Predicting the effect of build orientation and process temperatures on the performance of parts made by fused filament fabrication

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fernando Moura Duarte ◽  
José António Covas ◽  
Sidonie Fernandes da Costa
Keyword(s):  
Molecular Diffusion ◽  
Operating Conditions ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Build Orientation ◽  
Thermal Boundary Conditions ◽  
Chamber Temperature ◽  
3D Printed ◽  
Time Required

Purpose The performance of the parts obtained by fused filament fabrication (FFF) is strongly dependent on the extent of bonding between adjacent filaments developing during the deposition stage. Bonding depends on the properties of the polymer material and is controlled by the temperature of the filaments when they come into contact, as well as by the time required for molecular diffusion. In turn, the temperature of the filaments is influenced by the set of operating conditions being used for printing. This paper aims at predicting the degree of bonding of realistic 3D printed parts, taking into consideration the various contacts arising during its fabrication, and the printing conditions selected. Design/methodology/approach A computational thermal model of filament cooling and bonding that was previously developed by the authors is extended here, to be able to predict the influence of the build orientation of 3D printed parts on bonding. The quality of a part taken as a case study is then assessed in terms of the degree of bonding, i.e. the percentage of volume exhibiting satisfactory bonding between contiguous filaments. Findings The complexity of the heat transfer arising from the changes in the thermal boundary conditions during deposition and cooling is well demonstrated for a case study involving a realistic 3D part. Both extrusion and build chamber temperature are major process parameters. Originality/value The results obtained can be used as practical guidance towards defining printing strategies for 3D printing using FFF. Also, the model developed could be directly applied for the selection of adequate printing conditions.

scholarly journals Experimental and numerical investigations on heat transfer in fused filament fabrication 3D-printed specimens

2021 ◽  
Author(s):  
Nathalie Ramos ◽  
Christoph Mittermeier ◽  
Josef Kiendl
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer Coefficient ◽  
Numerical Data ◽  
Fused Filament Fabrication ◽  
Thermal Boundary Conditions ◽  
Thermal Measurements ◽  
Stress Prediction ◽  
3D Printed ◽  
Air Void

AbstractA good understanding of the heat transfer in fused filament fabrication is crucial for an accurate stress prediction and subsequently for repetitive, high-quality printing. This work focuses on two challenges that have been presented when it comes to the accuracy and efficiency in simulating the heat transfer in the fused filament fabrication process. With the prospect of choosing correct thermal boundary conditions expressing the natural convection between printed material and its environment, values for the convective heat transfer coefficient and ambient temperature were calibrated through numerical data fitting of experimental thermal measurements. Furthermore, modeling simplifications were proposed for an efficient numerical discretization of infill structures. Samples were printed with varying infill characteristics, such as varying air void size, infill densities and infill patterns. Thermal measurements were performed to investigate the role of these parameters on the heat transfer and based on these observations, possible modeling simplifications were studied in the numerical simulations.

Temperature-compensated constitutive model of fused filament fabrication 3D printed PLA materials with full extrusion temperatures

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kaiyang Zhu ◽  
Zichen Deng ◽  
Shi Dai ◽  
Yajun Yu
Keyword(s):  
Mechanical Properties ◽  
Thermal Decomposition ◽  
Constitutive Model ◽  
Polylactic Acid ◽  
Extrusion Temperature ◽  
Fused Filament Fabrication ◽  
Printing Process ◽  
Content Type ◽  
3D Printed ◽  
Interlayer Bonding

