Research on Curved Layer Fused Deposition Modeling (CLFDM) With Variable Extruded Filament (VEF)

Author(s):  
Donghua Zhao ◽  
Weizhong Guo

Fused Deposition Modeling (FDM), an Additive Manufacturing (AM) technique, is widely used due to its low-cost and open source. Geometry accuracy and strength performance of the printed parts are closely related to inter-layer bonding between adjacent layers and inter-road bonding in the layer. Because of the limit of layer-based AM, the longitudinal tensile strength of the filaments is much higher than the bonding strength between adjacent filaments, which brings anisotropy of the printed part. While CLFDM is devoted to solve this problem and obtain better geometry accuracy and meanwhile decrease build time by virtue of high continuity of filament, reduced stair-step effect, and lesser number of layers, especially when manufacturing thin and curved parts (shells). However, to the best of our knowledge in the aspects of process modeling of CLFDM, available researches focus mainly on simple curved layer, instead of more intricate ones possessing tiny features, which are more common in manufacturing. Therefore, to realize Solid Freeform Fabrication (SFF), this paper researches CLFDM with VEF (simultaneously changing the direction and the dimension of extruded filament according to manufacturing demand of the curved layer), which would be a fundamental study and a foundation for Advanced Design for Additive Manufacturing (ADFAM), slicing and path planning (extruder path generation) in 3D space. To realize slicing and printing with homogeneous and inhomogeneous extruded filament between consecutive layers and within the layer (flat or curved), models of flat layer FDM and CLFDM with VEF are respectively established. Then, the relationships among key process parameters are analyzed. Finally, graphical simulation of the proposed strategy based on a vase is provided to verify its effectiveness and advantages from a theoretical point of view. In general, variable direction of extruded filament along tangential directions of part surface imparts smoother surfaces, instead of rough exterior appearance resulting from stair-step effects. And variable dimension of extruded filament maximizes material extruded to increase build speed wherever allowed and minimizes deposition size for resolution whenever needed, resulting in curved layer surfaces with uneven layer thickness and having tiny features.

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1946 ◽  
Author(s):  
Héctor García-Martínez ◽  
Ernesto Ávila-Navarro ◽  
Germán Torregrosa-Penalva ◽  
Alberto Rodríguez-Martínez ◽  
Carolina Blanco-Angulo ◽  
...  

This work presents a study on the implementation and manufacturing of low-cost microwave electronic circuits, made with additive manufacturing techniques using fused deposition modeling (FDM) technology. First, the manufacturing process of substrates with different filaments, using various options offered by additive techniques in the manufacture of 3D printing parts, is described. The implemented substrates are structurally analyzed by ultrasound techniques to verify the correct metallization and fabrication of the substrate, and the characterization of the electrical properties in the microwave frequency range of each filament is performed. Finally, standard and novel microwave filters in microstrip and stripline technology are implemented, making use of the possibilities offered by additive techniques in the manufacturing process. The designed devices were manufactured and measured with good results, which demonstrates the possibility of using low-cost 3D printers in the design process of planar microwave circuits.


Author(s):  
Xuan Song ◽  
Yayue Pan ◽  
Yong Chen

Most additive manufacturing (AM) processes are layer-based with three linear motions in the X, Y, and Z axes. However, there are drawbacks associated with such limited motions, e.g., nonconformal material properties, stair-stepping effect, and limitations on building-around-inserts. Such drawbacks will limit AM to be used in more general applications. To enable 6-axis motions between a tool and a work piece, we investigated a Stewart mechanism and the feasibility of developing a low-cost 3D printer for the multidirectional fused deposition modeling (FDM) process. The technical challenges in developing such an AM system are discussed including the hardware design, motion planning and modeling, platform constraint checking, tool motion simulation, and platform calibration. Several test cases are performed to illustrate the capability of the developed multidirectional AM system. A discussion of future development on multidirectional AM systems is also given.


