bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid Manufacturing in Minutes: The Development of a Mask Projection Stereolithography Process for High-Speed Fabrication
Authors: Pan Yayue , Zhou Chi , Chen Yong
Published: July 2013

The purpose of this paper is to present a direct digital manufacturing (DDM) process that is an order of magnitude faster than other DDM processes currently available. The developed process is based on a mask-image-projection-based Stereolithography process (MIP-SL), during which a Digital Micromirror Device (DMD) controlled projection light cures and cross-links liquid photopolymer resin. In order to achieve high-speed fabrication, we investigated the bottom-up projection system in the MIP-SL process. A set of techniques including film coating and the combination of two-way linear motions have been developed for the quick spreading of liquid resin into uniform thin layers. The process parameters and related settings to achieve the fabrication speed of a few seconds per layer are presented. Additionally, the hardware, software, and material setups developed for fabricating given three-dimensional (3D) digital models are presented. Experimental studies using the developed testbed have been performed to verify the effectiveness and efficiency of the presented fast MIP-SL process. The test results illustrate that the newly developed process can build a moderately sized part within minutes instead of hours that are typically required.
Formation Condition of Scale Layer on Work Roll in Hot Steel Rolling
Authors: Azushima Akira , Nakazawa Kento
Published: July 2013

It is well known that scale layer on work roll forms in hot sheet rolling of steel and scale layer on work roll plays an important role for hot rolling process. The formation conditions of scale layer on work roll are slightly known qualitatively and are hardly understood quantitatively. In order to investigate quantitatively the conditions of scale formation, three steels with different Si content are used and the slip rolling is carried out at a constant roll speed changing the scale thickness of steel workpiece and the reduction. The formation conditions of scale layer on work roll are examined quantitatively by observation of work roll surface after slip rolling. The experiments are carried out at constant rolling conditions of a velocity ratio of 20, a rolling speed of 50 m/min and a furnace temperature of 800 °C, changing the rolling reductions of 0.3, 0.5 and 1.0 mm and scale thickness of workpiece. The colza oil is used as base oil. The emulsion concentration is 3.0%. The emulsion temperature is controlled at 40 °C. Scale layer on work roll forms easily with increasing rolling reduction and decreasing scale thickness of workpiece for three steels A, B and C. In order to estimate quantitatively the formation condition of scale layer on work roll, parameter α which is given by a ratio of the rolling reduction to scale thickness of workpiece is proposed. Scale layer on work roll forms when values of parameter α become same for each steels. Values of parameter α become larger in order of steels A, B and C and it can be understood that scale layer on work roll forms easily in order of steels A, B and C. When FeO layer in scale of the steel surface adheres on work roll surface, it is expected that scale layer on work roll forms easily and strongly by transformation from FeO to Fe3O4, considering that the chemical composition of scale layer on work roll is Fe3O4.
Higher Competitiveness of Speed-Stroke Grinding by Using Increased Wheel Speeds
Authors: Duscha M. , Linke B. , Klocke F. , Dornfeld D.
Published: July 2013

Production engineering faces the challenge to satisfy the increasing industrial demand for higher productivity and high requirements on workpiece quality at the same time. Furthermore, the rising environmental awareness adds additional constraints. Especially grinding processes have high relevance for industrial applications because they generate high quality surfaces and they are most effective for hard-to-machine materials. New technologies like speed-stroke grinding and high cutting speeds enable higher productivity. However, to be competitive to conventional grinding operations energy aspects have to be regarded thoroughly. This work shows how the combination of speed-stroke grinding and high speed machining can boost process performance, workpiece quality and process sustainability.
Mixed Lubrication Model for Cold Rolling Considering the Inlet and Deformation Zones
Authors: Bergmann Martin , Zeman Klaus , Kainz Alexander , Krimpelstätter Konrad , Paesold Dieter , Schellingerhout Peter , Smeulders Bas
Published: July 2013

