bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Time Spacing and Hatch Spacing on Thermal Material Properties and Melt Pool Geometry in Additive Manufacturing of S316L
Authors: Mirkoohi Elham , Sievers Daniel E. , Liang Steven Y.
Published: November 2019

A physics-based analytical solution is proposed in order to investigate the effect of hatch spacing and time spacing (which is the time delay between two consecutive irradiations) on thermal material properties and melt pool geometry in metal additive manufacturing processes. A three-dimensional moving point heat source approach is used in order to predict the thermal behavior of the material in additive manufacturing process. The thermal material properties are considered to be temperature dependent since the existence of the steep temperature gradient has a substantial influence on the magnitude of the thermal conductivity and specific heat, and as a result, it has an influence on the heat transfer mechanisms. Moreover, the melting/solidification phase change is considered using the modified heat capacity since it has an influence on melt pool geometry. The proposed analytical model also considers the multi-layer aspect of metal additive manufacturing since the thermal interaction of the successive layers has an influence on heat transfer mechanisms. Temperature modeling in metal additive manufacturing is one of the most important predictions since the presence of the temperature gradient inside the build part affect the melt pool size and geometry, thermal stress, residual stress, and part distortion. In this paper, the effect of time spacing and hatch spacing on thermal material properties and melt pool geometry is investigated. Both factors are found statistically significant with regard to their influence on thermal material properties and melt pool geometry. The predicted melt pool size is compared to experimental values from independent reports. Good agreement is achieved between the proposed physics-based analytical model and experimental values.
Recycling of Printed Circuit Boards by Direct Molding Technology
Authors: Quadrini F. , Bellisario D. , Tedde G. M. , Santo L.
Published: November 2019

The recovery and reuse of printed circuit boards (PCBs) is becoming crucial in the management of electronic waste that is undergoing an exponential increase. In this study, a simple and eco-friendly process for recycling waste PCBs is discussed. In particular, composite panels were produced by reusing 100% of waste PCBs without the addition of any additive or virgin material. After a two-step grinding process, ground PCB was used to mold panels by direct molding which is pure compression molding without material sorting. Results were very promising in terms of process feasibility and part performances. Molded samples had density about 1.45 g/cm3, flexural modulus and flexural about 3 GPa and 16 MPa, respectively. A smooth surface with low friction coefficient was obtained for the recycled panels. The study shows that despite the presence of metal and other non-metal non-organic fractions, waste PCBs can be re-processed in profitable and environmentally conscious way without the addition of any bonding agent or additive. The recycling technology can be extended to the reuse of the non-metallic fraction only, after separation and recovery of metals.
Sedimentation Study of Bioink Containing Living Cells
Authors: Xu Heqi , Xu Changxue , Zhang Zhengyi
Published: November 2019

3D bioprinting has more and more applications in tissue engineering, in vitro drug testing, and regenerative medicine. The bioink consisting of the biocompatible polymer (as extracellular matrix) and the living cells is the starting material. Because the typical bioprinting process may take several hours, the suspended cells in the bioink sediment with time, which significantly affects the bioink stability as well as the following bioprinting quality and reliability. The cell sedimentation is determined by the integral effects of drag force and buoyancy and gravity. The gravitational force is related to the cells, and the drag force and buoyant force is related to the polymer concentration. This paper is the first paper to quantify the cell sedimentation process of the bioink within 0.5% and 1% (w/v) polymer concentrations respectively. The cell sedimentation phenomenon has been observed using the bioink within 0.5% and 1% (w/v) polymer concentrations. The cell sedimentation velocity has been estimated to be 1.18 μm/s with the polymer concentrations to be 0.5% (w/v) and 0.88 μm/s for the bioink with the polymer concentrations to be 1% (w/v). It is also found that the cell concentration increases significantly at the bottom of the bioink reservoir, resulting in cell aggregates due to cell-cell interaction.
Experimental and Numerical Analyses on the Poly(Lactide-Co-Glycolide) Hollow Fiber Membranes
Authors: Wang Zonghuan , Yin Jun
Published: November 2019

The hollow fiber membranes (HFMs) were widely used as tissue engineering scaffold. The efficacy of the HFMs were affected by the porosity of the HFMs. In this study, the HFMs were prepared with dry-jet wet spinning method. In order to improve the performance of the HFMs, different spinning parameters were applied to systematically investigating the effects of the fabrication conditions on the porosity of the HFMs. A 1-D diffusion model was set to numerically study the volume fraction distribution along the wall thickness. The porosity of the HFMs show a significant decrease in the porosity as the dope concentration increases. The morphology analyses showed that a higher dope concentration leads to a denser porous structure which result in a lower porosity. The results were discussed based on the phase inversion process and the 1-D model was built to numerically analyze the polymer volume fraction distribution in the HFMs cross section. This study can help to better understand the effects of the different fabrication conditions on the morphology of the HFMs.
Modeling and Experimental Study of the Impact on Free Abrasive Machining (FAM) due to Vibration of a Thin Wire Subject to an Oscillating Boundary Condition
Authors: Li Liming , Kao Imin
Published: November 2019

