consistent surface roughness (Ra).

Analysis of the Technical Accuracy of a Patient-Specific Stereotaxy Platform for Brain Biopsy.

The use of stereotactic frames is a common practice in neurosurgical interventions such as brain biopsy and deep brain stimulation. However, conventional stereotactic frames have been shown to require modification and adaptation regarding patient and surgeon comfort as well as the increasing demand for individualized medical treatment. To meet these requirements for carrying out state-of-the-art neurosurgery, a 3D print-based, patient-specific stereotactic system was developed and examined for technical accuracy. Sixteen patient-specific frames, each with two target points, were additively manufactured from PA12 using the Multi Jet Fusion process. The 32 target points aim to maximize the variability of biopsy targets and depths for tissue sample retrieval in the brain. Following manufacturing, the frames were measured three-dimensionally using an optical scanner. The frames underwent an autoclave sterilization process prior to rescanning. The scan-generated models were compared with the planned CAD models and the deviation of the planned target points in the XY-plane, Z-direction and in the resulting direction were determined. Significantly lower (p < 0.01) deviations were observed when comparing CAD vs. print and print vs. sterile in the Z-direction (0.17 mm and 0.06 mm, respectively) than in the XY-plane (0.46 mm and 0.16 mm, respectively). The resulting target point deviation (0.51 mm) and the XY-plane (0.46 mm) are significantly higher (p < 0.01) in the CAD vs. print comparison than in the print vs. sterile comparison (0.18 mm and 0.16 mm, respectively). On average, the results from the 32 target positions examined exceeded the clinically required accuracy for a brain biopsy (2 mm) by more than four times. The patient-specific stereotaxic frames meet the requirements of modern neurosurgical navigation and make no compromises when it comes to accuracy. In addition, the material is suitable for autoclave sterilization due to resistance to distortion.

Innovative Approaches to 3D Printing of PA12 Forearm Orthoses: A Comprehensive Analysis of Mechanical Properties and Production Efficiency.

This research paper aims to explore the mechanical characteristics of polyamide PA12 (PA12) as a 3D material printed utilizing Selective Laser Sintering (SLS) and HP MultiJet Fusion (HP MJF) technologies in order to design and manufacture forearm orthoses. The study assessed the flowability of the materials used and compared the mechanical performance of PA12 with each other using tensile, flexure, and impact tests in five different fabrication orientations: X, Y, Z, tilted 45° XZ, and tilted 45° YZ. The results of the study provide, firstly-the data for testing the quality of the applied polyamide powder blend and, secondly-the data for the design of the orthosis geometry from the aspect of its strength parameters and the safety of construction. The mechanical parameters of SLS specimens had less variation than MJF specimens in a given orientation. The difference in tensile strength between the 3D printing technologies tested was 1.8%, and flexural strength was 4.7%. A process analysis of the forearm orthoses revealed that the HP MJF 5200 system had a higher weekly production capacity than the EOS P396 in a production variance based on obtaining maximum strength parameters and a variance based on maximizing economic efficiency. The results suggest that medical device manufacturers can use additive manufacturing technologies to produce prototypes and small-batch parts for medical applications. This paper pioneers using 3D printing technology with Powder Bed Fusion (PBF) methods in designing and manufacturing forearm orthoses as a low- to medium-volume product. The applied solution addresses the problem of medical device manufacturers with regard to the analysis of production costs and mechanical properties when using 3D printing for certified medical devices.

Prediction of absorptivity in Multi-Jet Fusion manufactured polypropylene structures through laser flash and corrected porosity method

For the first time in the literature, this study validates the absorption phenomena in Multi-Jet Fusion (MJF) printed polypropylene (PP) structures through Laser Flash (LFA) and Corrected Porosity (CP) methods. The influence of process parameters such as build height and build orientation was investigated on tensile properties, crystallinity, porosity and thermophysical attributes in MJF printed PP coupons. Results showed that both crystallinity and tensile performance did not significantly vary with either location or build orientation. Interestingly, samples printed in the Z orientation showed a 35% decrease in strain, indicating that Z-oriented MJF coupons were more brittle than the flat samples (XY). Samples printed in Z orientation also possessed higher porosity and relatively lower crystallinity than the XY orientation. However, large deviations within porosity values were an obstacle to determining a suitable build chamber location for manufacturing dense samples. Therefore, a detailed investigation on porosity of printed samples using micro-CT scans and CT image analysis was necessary. Initially, poor contrast was obvious when MJF printed samples were positioned vertically in the micro-CT chamber which was mainly due to high value of horizontal intensity profile (HIP ~ 70%). Contrast in MJF samples improved significantly in the horizontal orientation (HIP ~ 40%). In parallel, the half-time and heat loss were measured in LFA to understand changes in absorption phenomena with height and orientation of the build. A direct correlation was found between LFA half-time and porosity only when the porosity correction method was implemented. Corrected porosity value was found to be inversely proportional to the heat loss of printed PP samples which indicated higher absorption for samples printed in the bottom of build chamber, XY12, whereas lower absorption was observed for less dense Z samples. Finally, heat loss phenomenon was verified using dense reference Pyroceram samples as they possess high diffusivity and low half-time and porosity compared to MJF printed samples. There is a science behind understanding the absorptivity of the MJF process which is related to the complexity of the process and is challenging to address in MJF PP samples when mixed with carbon black. The study showed that accurately determining the level of porosity is the key to validate absorption phenomena within MJF printed coupons. The contributions of this work are the investigation of the light absorption phenomena in MJF printed PP structures, and the establishment of the absorption-porosity correlation. These contributions help to predict the mechanical properties and subsequently the overall quality of the produced parts which can save cost and time in effectively utilising the MJF process.

Selective Laser Sintering versus Multi Jet Fusion: A Comprehensive Comparison Study Based on the Properties of Glass Beads‐Reinforced Polyamide 12

Selective laser sintering (SLS) and multi jet fusion (MJF) are the most widespread powder bed fusion additive manufacturing techniques for fabricating polymeric parts since they offer great design flexibility, productivity, and geometrical accuracy. However, these technologies differ in the thermal energy source used to melt the powders as well as the innovative use of printing agents featured in the latter one to promote material consolidation and to avoid thermal bleeding at the part contours. The use of a single powder made of glass beads‐reinforced polyamide 12 (PA12/GB) for the fabrication of MJF and SLS samples makes possible a systematic comparison of the printed parts properties. A thoughtful analysis of the microstructure and mechanical properties of the samples reveals differences and peculiarities between the two technologies. SLS exhibits lower porosity and higher mechanical performances when the parts are printed along the build plane thanks to the powerful heating ensured by the laser. In contrast, MJF samples show higher mechanical isotropy with great flexural and tensile behavior for vertically oriented parts. The role of glass beads in the material behavior is defined by their mechanical properties, meaning higher rigidity and lower strength compared to neat PA12, and fracture mechanism.