Rapid Prototyping Journal

Lovo, João Fiore Parreira; Gerlin Neto, Vicente; Piedade, Lucas Pereira; Massa, Renan Cesar; Pintão, Carlos Alberto; Foschini, Cesar Renato; Fortulan, Carlos Alberto

2023 Rapid Prototyping Journal

doi: 10.1108/rpj-03-2022-0067

This paper aims to evaluate the resin infiltration influence on the mechanical properties of components 3D printed by the material extrusion-based additive manufacturing (AM), also known as fused deposition modeling and commonly uses the acrylonitrile butadiene styrene (ABS) as depositing material. Improvements in their mechanical properties are desirable due failure resulting from the extrusion process. In this way, resin infiltration is considered a candidate solution to enhance 3D printed components’ strength.Design/methodology/approachThe mechanical properties of AM samples produced with and without the resin infiltration were assessed under torsion, tensile and flexural stresses. Torsional tests are rarely found applied for this case, an alternative torsion test developed by one of the authors was used. The torsion modulus (G) is obtained without the Poisson’s ratio, which is usually unknown for recently made composites. Scanning electron microscopy was also done to verify the resin infiltration on the samples.FindingsResults demonstrated that the resin infiltration on ABS can improve the mechanical properties of samples compared to non-infiltrated. The tensile and bending strength increased more than 6%. Both Young’s and torsion modulus also presented a significant increase. The samples did not present any considerable change in their weight property.Originality/valueThis paper discusses on resin infiltration on print ABS, as to produce a composite material, enhancing ABS properties without gaining weight. This paper also used the torsion modulus instead of the common approach of bringing only tensile and flexure strength.

Mundada, Piyush Suresh; Yang, Che-Hao; Chen, Roland K.

2023 Rapid Prototyping Journal

doi: 10.1108/rpj-02-2021-0033

The purpose of this study is to propose the use of a pre-deposition heating system for fused filament fabrication (FFF) as a means to enhance interlayer bonding by elevating the substrate temperature. The effects of the heating on thermal profile at the bonding interface and the mechanical properties of three-dimensional printed parts are investigated.Design/methodology/approachA 12-W laser head is integrated to a commercial printer as the pre-deposition heating system. The laser beam heats up substate before the deposition of a fresh filament. Effects of laser powers are investigated and the thermal profile is measured with thermocouple, infrared camera and finite element model. The correlation between the temperature at the bonding interface and the bonding quality is investigated by conducting tensile testing and neck width measurement with microscope.FindingsThe pre-deposition heating system is proven to be effective in enhancing the inter-layer strength in FFF parts. Tensile testing of specimens along build direction (Z) shows an increase of around 50% in ultimate strength. A linear relationship is observed between the pre-deposition temperature at bond interface and bonding strength. It is evident that elevating the pre-deposition temperature promotes interlayer polymer diffusion as shown by the increased neck width between layers.Originality/valueThermocouples that are sandwiched between layers are used to achieve accurate measurement of the interfacial temperature. The temperature profiles under pre-deposition heating are analyzed and correlated to the interlayer bonding strengths.