Purpose This study aims to focus on the effect of interlayer bonding and thermal decomposition on the mechanical properties of fused filament fabrication-printed polylactic acid specimens at high extrusion temperatures. Design/methodology/approach A printing process, that is simultaneous manufacturing of contour and specimen, is used to improve the printing accuracy at high extrusion temperatures. The effects of the extrusion temperature on the mechanical properties of the interlayer and intra-layer are evaluated via tensile experiments. In addition, the microstructure evolution affected by the extrusion temperature is observed using scanning electron microscopy. Findings The results show that the extrusion temperature can effectively improve the interlayer bonding property; however, the mechanical properties of the specimen for extrusion temperatures higher than 270°C may worsen owing to the thermal decomposition of the polylactic acid (PLA) material. The optimum extrusion temperature of PLA material in the three-dimensional (3D) printing process is recommended to be 250–270°C. Originality/value A temperature-compensated constitutive model for 3D printed PLA material under different extrusion temperatures is proposed. The present work facilitates the prediction of the mechanical properties of specimens at an extrusion temperature for different printing temperatures and different layers.

Additive manufacturing of 316L stainless-steel structures using fused filament fabrication technology: mechanical and geometric properties

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Miguel Ángel Caminero ◽  
Ana Romero ◽  
Jesús Miguel Chacón ◽  
Pedro José Núñez ◽  
Eustaquio García-Plaza ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
Austenitic Stainless Steel ◽  
Material Properties ◽  
Steel Structures ◽  
Fused Filament Fabrication ◽  
Geometric Properties ◽  
Content Type ◽  
Build Orientation ◽  
Manufacturing Alternatives

Purpose Fused filament fabrication (FFF) technique using metal filled filaments in combination with debinding and sintering steps can be a cost-effective alternative for laser-based powder bed fusion processes. The mechanical behaviour of FFF-metal materials is highly dependent on the processing parameters, filament quality and adjusted post-processing steps. In addition, the microstructural material properties and geometric characteristics are inherent to the manufacturing process. The purpose of this study is to characterize the mechanical and geometric performance of three-dimensional (3-D) printed FFF 316 L metal components manufactured by a low-cost desktop 3-D printer. The debinding and sintering processes are carried out using the BASF catalytic debinding process in combination with the BASF 316LX Ultrafuse filament. Special attention is paid on the effects of build orientation and printing strategy of the FFF-based technology on the tensile and geometric performance of the 3-D printed 316 L metal specimens. Design/methodology/approach This study uses a toolset of experimental analysis techniques [metallography and scanning electron microcope (SEM)] to characterize the effect of microstructure and defects on the material properties under tensile testing. Shrinkage and the resulting porosity of the 3-D printed 316 L stainless steel sintered samples are also analysed. The deformation behaviour is investigated for three different build orientations. The tensile test curves are further correlated with the damage surface using SEM images and metallographic sections to present grain deformation during the loading progress. Mechanical properties are directly compared to other works in the field and similar additive manufacturing (AM) and Metal Injection Moulding (MIM) manufacturing alternatives from the literature. Findings It has been shown that the effect of build orientation was of particular significance on the mechanical and geometric performance of FFF-metal 3-D printed samples. In particular, Flat and On-edge samples showed an average increase in tensile performance of 21.7% for the tensile strength, 65.1% for the tensile stiffness and 118.3% for maximum elongation at fracture compared to the Upright samples. Furthermore, it has been able to manufacture near-dense 316 L austenitic stainless steel components using FFF. These properties are comparable to those obtained by other metal conventional processes such as MIM process. Originality/value 316L austenitic stainless steel components using FFF technology with a porosity lower than 2% were successfully manufactured. The presented study provides more information regarding the dependence of the mechanical, microstructural and geometric properties of FFF 316 L components on the build orientation and printing strategy.

