Layered Manufacturing Method Research Articles

Amidation-Reaction Strategy Constructs Versatile Mixed Matrix Composite Membranes towards Efficient Volatile Organic Compounds Adsorption and CO2 Separation.

Mixed matrix composite membranes (MMCMs) have shown advantages in reducing VOCs and CO2 emissions. Suitable composite layer, substrate, and good compatibility between the filler and the matrix in the composite layer are critical issues in designing MMCMs. This work develops a high-performance UiO-66-NA@PDMS/MCE for VOCs adsorption and CO2 permea-selectivity, based on a simple and facile fabrication of composite layer using amidation-reaction approach on the substrate. The composite layer shows a continuous morphological appearance without interface voids. This outstanding compatibility interaction between UiO-66-NH2 and PDMS is confirmed by molecular simulations. The Si─O functional group and UiO-66-NH2 in the layer leads to improved VOCs adsorption via active sites, skeleton interaction, electrostatic interaction, and van der Waals force. The layer and ─CONH─ also facilitate CO2 transport. The MMCMs show strong four VOCs adsorption and high CO2 permeance of 276.5 GPU with a selectivity of 36.2. The existence of VOCs in UiO-66-NA@PDMS/MCE increases the polarity and fine-tunes the pore size of UiO-66-NH2, improving the affinity towards CO2 and thus promoting the permea-selectivity for CO2, which is further verified by GCMC and EMD methods. This work is expected to offer a facile composite layer manufacturing method for MMCMs with high VOC adsorption and CO2 permea-selectivity.

ANALISIS UJI TARIK DAN UJI BENDING DENGAN KARAKTERISTIK HONEYCOMB POLYLACTIC ACID (PLA) TERHADAP VARIASI SUHU RUANGAN

Three Dimension (3D) Printing is a technology for printing a material by producing a three-dimensional object using the Additive Manufacturing technique, with the layer manufacturing method. In this study, printing three-dimensional objects using materials made from polylactic acid. Polylactic acid is a type of plastic filament material that is biodegradable, more easily decomposed than other plastic filaments, so it is environmentally friendly. This research discusses about the printing and testing of materials made from polylactic acid with room temperature variations of 18⁰C, 25⁰C, 30⁰C. Tests were carried out to determine the effect of room temperature on the honeycomb structure by conducting a tensile test and a bending test. Printouts at room temperature variations of 18⁰C have a higher average stress value in the bending test and have a higher average Young's modulus value in the tensile test compared to 25⁰C and 30⁰C. Based on the results of the bending test at 18⁰C it has an average stress value of 0.000126 MPa, for the tensile test at 18⁰C it has an average Young's modulus value of 1.13827MPa.

Tensile properties of sandwich-designed carbon fiber filled PLA prepared via multi-material additive layered manufacturing and post-annealing treatment

Abstract Polylactic Acid (PLA) experiences widely spread applications in Fused Filament Fabrication (FFF) owing to its relatively high stiffness, strength, and environmentally friendly biodegradability. Reinforcing inclusions like short carbon fibers are introduced to virgin PLA feedstock aiming to improve the mechanical performance of FFF-made products. Nevertheless, the rigid fibers significantly reduce the ductility of the overall fabricated parts. This study prepares sandwich specimens with PLA as core and its 10 wt% chopped carbon fiber reinforced composites (i.e., CF/PLA) as shell via a low-cost FFF-based multi-material additive layered manufacturing method. The sandwich specimen has three layers, which are changed according to different material volumes, which is able to design the local strength and toughness performances of a printed part. Tensile properties of these sandwich samples printed in the different volumetric rates of virgin PLA constituents are measured. It is found that the strength of sandwich specimens with 20% vol of PLA reduces noticeably as compared to the full CF/PLA specimens. The 80% vol specimens exhibit a competitive strength as compared to the 40% and 60% vol specimens, while its toughness increases notably as compared to the other cases. Finite element simulations of the layered manufacturing process show that the thermal residual stresses of 20% vol sandwich accumulates most significantly. We also explore the effects of thermal annealing on the prepared sandwiches. Experimental results indicated that the post-annealing process improved the strength and stiffness of the sandwich specimens, while enhancing the stability of the mechanical properties of the FFF printed sandwich.

A review of additive manufacturing applications in ophthalmology.

