Metallization of Thermoplastic Polymers and Composites 3D Printed by Fused Filament Fabrication

Fused filament fabrication allows the direct manufacturing of customized and complex products although the layer-by-layer appearance of this process strongly affects the surface quality of the final parts. In recent years, an increasing number of post-processing treatments has been developed for the most used materials. Contrarily to other additive manufacturing technologies, metallization is not a common surface treatment for this process despite the increasing range of high-performing 3D printable materials. The objective of this work is to explore the use of physical vapor deposition sputtering for the chromium metallization of thermoplastic polymers and composites obtained by fused filament fabrication. The thermal and mechanical properties of five materials were firstly evaluated by means of differential scanning calorimetry and tensile tests. Meanwhile, a specific finishing torture test sample was designed and 3D printed to perform the metallization process and evaluate the finishing on different geometrical features. Furthermore, the roughness of the samples was measured before and after the metallization, and a cost analysis was performed to assess the cost-efficiency. To sum up, the metallization of five samples made with different materials was successfully achieved. Although some 3D printing defects worsened after the post-processing treatment, good homogeneity on the finest details was reached. These promising results may encourage further experimentations as well as the development of new applications, i.e., for the automotive and furniture fields.

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Surface finish of Additively Manufactured Metals: biofilm formation and cellular attachment

10.25518/esaform21.2089 ◽

2021 ◽

Author(s):

Paola Ginestra ◽

Leonardo Riva ◽

Elisabetta Ceretti ◽

David Lobo ◽

Sophie Mountcastle ◽

...

Keyword(s):

Surface Properties ◽

High Performance ◽

Antimicrobial Properties ◽

Region Of Interest ◽

Titanium Implants ◽

Surface Finishing ◽

Layer By Layer ◽

Post Processing ◽

3D Printed ◽

Manufacturing Technologies

Powder bed fusion techniques enable the production of customized and complex devices that meet the requirements of the end user and target application. The medical industry relies on these additive manufacturing technologies for the advantages that these methods offer to accurately fit the patients’ needs. Besides the recent improvements, the production process of 3D printed bespoke implants still requires optimization to achieve the optimal properties that can mimic both the chemical and mechanical characteristics of the anatomical region of interest. In particular, the surface properties of an implant device are crucial to obtain a strong interface and connection with the physiological environment. The layer by layer manufacturing processes lead to the production of complex and high-performance substrates but always require surface treatments during post-processing to improve the implant interaction with the natural tissues and promote a shorter assimilation for the fast recovery and wellness of the patient. Although the surface finishing can be tailored to enhance cells adhesion, proliferation and differentiation in contact with a metal implant, the same surface properties can have a different outcome when dealing with bacteria. This work aims to provide a preliminary analysis on how different post-processing techniques have distinct effects on cells and bacteria colonization of 3D printed titanium implants. The goal of the paper is to highlight the importance of the identification of an optimized methodology for the surface treatment of Ti6Al4V samples produced by Selective Laser Melting (SLM) that improves the implant antimicrobial properties and promotes the osseointegration in a long-term period.

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Deterioration of the Mechanical Properties of FFF 3D-Printed PLA Structures

Inventions ◽

10.3390/inventions6010001 ◽

2020 ◽

Vol 6 (1) ◽

pp. 1

Author(s):

Asahi Yonezawa ◽

Akira Yamada

Keyword(s):

Mechanical Properties ◽

3D Printing ◽

Test Piece ◽

Tensile Tests ◽

Poly Lactic Acid ◽

Uniaxial Tensile ◽

Layer By Layer ◽

Fused Filament Fabrication ◽

Test Pieces ◽

3D Printed

Poly(lactic acid) (PLA) is a biodegradable polymer material used for the fabrication of objects by fused filament fabrication (FFF) 3D printing. FFF 3D printing technology has been quickly spreading over the past few years. An FFF-3D-printed object is formed from melted polymer extruded from a nozzle layer-by-layer. The mechanical properties of the object, and the changes in those properties as the object degrades, differ from the properties and changes observed in bulk objects. In this study we evaluated FFF-3D-printed objects by uniaxial tensile tests and four-point flexural tests to characterize the changes of three mechanical properties, namely, the maximum stress, elastic modulus, and breaking energy. Eight types of test pieces printed directly by an FFF 3D printer using two scan patterns and two interior fill percentages (IFPs) were tested by the aforesaid methods. The test pieces were immersed in saline and kept in an incubator at 37 °C for 30, 60, or 90 days before the mechanical testing. The changes in the mechanical properties differed largely between the test piece types. In some of the test pieces, transient increases in strength were observed before the immersion degraded the strength. Several of the test piece types were found to have superior specific strength in the tests. The results obtained in this research will be helpful for the design of PLA structures fabricated by FFF 3D printing.