A mixed lubrication model for cold rolling was developed by separating, according to common concepts, the domain of calculation into two zones: the inlet zone and the zone of plastic strip bulk deformation. The analysis of the inlet zone mainly focuses on film formation from different lubricants based on the evolution of layers consisting of neat oil on the metallic surfaces. In the zone of plastic strip bulk deformation, contributions of boundary and hydrodynamic friction are modeled incorporating longitudinal and transversal roughness components. Lubricant pressure, which is influenced by the geometry of these roughness structures, is governed by hydrodynamic mechanisms. Additionally, lubricant temperature in the roll bite is predicted by an integrated thermodynamics sub-model. While coupling between the inlet and plastic deformation zones is performed iteratively, the highly non-linear and coupled equations for the latter zone are solved simultaneously by applying a variant of the well-known damped Newton-Raphson method.
Intelligent Modeling and Optimization of Material Removal Rate in Electric Discharge Diamond Grinding
Authors: Shrivastava Pankaj Kumar , Dubey Avanish Kumar
Published: July 2013

Metal matrix composites (MMCs) have wide applications in modern manufacturing industries due to their specific and improved technological characteristics such as high strength to weight ratio, high hardness, high thermal, corrosion and wear resistances. Such characteristics are highly demanded in automobile, aircraft and space research organizations. Shaping of MMCs has been a big challenge for manufacturing industries due to their superior mechanical properties and the peculiar microstructure composed of different phases in MMCs poses machining challenges. Unconventional machining methods have become an alternative to give desired shapes with intricate profiles and stringent design requirements. The aim of present research is to investigate the machining performance of copper-iron-carbide MMC using hybrid machining process, electric discharge diamond grinding (EDDG). A hybrid approach of neural network and genetic algorithm has been used to develop the intelligent model for material removal rate (MRR) and subsequent optimization with the experimental data obtained by scientifically designed experimentation.
Force Model for Needle-Tissue Interaction
Authors: Han Peidong , Pallav Kumar , Ehmann Kornel
Published: July 2013

Force modeling of needle insertion into soft tissue is important for accurate needle placement and efficient tissue cutting. In this paper, we studied the pre-puncture and puncture forces during needle insertion. A plane strain FE model was developed to simulate the pre-puncture force prior to tissue rupture. A sensitivity study was performed to investigate the influence of needle and tissue characteristics on pre-puncture force using FE simulation. A force model that incorporates needle geometry and tissue properties was proposed. The force model was able to accurately predict the needle tip force prior to tissue rupture. In addition to studying the pre-puncture force, the puncture force was experimentally characterized for different needle diameters and tip angles. The experimental results show that the puncture force has a strong dependency on needle geometry.
Joint Maintenance and Production Operations Decision Making in Flexible Manufacturing Systems
Authors: Celen Merve , Djurdjanovic Dragan
Published: July 2013

In highly flexible and integrated manufacturing systems such as those in semiconductor manufacturing, there exist strong dynamic interactions between the equipment condition, operations executed on the equipment and the resulting product quality. These interactions necessitate a methodology that integrates the decisions of maintenance scheduling and production operations. Currently, maintenance and production operations decision-making are two decoupled processes. In this paper we aim to devise an integrated decision making policy for maintenance scheduling and production sequencing with the objective of maximizing an adaptive profit function, while taking into account operation-dependent degradation models and a production target. In order to obtain the optimal decision policy, a metaheuristic method based on the results of discrete-event simulations of the target manufacturing system is used. The new approach is demonstrated in simulations of a generic cluster tool routinely used in semiconductor manufacturing. The results show that jointly making maintenance and production sequencing decisions consistently outperforms the current practice of making these decisions separately.
Estimation of Cutting Force Model Coefficients to Track Wear in Milling Using Bayesian Analysis
Authors: Nouri Mehdi , Fussell Barry K. , Jerard Robert B. , Gao Lei , Linder Ernst
Published: July 2013

Our previous research has demonstrated the feasibility of monitoring tool wear during milling by continuously updating the coefficients of a cutting force model. The method requires a robust method for on-line model coefficient estimation. Estimation using Least Square Regression (LSR) is easily implemented but requires that the data points come from different cutting conditions which is not always possible. In this paper, a method for coefficient estimation and wear tracking based on Bayesian updating is described. The Bayesian method has the advantage that it can be used when the cutting conditions are constant.
Minimized Wear and Debris Generation Through Optimized Machining of Co-Cr-Mo Alloys for Use in Metal-on-Metal Hip Implants
Authors: Deshpande Ashish , Yang Shu , Puleo Dave , Pienkowski David , Dillon Oscar , Outeiro Jose , Jawahir I. S.
Published: July 2013