Additive Manufacturing (AM) capabilities in terms of product customization, manufacture of complex shape, minimal time, and low volume production those are very well suited for medical implants and biological models. AM technology permits the fabrication of physical object based on the 3D CAD model through layer by layer manufacturing method. AM use Magnetic Resonance Image (MRI), Computed Tomography (CT), and 3D scanning images and these data are converted into surface tessellation language (STL) file for fabrication. The applications of AM in ophthalmology includes diagnosis and treatment planning, customized prosthesis, implants, surgical practice/simulation, pre-operative surgical planning, fabrication of assistive tools, surgical tools, and instruments. In this article, development of AM technology in ophthalmology and its potential applications is reviewed. The aim of this study is nurturing an awareness of the engineers and ophthalmologists to enhance the ophthalmic devices and instruments. Here some of the 3D printed case examples of functional prototype and concept prototypes are carried out to understand the capabilities of this technology. This research paper explores the possibility of AM technology that can be successfully executed in the ophthalmology field for developing innovative products. This novel technique is used toward improving the quality of treatment and surgical skills by customization and pre-operative treatment planning which are more promising factors.

Design and Production of Smart Wearable Textile Products Using Layered Manufacturing Technology with Photovoltaic Energy

Smart textiles are used in a wide range of areas, such as defense industry, security, medicine, health, aviation, space sciences, environment, energy, biotechnology, agriculture, food, cosmetics and fashion design. In this study, with the progress of technology in the area of the wearable smart textile industry, 3D manufacturing which has started to take place in the industry as a new manufacturing method or in other words layered manufacturing practices are discessed. For this purpose, a solar panel was placed in the 3D printed material obtained by FDM method, one of the layered manufacturing methods, and integrated into the textile material and to charge our electronic devices from photovoltaic energy was explained. It is aimed to produce, using the knowledge gained as a result of the study, smart textile products that facilitate human life with 3D printed materials obtained from filaments with conductive additive.

Selective Laser Melting for processing of regolith in support of a lunar base

Future space exploration will focus on destinations beyond the Earth’s orbit, which necessitates new technologies such as In-Space Resource Utilization. This paper presents a technological approach for the processing of lunar regolith via an adapted laser based Additive Layer Manufacturing method, which needs no binding additives or other supply from Earth. In support of large scaled structure construction on the lunar surface, the proposed Selective Laser Melting technology has the potential to drastically lower the transportation needs of such a mission while enabling high flexibility.

Investigations on the Influence of Operating Parameters on the Lubricated Wear of SLS Materials

Selective laser sintering is a layered manufacturing method that fuses the powder material with the help of a laser into a physical part directly from a 3D model without intermediate tooling. Iron powder of grain size 20 μm with a resin coating of 3μm was sintered by selective laser sintering method, which was later infiltrated with bronze particles. To find out the behavior of the sintered ferrous-bronze in functional applications, it was necessary to find out the wear rate of this material under real world operating conditions. Tests were conducted using a linearly reciprocating ball-on-flat sliding wear testing machine at different temperatures in a lubricated environment. Wear rates were determined under different operating conditions. Micro structural studies of the samples were conducted using Field Emission Scanning Electron Microscope (FESEM). EDAX analysis was done to study the chemical changes occurred during tests.

Consolidation & Factors Influencing Sintering Process in Polymer Powder Based Additive Manufacturing

Additive Manufacturing (AM) is two decade old technology; where parts are build layer manufacturing method directly from a CAD template. Over the years, AM techniques changes the future way of part fabrication with enhanced intricacy and custom-made features are aimed. Commercially polymers, metals, ceramic and metal-polymer composites are in practice where polymers enhanced the expectations in AM and are considered as a kind of next industrial revolution. Growing trend in polymer application motivated to study their feasibility and properties. Laser sintering, Heat sintering and Inhibition sintering are the most successful AM techniques for polymers but having least application. The presentation gives up selective sintering of powder polymers and listed commercially available polymer materials. Important significant factors for effective processing and analytical approaches to access them are discussed.