Mussi, Elisa; Servi, Michaela; Facchini, Flavio; Furferi, Rocco; Volpe, Yary

2023 Rapid Prototyping Journal

doi: 10.1108/rpj-02-2022-0046

Among thoracic malformations, pectus deformities have the highest incidence and can result in a wide range of severe and mild clinical manifestations. Recently, the treatment of pectus deformities is shifting from traditional approaches toward customized solutions. This occurs by leveraging innovative rapid prototyping tools that allow for the design and fabrication of patient-specific treatments and medical devices. This paper aims to provide a comprehensive view of the growing literature in this area to analyze the progress made in this direction.Design/methodology/approachThe search was performed on major search engines through keywords inherent to reverse engineering (RE) and additive manufacturing (AM) technologies applied to pectus deformities and related treatments, selecting 54 papers. These were analyzed according to the addressed pathology, the hardware and software tools used and/or implemented and their integration within the clinical pathway.FindingsFirst, the analysis led to analyze and divide the papers according to how RE and AM technologies are applied for surgical and non-surgical treatments, pathological assessment and preoperative simulation and planning. Second, all papers were considered within the typical rapid prototyping framework consisting of the three phases of three-dimensional (3D) scanning, 3D modelling and 3D printing.Originality/valueTo the best of the authors’ knowledge, to date, no survey has provided a comprehensive view of innovative and personalized treatment strategies for thoracic malformations; the present work fills this gap, allowing researchers in this field to have access to the most promising findings on the treatment and evaluation of pathology.

Verma, Virendra Kumar; Kamble, Sachin S.; Ganapathy, L.; Tarei, Pradeep Kumar

2023 Rapid Prototyping Journal

doi: 10.1108/rpj-08-2021-0208

The purpose of this study is to identify, analyse and model the post-processing barriers of 3D-printed medical models (3DPMM) printed by fused deposition modelling to overcome these barriers for improved operational efficiency in the Indian context.Design/methodology/approachThe methodology used interpretive structural modelling (ISM), cross-impact matrix multiplication applied to classification (MICMAC) analysis and decision-making trial and evaluation laboratory (DEMATEL) to understand the hierarchical and contextual relations among the barriers of the post-processing.FindingsA total of 11 post-processing barriers were identified in this study using ISM, literature review and experts’ input. The MICMAC analysis identified support material removal, surface finishing, cleaning, inspection and issues with quality consistency as significant driving barriers for post-processing. MICMAC also identified linkage barriers as well as dependent barriers. The ISM digraph model was developed using a final reachability matrix, which would help practitioners specifically tackle post-processing barriers. Further, the DEMATEL method allows practitioners to emphasize the causal effects of post-processing barriers and guides them in overcoming these barriers.Research limitations/implicationsThere may have been a few post-processing barriers that were overlooked by the Indian experts, which might have been important for other country’s perspective.Practical implicationsThe presented ISM model and DEMATEL provide directions for operation managers in planning operational strategies for overcoming post-processing issues in the medical 3D-printing industry. Also, managers may formulate operational strategies based on the driving and dependence power of post-processing barriers as well as the causal effects relationships of the barriers.Originality/valueThis study contributes to identifying, analyzing and modelling the post-processing barriers of 3DPMM through a combined ISM and DEMATEL methodology, which has not yet been reviewed. This study also contributes to decision makers developing suitable strategies to overcome the post-processing barriers for improved operational efficiency.

Yousefi Kanani, Armin; Rennie, Allan E.W.; Abd Rahim, Shayfull Zamree Bin

2023 Rapid Prototyping Journal

doi: 10.1108/rpj-03-2022-0100

This study aims to make foamed polylactic acid (PLA) structures with different densities by varying deposition temperatures using the material extrusion (MEX) additive manufacturing process.Design/methodology/approachThe extrusion multiplier (EM) was calibrated for each deposition temperature to control foaming expansion. Material density was determined using extruded cubes with the optimal EM value for each deposition temperature. The influence of deposition temperature on the tensile, compression and flexure characteristics of the foamable filament was studied experimentally.FindingsThe foaming expansion ratio, the consistency of the raster width and the raster gap significantly affect the surface roughness of the printed samples. Regardless of the loading conditions, the maximum stiffness and yield strength were achieved at a deposition temperature of 200°C when the PLA specimens had no foam. When the maximum foaming occurred (220°C deposition temperature), the stiffness and yield strength of the PLA specimens were significantly reduced.Practical implicationsThe obvious benefit of using foamed materials is that they are lighter and consume less material than bulky polymers. Injection or compression moulding is the most commonly used method for creating foamed products. However, these technologies require tooling to fabricate complicated parts, which may be costly and time-consuming. Conversely, the MEX process can produce extremely complex parts with less tooling expense, reduction in energy use and optimised material consumption.Originality/valueThis study investigates the possibility of stiff, lightweight structures with low fractions of interconnected porosity using foamable filament.

