On the use of high viscosity polymers in the fused filament fabrication process

2017 ◽  
Vol 23 (4) ◽  
pp. 727-735 ◽  
Author(s):  
Muhammad Hussam Khaliq ◽  
Rui Gomes ◽  
Célio Fernandes ◽  
João Nóbrega ◽  
Olga Sousa Carneiro ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
High Viscosity ◽  
Polymer Processing ◽  
General Purpose ◽  
Good Choice ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Performance Requirements ◽  
Functional Prototype ◽  
The One

Purpose This work aims to provide additional insights regarding the practicability of using conventional materials in the fused filament fabrication (FFF) process. Design/methodology/approach Two different acrylonitryle butadiene styrene (ABS) grades are studied and compared, aiming to check to what extent the regular ABS developed for conventional polymer processing, with a different rheology than the one provided for the FFF process, can also be used in this process (FFF). Findings The rheological results show that a general-purpose ABS (ABS-GP) melt is much more viscous and elastic than ABS-FFF. It is clear that using ABS-GP as feedstock material in the FFF process results in poor coalescence and adhesion between the extruded filaments, which has a detrimental effect on the mechanical properties of the printed specimens. Despite its lower performance, ABS-GP can be a good choice if the objective is to produce an aesthetical prototype. If the objective is to produce a functional prototype or a final part, its mechanical performance requirements will dictate the choice. Originality/value This work provides insightful information regarding the use of high viscosity materials on the 3D printing process.

scholarly journals 3D Printing of Fibre-Reinforced Thermoplastic Composites Using Fused Filament Fabrication—A Review

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2188
Author(s):  
Andrew N. Dickson ◽  
Hisham M. Abourayana ◽  
Denis P. Dowling
Keyword(s):  
3D Printing ◽  
Polymer Composites ◽  
Mechanical Performance ◽  
Polymer Processing ◽  
Thermoplastic Composites ◽  
Fused Filament Fabrication ◽  
Compression Moulding ◽  
Processing Technologies ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer

Three-dimensional (3D) printing has been successfully applied for the fabrication of polymer components ranging from prototypes to final products. An issue, however, is that the resulting 3D printed parts exhibit inferior mechanical performance to parts fabricated using conventional polymer processing technologies, such as compression moulding. The addition of fibres and other materials into the polymer matrix to form a composite can yield a significant enhancement in the structural strength of printed polymer parts. This review focuses on the enhanced mechanical performance obtained through the printing of fibre-reinforced polymer composites, using the fused filament fabrication (FFF) 3D printing technique. The uses of both short and continuous fibre-reinforced polymer composites are reviewed. Finally, examples of some applications of FFF printed polymer composites using robotic processes are highlighted.

scholarly journals A study on extruded filament bonding in fused filament fabrication

2019 ◽  
Vol 25 (3) ◽  
pp. 555-565 ◽  
Author(s):  
Ana Elisa Costa ◽  
Alexandre Ferreira da Silva ◽  
Olga Sousa Carneiro
Keyword(s):  
Control Systems ◽  
Design Methodology ◽  
Mechanical Performance ◽  
Tensile Axis ◽  
Dimensional Accuracy ◽  
Fused Filament Fabrication ◽  
Bonding Quality ◽  
Content Type ◽  
Extrusion Rate ◽  
Forced Cooling

Purpose The performance of parts produced by fused filament fabrication is directly related to the printing conditions and to the rheological phenomena inherent to the process, specifically the bonding between adjacent extruded paths/raster. This paper aims to study the influence of a set of printing conditions and parameters, namely, envelope temperature, extrusion temperature, forced cooling and extrusion rate, on the parts performance. Design/methodology/approach The influence of these parameters is evaluated by printing a set of test specimens that are morphologically characterized and mechanically tested. At the morphological level, the external dimensions and the voids content of the printed specimens are evaluated. The bonding quality between adjacent extruded paths is assessed through the mechanical performance of test specimens, subjected to tensile loads. These specimens are printed with all raster oriented at 90º relative to the tensile axis. Findings The best performance, resulting from a compromise between surface quality, dimensional accuracy and mechanical performance, is achieved with a heated printing environment and with no use of forced cooling. In addition, for all the conditions tested, the highest dimensional accuracy is achieved in dimensions defined in the printing plane. Originality/value This work provides a relevant result as the majority of the current printers comes without enclosure or misses the heating and envelope temperature control systems, which proved to be one of the most influential process parameter.