Modeling and process planning for curved layer fused deposition

Fused deposition modeling (FDM), one of the earliest and typical additive manufacturing (AM) technologies, holds great potential in a wide range of industrial applications due to their increasing availability, simplicity, affordability, and capability to fabricate both prototypes and functional parts without limitation on geometric complexity. Notwithstanding many evident advantages over traditional subtractive manufacturing methods, there are still some limitations of this rapidly developing technique. One intractable problem is the undesirable surface finish from the layer-by-layer manufacturing process, where the stair-step issue appears unavoidably. This problematic phenomenon becomes much more serious when fabricating the surface with some minute but critical features. In order to solve these problems, curved layer manufacturing method is a good substitute for general flat fused deposition modeling. This work is an exploratory study for curved layer fused deposition (CLFD), involving the modeling and process planning, which are the foundation for the implementation of CLFD. The physical model for CLFD is developed firstly, and subsequently, the process planning, including the slicing procedure and the extruder path generation, is analyzed and presented. The output from the process planning could be applied in the fabrication of curved surfaces, which would possess tiny features and exhibit excellent smoothness instead of annoying exterior appearance. At last, the implementation of the proposed strategies and approaches on a bowl-like surface is provided to verify the effectiveness and advantages of CLFD.

Shaped metal deposition technique in additive manufacturing: A review

Shaped metal deposition is a relatively new additive layered manufacturing method. It is a novel technique to build net-shaped or near-net-shaped metal components in a layer-by-layer manner via applying metal wire and selection of a heat source such as laser beam, electron beam, or electric arc. It is a manufacturing method used for production of complex featured and large-scaled parts, especially in aerospace and metal-die industries. This method can lower the cost of fabricated parts by reducing further machining and finishing processes and shortening lead time. This article presents a comprehensive literature review on shaped metal deposition, and it mainly aims to highlight some of the areas which were reported by the researchers in this field to give an extensive overview of shaped metal deposition processes, classification of its methods, and their applications. The presented literature review covers extensive details on microstructure, mechanical properties, and residual stresses induced in the metallic parts produced by various shaped metal deposition techniques as well as fabrication of dual-material parts. Additionally, grain refinement of the deposition morphologies using various techniques, especially the arc pulsation process, was mentioned. This study demonstrates that shaped metal deposition method using wire can be considered as a distinctive low-cost method for fabricating large-scaled components due to high deposition rates, high efficiencies, and dense part production capabilities. However, the accuracy and surface finish are less compared to laser and electron beam melting methods.

Microstructure characterization of SS308LSi components manufactured by GTAW-based additive manufacturing: shaped metal deposition using pulsed current arc

Shaped metal deposition method using gas tungsten arc welding is a novel manufacturing technology that can be used for fabricating solid dense parts in layered manufacturing. This paper reports for the first time using the pulsed current shaped metal deposition technique for fabricating components using cold wire of AISI 308LSi stainless steel. The aim of this work was to investigate and compare the effect of pulse frequency and other deposition process parameters on the morphology aspects and microstructure characteristics of the manufactured components using pulsed and continuous current processes. The obtained results reveal that the structure of the deposited specimens produced via pulsed arc current is generally having finer grains, high residual ferrite, and absence of columnar grains. Pulse frequency and current ratio have a significant influence on the surface morphology and microstructure of the manufactured parts. Good metallurgical bonding with no sensitization effects can be seen in all tested specimens. The presented additive layered manufacturing method can be recommended for near net-shaped processing of austenitic stainless steel components, and it can be used as an alternative manufacturing method for fabricating metal components with free defects, higher corrosion resistance, and superior mechanical properties.

Developments of 3D Printing Microfluidics and Applications in Chemistry and Biology: a Review

AbstractThree‐dimensional (3D) printing, also called additive manufacturing (AM) or rapid prototyping (RP), is a layer by layer manufacturing method and now has been widely used in many areas such as organ printing, aerospace and industrial design. Now 3D printed microfluidics attract more and more interests for its rapid printing in the lab. In this review, we focused on the advances of 3D printed microfluidic chips especially the use in the chemistry and biology (vascularization and organs on chips). Based on the brief review of different 3D printing methods, we discussed how to choose the suitable 3D printing methods to print the desired microfluidics. We predict that microfluidics will be evolved from 2D chips to 3D cubes, printed hydrogel‐based microfluidics will be reported and widely used, sensors & actuators could be integrated in the microfluidics during printing, and rapid assembling chips with printed microfluidic modules will be popular in the near future.

