scholarly journals Implementation of viscosity and density models for improved numerical analysis of melt flow dynamics in the nozzle during extrusion-based additive manufacturing

2021 ◽  
Author(s):  
Ases Akas Mishra ◽  
Affaf Momin ◽  
Matteo Strano ◽  
Kedarnath Rane
Keyword(s):  
Additive Manufacturing ◽  
Flow Behavior ◽  
Constant Density ◽  
Print Quality ◽  
Axial Distance ◽  
Flow Profile ◽  
Layer By Layer ◽  
Melt Flow ◽  
Fused Filament Fabrication ◽  
Printing Parameters

AbstractFused Filament Fabrication (FFF) is an Additive Manufacturing (AM) process that builds up a part via layer by layer deposition of polymeric material. The purpose of this study is to implement viscosity and density models for improving the assessment of melt flow behavior inside the nozzle during deposition. Numerical simulations are carried out for different combinations of important process parameters like extrusion velocity Ve, extrusion temperature Te, and filament material (Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA)). Cross-Williams–Landel–Ferry (Cross-WLF) viscosity and Pressure–Volume–Temperature (PVT) density models are incorporated to get realistic results. Distribution of printing parameters like pressure, temperature, velocity and viscosity inside the nozzle are observed at steady state and their relationship with the print quality is discussed. Effect of the PVT model on polymer deposition is illustrated by comparing it with deposition considering a constant density. Velocity profiles are obtained for the different cases considered and locations where the flow is fully developed, along the axial distance of the nozzle, are determined and termed as stable zones. A direct correlation between the position of the developed melt flow profile and printing quality is established and the best combination of printing parameters is proposed for ABS and PLA. Extended stable zones are obtained for the polymer melt in the nozzle at Ve = 60 mm/s, Te = 220 °C for ABS and Ve = 30 mm/s and Te = 195 °C for PLA and hence, these can be considered as the optimum values of the printing parameters.

Design and Analysis of Hybrid Fused Filament Fabrication Apparatus for Fabrication of Composites

2021 ◽  
Vol 14 ◽  
Author(s):  
Aniket Yadav ◽  
Piyush Chohan ◽  
Ranvijay Kumar ◽  
Jasgurpreet Singh Chohan ◽  
Raman Kumar
Keyword(s):  
Additive Manufacturing ◽  
Composite Materials ◽  
Design Process ◽  
Low Cost ◽  
Matrix Material ◽  
Fabrication Process ◽  
Layer By Layer ◽  
Fused Filament Fabrication ◽  
Composite Manufacturing ◽  
Tool Paths

Background: Additive manufacturing is the most famous technology which requires materials or composites to be fabricated with layer by layer deposition strategy. Due to its lower cost, higher accuracy and less material wastage; this technology is used in almost every sector. But in many applications there is a need to alter the properties of a product in a certain direction with the help of some reinforcements. With the use of reinforcements, composite layers can be fabricated using additive manufacturing technique which will enhance the directional properties. A novel apparatus is designed to spray the reinforcement material into the printed structures in a very neat and precise manner. This spray nozzle is fully automated, which works according to tool-paths generated by slicing software. The alternate deposition of layers of reinforcement and build materials helped to fabricate customized composite products. Objective: The objective of present study is to design and analyze the working principle of novel technique which has been developed to fabricate composite materials using additive manufacturing. The apparatus is numerically controlled by computer according to CAD data which facilitates the deposition of alternate layers of reinforcement and matrix material. The major challenges during the design process and function of each component has been explored. Methods: The design process is initiated after comprehensive literature review performed to study previous composite manufacturing processes. The recent patents published by different patent offices of the world are studied in detail and analysis has been used to design a low cost composite fabrication apparatus. A liquid dispensing device comprises a storage tank attached with a pump and microprocessor. The microprocessor receives the signal from the computer as per tool paths generated by slicing software which decides the spray of reinforcements on polymer layers. The spraying apparatus moves in coordination with the primary nozzle of the Fused Filament Fabrication process. Results: The hybridization of Fused Filament Fabrication [process with metal spray process has been successfully performed. The apparatus facilitates the fabrication of low cost composite materials along with flexibility of complete customization of composite manufacturing process. The anisotropic behaviour of products can be easily controlled and managed during fabrication which can be used for different applications.

scholarly journals Suitability of Recycled PLA Filament Application in Fused Filament Fabrication Process

2021 ◽  
Vol 15 (4) ◽  
pp. 491-497
Author(s):  
Tomislav Breški ◽  
Lukas Hentschel ◽  
Damir Godec ◽  
Ivica Đuretek
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Polylactic Acid ◽  
Design Of Experiment ◽  
Experimental Approach ◽  
Manufacturing Processes ◽  
Support Structures ◽  
Fused Filament Fabrication ◽  
Layer Height ◽  
Printing Parameters