Stiffness prediction of 3D printed fiber-reinforced thermoplastic composites

2019 ◽  
Vol 26 (3) ◽  
pp. 549-555
Author(s):  
Jin Young Choi ◽  
Mark Timothy Kortschot
Keyword(s):  
Mechanical Properties ◽  
Extrusion Direction ◽  
Analytical Models ◽  
Thermoplastic Composites ◽  
Fiber Reinforced ◽  
Flat Plates ◽  
Fused Filament Fabrication ◽  
Element Analysis ◽  
Content Type ◽  
3D Printed

Purpose The purpose of this study is to confirm that the stiffness of fused filament fabrication (FFF) three-dimensionally (3D) printed fiber-reinforced thermoplastic (FRP) materials can be predicted using classical laminate theory (CLT), and to subsequently use the model to demonstrate its potential to improve the mechanical properties of FFF 3D printed parts intended for load-bearing applications. Design/methodology/approach The porosity and the fiber orientation in specimens printed with carbon fiber reinforced filament were calculated from micro-computed tomography (µCT) images. The infill portion of the sample was modeled using CLT, while the perimeter contour portion was modeled with a rule of mixtures (ROM) approach. Findings The µCT scan images showed that a low porosity of 0.7 ± 0.1% was achieved, and the fibers were highly oriented in the filament extrusion direction. CLT and ROM were effective analytical models to predict the elastic modulus and Poisson’s ratio of FFF 3D printed FRP laminates. Research limitations/implications In this study, the CLT model was only used to predict the properties of flat plates. Once the in-plane properties are known, however, they can be used in a finite element analysis to predict the behavior of plate and shell structures. Practical implications By controlling the raster orientation, the mechanical properties of a FFF part can be optimized for the intended application. Originality/value Before this study, CLT had not been validated for FFF 3D printed FRPs. CLT can be used to help designers tailor the raster pattern of each layer for specific stiffness requirements.

3D printing for chest wall reconstructive surgery

2020 ◽  
Vol 26 (7) ◽  
pp. 1217-1225
Author(s):  
Ranjeet Agarwala ◽  
Carlos J. Anciano ◽  
Joshua Stevens ◽  
Robert Allen Chin ◽  
Preston Sparks
Keyword(s):  
3D Printing ◽  
Chest Wall ◽  
Reconstructive Surgery ◽  
3D Model ◽  
Titanium Plate ◽  
Specific Patient ◽  
Content Type ◽  
3D Printed ◽  
Wall Construction

Purpose The purpose of the paper was to present a specific case study of how 3D printing was introduced in the chest wall construction process of a specific patient with unique medical condition. A life-size 3D model of the patient’s chest wall was 3D printed for pre-surgical planning. The intent was to eliminate the need for operative exposure to map the pathological area. The model was used for preoperative visualization and formation of a 1-mm thick titanium plate implant, which was placed in the patient during chest wall reconstructive surgery. The purpose of the surgery was to relive debilitating chronic pain due to right scapular entrapment. Design/methodology/approach The patient was born with a twisted spine. Over time, it progressed to severe and debilitating scoliosis, which required the use of a thoracic brace. Computerized tomography (CT) data were converted to a 3D printed model. The model was used to size and form a 1-mm thick titanium plate implant. It was also used to determine the ideal location for placement of the plate during thoracotomy preoperatively. Findings The surgery, aided by the model, was successful and resulted in a significantly smaller incision. The techniques reduced invasiveness and enabled the doctors to conduct the procedure efficiently and decreased surgery time. The patient experienced relief of the chronic debilitating pain and no longer need the thoracic brace. Originality/value The 3D model facilitated pre-operative planning and modeling of the implant. It also enabled accurate incision locations of the thoracotomy site and placement of the implant. Although chest wall reconstruction surgeries have been undertaken, this paper documents a specific case study of chest wall construction fora specific patient with unique pathological conditions.

M-Pesa: an evolution in organisational strategy

2015 ◽  
Vol 5 (8) ◽  
pp. 1-11
Author(s):  
Mariam Cassim ◽  
Linda Ronnie
Keyword(s):  
Change Management ◽  
Business Model ◽  
Financial Services ◽  
Critical Role ◽  
Business Environment ◽  
Subject Area ◽  
Operating Conditions ◽  
Content Type ◽  
Successful Business