More than 380,000 hips are replaced with total joint prostheses each year in the U.S. Wear debris generated by metal-on-metal implant designs is of concern due to potential adverse biological effects arising from chronic exposure of human tissue to the wear debris. This paper presents a new methodology for optimizing the wear performance of prosthesis made of Co-Cr-Mo alloys by varying tool edge geometry and machining conditions to alter the wear behavior of this alloy, while also controlling the residual stresses induced during the machining process. The machining process causes inhomogeneous inelastic deformations near the surface layer of machined parts which create residual stresses in the surface of machined components. Residual stresses in the machined surface and the subsurface are affected by cutting tool material, tool geometry, workpiece, tool-work interface conditions, and the cutting parameters such as feed rate, depth of cut and cutting speed. In the current work, residual stresses were measured using X-ray diffraction technique (XRD). The surface residual stresses in two directions (radial and hoop) were measured on the machined pins after machining with different machining conditions, but prior to the wear test. Wear behavior of Co-Cr-Mo alloy pin specimens, produced from machining with varying tool edge geometry and machining conditions, was studied using a custom-made biaxial motion pin-on-disc tribological testing system in which the pin specimen is immersed in a simulated bio-fluid environment. Wear-induced weight loss (± 10 μg) and changes in surface roughness (± 0.001 μm) were obtained at 100,000 cycle intervals upto 500,000 cycles. Metallographic analysis was performed on the machined pin specimens to analyze the microstructure and microhardness before and after testing. The rate of wear for the specimens was lowest for those pins where the change of the subsurface microhardness was small due to prevention of additional steady state wear after the initial run-in wear in the wear tester. A combination or response surface methodology and genetic algorithm (GA) was used in to optimize the various machining parameters for minimized wear generation. The optimal combination of the four machining parameters (feed 0.18mm/rev, nose radius 0.6 mm, cutting speed 27.6 m/min and depth of cut 0.38) produced the largest compressive residual stresses on the surface and subsurface of the implants thereby reducing the wear/debris generation by about fifty percent.
Experimental Investigation of Hard Turning Mechanisms by PCBN Tooling Embedded Micro Thin Film Thermocouples
Authors: Li Linwen , Li Bin , Li Xiaochun , Ehmann Kornel F.
Published: July 2013

Temperature-distribution measurements in cutting tools during the machining process are extremely difficult and remain an unresolved problem. In this paper, cutting temperature distributions are measured by thin film thermocouples (TFTCs) embedded into Polycrystalline Cubic Boron Nitride (PCBN) cutting inserts in the immediate vicinity of the tool-chip interface. Using these measurements, steady and dynamic phenomena during hard turning as well as the chip morphology and formation process were analyzed based on the cutting temperature distributions in the insert. The relationship between the cutting temperature-field distributions in the PCBN insert and the segmented chip formation is analyzed using temperature-distribution mapping. It is shown that the temperature-distribution in the cutting zone depends on the shearing band distribution in the chip and the thermal transfer rate from the heat generation zone to the cutting tool. Furthermore, it became evident that the material flow stress and the shearing bands greatly affect not only the chip formation morphology but also the cutting temperature field distributions in the cutting zone of the cutting insert.
Methodology to Determine Friction in Orthogonal Cutting With Application to Machining Titanium and Nickel Based Alloys
Authors: Ulutan Durul , Özel Tuğrul
Published: July 2013

Friction plays a very important role in machining titanium and nickel alloys. It is the source for the high amount of heat generation, and as a result, the excessive tool wear during machining these materials. The worn tool is known to create lower surface qualities with tensile surface residual stresses and machine-induced hardening at the surface, as well as high surface roughness. It is essential to create a method to determine how and to what extent the friction is built up on the tool. This study facilitates a determination methodology to estimate the friction coefficients between the tool and the chip on the rake face, as well as the tool and the workpiece on the flank face of the tool. The results are validated with experimental results from the titanium alloy Ti-6Al-4V and the nickel alloy IN-100.
Degradation-Based Swapping Policy With Application to System-Level Manufacturing Utilization
Authors: Almuhtady Ahmad , Lee Seungchul , Ni Jun
Published: July 2013

