Experimental Optimization of Polymer Jetting Additive Manufacturing Process Using Taguchi Design

2020 ◽  
Author(s):  
Nathan A. Weese ◽  
Chantz M. Rankin ◽  
Daguan Zhao ◽  
Christoph Hart ◽  
Patrick Quinlan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Light Intensity ◽  
Breaking Strength ◽  
Uv Light ◽  
Tissue Scaffolds ◽  
Femur Bone ◽  
Resolution Factor ◽  
Bone Structures ◽  
Head Temperature

Abstract Polymer jet printing (PJP) is a direct-write additive manufacturing process, emerging as a rapid high-resolution method particularly in the medical field for the fabrication of a wide spectrum of products, e.g., anatomical models, tissue scaffolds, implants, and prosthetics. PJP allows for non-contact multi-material deposition of functional polymer inks. The PJP process centers on simultaneous deposition of build and support photopolymer materials on a free surface, which are immediately cured in situ using a UV light source, allowing for solid-freeform fabrication. The PJP process is inherently complex, governed by a multitude of parameters as well as material-machine-process interactions, which collectively affect the functional properties of a fabricated structure. Consequently, physics-based characterization and optimization of the PJP process would be inevitable. In this study, a new test standard was forwarded for the characterization of the mechanical properties of PJP-fabricated bone structures; the standard was designed on the basis of an X-ray p-CT scan of a femur bone in addition to the ASTM D638-14 standard. Furthermore, the Taguchi L8 orthogonal array design was utilized to investigate the effects of influential PJP process parameters on the mechanical properties of the bone structures, including Young’s modulus of elasticity, tensile strength, breaking strength, and ductility. The selected process parameters (each at two levels) were: (i) print direction, (ii) resolution factor, (iii) UV light intensity, and (iv) deposition head temperature. The mechanical properties of the femur bone structures were measured using a tensile testing machine. The UV light intensity appeared as the most significant factor, influencing all the aforementioned mechanical properties, while the resolution factor was identified as an inconsequential factor. In addition, it was observed that the print direction and the head temperature significantly affected the breaking strength and the ductility, respectively. Overall, the results of this study pave the way for further investigation of the effects of the PJP parameters toward optimal fabrication of complex bone tissue scaffolds and implants with long-lasting functional characteristics.

scholarly journals A Review of Vat Photopolymerization Technology: Materials, Applications, Challenges, and Future Trends of 3D Printing

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 598
Author(s):  
Marek Pagac ◽  
Jiri Hajnys ◽  
Quoc-Phu Ma ◽  
Lukas Jancar ◽  
Jan Jansa ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Uv Light ◽  
Construction Materials ◽  
Future Trend ◽  
Future Trends ◽  
New Materials ◽  
Digital Light Processing ◽  
Printing Techniques

Additive manufacturing (3D printing) has significantly changed the prototyping process in terms of technology, construction, materials, and their multiphysical properties. Among the most popular 3D printing techniques is vat photopolymerization, in which ultraviolet (UV) light is deployed to form chains between molecules of liquid light-curable resin, crosslink them, and as a result, solidify the resin. In this manuscript, three photopolymerization technologies, namely, stereolithography (SLA), digital light processing (DLP), and continuous digital light processing (CDLP), are reviewed. Additionally, the after-cured mechanical properties of light-curable resin materials are listed, along with a number of case studies showing their applications in practice. The manuscript aims at providing an overview and future trend of the photopolymerization technology to inspire the readers to engage in further research in this field, especially regarding developing new materials and mathematical models for microrods and bionic structures.

scholarly journals ВПЛИВ ПАРАМЕТРІВ АДИТИВНОГО ВИРОБНИЦТВА НА ВЛАСТИВОСТІ ВИРОБІВ З ФОТОПОЛІМЕРУ

2022 ◽  
pp. 81-87
Author(s):  
ALEKSANDR SLIEPTSOV ◽  
RUSLAN ISKANDAROV ◽  
IGOR SLIEPTSOV ◽  
VYACHESLAV KOBZA
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Additive Manufacturing ◽  
Impact Strength ◽  
Manufacturing Process ◽  
Uv Light ◽  
Post Treatment ◽  
Uv Curable ◽  
Forming Parameters ◽  
Manufacturing Parameters