This paper investigates the impact on free abrasive machining (FAM) process using a vibrating wire with an oscillating boundary condition. The experimental results show that the vibration of wire in slurry with abrasive grits can result in material removal due to FAM on brittle material. We present a theoretical model of a wire moving axially at a constant speed, subject to an oscillating boundary condition with damping, and derive an analytical solution of the partial differential equation of motion. Based on the modeling and analysis, the frequency of vibration of wire corresponds to the frequency at the oscillating boundary at steady state. The damping factor suppresses the lateral movement of wire from the fixed boundary to moving boundary when it is increased. The change of axial wire speed or the oscillating frequency at boundary can counteract the suppression on the vibration response induced by increased damping factor. This study also presents an experimental study using an experimental setup of a slurry-fed wire with a periodic excitation to study the FAM process on silicon. The results of experiments show that vibration of wire can impart the silicon carbide abrasive grits in slurry to generate observable grooves and fractures on the surface of silicon in just a few minutes. The grooves and fractures are generated by the indentation of abrasive grits via loading and unloading on the silicon surface. When the vibrating wire is only fed with water without abrasives or under a dry condition, compressive deformation with shallow grooves on silicon is observed; however, the surface is found to be free of surface features of indentation and scratching. Furthermore, evidence of both wire compression and abrasive machining is more pronounced at the edges of silicon specimen, especially at the edge close to the periodic excitation, which is consistent to our modeling.
A High-Fidelity Thermal Model for a Novel Droplet-Based Additive Manufacturing Process for Polymers
Authors: Schroeffer Andreas , Maciuga Thomas , Struebig Konstantin , Lueth Tim C.
Published: November 2019

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.
Rotary Ultrasonic Machining of Basalt Rock Using Compressed Air As Coolant: A Study on Edge Chipping and Surface Roughness
Authors: Fernando Palamandadige , Zhang Meng , Pei Zhijian , Owens Adam
Published: November 2019

The aim of this study is to investigate the edge chipping and surface roughness of basalt rock processed by rotary ultrasonic machining (RUM) using compressed air as coolant. Basalt rock is commonly used as a building and construction material for foundations and dams, as well as in architectural designs such as constructing thin veneers and facades. Rotary ultrasonic machining, a hybrid process of grinding and ultrasonic machining, is employed to drill difficult-to-machine materials such as ceramics, composites, titanium alloys, stainless steel, etc. RUM has many advantages over conventional machining processes such as twist drilling. These advantages include lower cutting force, higher surface quality, lower tool wear, etc. This paper is the first in literature to report a study on edge chipping and surface roughness on RUM of basalt rock using cold compressed air as coolant. The effects of three input variables (tool rotation speed, feedrate, and ultrasonic power) on cutting force, torque, edge chipping, and surface roughness were studied. Experimental results obtained from this investigation show that RUM with cold air as the coolant has the capability to machine holes in basalt rock with a surface roughness of less than 3.5 μm without severe edge chipping.
An Analysis of Recent Standards on Composite Product Models to Enable Digital Transformation of Composite Product Manufacturing
Authors: Hedberg Thomas , Feeney Allison Barnard , Srinivasan Vijay , Hunten Keith
Published: November 2019

ASME and ISO are issuing new editions of their standards that deal with definitions and models for composite products. The new edition of ASME Y14.37 deals with standardized product definition for composite parts. The Edition 2 of ISO 10303-242 contains standardized data models for three-dimensional representations of composite products. This paper analyzes several salient features of these two standards with a focus on their potential impact on the digital transformation of composite product manufacturing. It also provides a mathematical and information theoretic exposition of ply table as an important representation for modeling some of the complex composite products and their manufacturing processes.
Ultrasonically-Induced Patterning of Viable Cells in Viscous Bioinks During 3D Biofabrication
Authors: Chansoria Parth , Shirwaiker Rohan
Published: November 2019

