An Experimental Study on the Impact of Layer Height and Annealing Parameters on the Tensile Strength and Dimensional Accuracy of FDM 3D Printed Parts

He Y., Shen M., Wang Q., Wang T., Pei X.

In this paper, the effects of FDM parameters (nozzle temperature, platform temperature, layer thickness, and printing speed) as well as annealing temperature on the mechanical properties of poly(ether ether ketone) (PEEK) were investigated through orthogonal experiments. And the tribological properties of PEEK were also studied before and after annealing. Results show that nozzle temperature and printing speed were main factors affecting the mechanical properties of PEEK, which was optimized to be 440 ℃ and 40 mm/s, respectively. The mechanical strength of PEEK was increased with increasing annealing temperature and reached the maximum at 300 ℃ with the sacrifice of elongation at break, and the ultimate tensile, flexural and compressive strength was increased by 36%, 54% and 21%, respectively. As for the tribo-properties, there appeared a minimum wear rate(1.37 × 10−6mm3/Nm) in 200 °C annealed PEEK when tested in parallel manner, combined influences of annealing and filament orientation were revealed, and appropriate annealing temperature was found to help enhance the formation of uniform and homogeneous transfer films on the counter steel surfaces.

Rahmatabadi D., Ghasemi I., Baniassadi M., Abrinia K., Baghani M.

In this study, PLA-TPU blends with different component ratios were prepared and printed by melt blending and fused deposition modeling (FDM), respectively. The shape memory effect (SME) was investigated considering the effect of loading mode, programming deformation, and temperature for three combinations of PLA50, 70, and 90 wt%. The results of the thermal analysis showed that each compound had two glass transition temperatures in the range of −20 and 67 °C, which return to TPU and PLA, respectively. SEM results confirmed that TPU droplets are observed in the PLA matrix and the printed samples had stretched the TPU phase. In both loading modes, with the increase in PLA concentration, the fixity ratio increased and the highest shape recovery value was obtained in the PLA70 samples, although the values were very close to PLA50. The crystalline segments of PLA, as a net point, play an essential role in restoring the original shape, and by increasing the amount of PLA, stricter limitations are created. In the compression mode, although the programming stress was the highest in the cold-programmed sample, the highest stress was released in the warm-programmed samples. The maximum recovery stress value for PLA70 was 12.85 MPa, which can be effective in reducing the limitations of applications for shape memory polymers. The shape recovery ratio was in the 90.9–96.4% range under compression loading. Also, the cold-programmed samples showed the highest and lowest fixity and recovery ratios. The results of this research show that by changing the composition and programming temperature, the desired properties for different applications can be achieved so that the highest fixity, recovery, and stress recovery were obtained in hot, cold, and warm-programmed samples by manipulating the input energy and temperature.

Cao L., Xiao J., Kim J.K., Zhang X.

The extrusion-based fused deposition modeling (FDM) has become the most frequently used additive manufacturing method because of its shorten production time and cost. However, low surface quality remains a limitation to meet the regulatory standards set by traditional manufacturing, which requires post-processing to improve it. In this work, annealing and acetone vapor treatments are applied to short glass fiber reinforced PLA/TPU composites parts obtained by FDM, respectively. Their effects on the surface finishing, dimensional accuracy and mechanical properties of FDM parts using different post-processing methods are compared. The result shows that the annealing treatment dramatically improves the surface finish, but can reduce the dimensional accuracy and ductility of the FDM parts. Better ductility and dimensional accuracy but lower tensile strength are obtained by using acetone vapor treatment.

Alarifi I.M.

This research presents a novel methodology for simulating the failure of a 3D-printed engineering design structure. Fused deposition modeling (FDM) of polyethylene terephthalate glycol (PETG)/Carbon fiber (CF) material was utilized to develop and build the structure's topology. The mechanical characteristics of PETG/CF materials were evaluated through modeling, which was quantitatively linked to the experimental results. Scanning electron microscopy (SEM) was used to evaluate the fracture surface material before and after failure testing. The actual tests and numerical studies used five different fabrication structures which were correlated with deformation, force, and failure mode. ANSYS software was used with experimental results and finite element analysis (FEA) under both dynamic and quasi-static conditions. Five 3D printed materials of PETG reinforced with short CFs of approximately 7.6 μm in a weight fraction of 20% were investigated. The overall goal was to create a cost-effective and straightforward material production technology that can retain high mechanical strength while also providing suitable flexibility. The tensile test results of the 3D-printed PETG/CF solid structural design revealed a 23% improvement in yield strength over the other conventional structures. The study illustrates how FEA of 3D printing is used to evaluate the performance of a helmet chinstrap design with different production conditions, hence possibly reducing the product design and development time.