Antibacterial silver submicron wire-polylactic acid composites for fused filament fabrication

2020 ◽  
Vol 26 (1) ◽  
pp. 32-38 ◽  
Author(s):  
Jenna Stephanie Walker ◽  
John Arnold ◽  
Cynthiya Shrestha ◽  
Damon Smith
Keyword(s):  
Mechanical Performance ◽  
Silver Ions ◽  
Additive Concentration ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Bacteria Growth ◽  
E Coli ◽  
Submicron Scale ◽  
Void Defects ◽  
Manufacturing Technologies

Purpose The purpose of this study is to explore the use of silver submicron-scale wire (AgSMW) additives in filament feedstock for fused filament fabrication (FFF) additive manufacturing technologies. The antibacterial effect of the additive on printed objects is assessed and its impact on mechanical behavior is determined. Design/methodology/approach AgSMW-PLA composite FFF filaments were fabricated by solution processing, granulation and extrusion. The reduction in the growth of Escherichia coli (E. coli) is measured after exposure to FFF-printed composite test specimens with AgSMW additive concentrations ranging from 0.0 to 10.0 weight per cent. The effect of the additive addition on the thermal properties and tensile mechanical performance was measured. Scanning electron microscopy (SEM) was used to analyze the composite microstructure and fracture behavior. Findings E. coli growth was reduced by approximately 50 per cent at the highest additive concentration of 10.0 weight per cent. This is attributed to the release of silver ions through water diffusion into the bulk of the composite. The ultimate tensile strength declined with increasing AgSMW concentration with a moderate reduction of 18 per cent at 10.0 weight per cent. The elastic modulus did not vary significantly at any of the concentrations studied. The ductility of the composite was only notably reduced at the highest concentration. The reduction in mechanical strength and strain at break is attributed to an increase in void defects in the composite with increasing additive concentration. Originality/value This study demonstrates the successful incorporation of AgSMWs into FFF-compatible filaments for use in commercially available printing systems. The results demonstrate significant reduction of bacteria growth when using these materials. While the mechanical performance degrades slightly, the results indicate the material’s efficacy for a variety of potential biomedical applications. As a proof of concept, surgical tools were printed using the composite.

A review on fibre reinforced composite printing via FFF

2019 ◽  
Vol 25 (6) ◽  
pp. 972-988 ◽  
Author(s):  
Isaac Ferreira ◽  
Margarida Machado ◽  
Fernando Alves ◽  
António Torres Marques
Keyword(s):  
High Performance ◽  
Mechanical Performance ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Performance Improvements ◽  
Different Types ◽  
Significant Research ◽  
Comprehensive Survey ◽  
3D Printed ◽  
Reinforced Thermoplastics

Purpose In industry, fused filament fabrication (FFF) offers flexibility and agility by promoting a reduction in costs and in the lead-time (i.e. time-to-market). Nevertheless, FFF parts exhibit some limitations such as lack of accuracy and/or lower mechanical performance. As a result, some alternatives have been developed to overcome some of these restrictions, namely, the formulation of high performance polymers, the creation of fibre-reinforced materials by FFF process and/or the design of new FFF-based technologies for printing composite materials. This work aims to analyze these technologies. Design/methodology/approach This work aims to study and understand the advances in the behaviour of 3D printed parts with enhanced performance by its reinforcement with several shapes and types of fibres from nanoparticles to continuous fibre roving. Thus, a comprehensive survey of significant research studies carried out regarding FFF of fibre-reinforced thermoplastics is provided, giving emphasis to the most relevant and innovative developments or adaptations undergone at hardware level and/or on the production process of the feedstock. Findings It is shown that the different types of reinforcement present different challenges for the printing process with different outcomes in the part performance. Originality/value This review is focused on joining the most important researches dedicated to the process of FFF-printed parts with different types reinforcing materials. By dividing the reinforcements in categories by shape/geometry and method of processing, it is possible to better quantify performance improvements.