In attempts to engineer human tissues in the lab, bio-mimicking the cellular arrangement of natural tissues is critical to achieve the required biological and mechanical form and function. Although biofabrication employing cellular bioinks continues to evolve as a promising solution over polymer scaffold based techniques in creating complex multi-cellular tissues, the ability of most current biofabrication processes to mimic the requisite cellular arrangement is limited. In this study, we propose a novel biofabrication approach that uses forces generated by bulk standing acoustic waves (BSAW) to non-deleteriously align cells within viscous bioinks. We computationally determine the acoustic pressure pattern generated by BSAW and experimentally map the effects of BSAW frequency (0.71, 1, 1.5, 2 MHz) on the linear arrangement of two types of human cells (adipose-derived stem cells and MG63) in alginate. Computational results indicate a non-linear relationship between frequency and acoustic pressure amplitude. Experimental results demonstrate that the spacing between adjacent strands of aligned cells is affected by frequency (p < 0.0001), and this effect is independent of the cell type. Lastly, we demonstrate a synergistic technique of gradual crosslinking in tandem with the BSAW-induced alignment to entrap cells within crosslinked hydrogels. This study represents an advancement in engineered tissue biofabrication aimed at bio-mimicry.
Degradation Assessment of Reciprocating Seal Using Support Vector Regression
Authors: Ramachandran Madhumitha , Keegan Jon , Siddique Zahed
Published: November 2019

Reciprocating seal located directly on the rod/piston of a reciprocating equipment is used for preventing leakage and reducing wear between two parts that are in relative motion. Degradation assessment of reciprocating seal is extremely important in the manufacturing industry to avoid fatal breakdown of reciprocating equipment and machines. In this paper, we have proposed a data-driven prognostics approach using friction force to predict the degradation of reciprocating seal using Support Vector Regression. Statistical time domain features are extracted from friction force signal to reduce the complexity of raw data. Principal Component Analysis is used to fuse the relevant features and remove the redundant features from the process. Based on the selected features, a Support Vector Regression model is then built and trained for the prediction of seal degradation. A Grid search method is used to tune the hyperparameters in the SVR model. Run-to-failure data collected from an experimental test set-up is used to validate the proposed methodology. The study findings indicate that a small set of relevant features which can represent the pattern related to degradation is sufficient to have a high prediction accuracy. The seal tested for this study comes from oil and gas industry, but the proposed method can be implemented in any industry with reciprocating equipment and machines.
Design of Flexible Membrane Fixture for Automobile Door-Trim Infra Stake Welding Machine
Authors: Park Hong-Seok , Namjil Khash-Ochir
Published: November 2019

Flexible membrane fixture is new technology which can adapt to the workpiece shape and size change, such as automobile door-trim parts manufacturing. Due to the use of flexible membrane fixture, significantly reducing manufacturing cost and replacing fixture time. In this paper, the design of the flexible membrane fixture is generated, and the application is showed in a case. Natural rubber sheet used as a flexible membrane. The membrane inflation model generated by ANSYS using Mooney-Rivlin method and its simulation result compared with the experiment result. The door-trim model developed by AUTODESK INVENTOR modelling software. This 3-D geometric model was imported to using ANSYS Workbench 18.2. The Finite element analysis was done after assigning loading and boundary conditions. The applied load considered for this analysis is the pressure applied to the membrane while the door-trim clamped by side clamps. The result shows that Flexible membrane fixture has higher flexibility and fixtured door-trim has smaller deformation value than company requirement. Through comparing the design results, it is found that flexible membrane fixture has higher elastic behaviour.
Numerical Analysis of In-Process Heat Transfer and Material Flow During Dissimilar Friction Stir Welding Process
Authors: Chen Gaoqiang , Liu Xun , Shi Qingyu
Published: November 2019

Friction stir welding (FSW) has been successfully applied to join dissimilar materials in engineering applications. Fundamental understanding on the underlying physical principles of the dissimilar FSW process is generally required to achieve strong and reliable joints. In this study, we aim to develop a theoretical and numerical model based on computational fluid dynamics (CFD) in order to analyze the in-process heat transfer and material flow during the dissimilar FSW of aluminum and steel. The model describes the coupling behavior between the material distribution, thermal-mechanical properties, interfacial friction, heat generation and transfer. To account for the different material behaviors in stirring zone, a VOF-based approach is adopted. In this paper, preliminary numerical simulation is conducted. Simulation results show that the current modeling approach has the capability to capture the material mixing during the dissimilar FSW of aluminum and steel. The predicted temperature field is shown to be asymmetrical, which is attributed to the different properties of aluminum and steel. The predicted thermal history agrees with the experimental measurements in the literature.
Joint Formation and Mechanical Performance of Friction Self-Piercing Riveted Aluminum Alloy AA7075-T6 Joints
Authors: Ma YunWu , Li YongBing , Lin ZhongQin
Published: November 2019