Pokorný P., Delgado Sobrino D.R., Václav Š., Petru J., Gołębski R.

This paper introduces novel research into specific mechanical properties of composites produced by 3D printing using Continuous-Fiber Fabrication (CFF). Nylon (Onyx) was used as the composite base material, while carbon constituted the reinforcement element. The carbon fiber embedment was varied in selected components taking values of 0°, 45°, 90°, and 135° for parts undergoing tensile testing, while one specific part type was produced combining all angles. Carbon-fiber-free components with 100% and 37% fillings were also produced for comparison purposes. Parts undergoing the Charpy impact test had the fibers deposited at angles of 0° and 90°, while one part type was also produced combining the four angles mentioned before. Carbon-fiber-free parts with 100% and 37% fillings were also produced for comparison purposes as with the first part. The Markforged MARK TWO 3D printer was used for printing the parts. These were subsequently scanned in the METROTOM 1500 computed tomography and submitted to the tensile and impact tests. The results showed that adding carbon fiber to the base material increased the volume of defects in the samples as a result of the porosity increase. Although the tensile testing manifested an overall increase in tensile strength Rm of up to 12 times compared to the sample without reinforcement, it was proven that an improper fiber orientation significantly diminished the strength and that combining the four selected angles did not lead to the highest strength values. Finally, the impact tests also showed that fiber-reinforced parts implied up to 2.7 times more work to fracture, and that an improved fiber orientation also led to strength reduction.

Yu W., Wang X., Yin X., Ferraris E., Zhang J.

This article presents the effects of thermal annealing at elevated temperatures (> glass transition temperature Tg) on the performance of polymer parts via material extrusion 3D printing. Both semi-crystalline and amorphous filaments were used. As-printed parts were designed to be amorphous and then annealed at 60, 110 and 150 °C for different durations ranging from 50 to 6400 s. The flexural strength and Young’s modulus increased by a maximum of approximately 10%. The increase was ascribed to crystallisation development during annealing, as confirmed by thermal and morphology characterisations. Hence, this effect was only observed with semi-crystalline materials. On the other hand, all the annealed parts expanded in the thickness direction and shrank in the perpendicular plane. The maximum linear strain reached 20%, while the volume strain was negligible. These morphology changes after annealing reversed the strain-hardening of the strand and led to inferior strand performance against local tensile deformation. The degradation can outweigh the benefits of crystallinity development. For amorphous parts, the degradation reached approximately 25% in both the flexural strength and the modulus.

Li L., Liu W., Wang Y., Zhao Z.

Thermoplastic laminates are increasingly used in the automotive industry, so it is essential to study convenient and effective repair technologies. In this paper, an adhesively bonded repair method based on 3D printed patches is proposed. Multiple types of patches were fabricated using 3D printing technique and traditional laminate cutting process, respectively. Two stacking sequence laminates including angle-ply and quasi-isotropic were utilized in this study. The mechanical properties of the repaired specimens were tested under tensile loading, and the strain distribution and damage process were monitored by digital image correlation (DIC) technique. The damage characteristics and failure mechanisms are analyzed. The results indicate that the load-bearing capacity of the open-hole laminates can be significantly improved through the repair method. Compared with traditional patches, the 3D printed patches show more excellent repair performance. Moreover, 3D printed patches are easier to manufacture and have a lower cost. This study can provide some insight for the repair of automotive lightweight components manufactured by polymer composites.

Rahmatabadi D., Soltanmohammadi K., Aberoumand M., Soleyman E., Ghasemi I., Baniassadi M., Abrinia K., Bodaghi M., Baghani M.

Khan S.B., Irfan S., Lam S.S., Sun X., Chen S.