Gaur, Bhanupratap; Soman, Deepak; Ghyar, Rupesh; Bhallamudi, Ravi

2023 Rapid Prototyping Journal

doi: 10.1108/rpj-01-2022-0036

Additive manufacturing of metallic scaffolds using laser powder bed fusion is challenging because of the accumulation of extra material below overhanging and horizontal surfaces. It reduces porosity and pore size and increases the effective strut size. These challenges are normally overcome by using volumetric energy density (VED) values lower than the optimum values, which, however, results in poor physio-mechanical properties. The purpose of this study is to assist scaffold manufacturers with a novel approach to fabricate stronger yet accurate scaffolds.Design/methodology/approachThis paper presents a strategy for laser exposure that enables fabricating titanium-6–aluminum-4–vanedium (Ti6Al4V) alloy scaffolds with the required properties without compromising the geometric features. The process starts from computer-aided design models sliced into layers; dividing them into core (upper) and downskin (lower) layers; and fabrication using hybrid VED (low values for downskin layers and high values for core layers).FindingsWhile exposing the core layers, laser remelted the downskin layers, resulting in better physio-mechanical properties (surface roughness, microhardness and density) for the whole strut without affecting its dimensional accuracy. A regression equation was developed to select the downskin thickness for a given combination of strut thickness and core VED to achieve the desired range of properties. The proposed approach was validated using microstructure analysis and compression testing.Practical implicationsThis paper is expected to be valuable for the manufacturers of Ti6Al4V scaffolds, in achieving the desired properties.Originality/valueThis is probably the first time the hybrid VED approach has been applied for obtaining scaffolds with the desirable physio-mechanical and geometrical properties.

Ettaieb, Kamel; Godineau, Kevin; Lavernhe, Sylvain; Tournier, Christophe

2023 Rapid Prototyping Journal

doi: 10.1108/rpj-02-2022-0062

In Laser Power Bed Fusion (LPBF), the process and operating parameters influence the mechanical and geometrical characteristics of the manufactured parts. Therefore, the optimization and control of these parameters are mandatory to improve the quality of the produced parts. During manufacturing, the process parameters are usually constant whatever the part size or the built layer. With such settings, the manufacturing process may lead to an inhomogeneous thermal behavior and locally overheating areas, impacting the part quality. The aim of this study is to take advantage of an analytical thermal model to modulate the laser power upstream of manufacturing.Design/methodology/approachThe approach takes place in two steps: the first step consists in calculating the preheating temperature at the considered point and the second one determines the power modulation of the laser to reach the desired temperature at this point.FindingsNumerical investigations on several use cases show the effectiveness of the method to control the overheated areas and to homogenize the simulated temperature distribution.Originality/valueThe specificity of this model lies in its ability to directly calculate the amount of energy to be supplied without any iterative calculation. Furthermore, to be as close as possible to the technology used on LPBF machines, the kinematic behavior of the scanning head and the laser response time are also integrated into the calculation.

Ali, Shafahat; Abdallah, Said; Devjani, Deepak H.; John, Joel S.; Samad, Wael A.; Pervaiz, Salman