Purpose. Study of the influence of additive manufacturing parameters and post forming operations on complex mechanical properties of the articles formed from UV curable acrylic oligomer. Methodology. Determination of physical and mechanical properties of standard samples which was formed by additive manufacturing technics from UV curable polymer. Tensile strength and relative elongation at brake according to ISO 527-2:2012, impact strength according to: ISO 179-1:2010. Durometer hardness according to:ISO 2039-1:2001. Bending modulus according to: ISO 178:2010. Density according to: ISO 1183-1:2019Findings. Additive manufacturing parameters for stereolithography process was studied for liquid UV curable acrylic oligomer. Study was focused on influence of forming settings and post forming treatment of complex mechanical properties of final articles which was shaped as standard testing samples. Properties of additive manufactured samples was compared with the properties of samples which was cured by UV light is bulk inside shaped cavity with the same geometrical dimensions. Correct post forming treatment results in up to 2 – 3 times increase in tensile strength. Post forming treatment is necessary for achieving functional level of mechanical properties, comparable to the properties of typical industrial polymers. Study of influence of UV light exposure during additive manufacturing shows double fold increase in tensile strength but reduce overall forming speed. Impact strength increase with increasing exposure time and significantly increase with duration of post forming treatment. Post treatment operations with correct parameters can result in forming articles with level of properties sufficient for functional applications. Originality. Study was focused on mechanical properties of UV curable polymer in dependence from forming parameters of additive manufacturing process and post treatment operations. Application of correct post forming setting can lead to material properties with valuable for functional applications.Practical value Optimal parameters for additive manufacturing process based on UV curable resin and LCD exposure technology was investigated. Forming and post forming parameters significantly influence complex mechanical properties of formed articles.

Light Assisted Hybrid Direct Write Additive Manufacturing of Thermosets

2020 ◽  
Author(s):  
Abdulrahman Alrashdan ◽  
William Jordan Wright ◽  
Emrah Celik
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Uv Light ◽  
Crosslinking Agent ◽  
Complex Geometries ◽  
Direct Write ◽  
Direct Writing ◽  
Manufacturing Method ◽  
Wide Range ◽  
Material Systems

Abstract In the past recent years, numerous studies have been conducted on additive manufacturing of thermosets and thermoset composites. Thermosets are an important class of polymers used in engineering applications. Monomer units in these material systems irreversibly cross-link when external stimuli or a chemical crosslinking agent is applied in terms of the curing or photopolymerization process. Thermally curing thermosets mark unique mechanical properties including, high temperature resistance, strong chemical bond, and structural integrity and therefore these materials find wide range of applications currently. However, direct write additive manufacturing of these material systems at high resolution and at complex geometries is challenging. This is due to the slow curing rate of thermally curing thermoset polymers which can adversely affect the printing process, and the final shape of the printed object. On the other hand, VAT Polymerization additive manufacturing, which is based on curing the photopolymer resin by Ultraviolet (UV) light, can allow the fabrication of complex geometries and excellent surface finish of the printed parts due to the fast curing rate of photopolymers used in this technique. Mechanical properties of photopolymers, however, are usually weaker and more unstable compared to the thermally curing polymers used in the direct write additive manufacturing method. Therefore, this study focuses on taking the advantages of these two thermoset additive manufacturing methods by utilizing both the thermally cured epoxy and photopolymer resins together. Using the direct writing, the resin mixture is extruded though a nozzle and the final 3D object is created on the print bed. Simultaneously, the deposited ink is exposed to the UV light enhancing the yield strength of the printed material and partially curing it. Therefore, thermally cured epoxy is used to obtain the desirable mechanical properties, while the addition of the photopolymer resin allows the thermoset mixture to partially solidify the printed ink when exposed to the UV light. The results achieved in this study showed that, the hybrid additive manufacturing technology is capable of fabricating complex and tall structure which cannot be printable via additive manufacturing method. In addition, mechanical properties of the hybrid thermoset ink are comparable to the thermally cured thermoset polymer indicating the great potential of the light-assisted, hybrid manufacturing to fabricate mechanically strong parts at high geometrical resolution.

