A Rapid Manufacturing Process for Extrusion-Based 3D Printers

2019 ◽  
Author(s):  
Andreas Schroeffer ◽  
Matthias Trescher ◽  
Konstantin Struebig ◽  
Yannik Krieger ◽  
Tim C. Lueth
Keyword(s):  
Tensile Strength ◽  
Additive Manufacturing ◽  
Injection Molding ◽  
Manufacturing Process ◽  
Polymer Melt ◽  
Dimensional Accuracy ◽  
Casting Process ◽  
Extrusion Process ◽  
Mechanical Component ◽  
Plastic Parts

Abstract The generation of plastic parts in small volume batches has an enormous economic significance. Application fields for parts in small lot sizes are the fabrication of prototypes in the design process or individualized products. The goal thereby often is not only to produce show objects, but functional parts with specific materials, high dimensional accuracy and proper mechanical properties in a short amount of time. The conventional way to produce thermoplastic plastic parts is given by injection molding and extrusion. Characteristics for this technology are the resulting good and homogeneous mechanical component properties, but shape freedom is limited and the process is time consumptive because an individual tool is needed for each product. Depending on the design of the part the geometry of the tool can be complex and an iterative process is necessary to create a suitable mold. On the other hand, the technology of additive manufacturing is a growing market for the quick and cheap production of parts as prototypes, but still the range of materials is limited and anisotropic mechanical component properties are ongoing problems. The combination of both technologies is known as rapid tooling, where the mold is produced in an additive manufacturing process and then used in an injection molding or casting process. This approach combines the benefits of both technologies in term of time and cost efficiency and good component properties. Problems here are the combination of different materials for mold and component and the missing process knowledge and automatization. In this paper an extrusion-based additive manufacturing technology is used to combine additive manufacturing and injection infill generation for thermoplast in one process. The proposed working principle is to generate the outer contour of the part by filament extrusion as mold to ensure high accuracy and good surface quality and fill the mold using an extrusion process of polymer melt without filament generation. Accordingly, the mold becomes part of the component and the same material can be used for the mold and the infill. Since the viscosity of most thermoplastic polymer melts is too high to fill big structures and undercuts, an algorithm is proposed to generate a chamber structure inside the part. Consequently, the fabrication process consists of several iterative cycles of mold generation and injection processes. For this paper polyamide 6 is used to demonstrate the process. Experiments were performed to find the optimal chamber geometry and size to avoid holes and generate a high quality infill. Several component properties such as density, tensile strength and fabrication time are analyzed. In spite of still existing blowholes, a higher component density could be achieved with the proposed process compared to additive manufacturing. However, the tensile strength is still significantly lower. The failures appeared at the weld lines, where warm polymer melt was injected to already colder chambers below. Still manual processes are sources of possible defects as well. The integration of a RFID chip is shown as an additional feature of the process of easy integration of passive electronic elements.

A High-Fidelity Thermal Model for a Novel Droplet-Based Additive Manufacturing Process for Polymers

2019 ◽  
Author(s):  
Andreas Schroeffer ◽  
Thomas Maciuga ◽  
Konstantin Struebig ◽  
Tim C. Lueth
Keyword(s):  
Heat Transfer ◽  
Additive Manufacturing ◽  
Manufacturing Process ◽  
Thermal Model ◽  
Polymer Melt ◽  
Dimensional Accuracy ◽  
Detailed Knowledge ◽  
Mechanical Component ◽  
Wide Range ◽  
Working Principle

Abstract The claim in additive manufacturing (AM) changes from simply producing prototypes as show objects to the fabrication of final parts and products in small volume batches. Thereby the focus is on freedom of material, dimensional accuracy and mechanical component properties. A novel extrusion-based AM technology has been developed focusing on these issues. The working principle is to form spheres from a thermoplastic polymer melt and build parts by single droplets. The material preprocessing is similar to the injection molding technology and enables a wide range of different thermoplastic polymers as build materials. With the droplet-based working principle high mechanical component properties and dimensional accuracy can be reached compared to similar processes. Further improvements to the process need a detailed knowledge of the physical effects during the build process. The temperature distribution during the manufacturing process determines at which temperature material is fused and how solidification takes place and shrinkage can occur or is suppressed. Thus, it has a significant influence on the mechanical properties and warpage effects of produced parts. In this work a thermal model is presented that describes the heat transfer during the build process. The necessary input data are the material properties and a print job description including the part geometry and building strategy. The basic idea is to simulate each single droplet deposition by applying a dynamic Finite Element Method. All relevant heat transfer effects are analyzed and represented in the model. The model was validated with measurements using a thermal imaging camera. Several measurements were performed during the build process and compared to the simulation results. A high accuracy could be reached with an average model error of about 4° Celsius and a maximal error of 10° Celsius.