Surface water supply provides the vast majority of the world's drinkable water, however, surface water may contain a broad variety of pollutants originated from various sources, such as households, industry, and agriculture. As a result, it is critical to achieve acceptable water quality while also reducing the organic and inorganic impurities. Potable water production methods have been developed and tested in various ways. It is possible to manufacture high-quality drinking water using nanofiltration (NF) membranes. In contrast, fouling has remained the most significant barrier to membrane technology advancement. Renewable energy sources may decrease the extra energy needed by a membrane with tiny holes. Recent years have seen a significant increase in interest in three-dimensional printing (3D printing [3D-P]). Surface imprinting technologies, in general, have not yet reached the maturity stage of development, notably in membrane design and production. It is discussed in this review article how different 3D printing technologies are now accessible, how they relate to current breakthroughs in the area, and how they may be used to fabricate nanosheets, module spacers, or thin layers design for water purification as well as potential applications of surface imprinting in the near future. It is anticipated that the revolutionary synthesis of novel membrane module components will occur in the near future due to recent breakthroughs in 3D-P technology. It is predicted that 3D-P technologies would create a broader range of membrane module components with improved efficacy and efficiency due to speed, materials, and resolution improvements. Water purification methods comprising membrane separation are potential applications that might benefit from surface imprinting patterns with complicated topography in the future for water purification among them. • Recent years have significantly increased interest in three-dimensional printing (3D printing [3D-P]). • This study explores 3D printing to create nanosheets, spacers, or thin layers for water purification and surface imprinting. • The advancements in 3D-P technology could lead to the revolutionary synthesis of novel membrane module components. • Surface imprinting patterns with complex topography may assist water purification procedures involving membrane separation. • Surface imprinting technology has not yet reached maturity stage of development, notably in membrane design and production.

Li J., Durandet Y., Huang X., Sun G., Ruan D.

• 3D printing techniques to fabricate fiber-reinforced composites are summarized. • The mechanical properties of 3D printed fiber-reinforced composites are reviewed. • Effects of printing parameters on the properties of composites are discussed. • Applications and limitations of additively manufactured composites are presented. Recent developments in additive manufacturing techniques have facilitated the fabrication of fiber-reinforced composite materials. In this paper, the mechanical properties and deformation mechanisms of discontinuous and continuous fiber-reinforced composites fabricated by various additive manufacturing techniques are comprehensively reviewed. The effects of fiber type, orientation and weight/volume fraction, printing path, and stacking sequence on the mechanical properties of additively manufactured composites are discussed. In addition, the applications of additively manufactured composites, the main challenges of the current additive manufacturing techniques, and recommendations for future work are also presented.

Soleyman E., Rahmatabadi D., Soltanmohammadi K., Aberoumand M., Ghasemi I., Abrinia K., Baniassadi M., Wang K., Baghani M.

Abstract The main novelty of this paper is the use of poly-ethylene terephthalate glycol (PETG) as a new shape memory polymer with excellent shape memory effect (SME) and printability. In addition, for the first time, the effect of programming temperature on PETG 4D printed samples has been studied. The amorphous nature of the PETG necessitates that molecular entanglements function as net points, which makes the role of programming temperature critical. SME comprehensively was conducted under compression loading for three programming conditions as well as various pre-strains. Significant results were obtained that summarized the gross differences exhibiting that the hot, cold, and warm programmed samples had the highest shape fixity, shape recovery, and stress recovery, respectively. The recovery and fixity ratios fell and rose, respectively, as the programming temperature increased. This effect intensified in hot programmed samples as the applied strain (loading time) expanded. So, the recovery ratio dropped from 68% to 50% by raising the pre-strain from 20% to 80%. The maximum stress recovery was 16 MPa, suggesting the fantastic benefit of warm programming conditions in PETG 4D printed parts. The locking mechanism (recovery force storage) for cold and hot programming is quite different. The dominant mechanism in cold programming is increasing internal energy by potential energy level enhancement. Contrary to this, in hot programming, the entropy reduction applies to the majority of the molecular segments, playing this role. By cooling, the state of the material changes from rubbery to glassy, and with this phase change, the oriented conformation of the deformed polymer chains is maintained under deformation. The results of this research can be used for various applications that require high shape fixity, recovery, or stress recovery.