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Preliminary Characterization of Novel LDPE-Based Wear-Resistant Composite Suitable for FDM 3D Printing

Materials ◽

10.3390/ma12162520 ◽

2019 ◽

Vol 12 (16) ◽

pp. 2520 ◽

Cited By ~ 2

Author(s):

Piotr Olesik ◽

Marcin Godzierz ◽

Mateusz Kozioł

Keyword(s):

3D Printing ◽

Tensile Tests ◽

Waste Glass ◽

Scanning Calorimetry ◽

Path Direction ◽

Pin On Disc ◽

Static Tensile ◽

Fine Glass ◽

3D Printed ◽

Ldpe Composites

Low-density polyethylene (LDPE) composites reinforced with finely powdered waste glass were identified as a potential material for 3D printed structures for use in low-duty frictional applications. A recently published 3D printing model was used to calculate the limits in the filament feed rate and printing speed. Tribological tests (pin-on-disc method) of the printed composites were performed for different print-path directions. Differential scanning calorimetry (DSC) was performed on the samples and the composites showed a higher crystallinity compared with LDPE, which partially explains the higher elastic modulus of the composites determined during static tensile tests. Using a fine glass powder as reinforcement improved the wear resistance of LDPE by 50% due to the formation of a sliding film on the sample’s surface. An evident effect of friction direction vs. the printed path direction on wear was found; which was likely related to differences in the removal of friction products from the friction area for different print-path directions. The LDPE composites with fine waste glass particles are promising materials for low-duty frictional applications and should be the subject of further research.

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A 3D weaving infill pattern for fused filament fabrication

10.21203/rs.3.rs-295081/v1 ◽

2021 ◽

Author(s):

Yuan Yao ◽

Cheng Ding ◽

Mohamed Aburaia ◽

Maximilian Lackner ◽

Lanlan He

Keyword(s):

Additive Manufacturing ◽

Three Dimensional ◽

Layer By Layer ◽

Fused Filament Fabrication ◽

Repetitive Structure ◽

Mechanical Linkage ◽

Manufacturing Technologies ◽

Dimensional Object ◽

Anisotropy Of Mechanical Properties ◽

3D Weaving

Abstract The Fused Filament Fabrication process is the most used additive manufacturing process due to its simplicity and low operating costs. In this process, a thermoplastic filament is led through an extruder, melted, and applied to a building platform by the axial movements of an automated Cartesian system in such a way that a three-dimensional object is created layer by layer. Compared to other additive manufacturing technologies, the components produced have mechanical limitations and are often not suitable for functional applications. To reduce the anisotropy of mechanical strength in fused filament fabrication (FFF), this paper proposes a 3D weaving deposit path planning method that utilizes a 5-layer repetitive structure to achieve interlocking and embedding between neighbor slicing planes to improve the mechanical linkage within the layers. The developed algorithm extends the weaving path as an infill pattern to fill different structures and makes this process feasible on a standard three-axis 3D printer. Compared with 3D weaving printed parts by layer-to-layer deposit, the anisotropy of mechanical properties inside layers is significantly reduced to 10.21% and 0.98%.

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3D-Printed Drug Delivery Systems: The Effects of Drug Incorporation Methods on Their Release and Antibacterial Efficiency

Materials ◽

10.3390/ma13153364 ◽

2020 ◽

Vol 13 (15) ◽

pp. 3364

Author(s):

Bahaa Shaqour ◽

Inés Reigada ◽

Żaneta Górecka ◽

Emilia Choińska ◽

Bart Verleije ◽

...

Keyword(s):

Drug Delivery ◽

3D Printing ◽

Drug Delivery Systems ◽

Drug Distribution ◽

Delivery Systems ◽

Solvent Casting ◽

Fused Filament Fabrication ◽

3D Printed ◽

Manufacturing Technologies ◽

Drug Incorporation

Additive manufacturing technologies have been widely used in the medical field. More specifically, fused filament fabrication (FFF) 3D-printing technology has been thoroughly investigated to produce drug delivery systems. Recently, few researchers have explored the possibility of directly 3D printing such systems without the need for producing a filament which is usually the feedstock material for the printer. This was possible via direct feeding of a mixture consisting of the carrier polymer and the required drug. However, as this direct feeding approach shows limited homogenizing abilities, it is vital to investigate the effect of the pre-mixing step on the quality of the 3D printed products. Our study investigates the two commonly used mixing approaches—solvent casting and powder mixing. For this purpose, polycaprolactone (PCL) was used as the main polymer under investigation and gentamicin sulfate (GS) was selected as a reference. The produced systems’ efficacy was investigated for bacterial and biofilm prevention. Our data show that the solvent casting approach offers improved drug distribution within the polymeric matrix, as was observed from micro-computed topography and scanning electron microscopy visualization. Moreover, this approach shows a higher drug release rate and thus improved antibacterial efficacy. However, there were no differences among the tested approaches in terms of thermal and mechanical properties.