Thermal, structural, and mechanical effects of nanofibrillated cellulose in polylactic acid filaments for additive manufacturing

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 7954-7964
Author(s):  
Diego Gomez-Maldonado ◽  
Maria Soledad Peresin ◽  
Christina Verdi ◽  
Guillermo Velarde ◽  
Daniel Saloni
Keyword(s):  
Tensile Strength ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Polylactic Acid ◽  
Modulus Of Elasticity ◽  
Manufacturing Process ◽  
Thermal Characterization ◽  
Nanofibrillated Cellulose ◽  
Small Decrease ◽  
The Matrix

As the additive manufacturing process gains worldwide importance, the need for bio-based materials, especially for in-home polymeric use, also increases. This work aims to develop a composite of polylactic acid (PLA) and nanofibrillated cellulose (NFC) as a sustainable approach to reinforce the currently commercially available PLA. The studied materials were composites with 5 and 10% NFC that were blended and extruded. Mechanical, structural, and thermal characterization was made before its use for 3D printing. It was found that the inclusion of 10% NFC increased the modulus of elasticity in the filaments from 2.92 to 3.36 GPa. However, a small decrease in tensile strength was observed from 55.7 to 50.8 MPa, which was possibly due to the formation of NFC aggregates in the matrix. This work shows the potential of using PLA mixed with NFC for additive manufacturing.

Additive manufacturing using fine wire-based laser metal deposition

2019 ◽  
Vol 26 (3) ◽  
pp. 473-483
Author(s):  
Muhammad Omar Shaikh ◽  
Ching-Chia Chen ◽  
Hua-Cheng Chiang ◽  
Ji-Rong Chen ◽  
Yi-Chin Chou ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Tensile Strength ◽  
Additive Manufacturing ◽  
High Precision ◽  
Surface Finish ◽  
Dimensional Accuracy ◽  
Laser Metal Deposition ◽  
Cross Sectional ◽  
Content Type ◽  
Fine Wire

Purpose Using wire as feedstock has several advantages for additive manufacturing (AM) of metal components, which include high deposition rates, efficient material use and low material costs. While the feasibility of wire-feed AM has been demonstrated, the accuracy and surface finish of the produced parts is generally lower than those obtained using powder-bed/-feed AM. The purpose of this study was to develop and investigate the feasibility of a fine wire-based laser metal deposition (FW-LMD) process for producing high-precision metal components with improved resolution, dimensional accuracy and surface finish. Design/methodology/approach The proposed FW-LMD AM process uses a fine stainless steel wire with a diameter of 100 µm as the additive material and a pulsed Nd:YAG laser as the heat source. The pulsed laser beam generates a melt pool on the substrate into which the fine wire is fed, and upon moving the X–Y stage, a single-pass weld bead is created during solidification that can be laterally and vertically stacked to create a 3D metal component. Process parameters including laser power, pulse duration and stage speed were optimized for the single-pass weld bead. The effect of lateral overlap was studied to ensure low surface roughness of the first layer onto which subsequent layers can be deposited. Multi-layer deposition was also performed and the resulting cross-sectional morphology, microhardness, phase formation, grain growth and tensile strength have been investigated. Findings An optimized lateral overlap of about 60-70% results in an average surface roughness of 8-16 µm along all printed directions of the X–Y stage. The single-layer thickness and dimensional accuracy of the proposed FW-LMD process was about 40-80 µm and ±30 µm, respectively. A dense cross-sectional morphology was observed for the multilayer stacking without any visible voids, pores or defects present between the layers. X-ray diffraction confirmed a majority austenite phase with small ferrite phase formation that occurs at the junction of the vertically stacked beads, as confirmed by the electron backscatter diffraction (EBSD) analysis. Tensile tests were performed and an ultimate tensile strength of about 700-750 MPa was observed for all samples. Furthermore, multilayer printing of different shapes with improved surface finish and thin-walled and inclined metal structures with a minimum achievable resolution of about 500 µm was presented. Originality/value To the best of the authors’ knowledge, this is the first study to report a directed energy deposition process using a fine metal wire with a diameter of 100 µm and can be a possible solution to improving surface finish and reducing the “stair-stepping” effect that is generally observed for wires with a larger diameter. The AM process proposed in this study can be an attractive alternative for 3D printing of high-precision metal components and can find application for rapid prototyping in a range of industries such as medical and automotive, among others.