AA7xxx series aluminum alloys have great potentials in mass saving of vehicle bodies due to pretty high specific strength. However, the use of these high strength materials poses significant challenges to traditional self-piercing riveting (SPR) process. To address this issue, friction self-piercing riveting (F-SPR) was applied to join aluminum alloy AA7075-T6 sheets. F-SPR is realized by feeding a high speed rotating steel rivet to aluminum alloy sheets to form a dissimilar material joint. The effects of spindle speed and rivet feed rate on F-SPR joint cross-section geometry evolution, riveting force and energy input were investigated systematically. It was found that the rivet shank deformation, especially the buckling of the shank tip before penetrating through the top sheet has significant influence on geometry and lap-shear failure mode of the final joint. A medium rivet feed rate combined with a high spindle speed was prone to produce a defect free joint with sound mechanical interlocking. F-SPR joints with the failure mode of rivet shear fracture was observed to have superior lap-shear peak load and energy absorption over the joints with mechanical interlock failure. The optimized F-SPR joint in this study exhibited 67.6% and 13.9% greater lap-shear peak load compared to, respectively, SPR and refill friction stir spot welding joints of the same sheets. This research provides a valuable reference for further understanding the F-SPR process.
Cone Electrospinning Polycaprolactone / Collagen Scaffolds With Microstructure Gradient
Authors: Nowlin John , Islam Md Maksudul , Zhou Yingge , Tan George Z.
Published: November 2019

Polycaprolactone (PCL) is a synthetic biomaterial that has been widely used for tissue engineering scaffolds. Collagen, a natural polymer found in various tissues in the human body, can be electrospun in combination with PCL to improve the scaffold’s biological characteristics for cell attachment, growth and differentiation. Recreating the physical structure which mimics the extracellular matrix of musculoskeletal tissues generally requires fibrous patterns, including aligned, random, or a mixture of both to form a gradient structure. This study introduced a novel cone rotation electrospinning technique for nanofiber scaffold with microstructure gradient. The effects of key process parameters on nanofiber attributes were evaluated through a factorial design of experiment. We found that changing the rotation speed, electrospinning distance, and position on the cone had significant effects on the structure gradient of nanofiber mats. This cone rotation technique extends the capability of conventional electrospinning to create tunable anisotropic nanofiber scaffolds as potential biomimetic solutions for tissue regeneration.
Surface Roughness Measurement of Additive Manufactured Parts Using Focus Variation Microscopy and Structured Light System
Authors: Zhang Xiao , Suresh Vignesh , Zheng Yi , Wang Shaodong , Li Qing , Lyu Hao , Li Beiwen , Qin Hantang
Published: November 2019

Surface roughness is a significant parameter when evaluating the quality of products in the additive manufacturing (AM) industry. AM parts are fabricated layer by layer, which is quite different from traditional formative or subtractive methods. A uniform feature can be obtained along the direction of the AM printhead movement on the surface of manufactured components, and a large waviness value can be found in the direction perpendicular to printhead movement. This unique characteristic differentiates additive manufactured parts from casted or machined parts in the way of measuring and defining surface roughness. Therefore, it is necessary to set up new standards to measure surface roughness of AM parts and analyze the variation in the topographical profile. The most widely used instruments for measuring surface roughness are profilometer and laser scanner, but they cannot generate 3D topographical surfaces in real-time. In this work, two non-contact optical methods based on Focus Variation Microscopy (FVM) and Structured Light System (SLS) were adopted to measure the surface topography of the target components. The FVM captures images of objects at different focus levels. By translating the object’s position based on focus profile, a 3D image is obtained by data fusion. The lab-made microscopic SLS was used to perform simultaneous whole surface scanning with the potential to achieve real-time 3D surface reconstruction. The two optical metrology systems generated two totally different point cloud data sets. Limited research has been conducted to verify whether the point cloud data sets generated from different optical systems are following the same distribution. In this paper, a statistical method was applied to test the difference between two systems. By using data analytics approaches for comparison analysis, it was found that surface roughness based on the FVM and the SLS systems has no significant difference from a data fusion point of view, though point cloud data generated were completely different in values. In addition, this paper provided a standard measurement approach for a real-time, non-contact method to estimate the surface roughness of AM parts. The two metrology techniques can be applied for in-situ real-time surface analysis and process planning for AM.
Localized Microstructures Fabrication Through Standing Surface Acoustic Wave and User-Defined Waveguides
Authors: Wang Yancheng , Han Chenyang , Mei Deqing , Xu Chengyao
Published: November 2019

Polymer-based substrates with patterned microstructure on the surfaces, e.g., cell culturing scaffolds, have been utilized in biomedical applications. This paper develops a novel method to fabricate the localized microstructure on the polymer-based substrate with the assistance of standing surface acoustic wave (SAW) and user-defined acoustic waveguides. The specific designed acoustic waveguides can localize the standing acoustic waves and transmit to the liquid film and excite patterned microstructures on the surface, then using ultraviolet (UV) to solidify the substrate with patterned microstructures. The structural design and fabrication of the SAW device and three different shaped acoustic waveguides are presented. Then, experimental setup and procedures to verify the polymer-substrate with localized microstructures fabrication are performed. By using the different shape of the acoustic waveguides, several types of patterned microstructures with different morphologies are successfully fabricated. Results demonstrated that the proposed fabrication method is an effective way to fabricate polymer-based substrate with localized patterned microstructures, which may have potential in the research on tissue engineering, cell-cell interaction, and other biomedical applications.
A Review on Additive Manufacturing of Ceramics
Authors: Mansfield Brooke , Torres Sabrina , Yu Tianyu , Wu Dazhong
Published: November 2019