Degradation is an inevitable course of any manufacturing tool, machine or system. The degradation of the health state of manufacturing tools results in some sort of an ineludible maintenance action which could be both costly and happening in a critical production time. In most manufacturing systems, a fleet of identical machines are assigned different tasks towards satisfying requirements within the production process. We introduce a degradation-based resource allocation policy to optimally utilize a fleet of identical machines. The policy, denoted as Degradation Based Swapping Optimization (DBSO), incorporates the optimal implementation of swapping scheduled tasks and scheduling maintenance actions throughout a finite time horizon to minimize projected maintenance costs and/or utilize the manufacturing productivity towards pre-specified logistics objectives. A mathematical model for the policy is provided and this model is optimized using elitist genetic algorithm and simulated annealing algorithm where numerical results have been introduced. The proposed policy succeeds in establishing substantial savings in the simulated example which amount to 43% of the estimated maintenance costs in comparison to the scenario where fixed scheduling is applied.
Reduction of Vibrations in Ball Screw Driven Machine Tools by the Optimal Selection of Nut Parameters
Authors: Okwudire Chinedum E. , Zhao Peng
Published: July 2013

Due to the growing need for sustainable manufacturing processes, machine tool designers are constantly looking for ways to reduce unwanted structural vibrations without having to increase the mass/inertia of moving components, which in turn increases the energy consumption and cost of the machines. Recent research has shown that, due to the coupling introduced by the nut, the torque applied to ball screw drives by the motor causes undesirable lateral (bending) vibrations of the screw, which adversely affects the fatigue life and positioning accuracy of ball screw drives. By analyzing the stiffness matrix connecting the screw to the nut, this paper shows that the helix angle of the screw and the entry/exit angles of the balls have the most influence on the degree of coupling between motor torque and lateral vibrations of the screw. Consequently, by carefully selecting the helix angle of the screw together with the entry/exit angles of the balls, the undesirable lateral vibrations of the screw can be minimized, without having to increase the diameter (i.e. stiffness/inertia) of the ball screw. The merits and limitations of the proposed method are demonstrated using simulations on a single-axis ball screw driven machine.
Biaxial Work Hardening Characteristics of 6000 Series Aluminum Alloy Sheet for Large Strain Range
Authors: Yanaga Daisaku , Kuwabara Toshihiko , Uema Naoyuki , Asano Mineo
Published: July 2013

Deformation behavior of 0.9-mm-thick 6016-T4 aluminum alloy sheet with a high intensity of the cube orientation under biaxial tension was investigated. First, many linear stress paths in the first quadrant of stress space were applied to cruciform specimens to precisely measure the deformation behavior of the test material up to an equivalent strain of 0.04. True stress-true plastic strain curves, contours of plastic work in stress space and the directions of plastic strain rates were measured and compared with those calculated using selected yield functions. Second, in an effort to observe the plastic deformation behavior of the sample up to much larger strains over 0.1, the sample was bent and YAG-laser welded to fabricate tubular specimens with an inner diameter of 44.6mm. Using a servo-controlled tension-internal pressure testing machine, plane strain tension tests were performed. Hydraulic bulge test was also performed. The material exhibits significant differential work hardening; the Yld2000-2d yield functions with exponents of 6, 12 and 32 had the best agreement with the experimental work contours for the equivalent plastic strains of 0.002, 0.04 and 0.14, respectively.
A Preliminary Numerical Study of the Slurry Wire Sawing Process
Authors: Chung Chunhui
Published: July 2013

Slurry wire saw has been utilized to slice the brittle semiconductor wafer substrates for over 20 years. However, the complicated slicing process limits the further studies and advances of this exclusive slicing tool for big wafers. In this study, a numerical model of the slurry wire sawing process was developed based on the mechanism of brittle indentation cracks. The simulation results illustrate how the factors such as wire speed, wire tension, and feed rate of the ingot affect the slicing conditions including the bow angles of the wire and the local normal loads on both the workpiece and the wire. In addition, the results show that the steady-state condition would be reached via overshooting or non-overshooting approach based on the slicing parameters. A higher wire speed is suggested to reduce the bow angles and local loads during slicing process. However, the limitation of the wire speed depends on the material of the wire and the specification of the wire saw machine.
Development of a Fiber Orientation Measurement Methodology for Injection Molded Thermally-Enhanced Polymers
Authors: Hall Timothy , Subramoniam Arumugham Vaishnavi , Bruck Hugh A. , Gupta Satyandra K.
Published: July 2013