scholarly journals Morphology Control in a Dual-Cure System for Potential Applications in Additive Manufacturing

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 420 ◽  
Author(s):  
Jonathan Campbell ◽  
Harrison Inglis ◽  
Elson Ng WeiLong ◽  
Cheylan McKinley ◽  
David Lewis
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Uv Light ◽  
Light Exposure ◽  
Relative Rate ◽  
Control Sample ◽  
Polymer System ◽  
Phase System ◽  
Layer By Layer ◽  
Two Phase

The polymerisation, morphology and mechanical properties of a two-component in-situ reacting system consisting of a rubbery dimethacrylate and a rigid epoxy polymer were investigated. The methacrylate component of the mixture was photocured using UV light exposure and, in a second curing process, the mixture was thermally postcured. The polymers formed a partially miscible system with two glass transition temperature (Tg) peaks measured using dynamic mechanical thermal analysis (DMTA). The composition and relative rate of reaction of the two orthogonal polymerisations influenced the extent of miscibility of the two polymer-rich phases and the samples were transparent, indicating that the two phases were finely dispersed. The addition of a glycidyl methacrylate compatibiliser further increased the miscibility of the two polymers. The utility of this polymer system for additive manufacturing was investigated and simulated through layer-by-layer processing of the mixture in two steps. Firstly, the methacrylate component was photocured to solidify the material into its final shape, whilst the second step of thermal curing was used to polymerise the epoxy component. With the use of a simulated photomask, a simple shape was formed using the two orthogonal polymerisation stages to produce a solid object. The mechanical properties of this two-phase system were superior to a control sample made only of the methacrylate component, indicating that some reinforcing due to polymerisation of the epoxy across the interfaces had occurred in the postcuring stage.

Control of humping phenomenon and analyzing mechanical properties of Al–Si wire-arc additive manufacturing fabricated samples using cold metal transfer process

2021 ◽  
pp. 095440622199840
Author(s):  
Yashwant Koli ◽  
N Yuvaraj ◽  
Aravindan Sivanandam ◽  
Vipin
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Heat Input ◽  
Large Scale ◽  
High Deposition Rate ◽  
Bead Geometry ◽  
Layer By Layer ◽  
Cold Metal Transfer ◽  
Geometrical Shapes ◽  
Wire Arc Additive Manufacturing

Nowadays, rapid prototyping is an emerging trend that is followed by industries and auto sector on a large scale which produces intricate geometrical shapes for industrial applications. The wire arc additive manufacturing (WAAM) technique produces large scale industrial products which having intricate geometrical shapes, which is fabricated by layer by layer metal deposition. In this paper, the CMT technique is used to fabricate single-walled WAAM samples. CMT has a high deposition rate, lower thermal heat input and high cladding efficiency characteristics. Humping is a common defect encountered in the WAAM method which not only deteriorates the bead geometry/weld aesthetics but also limits the positional capability in the process. Humping defect also plays a vital role in the reduction of hardness and tensile strength of the fabricated WAAM sample. The humping defect can be controlled by using low heat input parameters which ultimately improves the mechanical properties of WAAM samples. Two types of path planning directions namely uni-directional and bi-directional are adopted in this paper. Results show that the optimum WAAM sample can be achieved by adopting a bi-directional strategy and operating with lower heat input process parameters. This avoids both material wastage and humping defect of the fabricated samples.

scholarly journals Development of a 3D Printable and Highly Stretchable Ternary Organic-Inorganic Nanocomposite Hydrogel

2021 ◽  
Author(s):  
Chen Hu ◽  
Malik Haider ◽  
Lukas Hahn ◽  
Mengshi Yang ◽  
Robert Luxenhofer
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Nanocomposite Hydrogel ◽  
Highly Stretchable ◽  
Manufacturing Techniques ◽  
Advanced Applications

Hydrogels that can be processed with additive manufacturing techniques and concomitantly possess favorable mechanical properties are interesting for many advanced applications. However, the development of novel ink materials with high...

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