Mixing in Extensional Flow Field

2000 ◽  
Vol 10 (1) ◽  
pp. 10-21 ◽  
Author(s):  
L. A. Utracki ◽  
A. Luciani
Keyword(s):  
High Efficiency ◽  
Extensional Flow ◽  
High Viscosity ◽  
Polymer Processing ◽  
General Purpose ◽  
Screw Extruder ◽  
Turbulent Flow Regime ◽  
Twin Screw ◽  
Dynamic Version ◽  
High Level

Abstract Mixing is the most important operation in polymer processing. Uniformity of the molecular weight, degree of entanglement, temperature, and composition, is the prerequisite for good performance. Mixing of molten polymers is always within the laminar (as opposed to turbulent) flow regime. This paper presents an overview of the effect of flow type on mixing. The distributive mixing is best modeled considering either laminar or chaotic mixing. Here the system is ”passive“, i.e.the rheological properties are identical and the interface is ”invisible“. Furthermore, the effects of flow and morphology are ”decoupled“. By contrast, the dispersive mixing is best modeled by means of microrheology, complemented by coalescence. Both models – the laminar mixing and the microrheology – show the unambiguous superiority of the extensional flows for dispersive and distributive mixing, in particular, when the viscosity ratio of two principal components is large. However this superiority is balanced by practical difficulties in generating a flow that may ascertain a high level of extension. Results of simulation and model experiments on drop deformabilty in converging and diverging (c-d) flow were used to develop a simple and inexpensive mixer capable of generating a high level of extension that lead to enhanced mixing capability. In consequence, an extensional flow mixer (EFM) was designed. In this device, a liquid mixture is repeatedly exposed to extensional flow fields and semi-quiescent zones. The c-d channels are of progressively increasing intensity. To reduce the pressure drop, and to prevent blockage, slit restrictions are used. The EFM (as well as its newer, dynamic version – DEFM) is fully adjustable, general-purpose mixers. Several its versions have been used for: polymer blending, incorporation of elastomers into resins, and dispersion of high viscosity polymers or ”gel particles“. For most mixing applications a singe-screw extruder equipped with either EFM or DEFM performed at least as well as a co-rotating, inter-meshing twin-screw extruder, with high efficiency screw configuration.

scholarly journals Interface geometries in 3D multi-material prints by fused filament fabrication

2019 ◽  
Vol 25 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Micaela Ribeiro ◽  
Olga Sousa Carneiro ◽  
Alexandre Ferreira da Silva
Keyword(s):  
Lactic Acid ◽  
Interface Design ◽  
Mechanical Performance ◽  
Thermoplastic Polyurethane ◽  
Poly Lactic Acid ◽  
Material Objects ◽  
Mechanical Interlocking ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Face To Face

Purpose An issue when printing multi-material objects is understanding how different materials will perform together, especially because interfaces between them are always created. This paper aims to address this interface from a mechanical perspective and evaluates how it should be designed for a better mechanical performance. Design/methodology/approach Different interface mechanisms were considered, namely, microscopic interfaces that are based on chemical bonding and were represented with a U-shape interface; a macroscopic interface characterized by a mechanical interlocking mechanism, represented by a T-shape interface; and a mesoscopic interface that sits between other interface systems and that was represented by a dovetail shape geometry. All these different interfaces were tested in two different material sets, namely, poly (lactic acid)–poly (lactic acid) and poly (lactic acid)–thermoplastic polyurethane material pairs. These two sets represent high- and low-compatibility materials sets, respectively. Findings The results showed, despite the materials’ compatibility level, multi-material objects will have a better mechanical performance through a macroscopic interface, as it is based on a mechanical interlocking system, of which performance cannot be achieved by a simple face-to-face interface even when considering the same material. Originality/value The paper investigates the importance of interface design in multi-material 3D prints by fused filament fabrication. Especially, for parts intended to be subjected to mechanical efforts, simple face-to-face interfaces are not sufficient and more robust and macroscopic-based interface geometries (based on mechanical interlocking systems) are advised. Moreover, such interfaces do not raise esthetic problems because of their working principle; the 3D printing technology can hide the interface geometries, if required.