Thermally-enhanced polymer composites are a promising alternative to exotic metals in seawater heat exchanger applications due to the low cost and corrosion resistance of base polymers and heat transfer rates competitive with corrosion-resistant metals such as titanium or stainless steel. While the properties of thermally-enhanced polymer composites are well-suited for heat exchanger applications, fiber orientation has a strong influence on the structural and thermal performance of the manufactured components. In this study, a method of creating samples, sectioning and polishing them for imaging, microscope sampling for the identification of fibers, image processing to characterize fiber orientation, and finally comparison to predictions from computer-aided engineering (CAE) software is demonstrated for collecting experimental information on fiber orientation of molded parts. Understanding fiber orientation in injection-molded polymer heat exchangers is important for ensuring ideal heat transfer and structural performance and this study presents an experimental methodology for determining the influence of injection molding process parameters on fiber orientation in thermally-enhanced polymer composite geometries.
Web Based Monitoring and Control of Distant Robotic Operations
Authors: Holm Magnus , Givehchi Mohammad , Mohammed Abdullah , Wang Lihui
Published: July 2013

In order to improve the production efficiency while facing today’s manufacturing uncertainty, responsive and adaptive capabilities for rapid production changes are essential. This paper presents how dynamic control and real-time monitoring (embedded in a web-based Wise-ShopFloor framework) can integrate virtual models with real shop floors. Wise-ShopFloor (Web-based integrated sensor-driven e-ShopFloor) uses Java technologies (e.g., Java Servlet and Java3D) for implementing the system. It allows the operators, both remote and on-site, to monitor and control machines, devices and operations on a shop floor, based on run-time information from the connected machines, devices and their sensors. Two case studies are presented to demonstrate the approach towards web-based adaptive manufacturing. The first demonstrating how OPC-technology is used to improve the monitoring and control capabilities of the production and the second one focusing on remote control of a robot eliminating the need of motion planning and tedious robot programming.
Multi-Scale Friction Modeling for Manufacturing Processes: The Boundary Layer Regime
Authors: Hol J. , Karupannasamy D. K. , Meinders T.
Published: July 2013

This paper presents a multi-scale friction model for large-scale forming simulations. A friction framework has been developed including the effect of surface changes due to normal loading and straining the underlying bulk material. A fast and efficient translation from micro to macro modeling, based on stochastic methods, is incorporated to reduce the computational effort. Adhesion and ploughing effects have been accounted for to characterize friction conditions on the micro scale. A discrete model has been adopted which accounts for the formation of contact patches ploughing through the contacting material. To simulate metal forming processes a coupling has been made with an implicit Finite Element code. Simulations on a typical metal formed product shows a distribution of friction values. The modest increase in simulation time, compared to a standard Coulomb-based FE simulation, proves the numerical feasibility of the proposed method.
Kernel Density Estimation and Metropolis-Hastings Sampling in Process Capability Analysis of Unknown Distributions
Authors: Huang Wenzhen , Pahwa Ankit , Kong Zhenyu
Published: July 2013

Strong normality assumption is associated with widely used process capability indices such as cp, cpk. Violation of the assumption will mislead the interpretation in applications. A nonparametric method is proposed for density estimation of any unknown distribution. Kernels are used for density estimation and metropolis-hastings (M-H) algorithm is adopted to generate samples from the density. M-H sampling provides a tool to accommodate different kernel functions and flexibility of future extension to multivariate cases. Conformity (yield) based indices (yp, y) are adopted to replace cp, cpk. These indices can be conveniently assessed by the proposed kernel density based M-H algorithm (K-M-H). The method is validated by several simulation case studies.
Numerical Investigation of Residual Formability and Deformation Localization During Continuous-Bending-Under-Tension
Authors: Nikhare Chetan , Kinsey Brad L. , Korkolis Yannis
Published: July 2013