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3D Printing of PLA/clay Nanocomposites: Influence of Printing Temperature on Printed Samples Properties

Materials ◽

10.3390/ma11101947 ◽

2018 ◽

Vol 11 (10) ◽

pp. 1947 ◽

Cited By ~ 29

Author(s):

Bartolomeo Coppola ◽

Nicola Cappetti ◽

Luciano Di Maio ◽

Paola Scarfato ◽

Loredana Incarnato

Keyword(s):

Elastic Modulus ◽

3D Printing ◽

Layered Silicate ◽

Tensile Tests ◽

Nucleating Agent ◽

Clay Nanocomposites ◽

Screw Extruder ◽

Scanning Calorimetry ◽

Dog Bone ◽

3D Printed

In this study, the possibility of using a layered silicate-reinforced polylactic acid (PLA) in additive manufacturing applications was investigated. In particular, the aim of this work was to study the influence of printing temperature in the 3D printing process of PLA/clay nanocomposites. For this reason, two PLA grades (4032D and 2003D, D-isomer content 1.5 and 4, respectively) were melt-compounded by a twin screw extruder with a layered silicate (Cloisite 30B) at 4 wt %. Then, PLA and PLA/clay feedstock filaments (diameter 1.75 mm) were produced using a single screw extruder. Dog-bone and prismatic specimens were 3D printed using the FDM technique at three different temperatures, which were progressively increased from melting temperature (185–200–215 °C for PLA 4032D and 165–180–195 °C for PLA 2003D). PLA and PLA/clay specimens were characterized using thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and tensile tests. Moreover, the morphology of the 3D printed specimens was investigated using optical microscopy and contact angle measurements. The different polymer matrix and the resulting nanocomposite morphology strongly influenced 3D printed specimen properties. DMA on PLA/clay filaments reported an increase in storage modulus both at ambient temperature and above the glass transition temperature in comparison to neat PLA filaments. Furthermore, the presence of nanoclay increased thermal stability, as demonstrated by TGA, and acted as a nucleating agent, as observed from the DSC measurements. Finally, for 3D printed samples, when increasing printing temperature, a different behavior was observed for the two PLA grades and their nanocomposites. In particular, 3D printed nanocomposite samples exhibited higher elastic modulus than neat PLA specimens, but for PLA 4032D+C30B, elastic modulus increased at increasing printing temperature while for PLA 2003D+C30B slightly decreased. Such different behavior can be explained considering the different polymer macromolecular structure and the different nanocomposite morphology (exfoliated in PLA 4032D matrix and intercalated in PLA 2003D matrix).

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On the Capabilities of a Multi-Modality 3D Bioprinter for Customized Biomedical Devices

Volume 2A: Advanced Manufacturing ◽

10.1115/imece2015-52204 ◽

2015 ◽

Cited By ~ 1

Author(s):

Prashanth Ravi ◽

Panos S. Shiakolas ◽

Tre Welch ◽

Tushar Saini ◽

Kristine Guleserian ◽

...

Keyword(s):

Additive Manufacturing ◽

Device Fabrication ◽

Layer By Layer ◽

Fused Filament Fabrication ◽

Stl File ◽

Diverse Application ◽

Multiple Materials ◽

Manufacturing Platform ◽

Single Construct ◽

Manufacturing Technologies

Currently, there is a major shift in medical device fabrication research towards layer-by-layer additive manufacturing technologies; mainly owing to the relatively quick transition from a solid model (.STL file) to an actual prototype. The current manuscript introduces a Custom Multi-Modality 3D Bioprinter (CMMB) developed in-house, combining the Fused Filament Fabrication (FFF), Photo Polymerization (PP), Viscous Extrusion (VE), and Inkjet (IJ) printing technologies onto a single additive manufacturing platform. Methodologies to address limitation in the ability to customize construct properties layer-by-layer and to incorporate multiple materials in a single construct have been evaluated using open source 3D printing softwares Slic3r and Repetier-Host. Such customization empowers the user to fabricate constructs with tailorable anisotropic properties by combining different print technologies and materials. To this end, procedures which allow the integration of more than one distinct modality of the CMMB during a single print session were developed and evaluated, and are discussed. The current setup of the CMMB provides the capability to fabricate personalized medical devices using patient data from an MRI or a CT scan. Initial experiments and fabricated constructs demonstrate the potential of the CMMB for research in diverse application areas within biomedical engineering.

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Tensile Properties of 3D Printed Polymeric Pieces: Comparison of Several Testing Setups

Ingeniería e Investigación ◽

10.15446/ing.investig.v41n1.84467 ◽

2021 ◽

Vol 41 (1) ◽

pp. e84467

Author(s):

Andres E Romero ◽

Marcelo T. Piovan ◽

Carlos A. Mainetti ◽

Darío Stechina ◽

Sandra Mendoza ◽

...