Process porosity and mechanical performance of fused filament fabricated 316L stainless steel

2019 ◽  
Vol 25 (7) ◽  
pp. 1319-1327 ◽  
Author(s):  
James Damon ◽  
Stefan Dietrich ◽  
Sasidhar Gorantla ◽  
Uwe Popp ◽  
Brando Okolo ◽  
...  
Keyword(s):  
Stainless Steel ◽  
316L Stainless Steel ◽  
Mechanical Performance ◽  
Formation Mechanisms ◽  
Micro Computed Tomography ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Powder Bed ◽  
Strongly Connected ◽  
Scanning Strategies

Purpose This study aims to investigate the correlation between build orientation characteristics, part porosity and mechanical properties of the fused filament fabrication (FFF) process to provide insight into pore formation mechanisms and to establish guidelines for optimal process configurations. Design/methodology/approach Micro computed tomography and metallographic sections provide the basis for a correlation between porosity and extrusion path. Using the correlations found in this study, the way to improve printing strategies and filament properties can be deduced directly from an analysis of the print path and the final influence on mechanical performance. Findings With metal-FFF 3D printing technology, near-dense parts (0.5 Vol.%) can be fabricated. The pore architecture is strongly connected to the build direction and print strategy with parallel, elongated pore channels. Mechanical values of FFF samples are similar to metal injection-molded (MIM) parts, except the elongation to fracture. The high difference of yield strength of sintered samples compared to laser powder bed fusion (LPBF) samples can be attributed to the finer grains and a Hall–Petch hardening effect. The conclusions derived from this study are that the presented process is capable of producing comparable part qualities compared to MIM samples, with higher build rates in comparison to LPBF processes. Originality/value 316L stainless steel was successfully manufactured via FFF. This paper also addresses the effects of scanning strategies on the resulting porosity and proposes improvements to reduce residual porosity, thus increasing the mechanical performance in the future.

Effect of nozzle diameter on mechanical and geometric performance of 3D printed carbon fibre-reinforced composites manufactured by fused filament fabrication

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jesús Miguel Chacón ◽  
Miguel Ángel Caminero ◽  
Pedro José Núñez ◽  
Eustaquio García-Plaza ◽  
Jean Paul Bécar
Keyword(s):  
Surface Roughness ◽  
Carbon Fibre ◽  
Mechanical Performance ◽  
Dimensional Accuracy ◽  
Nozzle Diameter ◽  
Fused Filament Fabrication ◽  
Manufacturing Costs ◽  
Content Type ◽  
3D Printed ◽  
Composite Samples

Purpose Fused filament fabrication (FFF) is one of the most popular additive manufacturing (AM) technologies due to its ability to build thermoplastic parts with complex geometries at low cost. The FFF technique has been mainly used for rapid prototyping owing to the poor mechanical and geometrical properties of pure thermoplastic parts. However, both the development of new fibre-reinforced filaments with improved mechanical properties, and more accurate composite 3D printers have broadened the scope of FFF applications to functional components. FFF is a complex process with a large number of parameters influencing product quality and mechanical properties, and the effects of the combined parameters are usually difficult to evaluate. An array of parameter combinations has been analysed for improving the mechanical performance of thermoplastic parts such as layer thickness, build orientation, raster angle, raster width, air gap, infill density and pattern, fibre volume fraction, fibre layer location, fibre orientation and feed rate. This study aims to assess the effects of nozzle diameter on the mechanical performance and the geometric properties of 3D printed short carbon fibre-reinforced composites processed by the FFF technique. Design methodology approach Tensile and three-point bending tests were performed to characterise the mechanical response of the 3D printed composite samples. The dimensional accuracy, the flatness error and surface roughness of the printed specimens were also evaluated. Moreover, manufacturing costs, which are related to printing time, were evaluated. Finally, scanning electron microscopy images of the printed samples were analysed to estimate the porosity as a function of the nozzle diameter and to justify the effect of nozzle diameter on dimensional accuracy and surface roughness. Findings The effect of nozzle diameter on the mechanical and geometric quality of 3D printed composite samples was significant. In addition, large nozzle diameters tended to increase mechanical performance and enhance surface roughness, with a reduction in manufacturing costs. In contrast, 3D printed composite samples with small nozzle diameter exhibited higher geometric accuracy. However, the effect of nozzle diameter on the flatness error and surface roughness was of slight significance. Finally, some print guidelines are included. Originality value The effect of nozzle diameter, which is directly related to product quality and manufacturing costs, has not been extensively studied. The presented study provides more information regarding the dependence of the mechanical, microstructural and geometric properties of short carbon fibre-reinforced nylon composite components on nozzle diameter.