Mani M., Karthikeyan A.G., Kalaiselvan K., Muthusamy P., Muruganandhan P.

3D printing and Rapid prototypic has a greater impact in modern manufacturing practices. The demands from industries have created a need to research and develop new techniques for 3D printing with affordable cost. In recent time’s variety of 3D printers are available in the market which are affordable by an individual and can be used to prototype functional parts. Hence, increasing the number of outsourcing platforms for Rapid Prototyping and 3D printing, it is important to recognize specific process parameters and optimize them when parts are produced in masses as it is not feasible to alter the parameters for every batch with same application. In this present work, the process parameters such as layer thickness (0.15 mm, 0.25 mm and 0.35 mm), nozzle temperature (210 °C, 215 °C, 220 °C) and infill density (55%, 60% and 65%) are manipulated to print specimens made of PLA (Polylactic Acid). These specimens are designed as per ASTM standards and printed using Fused Deposition Modeling technique. Taguchi Design is used to design an Orthogonal Array for the manipulated parameters according to which the specimens are printed. Finally, Surfaces Roughness test, tensile test and Hardness test are conducted; the data from these tests is used to optimize the manipulated parameters.

Cojocaru V., Frunzaverde D., Miclosina C., Marginean G.

Polylactic acid (PLA) is produced from renewable materials, has a low melting temperature and has a low carbon footprint. These advantages have led to the extensive use of polylactic acid in additive manufacturing, particularly by fused filament fabrication (FFF). PLA parts that are 3D printed for industrial applications require stable mechanical properties and predictability regarding their dependence on the process parameters. Therefore, the development of the FFF process has been continuously accompanied by the development of software packages that generate CNC codes for the printers. A large number of user-controllable process parameters have been introduced in these software packages. In this respect, a lot of articles in the specialized literature address the issue of the influence of the process parameters on the mechanical properties of 3D-printed specimens. A systematic review of the research targeting the influence of process parameters on the mechanical properties of PLA specimens additively manufactured by fused filament fabrication was carried out by the authors of this paper. Six process parameters (layer thickness, printing speed, printing temperature, build plate temperature, build orientation and raster angle) were followed. The mechanical behavior was evaluated by tensile, compressive and bending properties.

Valvez S., Silva A.P., Reis P.N., Berto F.

Fused filament fabrication (FFF) is the most popular additive manufacturing method, with which it is possible to obtain highly complex three-dimensional parts without wasting materials. In order to improve the mechanical properties of 3D printed materials, literature suggests the thermal annealing process. Therefore, this work aims to study the effect of thermal annealing on the bending properties of PETG and PETG reinforced with carbon and aramid fibres. For this purpose, the samples were printed using a B2X300 printer, with a hardened steel nozzle of 0.6 mm diameter, and the printing parameters were optimized for each material. Five specimens were tested according to ASTM D790-17 for each condition. Three temperatures (90ºC, 110ºC and 130ºC) and three annealing times (30 min, 240 min and 480 min) were used to study the benefits obtained with the thermal annealing. Finally, the samples were evaluated in terms of geometrical parameters, hardness, and flexural properties. Regardless of the materials studied, the best mechanical properties were obtained for the highest temperature and the longest exposure time, but due to the high geometric distortions, a temperature of 90 °C and an exposure of 30 minutes proved to be more effective.

Arjun P., Bidhun V.K., Lenin U.K., Amritha V.P., Pazhamannil R.V., Govindan P.

The major limitation of the widely used Additive manufacturing technology, Fused Filament Fabrication is the low mechanical strength of printed geometries. Investigations into the impact of process variables and thermal annealing on the tensile strength of composite carbon fiber polylactic acid thermoplastics to overcome the above-mentioned issue were the main aspects of this study. ASTM D638 Type IV tensile models of 20% carbon-infused polylactic acid were used for the investigations. The selected process parameters were infill density, infill pattern, nozzle temperature, layer height, and print speed. Results reveal that the specimen with 90% infill density, gyroid pattern of printing at 230 °C nozzle temperature with a layer height of 0.1 mm and print speed of 40 mm/s exhibited the maximum tensile strength of 37.27 MPa. Further, thermal annealing was carried out at 65 °C, 95 °C, 125 °C, and 155 °C considering the glass-transition temperature and melting point for a duration of 30, 60, 120, and 240 min as a post-treatment technique to improve the mechanical characteristics of the specimen. Annealing done at 95 °C for 120 min enhanced the tensile strength by 14%, thus giving an overall strength of 42.49 MPa. Hence, the optimum selection of process parameters and post-processing conditions could significantly improve the mechanical strength of fused filament fabricated thermoplastics.