Additive manufacturing (AM), also known as 3D printing, has been used for rapid prototyping due to its ability to produce parts with complex geometries from computer-aided design files. Currently, polymers and metals are the most commonly used materials for AM. However, ceramic materials have unique mechanical properties such as strength, corrosion resistance, and temperature resistance. This paper provides a review of recent AM techniques for ceramics such as extrusion-based AM, the mechanical properties of additively manufactured ceramics, and the applications of ceramics in various industries, including aerospace, automotive, energy, electronics, and medical. A detailed overview of binder-jetting, laser-assisted processes, laminated object manufacturing (LOM), and material extrusion-based 3D printing is presented. Finally, the challenges and opportunities in AM of ceramics are identified.
Numerical Study of Porosity Formation With Implementation of Laser Multiple Reflection in Selective Laser Melting
Authors: Cheng Bo , Tuffile Charles
Published: November 2019

In selective laser melting (SLM) process, the build part quality is determined by process parameters such as laser scanning speed and power. The presence of porosity, a major printing defect that significantly affects part performance, may arise in laser melting process due to insufficient or excess energy input. The improvement of build quality heavily depends on fundamental understanding of porosity formation in the SLM process. In this study, the discrete element method (DEM) has been utilized to simulate the creation of a newly deposited powder layer. A computational fluid dynamics (CFD) model was developed to simulate the melting and solidification process of Ti-6Al-4V powders in the SLM process. The thermo-fluid model includes effect of surface tension and recoil pressure as well as laser ray multi-reflection in keyhole. The predictability of the developed CFD model has been validated against literature experimental data. It is found that the collapse of an unstable deep keyhole was responsible for the formation of pores. In addition, higher laser scanning speeds tend to form unstable melt pools, e.g., melt pool break-up.
Effect of Post Laser Shock Peening on Microstructure and Mechanical Properties of Inconel 718 by Selective Laser Melting
Authors: Sidhu Kuldeep Singh , Wang Yachao , Shi Jing , Vasudevan Vijay K. , Mannava Seetha Ramaiah
Published: November 2019

This study investigates the effects of laser shock peening (LSP) on residual stress, near surface modification, and hardness of Inconel 718 (IN718) specimens manufactured by selective laser melting (SLM) technique. Optical microscope and electron backscattered diffraction (EBSD) is used to characterize the microstructures of both heat-treated and as-built specimens. A nanoindentation test is performed to determine the properties such as the hardness of as-built and heat-treated specimens. Afterward, the hardness along the distance from the LSP treated surface is also defined. To investigate the effect of LSP energy on the mechanical properties of specimens, two levels of LSP energy, e.g., low energy LSP (6.37 GW/cm2) and high energy LSP (8.60 GW/cm2), are carried out on selected samples. With the increase in laser energy density, it is found that both compressive residual stress and hardness increase after LSP treatment. The as-built specimens after high energy LSP treatment show the compressive residual stress of −875 MPa, and the surface hardness increases from 468 HV to 853 HV.
Modeling and Experimental Validation of Part-Level Thermal Profile in Fused Filament Fabrication
Authors: Roy Mriganka , Yavari Reza , Zhou Chi , Wodo Olga , Rao Prahalad
Published: November 2019

Part design and process parameters directly influence the spatiotemporal distribution of temperature and associated heat transfer in parts made using additive manufacturing (AM) processes. The temporal evolution of temperature in AM parts is termed herein as thermal profile or thermal history. The thermal profile of the part, in turn, governs the formation of defects, such as porosity and shape distortion. Accordingly, the goal of this work is to understand the effect of the process parameters and the geometry on the thermal profile in AM parts. As a step towards this goal, the objectives of this work are two-fold: (1) to develop and apply a finite element-based framework that captures the transient thermal phenomena in the fused filament fabrication (FFF) additive manufacturing of acrylonitrile butadiene styrene (ABS) parts, and (2) validate the model-derived thermal profiles with experimental in-process measurements of the temperature trends obtained under different feed rate settings (viz., the translation velocity, also called scan speed or deposition speed, of the extruder on the FFF machine). In the specific context of FFF, this foray is the critical first-step towards understanding how and why the thermal profile directly affects the degree of bonding between adjacent roads (linear track of deposited material), which in turn determines the strength of the part, as well as, propensity to form defects, such as delamination. From the experimental validation perspective, we instrumented a Hyrel Hydra FFF machine with three non-contact infrared temperature sensors (thermocouples) located near the nozzle (extruder) of the machine. These sensors measure the surface temperature of a road as it is deposited. Test parts are printed under three different settings of feed rate, and subsequently, the temperature profiles acquired from the infrared thermocouples are juxtaposed against the model-derived temperature profiles. Comparison of the experimental and model-derived thermal profiles confirms a high-degree of correlation therein, with maximum absolute error less than 10%. This work thus presents one of the first efforts in validation of thermal profiles in FFF via in-process sensing. In our future work, we will focus on predicting defects, such as delamination and inter-road porosity based on the thermal profile.
Micro-Scale Fiber Cutting Geometry Predictions During Milling of Carbon Fiber Reinforced Polymers (CFRP) Composites
Authors: Fu Xingyu , Song Kyeongeun , Kim Dongmin , Kim Gyuho , Min Byung-Kwon , Jun Martin Byung-Guk
Published: November 2019