2023 Rapid Prototyping Journal

doi: 10.1108/rpj-11-2021-0301

This paper aims to investigate the effects of build parameters and strain rate on the mechanical properties of three-dimensional (3D) printed polylactic acid (PLA) by integrating digital image correlation and desirability function analysis. The build parameters included in this paper are the infill density, build orientation and layer height. These findings provide a framework for systematic mechanical characterization of 3D-printed PLA and potential ways of choosing process parameters to maximize performance for a given design.Design/methodology/approachThe Taguchi method was used to shortlist a set of 18 different combinations of build parameters and testing conditions. Accordingly, 18 specimens were 3D printed using those combinations and put through a series of uniaxial tensions tests with digital image correlation. The mechanical properties deduced for all 18 tests were then used in a desirability function analysis where the mechanical properties were optimized to determine the ideal combination of build parameters and strain rate loading conditions.FindingsBy comparing the tensile mechanical experimental properties results between Taguchi's recommended parameters and the optimal parameter found from the response table of means, the composite desirability had increased by 2.08%. The tensile mechanical properties of the PLA specimens gradually decrease with an increase in the layer height, while they increase with increasing the infill densities. On the other hand, the mechanical properties have been affected by the build orientation and the strain rate in similar increasing/decreasing trends. Additionally, the obtained optimized results suggest that changing the infill density has a notable impact on the overall result, with a contribution of 48.61%. DIC patterns on the upright samples revealed bimodal strain patterns rendering them more susceptible to failures because of printing imperfections.Originality/valueThese findings provide a framework for systematic mechanical characterization of 3D-printed PLA and potential ways of choosing process parameters to maximize performance for a given design.

Kaill, Nathaniel; Campbell, Robert; Pradel, Patrick

2023 Rapid Prototyping Journal

doi: 10.1108/rpj-02-2022-0058

The purpose of this paper is to select a product suitable for printing via multi-axis additive manufacturing (MAAM), print it and test it to determine if, by using a multi-axis approach, it would be possible to create end use products that can withstand mechanical loading.Design/methodology/approachThe methodology used in this study is a MAAM approach, and through the creation of an initial model and finite element analysis (FEA), the dominant stress vectors are identified. Using the orientation of these vectors, a three-dimensional tool path is constructed that follows the directionality as close as can be achieved while accounting for rotational road paths. This tool path is converted into a G-code and run on a 5-axis material extrusion printer. The printed samples were then tested according to the ISO standard to determine whether this can be a viable manufacturing technique.FindingsThe methodology used in this study enabled the production samples to withstand an average force of 1,100 N. This level is above the required safety threshold for the given standard. Furthermore, this reactive force is within 300 N of the typical metal sample, while being 25% of the typical weight for a conventional sample product. With a redesign and further research, it is possible to match the mechanical behaviour.Originality/valueRecently, there has been an increased level of interest in MAAM. The research contained within this paper is original in its application of this printing method to explore whether it is possible to make end use products that meet the existing standards required by them.

Xiao, Haifeng; Zhang, Changchun; Zhu, Haihong

2023 Rapid Prototyping Journal

doi: 10.1108/rpj-03-2022-0085

This paper aims to systematically investigate the effect of the heat treatment process parameters on the microstructure and mechanical properties of the selective laser melting (SLM) AlSi10Mg alloy.Design/methodology/approachThe samples with very low porosity were fabricated with optimized processing parameters on a self-developed SLM system. The heat treatment of using the temperature of 170°C∼400°C and the holding time of 0.5∼12 h was studied, and the evolution of the microstructure and mechanical properties of AlSi10Mg alloy under direct aging and annealing was investigated and obtained.FindingsAfter annealing above 300°C for 1 h, the dendrite Si in the sample occurs spheroidization, and the molten pool contour becomes blurred or even disappeared completely, but low-temperature heat treatment does not change the morphology and size of grains significantly. Except for holding at 200°C for 1 h, all other heat treatment processes cause the tensile and yield strengths of SLM AlSi10Mg alloys to decrease and the elongation to increase. When the annealing temperature is higher than 200°C, the higher the temperature and the longer the holding time, the more obvious this effect is.Originality/valueThe correlation between the mechanical properties and microstructure of SLM AlSi10Mg alloy under different conditions was obtained. According to the characteristics of SLM forming, the direct aging and annealing process are mainly studied, which provided new information for the heat treatment of SLM AlSi10Mg alloy and promoted the engineering application of SLM AlSi10Mg alloy.