Subject area Change Management. Study level/applicability Postgraduate business courses, including MBA courses in change management and human resource management. Case overview This case study emphasises how important it is for organisations operating in today's turbulent and rapidly changing business environment to have an emergent approach to change. It focuses on the dilemmas faced by Hemmanth Singh, the newly appointed Managing Executive responsible for Mobile Commerce at Vodacom South Africa. Singh is responsible for the execution of the new strategy into financial services, the relaunch of M-Pesa into the South African market being the immediate task. The case sets the context for the relaunch of M-Pesa, and the reader is introduced to some of the limitations and challenges experienced by the company when trying to replicate a successful business model from one market to another, especially after an unsuccessful initial launch. Expected learning outcomes After reading and analysing the information contained in the case study and appendices, students should be able to evaluate the critical role that leadership needs to play when introducing and implementing a change initiative at an organisation that is stimulated by evolving external market conditions; understand the importance of adopting an emergent approach to change in current operating conditions; identify the factors that contribute to or hinder the creation and sustainability of an adaptive culture within an organisation; and appreciate the challenges of attempting to replicate a successful business model from one market into another. Supplementary materials Teaching Notes are available for educators only. Please contact your library to gain login details or email [email protected] to request teaching notes.

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.

On the build orientation effect in as-printed and as-sintered bending properties of 17-4PH alloy fabricated by metal fused filament fabrication

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chanun Suwanpreecha ◽  
Anchalee Manonukul
Keyword(s):  
Design Methodology ◽  
Bending Strength ◽  
Low Cost ◽  
Bending Properties ◽  
Fused Filament Fabrication ◽  
Flexural Mode ◽  
Content Type ◽  
Edge Orientation ◽  
Build Orientation ◽  
Bending Strain

Purpose The purpose of this paper is to systematically investigate the influence of build orientation on the anisotropic as-printed and as-sintered bending properties of 17-4PH stainless steel fabricated by metal fused filament fabrication (MFFF). Design/methodology/approach The bending properties of 17-4PH alloy fabricated by low-cost additive manufacturing (MFFF) using three build orientations (the Flat, On-edge and Upright orientations) are examined at both as-printed and as-sintered states. Findings Unlike tensile testing where the Flat and On-edge orientations provide similar as-sintered tensile properties, the On-edge orientation produces a significantly higher bending strain with a lower bending strength than the Flat orientation. This arises from the printed layer sliding due to the Poisson's effect, which is only observed in the On-edge orientation together with the alternated layers of highly deformed and shifted voids. The bending properties show that the Upright orientation exhibits the lowest bending properties and limited plasticity due to the layer delamination. Originality/value This study is the first work to study the effect of build orientation on the flexural properties for MFFF. This work gives insight information into anisotropy in flexural mode for MFFF part design.

Co-delivered and co-produced: creating a recovery college in partnership

2014 ◽  
Vol 9 (1) ◽  
pp. 16-25 ◽  
Author(s):  
Sara Meddings ◽  
Diana Byrne ◽  
Su Barnicoat ◽  
Emogen Campbell ◽  
Lucy Locks
Keyword(s):  
Design Methodology ◽  
Shared Vision ◽  
Training Curriculum ◽  
Additional Time ◽  
Content Type ◽  
Time Required ◽  
Partnership Approach ◽  
Organisational Cultures ◽  
And Training

Purpose – The purpose of this paper is to explore the process of using a co-production partnership approach in the development of a Recovery College pilot. Design/methodology/approach – This is a case study of the co-production process, using action research to learn from ongoing reflection, mid-project review and feedback questionnaires. Findings – The partnership process is an integral and valued aspect of the Recovery College. Challenges include different organisational cultures and processes and the additional time required. Mutual respect, appreciation of different expertise, communication, a shared vision and development plan have been key to success. The paper focused on governance and fidelity; recruitment and training; curriculum development and evaluation. People are enthusiastic and motivated. Co-production and equal partnership are a valuable approach to developing a Recovery College. Originality/value – At present many regions are developing Recovery Colleges. This paper describes one approach and shows that co-production is valuable to the process of developing a Recovery College.

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