Carbon Fiber Reinforced Polymer (CFRP) is a light-weight material with high strength and highly corrosion resistance, and hence is widely applied in aerospace industries. However, milling of CFRP usually generates machining defects (for instance, delamination and pull-out fibres), making processed surface unqualified to meet the requirement of aerospace application. Therefore, prediction for machining quality should be conducted before milling processing to avoid potential loss in massive production. Fracture behaviours of micro-scale fibres and matrix have a significant influence on the final machined surface, and such material removal mechanism can be mainly determined by micro-scale geometrical relationships between carbon fibers and milling teeth. In this paper, a micro-scale geometrical calculation software for CFRP milling is provided based on Dexel model. The software can generate geometrical parameters, for example, cutting angle, cutting length and engagement angle, for the whole milling process. Milling defects and milling forces can be conducted based on those micro-scale geometrical parameters.
Preliminary Study on Fractal-Based Monopole Antenna Fabricated Using 3D Polymer Printing and Selective Electrodeposition Process
Authors: James Sagil , Birar Shubham , Parekh Riken , Jain Kushal , George Kiran
Published: November 2019

Modern wireless communication industries need high performance antennas having better connectivity, ultra-wide bandwidth, lightweight and miniaturized. The current design and manufacturing process for antennas have several limitations. This study aims to address some of the limitations of designing and fabricating modern radio frequency wireless antennas. The study proposes a combination of fractal-based monopole antenna design followed by fabrication using additive manufacturing and selective electrochemical deposition process. Multiple designs of monopole antennas are compared, and the performance testing showed that the three-dimensional fractal-based antenna design showed the highest performance. The results of this study would be extremely crucial for overcoming challenges of modern antenna technologies.
Developing Measurement Science to Verify and Validate the Identification of Robot Workcell Degradation
Authors: Weiss Brian A.
Published: November 2019

Robot systems have become more prevalent in manufacturing operations as the technology has become more accessible to a wider range of manufacturers, especially small to medium-sized organizations. Although these robot technologies have become more affordable, easier to integrate, and greater in functional capability, these advanced systems increase workcell complexity leading to the presence of more fault and failure modes. Given increasing manufacturing competitiveness, maximizing asset availability and maintaining desired quality and productivity targets have become essential. The National Institute of Standards and Technology (NIST) is developing measurement science (e.g., test methods, performance metrics, reference data sets) to monitor the degradation within a manufacturing workcell that includes a six-degree-of-freedom robot arm. Numerous components of the workcell influence the accuracy of the robot’s tool center position. Identifying the component(s) responsible for process degradation prior to the process performing out of specification will provide manufacturers with advanced intelligence to maintain or maximize their performance targets and asset availability. NIST’s research in robot workcell health promotes workcell component health characterization and develops methods and tools to verify and validate this approach. This paper presents the overall research plan and the efforts to date in developing appropriate test methods, identifying key sources of workcell degradation, and presenting baseline performance data that is leveraged for health assessment.
Waste Reduction: A Review of Common Options and Alternatives
Authors: Williams Jewel , Warrington Shelby , Layton Astrid
Published: November 2019

Circular economy aims to address limited resources through the continuous circulation of materials and energy. Recirculating low quality materials for reuse is a sustainability goal that is analogous to the primary function of Nature’s detritus species, a keystone for the proper functioning of ecosystems. Prior applications of ecosystem structure to human network design uncovered that even the most economically successful networks of industries demonstrate a lack of analogous detritus actors in the form of reuse and recycling. The recycling industry’s volatile nature, dependency on international factors, and financial difficulties prevent this strategy from becoming an efficient alternative. Creativity in design, inspired by ecosystems, is proposed here as a method to repurpose manufacturing byproducts that are otherwise seen as low quality waste materials. Realizing the reuse potential of these materials can create detrital-type feedback loops, an attribute that supports the characteristic resilience and efficiency of ecosystems. The work here analyzes existing methods of pursuing circular economy and investigates the potential benefits generated by purposefully adding connects that create detrital-feedback-loops at the consumer and producer levels.
Mechanical Recycling of Low-Density Polyethylene/Carbon Nanotube Composites and its Effect on Material Properties
Authors: Stan Felicia , Stanciu Nicoleta-Violeta , Fetecau Catalin , Sandu Ionut-Laurentiu
Published: November 2019