MECHANICAL PROPERTIES AND RELIABILITY OF GLASS-ALUMINIUM COMPOSITE AS INSERT MOLD

Plastic injection mold made of tool steel is generally utilized for large lots production. Running for small lots of product is a new trend of demand, so that the mold would be relatively expensive and not competitive. The aim of the present work is to find an alternative material and process for low cost injection mold that suitable for small lots. For these reasons, aluminum-glassacrylic particulate composite would be proposed as a material for manufacturing of low cost plastic injection mold. In this work, an insert mold as part of the injection molding was selected for the case study. Composite was examined to know its characteristics. The part with size of (80mm x 10mm x 10mm) and (30mm x30mm x30mm) made of particulate composite material was selected as specimen. Material of the specimen was aluminum powders (<297 μm), glass powders (<74 μm) and acrylic powders (<74 μm); the volume ratio is 1:1:1. Acrylic was used for binder when composite made by layer manufacturing method, using Selective Heater Melting (SHM) machine. The specimen was prepared into three steps: manufacturing of composite (green specimen) by SHM machine, heating green specimen to burn up the acrylic, and resin impregnation. There were 3 types of specimens: green specimen before heating at 700°C, green specimen after heating at 700°C, and green specimen after heating at 700°C that continued by resin impregnation. Tests was performed to investigate its bending strength, surface hardness, surface roughness, and dimensional error. The other composite (specimen) was insert mold, made by layer manufacturing method, using SHM machine. Case study was carried out by testing an insert mold to know the reliability of insert mold. Bending strengths of green specimen, before and after heating at 700°C, were 2.07 and 8.23 MPa, respectively; and after resin impregnation was 17.15 MPa. Dimensional errors in the direction of X, Y, and Z-axis for green specimen of (30mm x 30mm x30mm) before heating at 700°C were 8.65, 2.7, and 3.8 mm, respectively; and after heating at 700°C were 7.90, 1.10 and 0.90 mm, respectively. Surface roughness of green specimen before and after heating at 700°C were 46.12 and 33.48 μm, respectively; and after resin impregnation was 12.17 μm. Surface hardness of specimen after resin impregnation was 14.199 BHN. The amount of plastic parts that could be produced by insert mold was 120 and 126 pieces. Although mechanical strength of this composite was lower than that of tool steel that used for common plastic injection mold, but this composite material was less expensive and suitable for small lots production.

The effect of location on the microstructure and mechanical properties of titanium aluminides produced by additive layer manufacturing using in-situ alloying and gas tungsten arc welding

An innovative and low cost additive layer manufacturing (ALM) process is used to produce γ-TiAl based alloy wall components. Gas tungsten arc welding (GTAW) provides the heat source for this new approach, combined with in-situ alloying through separate feeding of commercially pure Ti and Al wires into the weld pool. This paper investigates the morphology, microstructure and mechanical properties of the additively manufactured TiAl material, and how these are affected by the location within the manufactured component. The typical additively layer manufactured morphology exhibits epitaxial growth of columnar grains and several layer bands. The fabricated γ-TiAl based alloy consists of comparatively large α2 grains in the near-substrate region, fully lamellar colonies with various sizes and interdendritic γ structure in the intermediate layer bands, followed by fine dendrites and interdendritic γ phases in the top region. Microhardness measurements and tensile testing results indicated relatively homogeneous mechanical characteristics throughout the deposited material. The exception to this homogeneity occurs in the near-substrate region immediately adjacent to the pure Ti substrate used in these experiments, where the alloying process is not as well controlled as in the higher regions. The tensile properties are also different for the vertical (build) direction and horizontal (travel) direction because of the differing microstructure in each direction. The microstructure variation and strengthening mechanisms resulting from the new manufacturing approach are analysed in detail. The results demonstrate the potential to produce full density titanium aluminide components directly using the new additive layer manufacturing method.

412 アディティブ・マニュファクチャリングによる関節補装具の製作に関する研究 : 複数材料を用いた積層造形による指装具の製作(OS4-3 アディティブ・マニュファクチャリングの生産システムII)

Prosthetic joint is used for the treatment of rheumatism, etc. The prosthetic joints are used as auxiliary for lost function, and the correction of deformation and protection of abnormal tissues. Because prosthetist makes a prosthetic joint for a user individually, it is costly and time consuming. On the other hand, it is possible to fabricate the prosthetic joint suitable for the user by using a layered manufacturing method simply. In this study, we have fabricated a single-piece dynamic orthosis which has a movement mechanism by means of the layered manufacturing using multiple materials.