Green Material for Fused Filament Fabrication

2020 ◽  
pp. 1-27 ◽  
Author(s):  
Mastura Mohammad Taha ◽  
Ridhwan Jumaidin ◽  
Nadlene M. Razali ◽  
Syahibudil Ikhwan Abdul Kudus
Keyword(s):  
Additive Manufacturing ◽  
Composite Materials ◽  
Manufacturing Process ◽  
Extrusion Process ◽  
Fused Filament Fabrication ◽  
Green Material ◽  
Additive Manufacturing Technology ◽  
Green Materials ◽  
Composites Materials ◽  
The Right

Fused filament fabrication (FFF) has been developed in additive manufacturing technology as a fast and simple manufacturing process in product design. Advantage of the process such as flexibility in terms of the materials employment has attracted many researchers to develop new materials for the feed stock filament in the heat extrusion process of FFF. Green materials or bio-composites materials have been found in FFF and successfully commercialized in the market. However, a deep research should have been performed prior the application because of the unique characteristics of the material itself. The challenge for the researchers to develop bio-composite materials as the filament in FFF technology is to determine the right composition of the composites with the right thermal, mechanical, and rheological properties. Therefore, in this study, a review has been conducted to highlight the important requirements of the process and materials. Green materials such as bio-composites have a great potential in the FFF technology and could improve the sustainability impact.

Product Strength and Orientation Manipulation via Vibration-Assisted Injection Molding

2002 ◽  
Author(s):  
David C. Angstadt ◽  
John P. Coulter
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Injection Molding ◽  
Molecular Orientation ◽  
Polymer Melt ◽  
Polymer Processing ◽  
Shear Yielding ◽  
Processing Methods ◽  
Improve Product

This investigation focuses on determining why polystyrene ASTM specimens exhibit an increase in tensile strength when processed by vibration assisted injection molding (VAIM) while polycarbonate parts do not. VAIM is one of several polymer processing methods that attempt to improve product properties via manipulation of the polymer melt. Observation of birefringence patterns in VAIM processed polystyrene samples show a significant impact on molecular orientation. The same studies were conducted on opaque polycarbonate and were unable to determine the degree of molecular orientation via birefringence measurement. It was theorized that VAIM did not produce significant orientation due to its higher thermal conductivity and stiffer backbone. It has been determined by this investigation that VAIM processing does impart significant molecular orientation in polycarbonate specimens but still does not increase its UTS. It is proposed that increased molecular orientation induced by VAIM processing inhibits crazes from growing into cracks. VAIM therefore favors polymers that fail by crazing (e.g., polystyrene) rather than those that fail by shear yielding (e.g., polycarbonate).

A method to improve dimensional accuracy and mechanical properties of injection molded polypropylene parts

2017 ◽  
Vol 37 (4) ◽  
pp. 323-334 ◽  
Author(s):  
Shuai Li ◽  
Guoqun Zhao ◽  
Jiachang Wang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Flexural Strength ◽  
Injection Molding ◽  
Weld Line ◽  
Dimensional Accuracy ◽  
Holding Time ◽  
Dimensional Shrinkage ◽  
Injection Molded ◽  
The Impact

Abstract Gas counter pressure (GCP) technology can impose a reverse pressure to melt and thereby effectively increase the pressure acting on the melt at flow front. Theoretically, it has a potential to solve some defects often occurring in conventional injection molding (CIM) process. This paper designed and manufactured a GCP injection mold. GCP injection molding experiments were conducted. Effects of GCP process on melt flow and density, dimensional accuracy, and mechanical properties of molded samples were investigated. The results showed that GCP process can effectively inhibit the “fountain effect” in melt filling process, decrease the dimensional shrinkage of molded samples, increase dimensional accuracy of samples, and effectively improve impact property of samples. For the samples without weld line, tensile strength and flexural strength of GCP injection molded samples are slightly increased in comparison with those of CIM samples, but for the samples with weld line, GCP process can greatly improve the tensile strength and flexural strength of molded samples. When GCP is 9 MPa and GCP holding time is 10 s, the dimensional accuracy of molded samples without weld line, the tensile strength and flexural strength of the molded samples with weld line all increase up to maximum values. In comparison with CIM samples, the dimensional shrinkage of samples without weld line decreases by 17.2%, the tensile strength and flexural strength of samples with weld line increase by 30.51% and 23.69%, respectively. The impact value of the samples molded by process parameter combination of GCP 9 MPa and GCP holding time 20 s is the highest, and the impact value increases by 18.65%.

scholarly journals Experimental Investigation on Mechanical Properties of Part Fabricated by Wire Arc Additive Manufacturing Process

2021 ◽  
Author(s):  
Vivek Kumar P ◽  
◽  
Soundrapandian E ◽  
Jenin Joseph A ◽  
Kanagarajan E ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Manufacturing Process ◽  
Three Dimensional ◽  
Casting Process ◽  
Significant Rise ◽  
Layer By Layer ◽  
Cnc Machine ◽  
Hardness Tester ◽  
Wire Arc Additive Manufacturing