Author(s):  
Scott Hill ◽  
Stephen Canfield

There is a significant rise in the design of robots performing ever-more complicated tasks. This has motivated more-anthropomorphic grasping hands for these robots. These hands or grippers are complex machines requiring numerous joints to provide high mobility within a relatively small device. Compliant mechanisms and grippers based on compliant joints provide a viable approach to design improved grippers. The use of compliant joints in the design of a hand yields a number of features that can potentially benefit the design; it allows for more lifelike mobility and can eliminate the need for traditional bearings that yield high contact stresses. This allows for much more variety in material choices. The freedom of choosing from a wider range of materials provides many benefits. For example, plastics can provide softer finger members, improved gripping characteristics and components that are less stiff, making them inherently safer for systems that operate in proximity to people. They can provide the flexibility to more naturally conform to the contour of a particular object when grasping it and reduce the necessary gripping forces to achieve reliable operation. Additionally, a solid-state design compliant mechanism design allows more freedom in designing mechanisms that will be constructed for high mobility and operating in a small space. This approach is further enhanced by the increased availability of additive manufacturing tools that enables ready implementation of compliant mechanism designs with almost any topology. This paper will examine the application additive manufacturing tools to create an anthropomorphic gripper based on compliant mechanism components. The primary contribution of this paper is the empirical evaluation of a set of compliant joints for use as the fingers in an anthropomorphic robotic hand produced using additive manufacturing. Three compliant joints will be considered: the simple straight-axis flexural pivot, cross-axis flexural pivot, and leaf-type isosceles-trapezoidal flexural pivot. Each joint type has demonstrated characteristics that may be suitable for fingers in gripping mechanism and are readily suited to be manufactured using low-cost fused deposition modeling techniques that allow for quick and low-cost production. Further, three materials are evaluated for application as the build material of each compliant joint individually and as a complete solid-state anthropomorphic gripper. These materials are: acrylonitrile butadiene styrene (ABS), Nylon 6, and thermoplastic polyurethane (TPU). Each joint and each material option is compared on the basis of their feasibility for rapid prototyping and suitability for substitution of the interphalangeal joints of the human hand. Deflection tests and finite element analysis are used to gather the empirical data for comparison. An evaluation of the tests is provided to determine which compliant joints are well suited for this application. The paper will also consider the as-built material characteristics relative to their application as gripper elements and will compare and contrast the suitability and any impact on the empirical testing and design. This work will provide information on the combination of joint topology, material and manufacturing processes and can be used to inform the design of soft or highly compliant mechanisms.


Author(s):  
Donghua Zhao ◽  
Weizhong Guo ◽  
Feng Gao

Abstract The process of layered additive manufacturing (AM) limits manufactured parts, which leads to the stair-step error, support structures and the anisotropy. Curved layer fused deposition modeling (CLFDM) has been proposed by researchers to alleviate these problems. However, to the best of our knowledge, available CLFDM mainly focuses on filling with the uniform extruded filament in the same layer. While intricate parts usually possess small and critical features, as well as manufacturing error and assembling error. Geometry accuracy and mechanical property of fused deposition modeling (FDM) parts are closely related to interlayer and interroad bonding. Therefore, inspired by nonuniform layers of the onion, this paper pays attention to CLFDM with variable extruded filament (VEF) in the layer and between adjacent layers innovatively, whereby the direction and the dimension of the extruded filament are variable. The literature review of slicing and path planning is given first to make readers better understand the current status and the research gap to highlight the innovation of this paper. Then, flat layer FDM and CLFDM with VEF are modeled, respectively, from the aspect of interlayer and interroad bonding. After that, the relationships among key process parameters are analyzed. Finally, the simulation is provided to verify the effectiveness and advantages of our method from a theoretical point of view. Generally, this research can be a foundation for CLFDM with VEF, and the preliminary research has shown broad applications.


2019 ◽  
Vol 894 ◽  
pp. 9-14
Author(s):  
Yu Wen Tseng ◽  
Chao Yaug Liao ◽  
Idram Irwansyah ◽  
Jiing Yih Lai

This study proposes a design process for printable bone models featuring fracture lines. The bone model was printed using a low-cost dual-head FDM (Fused Deposition Modeling) machine. Two different colors were used to identify the bone model and the fracture lines. Real bone model fractures with fracture lines were prepared and printed to verify the feasibility of the proposed method.