Bharat N., Kumar V., Veeman D., Vellaisamy M.

Veeman D., Dutta H., Vellaisamy M.

Abstract This work details the experimental investigations of additive manufacturing (AM) of components based on Polyethylene Terephthalate Glycol (PETG) and subsequent multi-response optimization through grey relational analysis (GRA). The effect of layer thickness (LT), infill density (ID), and raster angle (RA) on the hardness and compressive strength of the PETG component was assessed. The GRA revealed that the optimal values of the input parameters for the best combination of hardness and compressive strength are LT – 0.1 mm, ID – 1, and RA – 90°. The values of compressive strength and hardness at the optimal condition were 42.98 MPa and 84.97, respectively. The high F-value for ID (453.17) obtained from the variance analysis indicates that the ID has the most significant influence on the responses. The R-sq value for grey relational grade (GRG) being 97.92% signifies the fitness of the regression model. The delamination and crushing of layers were observed in the optical micrographs of the tested specimens.

Rizea A., Banică C., Georgescu T., Sover A., Anghel D.

Splined assemblies ensure precise torque transmission and alignment in mechanical systems. Three-dimensional printing, especially FDM, enables fast production of customized components with complex geometries, reducing material waste and costs. Optimized printing parameters improve dimensional accuracy and performance. Dimensional accuracy is a critical aspect in the additive manufacturing of mechanical components, especially for splined shafts and hubs, where deviations can impact assembly precision and functionality. This study investigates the influence of key FDM 3D printing parameters—layer thickness, infill density, and nominal diameter—on the dimensional deviations of splined components. A full factorial experimental design was implemented, and measurements were conducted using a high-precision coordinate measuring machine (CMM). To optimize dimensional accuracy, artificial neural networks (ANNs) were trained using experimental data, and a genetic algorithm (GA) was employed for multi-objective optimization. Three ANN models were developed to predict dimensional deviations for different parameters, achieving high correlation coefficients (R2 values of 0.961, 0.947, and 0.910). The optimization process resulted in an optimal set of printing conditions that minimize dimensional errors. The findings provide valuable insights into improving precision in FDM-printed splined components, contributing to enhanced design tolerances and manufacturing quality.

AlQaissi S.D., AlDuroobi A.A., Kadaw A.A.

Waly C., Schulnig S., Arbeiter F.

Kahya Ç., Tunçel O., Çavuşoğlu O., Tüfekci K.

Kartal Y.

Thermoplastic polymers are widely used materials in the biomedical field due to their biocompatibility, ease of production and chemical stability; however, their mechanical properties are generally low. In this study, a short carbon fiber reinforced composite was produced to improve the mechanical properties of thermoplastic materials. Pre-processing and post-processing were applied to further improve the mechanical properties of the composite. Optimization of process parameters such as infill density and infill pattern and post-processing parameter such as annealing were performed. As a result of the experiments, the highest impact strength for PLA material is 18.98 kJ/m2 and the lowest impact strength is 6.33 kJ/m2. In addition, the highest tensile strength was 44.68 MPa and the lowest tensile strength was 5.38 MPa. The reliability rates of tensile and impact strength analyses are 98.18% and 96.67%, respectively. SEM and XRD analysis indicated that the parameters affecting the product properties are not only critical for mechanical properties but also affect the internal structure. Mechanical properties and crystal percentage value increased by annealing the reinforced biocomposite at 90°C for 30 min. It has been determined that the build orientation (or printing direction) has a critical importance on the mechanical properties and the mechanical properties of the specimens obtained as a result of on-edge production are higher.

Basak A.K., Ghasseb J., Pramanik A.