Additive manufacturing process is a method of layer by layer joining of materials to create components from three-dimensional (3D) model data. After their introduction in the automotive sector a decade ago, it has seen a significant rise in research and growth. The Additive manufacturing is classified into different types based upon the energy source use in the fabrication process. In our project, we used self-build CNC machine that runs MACH3 software, as well as the MACH3 controller is used to control the welding torch motion for material addition through three axis movement (X, Y and Z). In the project we used ER70 S-6 weld wire for the fabrication and examined its microstructure and mechanical properties. Different layers of the specimen had different microstructures, according to microstructural studies of the product. Rockwell hardness tester used for testing hardness of the product. According to the observation of the part fabricated components using the Wire Arc Additive Manufacturing process outperformed the mechanical properties of mild steel casting process. The product fabricated by Wire Arc Additive Manufacturing process properties is superior to conventional casting process.

scholarly journals Laser-Facilitated Additive Manufacturing Enables Fabrication of Biocompatible Neural Devices

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6614
Author(s):  
Ailke Behrens ◽  
Jan Stieghorst ◽  
Theodor Doll ◽  
Ulrich P. Froriep
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing Process ◽  
Neurological Diseases ◽  
Extrusion Process ◽  
Neural Implants ◽  
Accelerated Curing ◽  
Minimal Structure ◽  
Thermal Crosslinking ◽  
Electrical Activities

Current personalized treatment of neurological diseases is limited by availability of appropriate manufacturing methods suitable for long term sensors for neural electrical activities in the brain. An additive manufacturing process for polymer-based biocompatible neural sensors for chronic application towards individualized implants is here presented. To process thermal crosslinking polymers, the developed extrusion process enables, in combination with an infrared (IR)-Laser, accelerated curing directly after passing the outlet of the nozzle. As a result, no additional curing steps are necessary during the build-up. Furthermore, the minimal structure size can be achieved using the laser and, in combination with the extrusion parameters, provide structural resolutions desired. Active implant components fabricated using biocompatible materials for both conductive pathways and insulating cladding keep their biocompatible properties even after the additive manufacturing process. In addition, first characterization of the electric properties in terms of impedance towards application in neural tissues are shown. The printing toolkit developed enables processing of low-viscous, flexible polymeric thermal curing materials for fabrication of individualized neural implants.

Numerical Simulation in a Multiple Flow Control Valve System of Polymer Melt During Injection Molding Processes

2005 ◽  
Author(s):  
Gregory S. Layser ◽  
John P. Coulter
Keyword(s):  
Injection Molding ◽  
Flow Control ◽  
Current System ◽  
Control Valve ◽  
Polymer Melt ◽  
Flow Control Valve ◽  
Flow Modulation ◽  
Valve System ◽  
Plastic Parts ◽  
Critical Process

Process control is an important factor for improving the performance and consistency of thermoplastic parts manufactured by injection molding processes. A critical process parameter for manufacturing of high quality plastic parts is cavity pressure. This paper presents a continuation of a numerical based study of flow control utilized during multi-cavity injection molding processes and focuses in more detail on multiple flow control valve systems, since the valves are coupled with one injection source. The capabilities of the current system design are limited by multiple valve interactions, which may produce undesirable effects in regards to flow modulation and pressure distribution in multiple cavities and should be studied further. Understanding the flow modeling details through a single valve system is essential, thereby reducing the computational work involved with a multiple valve system.

Produktivitätssteigerung durch Hybridisierung im 3D-Druck/Process development for the automated production of plastic parts with integrated functional components. Increased productivity through hybridization in 3D printing

2020 ◽  
Vol 110 (07-08) ◽  
pp. 521-525
Author(s):  
Michael Baranowski ◽  
Markus Netzer ◽  
Sven Coutandin ◽  
Jürgen Fleischer
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Manufacturing Process ◽  
Process Development ◽  
Flexible Production ◽  
Additive Fertigung ◽  
Automated Production ◽  
Individualized Production ◽  
Plastic Parts ◽  
Functional Components

Die additive Fertigung erlaubt eine standortunabhängige sowie de facto individualisierte Produktion von Bauteilen mit nahezu beliebiger Komplexität. Für die flexible Herstellung von hochfunktionalen Hybridbauteilen fehlt es allerdings an entsprechenden Maschinenkonzepten sowie Automatisierungslösungen. Durch ein hier vorgestelltes Anlagenkonzept sollen Funktionskomponenten in den additiven Herstellungsprozess integriert und neue Möglichkeiten der Bauteilhybridisierung erforscht werden.   Additive manufacturing allows a location-independent and de facto individualized production of components of almost any complexity. However, there is a need for appropriate machine concepts and automation solutions for the flexible production of highly functional hybrid components. A plant concept presented here is intended to integrate functional components into the additive manufacturing process and to explore new possibilities for component hybridization.

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