In this paper, the impact of recycling and remanufacturing on the behavior of low-density polyethylene/multi-walled carbon nanotube (LDPE/MWCNT) composites is investigated. LDPE/MWCNT composites with 0.1–5 wt.%, previously manufactured by injection molding, were mechanically recycled and remanufactured by injection molding and 3D filament extrusion, and the rheological, electrical, and mechanical properties were analyzed and compared with those of virgin composites under the same conditions. Experimental results demonstrate that the recycled LDPE/MWCNT composites have similar rheological, electrical, and mechanical properties to virgin composites, if not better. Therefore, the recycled LDPE/MWCNT composites have a great potential for being used in engineering applications, while reducing the environmental impact.
Failure Detection and Remaining Life Estimation for Ion Mill Etching Process Through Deep-Learning Based Multimodal Data Fusion
Authors: He Anqi , Jin Xiaoning
Published: November 2019

Ion Mill Etching (IME) is an advanced process technology that uses ion-beam sources to remove materials by atomic sandblasting in order to reveal a specific pattern on the substrate. The high-precision capability requires stringent process monitoring and control of the flowcool system which is critical to prevent thermal deformation for temperature sensitive materials from the heat generated from the ion beam irradiation. This study focuses on a multi-sensor data analytics to monitoring the IME process condition — enabling diagnostics and prediction of three main failure mechanisms of the IME flowcool system. A generalizable framework of engineering-based data-driven failure diagnostics and prediction is developed using random forest-based classification and a Deep Long Short-Term Memory (LSTM)-based failure prediction. The proposed framework and methods are demonstrated and validated in an ion mill etching process using multi-sensor data collected from multiple run-to-failure cycles. Three different failure modes related to the flowcool system are detected, identified in real time and the time to the next failure is accurately predicted. The proposed method provides a systematic and generalizable approach for process monitoring and early prediction of failures by using heterogeneous sensor measurements and operational data when under various operating conditions and settings.
Ultrasonic Welding of Soft Polymer and Metal: A Preliminary Study
Authors: Meng Yuquan , Peng Dingyu , Nazir Qasim , Kuntumalla Gowtham , Rajagopal Manjunath C. , Chang Ho Chan , Zhao Hanyang , Sundar Sreenath , Ferreira Placid M. , Sinha Sanjiv , Miljkovic Nenad , Salapaka Srinivasa M. , Shao Chenhui
Published: November 2019

Joining soft polymers and metals is receiving increasing attention in both industry and academia to enable the manufacturing of innovative products. One motivation arises from the production of next-generation heat exchanges, the structure of which is primarily composed of polymers and metals. Waste heat coming from low temperature exhaust gas stream is significant in industries in the U.S. However, traditional heat exchangers that are available to recover heat in the presence of small temperature difference are large and costly, restricting the wide application of such heat exchangers. To address this challenge, a hybrid materials design is proposed to achieve a balance between thermal conductivity and mechanical strength. High quality requirement induced by the changing operating conditions necessitates a strong bonding between polymers and copper. In this research, the possibility of using ultrasonic welding, which is conventionally employed to join dissimilar or similar metal layers, is explored. Preliminary results from welding experiments and tensile shear tests reveal that two bonding modes exist in the welding of PET and copper. Furthermore, analysis of power signals collected during welding shows that one can potentially monitor and optimize welding processes using monitoring signals. It is concluded from this study that ultrasonic welding has excellent potential in joining soft polymers and metals. Future work is also discussed on the process improvement and mechanism investigation.
Fabrication of Copper Foam Plate Using Friction Sintering
Authors: Sharma Vyas Mani , Racherla Vikranth , Pal Surjya Kanta
Published: November 2019

A novel friction sintering process is used to obtain large copper foam plates using sintering and dissolution process. The process ensures easy and quick removal of the sintered product. Heat and pressure generated by downfeed of rotating tungsten tool pressed against a “top plate” results in solid-state sintering of copper powder particles. The large sized sintered part was obtained by providing a scan path for tool covering the “die” containing Cu-NaCl mixture. Note that no pre-compression of Cu-NaCl is done before the start of the process. Compaction and sintering both happen during the course of friction sintering. Scanning electron microscopy (SEM) images of fracture surface indicate that pore morphology is dictated by the morphology of NaCl particles. Temperature increases with the increase in plunge depth. The stress-strain curves for obtained foam in compression are similar to the reported in.
Cutting Process Simulation in Micro Dimple Machining
Authors: Matsumura Takashi , Musha Yuji
Published: November 2019