Bound metal deposition (BMD) additive manufacturing technique was used to fabricate gears of PH 17-4 stainless steel material. The gears were fabricated with different layer heights (namely 150 μm and 50 μm) and also subjected to post-fabrication machining. Each gear was tested against commercially available gear in a high-precision control test rig. The operational temperature and noise level were measured during the test, while the material loss due to wear was evaluated at the end of the test. The 50 μm layer height gear performed the best with the least wear loss, minimum noise generation, and temperature rise. The 150 μm layer height gear, which was mechanically polished, performed very similarly to it (50 μm layer height gear) and cost 33% less to print; thus, it was considered the best performing when cost was incorporated. The conclusions found that post machining of printed parts greatly impacts their performance, and thus, the post-print conditions should be considered just as much as the printing conditions.

Mohd Radzuan N.A., Mohd Foudzi F., Sulong A.B., Furjan M.

Numerous studies have investigated polymeric composites fabricated using fused deposition modelling. However, the mechanical performance of these composites, which is influenced by various factors, including materials and printing parameters, remains unknown. Further understanding these factors helps improve the accuracy of mechanical performance predictions. Therefore, this study fabricates in-house polyamide reinforced with carbon fibre at a composition of 20 wt.% and controls its printing parameters, including layer height and printing orientations. Results indicated that controlling the orientation at a 0° angle are the most crucial factor compared to layer height, which leads to a maximum flexural strength of ∼21 MPa due to improvements in load-bearing capacity and adhesion bonding between the fibre and matrix.

Battistelli C., Seriani S., Lughi V., Slejko E.A.

ABSTRACTThis study investigates the influence of three critical 3D‐printing parameters—layer height, print speed, and extrusion temperature—on the mechanical properties of liquid crystalline polymer 3D‐printed specimens, using a low‐end 3D‐printer. The extrusion process during 3D‐printing can further align the molecular domains within the material along a common direction, leading to a reinforced polymer structure with superior properties. Specifically, the tensile strength, deformation at rupture, and flexural elastic modulus were evaluated to determine how layer height, print speed, and extrusion temperature affect the structural integrity of the printed components. The results demonstrate a significant improvement in both tensile strength and flexural modulus with the reduction of layer height from 0.16 to 0.08 mm. The study highlights the challenges associated with interlayer adhesion in liquid crystalline polymers 3D‐printing, which is crucial for optimizing the mechanical performance of printed parts. Post‐processing annealing was conducted over a wide temperature range (100°C–250°C), revealing its potential to further enhance material strength, though molecular diffusion emerged as a limiting factor in its effectiveness. By successfully demonstrating these advancements with a low‐end 3D printer, this research paves the way for wider adoption of liquid crystalline polymers in additive manufacturing. The use of accessible and cost‐effective equipment ensures that these high‐performance materials can be integrated into diverse applications, promoting democratization of advanced polymer technologies.

Böhm M., Buss C.

One major disadvantage of fused filament fabricated components (FFF) is its well-known anisotropy, which results from the layer-wise adding of material, and that it is not always possible to avoid loading in the layer build-up direction. In particular, components that are exposed to multi-axial load conditions must manage with reduced tensile strength in the build-up direction. This work is therefore concerned with improving the tensile strength transverse to the layering by changing the layer structure without directly changing the material itself. Therefore, the print-defining G-Code was modified to change the arrangement between the layers. The effectiveness of this method was investigated by means of tensile tests using thermoplastic samples made of Acrylonitrile Styrene Acrylate (ASA), Poly Cyclohexylenedimethylene Terephthalate Glycol (PCTG), Poly Ethylene Terephthalate Glycol (PETG) and Poly Lactic Acid (PLA) for layer thicknesses of 0.16 mm and 0.28 mm. The results show that the G-Code modification generally resulted in an increase in tensile strength. For PETG, an improvement of 25% was achieved.

Ziółkowski D., Maćkowiak P., Marzec M.

Abstract In recent years, there has been a dynamic development of technology FDM (Fused Deposition Modeling). This has opened up new possibilities for manufacturing components, both prototypes and final devices in low-volume production. Due to this, in addition to visual values, the mechanical properties of the manufactured elements are also becoming crucial. The aim of this work is to analyze the influence of selected FDM process parameters such as nozzle diameter and layer height on mechanical properties. The obtained results will allow for a more informed selection of parameters and shortening of the production time. The first part describes the influence of individual parameters on the production time and strength based on a review of publications. The second part presents the method and results of three-point bending tests for specimens differing in layer height and nozzle diameter used to produce them using FDM technology. The tests performed allowed us to determine the effect of these parameters on the obtained mechanical properties.