Keyword(s):

Experimental Data ◽

Tensile Tests ◽

Measuring Systems ◽

Testing Procedures ◽

Measuring Devices ◽

Deposition Modeling ◽

3D Printed ◽

Manufacturing Technologies ◽

Testing Standards ◽

Precision Machines

This work aims to evaluate and compare variations of a methodology for performing tensile tests on thermoplastic specimens constructed by additive manufacturing technologies (AMT) with filament deposition modeling (FDM). The testing procedures of pieces made in FDM machines do not yet have any conclusive standards because 3D printing, as a disruptive and exponentially growing technology, has not allowed enough time to reach a definitive scientific consensus. Nowadays, testing standards for injected thermoplastic parts or laminated composites are employed as substitutes with careful implementation. A comparative study was carried out on the elasticity modulus, determined within the framework of the same standard but with different measuring devices and testing machines. These machines cover a broad range from professional automated high precision machines to lab and specialized machines. Sets of 3Dprinted specimens with identical manufacturing parameters were constructed in a commercial 3D printer. An analysis of variance was performed in order to evaluate the consistency and significance of experimental data for the same polymer, considering the machine type and its corresponding setup. From the experimental data, it is concluded that, with the due care, all evaluated testing setups can reach comparable results, especially in the absence of sophisticated and expensive measuring systems.

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Influence of Infill Pattern on the Elastic Mechanical Properties of Fused Filament Fabrication (FFF) Parts through Experimental Tests and Numerical Analyses

Materials ◽

10.3390/ma14185459 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5459

Author(s):

Jordi Bonada ◽

Mª Magdalena Pastor ◽

Irene Buj-Corral

Keyword(s):

Mechanical Properties ◽

Manufacturing Process ◽

Experimental Tests ◽

Tensile Tests ◽

Numerical Analyses ◽

Layer By Layer ◽

Fused Filament Fabrication ◽

Element Analysis ◽

Young’S Moduli ◽

Printing Parameters

Fused Filament Fabrication (FFF) is one of the most extensive additive manufacturing technologies for printing prototypes or final parts in various fields. Some printed parts need to meet structural requirements to be functional parts. Therefore, it is necessary to know the mechanical behavior of the printed samples as a function of the printing parameters in order to optimize the material used during the manufacturing process. It is known that FFF parts can present orthotropic characteristics as a consequence of the manufacturing process, in which the material is deposited layer by layer. Therefore, these characteristics must be considered for a correct evaluation of the printed parts from a structural point of view. In this paper, the influence of the type of filling pattern on the main mechanical properties of the printed parts is analyzed. For this purpose, the first parts are 3D printed using three different infill patterns, namely grid, linear with a raster orientation of 0 and 90°, and linear with a raster orientation of 45°. Then, experimental tensile tests, on the one hand, and numerical analyses using finite elements, on the other hand, are carried out. The elastic constants of the material are obtained from the experimental tests. From the finite element analysis, using a simple approach to create a Representative Volume Model (RVE), the constitutive characteristics of the material are estimated: Young’s Moduli and Poisson’s ratios of the printed FFF parts. These values are successfully compared with those of the experimental tests. The results clearly show differences in the mechanical properties of the FFF printed parts, depending on the internal arrangement of the infill pattern, even if similar 3D printing parameters are used.

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Characterization of PLA/TPU composite filaments manufactured for 3D printing with FDM

Journal of Thermoplastic Composite Materials ◽

10.1177/08927057211062561 ◽

2021 ◽

pp. 089270572110625

Author(s):

Ajay Jayswal ◽

Sabit Adanur

Keyword(s):

3D Printing ◽

Fused Deposition Modeling ◽

Thermoplastic Polyurethane ◽

Tensile Tests ◽

Optical Microscope ◽

Mechanical Analysis ◽

Uniaxial Tensile ◽

Scanning Calorimetry ◽

Fused Deposition ◽

3D Printed

Polylactic acid (PLA) and thermoplastic polyurethane (TPU) were mixed in different proportions and extruded through twin-screw and single-screw extruders to obtain composite filaments to be used for 3D printing with fused deposition modeling (FDM) method. The properties of the filaments were characterized using uniaxial tensile tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), rheology, polarized optical microscope (POM), and scanning electron microscope (SEM). 3D printed samples from composite filaments were tested using dynamic mechanical analysis (DMA). It was found that the tensile strength and modulus of the filaments decrease while elongation at break increases with the increasing TPU content in the composite. The analysis also showed a partial miscibility of the polymer constituents in the solution of composite filaments. Finally, a flexible structure, plain weave fabric, was designed and 3D printed using the composite filaments developed which proved that the filaments are well suited for 3D printing.

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