Increased stability in laser metal wire deposition through feedback from optical measurements

Robotized laser metal-wire deposition is a fairly new technique being developed at University West in cooperation with Swedish industry for solid freeform fabrication of fully densed metal structures. It is developed around a standard welding cell and uses robotized fiber laser welding and wire filler material together with a layered manufacturing method to create metal structures. In this work a monitoring system, comprising two cameras and a projected laser line, is developed for on-line control of the deposition process. The controller is a combination of a PI-controller for the bead width and a feed-forward compensator for the bead height. It is evaluated through deposition of single-bead walls, and the results show that the process stability is improved when the proposed controller is used.

Experimental investigation into selective laser melting of austenitic and martensitic stainless steel powder mixtures

Selective laser melting (SLM) is a novel additive layer manufacturing method that has been used to directly consolidate a wide range of metallic powders to form net-shape metallic parts for various engineering applications. It is capable of processing steel powders in a range of grades and also allowing the creation of custom alloys by consolidating the mixed powders of two or more grades. This study investigates the effects of varying the ratio of austenitic and martensitic powder mixtures on the laser consolidation of steel parts. Specimens were fabricated by SLM processing from 316L austenitic and 17-4PH martensitic stainless steel powder mixtures with varying composition ratios. Mechanical and magnetic properties of the specimens were assessed by micro-hardness testing and comparison of ‘magnetic adherence’ forces. The composition ratios of the mixed powders have been found to influence the laser consolidation mechanisms and the resulting microstructures in the specimens. The microstructures play an important role in altering the micro-hardness and the magnetic properties of the specimens and determining a definite relationship between these two properties. The results of this study prove that a new stainless steel grade can be produced via the SLM process to have tailored mechanical and magnetic properties.

Freeform fabrication of Ti–Al alloys by 3D micro-welding

3D micro-welding (3DMW) is a newly developed rapid prototyping method for metals. It combines a micro-tungsten inert gas (TIG) welding with a layered manufacturing method. A tip of a thin metal wire is melted by a micro-TIG welder to form a small metal bead. By building up metal beads layer by layer under computer control, a 3D metal object is eventually formed. A wide variety of metals and alloys can be used. The Ti–Al based intermetallic alloys have superior mechanical and chemical properties. However, the forming process is difficult and costly. We have tried to fabricate 3D objects of the Ti–Al alloy system by using several thin Ti and Al wires. Some simple objects with a unique microstructure or graded composition are demonstrated.

Freeform fabrication of superalloy objects by 3D micro welding

3D Micro welding (3DMW) is a newly developed rapid prototyping method for metals. It is a combination of micro tungsten inert gas (micro-TIG) welding and a layered manufacturing method. The tip of a thin metal wire is melted by a micro-TIG welder to form a small metal bead. By building up metal beads layer by layer under computer control, a 3D metal object is eventually formed. The fabrication of simple 3D objects made of Inconel alloy 600 was studied. The interface between adjacent beads had good adhesion. No cracks or pores remained in the formed objects. The tensile strength, elongation, density, and Vickers hardness were measured and compared to those of the commercial superalloy. The obtained results suggest that actual micro components or tools of refractory metals with high strength and oxidization resistance can be formed without molds by 3DMW.

Control Design for Automation of Robotized Laser Metal-wire Deposition

In this paper a novel approach towards automation of robotized laser metal-wire deposition (RLMwD) is described. The RLMwD technique is being developed at University West in cooperation with Swedish industry for solid freeform fabrication of fully dense metal structures. The process utilizes robotized fiber laser welding and metal wire filler material, together with a layered manufacturing method, to create metal structures directly from a CAD drawing. The RLMwD process can also be used for repair or modification of existing components. This paper faces the challenge of designing a control system for maintaining stable process variables, such as a constant layer height and a stable component temperature, during the entire manufacturing process. Several problems are identified and discussed in the paper, e.g. the difficulty of obtaining the bead height in the weld pool environment. The case study is a repair application for stamping tools, where worn out trim edges are to be repaired. Issues regarding the control design, system identification, and the practical implementation of this application are discussed.