Supportless printing of lattice structures by metal fused filament fabrication (MF3) of Ti-6Al-4V: design and analysis

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammad Qasim Shaikh ◽  
Serena Graziosi ◽  
Sundar Vedanarayan Atre
Keyword(s):  
Relative Density ◽  
Mechanical Performance ◽  
Unit Cell ◽  
Lattice Structures ◽  
Fused Filament Fabrication ◽  
Cross Sectional ◽  
Content Type ◽  
Aspect Ratios ◽  
Lattice Geometry ◽  
Starting Point

Purpose This paper aims to investigate the feasibility of supportless printing of lattice structures by metal fused filament fabrication (MF3) of Ti-6Al-4V. Additionally, an empirical method was presented for the estimation of extrudate deflection in unsupported regions of lattice cells for different geometric configurations. Design/methodology/approach Metal-polymer feedstock with a solids-loading of 59 Vol.% compounded and extruded into a filament was used for three-dimensional printing of lattice structures. A unit cell was used as a starting point, which was then extended to multi-stacked lattice structures. Feasible MF3 processing conditions were identified to fabricate defect-free lattice structures. The effects of lattice geometry parameters on part deflection and relative density were investigated at the unit cell level. Computational simulations were used to predict the part quality and results were verified by experimental printing. Finally, using the identified processing and geometry parameters, multi-stacked lattice structures were successfully printed and sintered. Findings Lattice geometry required considerable changes in MF3 printing parameters as compared to printing bulk parts. Lattice cell dimensions showed a considerable effect on dimensional variations and relative density due to varying aspect ratios. The experimental printing of lattice showed large deflection/sagging in unsupported regions due to gravity, whereas simulation was unable to estimate such deflection. Hence, an analytical model was presented to estimate extrudate deflections and verified with experimental results. Lack of diffusion between beads was observed in the bottom facing surface of unsupported geometry of sintered unit cells as an effect of extrudate sagging in the green part stage. This study proves that MF3 can fabricate fully dense Ti-6Al-4V lattice structures that appear to be a promising candidate for applications where mechanical performance, light-weighting and design customization are required. Originality/value Supportless printing of lattice structures having tiny cross-sectional areas and unsupported geometries is highly challenging for an extrusion-based additive manufacturing (AM) process. This study investigated the AM of Ti-6Al-4V supportless lattice structures using the MF3 process for the first time.

PENGARUH LATIHAN RANGE OF MOTION (ROM) AKTIF ASSITIF TERHADAP RENTANG GERAK SENDI PADA LANSIA YANG MENGALAMI IMMOBILISASI FISIK

2019 ◽  
Vol 13 (2) ◽  
Author(s):  
Andri Setyorini ◽  
Niken Setyaningrum
Keyword(s):  
Range Of Motion ◽  
Human Life ◽  
The Elderly ◽  
General Purpose ◽  
Test Statistic ◽  
Physical Mobility ◽  
Motion Exercise ◽  
The One ◽  
The Individual ◽  
Active Training

Background: Elderly is the final stage of the human life cycle, that is part of the inevitable life process and will be experienced by every individual. At this stage the individual undergoes many changes both physically and mentally, especially setbacks in various functions and abilities he once had. Preliminary study in Social House Tresna Wreda Yogyakarta Budhi Luhur Units there are 16 elderly who experience physical immobilization. In the social house has done various activities for the elderly are still active, but the elderly who experienced muscle weakness is not able to follow the exercise, so it needs to do ROM (Range Of Motion) exercise.   Objective: The general purpose of this research is to know the effect of Range Of Motion (ROM) Active Assitif training to increase the range of motion of joints in elderly who experience physical immobility at Social House of Tresna Werdha Yogyakarta unit Budhi Luhur.   Methode: This study was included in the type of pre-experiment, using the One Group Pretest Posttest design in which the range of motion of the joints before (pretest) and posttest (ROM) was performed  ROM. Subjects in this study were all elderly with impaired physical mobility in Social House Tresna Wreda Yogyakarta Unit Budhi Luhur a number of 14 elderly people. Data analysis in this research use paired sample t-test statistic  Result: The result of this research shows that there is influence of ROM (Range of Motion) Active training to increase of range of motion of joints in elderly who experience physical immobility at Social House Tresna Wredha Yogyakarta Unit Budhi Luhur.  Conclusion: There is influence of ROM (Range of Motion) Active training to increase of range of motion of joints in elderly who experience physical immobility at Social House Tresna Wredha Yogyakarta Unit Budhi Luhur.

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