Wang Z., Zhang B., Sun J., Wang J.

This study employed a high-extrusion-rate Fused Deposition Modeling (HFDM) 3D printer, with the nozzle diameter enlarged from 0.4 mm to 1.0 mm. The increase in nozzle diameter (from 0.4 mm to 1.0 mm) significantly enhanced the volumetric deposition rate, thereby reducing the time required to print each layer and shortening the overall manufacturing cycle. In addition, the larger nozzle diameter increased the width and height of each printed bead, which shortened the required path length per layer, further improving printing efficiency. Short-carbon-fiber filled polyamide 12 (PA12-CF) is used as the test material. The three-point bending test samples are prepared with the HFDM system, where the effects of extrusion width and layer height, as printing parameters, on the flexural properties are investigated. Furthermore, the fiber orientation within the deposited beads is measured using optical microscopy and imaging process software ImageJ. Experimental results indicate that with an increased layer height and extrusion width, PA12-CF samples exhibit improved mechanical properties, where the bending strength and stiffness can be increased up to ~ 20%, and ~ 30%, respectively. The fiber orientation angle measurements indicate that with smaller values of layer height and extrusion width, the fibers tend to align more parallel to the material extrusion direction. As these printing parameters increased, the fibers tend to align more diversely to the transverse directions, which ultimately benefits the increment of the flexural resistance of the entire samples. Additionally, isothermal annealing process improves the bending strength and bending modulus of the samples by approximately 12% and 13%, respectively.

Potapov Andrey A., Volgin Vladimir M., Malakho Artem P., Gnidina Inna V.

The application of additive technologies to the manufacture of polymer and composite products is now actively expanding. The FDM printing process is popular because of its ability to adapt to specific tasks and to bring products with complex geometries into production quickly and at minimal cost, and is seen as a technology that can compete with injection molding. However, due to the nature of the process, FDM printed parts are significantly inferior in quality to injection molded parts. Much attention is now being paid to research into supplementary treatment methods to improve the properties of FDM printing parts. However, there is no complete and clear description of such methods, nor are there any recommendations on the choice of treatment methods aimed at improving the specific parts properties. The aim of this review is to analyse the research in the field of post-treatment of parts in order to systematise their advantages and limitations, which will allow a more reasoned choice of a post-treatment method to improve specific properties of FDM printing parts.The bibliography includes 120 references.

Wang Z., Zhang B., Wang J.

AbstractFused deposition modeling (FDM) based large‐area additive manufacturing has advanced significantly, particularly for producing large parts with high‐performance short fibrous composites. To improve the mechanical performance of these manufactured parts, isothermal annealing is often employed as a post‐treatment for FDM‐produced components. Hence, this study examines the impact of isothermal annealing on the mechanical properties of short carbon fiber‐filled Polyamide 12 (PA12‐CF) and polyethylene terephthalate glycol (PETG‐CF). Samples are prepared using a customized high‐extrusion‐rate FDM (HFDM) system with varying key printing parameters (layer height and extrusion width). Three‐point bending tests are employed to assess the bending strength, modulus, and fracture deflection of the samples. Results show that annealing treatment significantly enhances the bending performance of PA12‐CF, with strength and modulus increasing by 27.8% and 31.2%, respectively. In contrast, PETG‐CF exhibits relatively minor improvements in bending strength (8.1%) and modulus (2.7%). Optical microscopy reveals that different printing parameters notably influence the alignment of short carbon fibers, affecting the mechanical properties, while the annealing treatment does not alter these parameter‐dependent trends. Finite element simulations further demonstrate that the presence of carbon fibers contributes to a progressive enhancement of the polymer matrix, which impacts mechanical improvement during annealing.Highlights High‐extrusion‐rate FDM is used to prepare PA12 and PETG composite samples. Annealing improves properties more in semi‐crystalline PA12‐CF samples. Meso‐structural analysis reveals that printing parameters play a crucial role. Short‐carbon‐fiber boosts strengths of the polymer matrix during annealing.