Fused filament fabrication (FFF) is currently one of the most popular additive manufacturing processes due to its simplicity and low running and material costs. Support structures, which are necessary for overhanging surfaces during production, in most cases need to be manually removed and as such, they become waste material. In this paper, experimental approach is utilised in order to assess suitability of recycling support structures into recycled filament for FFF process. Mechanical properties of standardized specimens made from recycled polylactic acid (PLA) filament as well as influence of layer height and infill density on those properties were investigated. Optimal printing parameters for recycled PLA filaments are determined with Design of Experiment methods (DOE).

scholarly journals In Search of the Optimal Conditions to Process Shape Memory Alloys (NiTi) Using Fused Filament Fabrication (FFF)

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4718
Author(s):  
Pedro Carreira ◽  
Fábio Cerejo ◽  
Nuno Alves ◽  
Maria Teresa Vieira
Keyword(s):  
Additive Manufacturing ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Sintering Temperature ◽  
Production Costs ◽  
Layer By Layer ◽  
Secondary Phases ◽  
Fused Filament Fabrication ◽  
Near Net Shape ◽  
Niti Shape Memory Alloys

This research was performed so as to investigate the additive manufacturing of NiTi shape memory alloys, which is associated with direct processes, such as selective laser melting. In addition to its expensive production costs, NiTi readily undergoes chemical and phase modifications, mainly as a result of Ni loss during processing as a result of high temperatures. This research explores the potential usefulness of NiTi as well as its limitations using indirect additive processes, such as fused filament fabrication (FFF). The first step was to evaluate the NiTi critical powder volume content (CPVC) needed to process high-quality filaments (via extrusion). A typical 3D printer can build a selected part/system/device layer-by-layer from the filaments, followed by debinding and sintering (SDS), in order to generate a near-net-shape object. The mixing, extruding (filament), printing (shaping), debinding, and sintering steps were extensively studied in order to optimize their parameters. Moreover, for the sintering step, two main targets should be met, namely: the reduction of contamination during the process in order to avoid the formation of secondary phases, and the decrease in sintering temperature, which also contributes to reducing the production costs. This study aims to demonstrate the possibility of using FFF as an additive manufacturing technology for processing NiTi.

scholarly journals A 3D weaving infill pattern for fused filament fabrication

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%.

scholarly journals Robotic additive manufacturing system for dynamic build orientations

2020 ◽  
Vol 26 (4) ◽  
pp. 659-667
Author(s):  
Nicholas R. Fry ◽  
Robert C. Richardson ◽  
Jordan H. Boyle
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Design Methodology ◽  
Degrees Of Freedom ◽  
Manufacturing System ◽  
Print Quality ◽  
Orientation Relationships ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Build Orientation

Purpose This paper aims to present a multi-axis additive robot manufacturing system (ARMS) and demonstrate its beneficial capabilities. Design/methodology/approach ARMS was constructed around two robot arms and a fused filament fabrication (FFF) extruder. Quantitative experiments are conducted to investigate the effect of printing at different orientations with respect to gravity, the effect of dynamically changing build orientation with respect to the build tray when printing overhanging features, the effect of printing curved parts using curved, conformal layers. These capabilities are combined to print an integrated demonstrator showing potential practical benefits of the system. Findings Orientation with respect to gravity has no effect on print quality; dynamically changing build orientation allows overhangs up to 90° to be cleanly printed without support structures; printing an arch with conformal layers significantly increases its strength compared to conventional printing. Research limitations/implications The challenge of automatic slicing algorithms has not been addressed for multi-axis printing. It is shown that ARMS could eventually enable printing of fully-functional prototypes with embedded components. Originality/value This work is the first to prove that the surface roughness of an FFF part is independent of print orientation with respect to gravity. The use of two arms creates a novel system with more degrees of freedom than existing multi-axis printers, enabling studies on printing orientation relationships and printing around inserts. It also adds to the emerging body of multi-axis literature by verifying that curved layers improve the strength of an arch which is steeply curved and printed with the nozzle remaining normal to the curvature.