The paper discusses micro dimple millings with inclined ball end mills. Cutting process models are presented to control the dimple shapes and predict the cutting forces. In micro dimple milling, the cutter rotation axis is inclined to have the non-cutting time, during which the cutting edges don’t remove the material in a rotation of cutter. The end mill is fed at a high rate so that the machining areas removed by the cutting edges are not overlapped each other. The shapes and the alignment of the dimples are simulated for the cutting parameters in the mechanistic model. Then, the cutting forces are predicted for high machining accuracies. The cutting experiments were conducted to verify the micro dimple machining. The dimple shape model is validated in comparison between the simulated and the actual dimple shapes. The cutting forces are simulated to compare the measured ones. The force model works well to predict the cutting forces with the chip flow direction during a rotation of the cutter.
Significance of Workpiece Conductivity on Resistance Spot Welding Process Map
Authors: Wu Xin , Du Jingtao , Cai Wayne
Published: November 2019

Resistance spot welding (RSW) is a sheet metal welding process with broad applications, known to be more suitable for low-conductive materials, such as steels, due to concentrated and steady-state heat generation and retention at the metal interface. However, for high conductive metals such as copper, conventional welding processes in resistance spot welding has not been successful. This paper provides a comparative study of resistance welding among steel, aluminum and copper through mechanistic analyses, i.e., analytical solutions calibrated by finite element analyses. It is found when lower conductivity metals, such as steels, are welded, the applied energy can be more concentrated on the interfaces, and the heat dissipation is relatively slow, so that a close to steady-state welding condition can be reached that provides a wide and robust operation window. For welding highly conductive metals having similar melting temperature as that of electrode, the process window becomes much narrower or does not always exist without additional conditioning of materials, design or the welding processes. The physics of RSW process is analyzed based on energy equilibrium, and a new concept of pulse welding process is proposed as a required operation mode for welding copper during temperature ramping up period and prior to electrode melting. A new type of welding limit diagram (WLD) is constructed that contains three welding limit curves (WLC) for nugget formation, and the transient region. The newly constructed WLD allows a clear distinction between welding low- and high-conductive metals, and provides new understanding and a theoretical guidance for widening the weldability window.
Ultrafast Laser Applications in Manufacturing Processes: A State of the Art Review
Authors: Lei Shuting , Zhao Xin , Yu Xiaoming , Hu Anming , Vukelic Sinisa , Jun Martin B. G. , Joe Hang-Eun , Yao Y. Lawrence , Shin Yung C.
Published: November 2019

With the invention of chirped pulse amplification for lasers in the mid-1980s, high power ultrafast lasers entered into the world as a disruptive tool, with potential impact on a broad range of application areas. Since then, ultrafast lasers have revolutionized laser-matter interaction and unleashed their potential applications in manufacturing processes. With unprecedented short pulse duration and high laser intensity, focused optical energy can be delivered to precisely defined material locations on a time scale much faster than thermal diffusion to the surrounding area. This unique characteristic has fundamentally changed the way laser interacts with matter and enabled numerous manufacturing innovations over the past few decades. In this paper, an overview of ultrafast laser technology with an emphasis on femtosecond laser is provided first, including its development, type, working principle, and characteristics. Then ultrafast laser applications in manufacturing processes are reviewed, with a focus on micro/nano machining, surface structuring, thin film scribing, machining in bulk of materials, additive manufacturing, bio manufacturing, super high resolution machining, and numerical simulation. Both fundamental studies and process development are covered in this review. Insights gained on ultrafast laser interaction with matter through both theoretical and numerical research are summarized. Manufacturing process innovations targeting various application areas are described. Industrial applications of ultrafast laser based manufacturing processes are illustrated. Finally, future research directions in ultrafast laser based manufacturing processes are discussed.
Corrective Maintenance Scheduling for Stochastic Manufacturing System by Online Task Allocation Method
Authors: Zhu Cheng , Yu Tian , Chang Qing , Arinez Jorge
Published: November 2019

Disruption events such as machine random failures significantly impact the throughput of the line. Maintenance actions could restore the machines to certain health levels. A real-time scheduling of corrective maintenance (CM) is critical to improve the machines’ performance, hence to improve overall system productivity and quality. Due to the limited quantity of technicians or robots in manufacturing system, when, where and assign what type of maintenance is a complicated decision to make. A proper strategy to assign CM can greatly reduce permanent production lost, resource and energy consumption. In this paper, an online task allocation (OTA) method is provided to solve the assignment of CM for a stochastics serial production line. Case study is given to demonstrate the effectiveness of OTA method in assigning CM.