2019 ◽  
Vol 25 (11) ◽  
pp. 1249-1264 ◽  
Author(s):  
Amoljit Singh Gill ◽  
Parneet Kaur Deol ◽  
Indu Pal Kaur

Background: Solid free forming (SFF) technique also called additive manufacturing process is immensely popular for biofabrication owing to its high accuracy, precision and reproducibility. Method: SFF techniques like stereolithography, selective laser sintering, fused deposition modeling, extrusion printing, and inkjet printing create three dimension (3D) structures by layer by layer processing of the material. To achieve desirable results, selection of the appropriate technique is an important aspect and it is based on the nature of biomaterial or bioink to be processed. Result & Conclusion: Alginate is a commonly employed bioink in biofabrication process, attributable to its nontoxic, biodegradable and biocompatible nature; low cost; and tendency to form hydrogel under mild conditions. Furthermore, control on its rheological properties like viscosity and shear thinning, makes this natural anionic polymer an appropriate candidate for many of the SFF techniques. It is endeavoured in the present review to highlight the status of alginate as bioink in various SFF techniques.


Author(s):  
Arash Alex Mazhari ◽  
Randall Ticknor ◽  
Sean Swei ◽  
Stanley Krzesniak ◽  
Mircea Teodorescu

AbstractThe sensitivity of additive manufacturing (AM) to the variability of feedstock quality, machine calibration, and accuracy drives the need for frequent characterization of fabricated objects for a robust material process. The constant testing is fiscally and logistically intensive, often requiring coupons that are manufactured and tested in independent facilities. As a step toward integrating testing and characterization into the AM process while reducing cost, we propose the automated testing and characterization of AM (ATCAM). ATCAM is configured for fused deposition modeling (FDM) and introduces the concept of dynamic coupons to generate large quantities of basic AM samples. An in situ actuator is printed on the build surface to deploy coupons through impact, which is sensed by a load cell system utilizing machine learning (ML) to correlate AM data. We test ATCAM’s ability to distinguish the quality of three PLA feedstock at differing price points by generating and comparing 3000 dynamic coupons in 10 repetitions of 100 coupon cycles per material. ATCAM correlated the quality of each feedstock and visualized fatigue of in situ actuators over each testing cycle. Three ML algorithms were then compared, with Gradient Boost regression demonstrating a 71% correlation of dynamic coupons to their parent feedstock and provided confidence for the quality of AM data ATCAM generates.


2018 ◽  
Vol 8 (8) ◽  
pp. 1275 ◽  
Author(s):  
Kai von Petersdorff-Campen ◽  
Yannick Hauswirth ◽  
Julia Carpenter ◽  
Andreas Hagmann ◽  
Stefan Boës ◽  
...  

Conventional magnet manufacturing is a significant bottleneck in the development processes of products that use magnets, because every design adaption requires production steps with long lead times. Additive manufacturing of magnetic components delivers the opportunity to shift to agile and test-driven development in early prototyping stages, as well as new possibilities for complex designs. In an effort to simplify integration of magnetic components, the current work presents a method to directly print polymer-bonded hard magnets of arbitrary shape into thermoplastic parts by fused deposition modeling. This method was applied to an early prototype design of a rotary blood pump with magnetic bearing and magnetic drive coupling. Thermoplastics were compounded with 56 vol.% isotropic NdFeB powder to manufacture printable filament. With a powder loading of 56 vol.%, remanences of 350 mT and adequate mechanical flexibility for robust processability were achieved. This compound allowed us to print a prototype of a turbodynamic pump with integrated magnets in the impeller and housing in one piece on a low-cost, end-user 3D printer. Then, the magnetic components in the printed pump were fully magnetized in a pulsed Bitter coil. The pump impeller is driven by magnetic coupling to non-printed permanent magnets rotated by a brushless DC motor, resulting in a flow rate of 3 L/min at 1000 rpm. For the first time, an application of combined multi-material and magnet printing by fused deposition modeling was shown. The presented process significantly simplifies the prototyping of products that use magnets, such as rotary blood pumps, and opens the door for more complex and innovative designs. It will also help postpone the shift to conventional manufacturing methods to later phases of the development process.


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