Dynamic Mechanical Analysis of ABS From Hybrid Additive Manufacturing by Fused Filament Fabrication and Shot Peening

2020 ◽  
Author(s):  
Haitham Hadidi ◽  
Brady Mailand ◽  
Tayler Sundermann ◽  
Ethan Johnson ◽  
Rakeshkumar Karunakaran ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Dynamic Mechanical Analysis ◽  
Shot Peening ◽  
Extrusion Process ◽  
Dynamic Mechanical Properties ◽  
Mechanical Analysis ◽  
Layer By Layer ◽  
Fused Filament Fabrication ◽  
Dynamic Mechanical

Abstract The mechanical properties of 3D printed polymers parts are process parameter dependent. Defects such as inadvertent voids between deposited rasters and layers lead to weakness in produced parts, which results in inferior mechanical properties as compared to injection molding. An alternative method to change energy absorption and stiffness of a polymer is hybrid additive manufacturing (AM). Hybrid-AM is the use of additive manufacturing with one or more secondary processes that are fully coupled and synergistically affect part quality, functionality, and/or process performance. In this study, fused filament fabrication (FFF) was coupled with layer-by-layer shot peening to study the dynamic mechanical properties of ABS 430 polymer using dynamic mechanical analysis (DMA). FFF is a heated extrusion process. Shot peening is a mechanical surface treatment that impinges a target with a stochastically dispersed, high velocity stream of beads. Compressive residual stress was imparted to preferential layer intervals during printing to modify the elasticity (stiffness), viscosity, toughness, and glass transition temperature. Viscoelastic and dynamic mechanical properties are important to the performance of polymers in automotive, aerospace, electronics, and medical components. Coupling printing and peening increased the storage and loss moduli as well as the tangent delta. DMA results suggest that preferential layer sequences exist that possess higher elasticity and better absorb energy upon sinusoidal dynamic loading.

Evaluation of the printing strategies design on the mechanical and tribological response of acrylonitrile styrene acrylate (ASA) additive manufacturing parts

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Juan Manuel Vázquez Martínez ◽  
David Piñero Vega ◽  
Jorge Salguero ◽  
Moises Batista
Keyword(s):  
Additive Manufacturing ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Mechanical Behavior ◽  
Layer Thickness ◽  
Fused Filament Fabrication ◽  
Friction Forces ◽  
Content Type ◽  
Printing Parameters ◽  
Manufacturing Parameters

Purpose The evaluation of novel materials such as the acrylonitrile styrene acrylate (ASA) for tribological and mechanical conditions can provide a structural protection against the environmental and wear effects that results in the long-term integrity of the 3 D printed parts. Results of the experimental stage are intended to identify the influence of the printing conditions on the functional characteristics of ASA parts that results in variations of the friction coefficient, wear rate and tensile response. In addition, this study aims to highlight the relevance of printing parameters to avoid the use of chemical post-processing stages, increasing the performance and sustainability of the process. Design/methodology/approach In this research, an evaluation of the influence of printing parameters of layer thickness and temperature on the mechanical and tribological response have been carried out for ASA specimens manufactured by fused filament fabrication technology. For this purpose, a range of three different values of thickness of fused layer and three different printing temperatures were combined in the manufacturing process of tests samples. Mechanical behavior of the printed parts was evaluated by standard tensile tests, and friction forces were measured by pin-on-disk tribological tests against steel spheres. Findings Higher layer thickness of the printed parts shows lower resistance to tribological wear effects; in terms of friction coefficient and wear rate, this type of parts also presents lower tensile strength. It has been detected that mechanical and tribological behavior is highly related to the micro-geometrical characteristics of the printed surfaces, which can be controlled by the manufacturing parameters. Under this consideration, a reduction in the coefficient of friction near to 65% in the average value was obtained through the variation of the layer thickness of printed surfaces. Originality/value This research aims to fill a gap in the scientific literature about the use of specific additive manufacturing materials under dynamic contact. This paper is mainly focused on the influence of the manufacturing parameters on the tribological and mechanical behavior of a weather resistant polymer (ASA).

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

2015 ◽  
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.

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

Materials ◽  
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.

scholarly journals Influence of FFF process parameters and macrostructure homogeneity on PLA impact strength

Polimery ◽  
2021 ◽  
Vol 66 (9) ◽  
Author(s):  
Michał Bączkowski ◽  
Dawid Marciniak ◽  
Marek Bieliński
Keyword(s):  
Image Analysis ◽  
Additive Manufacturing ◽  
Impact Strength ◽  
Cross Section ◽  
Process Parameters ◽  
Optical Microscope ◽  
Process Variables ◽  
Fused Filament Fabrication ◽  
The Impact ◽  
Printing Parameters

The article presents studies of the additive manufacturing printing parameters influence onthe impact strength of PLA samples obtained by the fused filament fabrication (FFF) method. Two processvariables were taken into account in the research program: the height of the printed layer andthe printing temperature. An optical microscope was used to analyze the cross-section image (breakthrough)of the samples. The impact strength was determined at −40°C and 23°C. Selected geometricfeatures of the macrostructure (uniformity and thickness of individual layers, voids) determined on thebasis of the sample cross-section image analysis, enhanced the possibility of assessing the PLA impactstrength, depending on the adopted process variables and the temperature at which the experiment wascarried out.

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