A ubiquitous experiment to characterize the formability of sheet metal is the standard uniaxial tension test. Past research [1–3] has shown that if the material is repeatedly bent and unbent during this test (termed Continuous-Bending-under-Tension, or CBT), the percent elongation at failure increases significantly (e.g., from 22% to 290% for an AISI 1006 steel [1]). However, past experiments have been conducted with a fixed stroke of the CBT device, which limits the formability improvements. This phenomenon has also been empirically observed in industry; the failure strains of a sheet which is passed through a drawbead (i.e., that has been bent and unbent three times before entering the die) are higher than those of the original sheet. Thus, the residual formability of the material after a specified number of CBT passes is of interest, to determine if multiple drawbeads would be beneficial in the process. Also of interest is the localization of the deformation during the process as this will provide a better physical understanding of the improved formability observed. In this paper, numerical simulations are presented to assess these effects. Results show that the formability during CBT is dictated by the uniaxial response of the material until the standard elongation at failure is exceeded. This limit can be exceeded by the CBT process. However, failure then occurs as soon as the CBT process is terminated. Also, the deformation is more uniformly distributed over the entire gauge length during the CBT process which leads to the increased elongations observed.
A Computer-Aided System for Sustainability Analysis for the Die-Casting Process
Authors: Singh Princepal , Madan Jatinder , Singh Amrik , Mani Mahesh
Published: July 2013

Currently available sustainability analysis systems for the die-casting process primarily depend on the material properties and do not account for process information. As a result they are unable to assess or compare the sustainability of parts made using different process plans. In this paper, we propose a new computer-aided system named Sustainability Analyzer for Die-casting Process. Here, we discuss the details of the architecture and the working of the proposed system. We analyze sustainability using three sustainability indicators, namely energy use, solid waste and carbon emissions. The proposed system is verified by comparing results with the actual data measured from the shop floor. The proposed system is beneficial for sustainability analysis comparing different plans alongside material properties, ultimately helping the die-casting industry to reduce carbon emissions and material waste besides improving energy efficiency.
Laser Joining of Continuous Glass Fiber Composite Pre-Forms
Authors: Tan Huade , Yao Y. Lawrence
Published: July 2013

A laser fusion joining method is investigated for the purpose of through thickness strengthening of fiber pre-forms used in the vacuum infusion fabrication of thick composite structures. Laser joining is achieved without filler materials to replace adhesives, pins or stitches used in conventional composite fabrication. A two step joining process is developed to fuse fibers within a single bundle and between multiple fiber bundles. Finite element analysis is used to investigate the joint strength with respect to joint morphology. Joint strength is found to be a function of the fiber contact angle and packing density at the joint interface. Tensile tests show that laser joined fiber bundles exhibit higher strength than comparable fastening methods. Lessons learned from the axial joining of fiber bundles are applied to joining in the radial and thickness directions of 3d pre-form architectures. Flow induced joint morphology and densification effects observed in the axial direction indicate the need for a two step joining process in the thickness direction. Fiber compaction effects on joint strength in the axial direction motivate the need for high fiber packing fraction at joint interfaces in the thickness direction.
Detection of Cutting Phenomena Using Sensor Fusion
Authors: Slotwinski J. A. , Vogl G. W. , Ivester R. W. , Younker I. M.
Published: July 2013

This paper presents an investigation of the application of a suite of sensors for simultaneous in-situ measurements of machining processes. While not every individual sensor responds to all machining phenomena, the suite of sensors together responds to many machining phenomena of interest, including chip segmentation, chip breakage, and vibrations. The simultaneous use of a suite of sensors with modest data-acquisition equipment and the use of careful preliminary laboratory testing for optimizing sensor performance distinguishes this present proof-of-concept work from prior process monitoring efforts using individual sensors. This paper includes a discussion of pre-deployment laboratory measurements and a full description of the instrumented tool holder, associated circuitry, and data analysis methods. The deployment of multiple sensors of varying sophistication and cost lays a technical foundation for the ultimate objective of industrially practical measurement and monitoring systems for metal cutting processes.
Effect of Continuous Direct Current on the Yield Stress of Stainless Steel 304 Micro Tubes During Hydroforming Operations
Authors: Wagner Scott W. , Ng Kenny , Emblom William J. , Camelio Jaime A.
Published: July 2013

Hydroforming at the macro scale offers the opportunity to create products that have superior mechanical properties and intricate complex geometries. Micro tube hydroforming is a process that is gaining popularity for similar reasons. At the same time, due to the physical size of the operations, there are many challenges including working with extremely high pressures and available materials that are typically difficult to form.

Increasing the formability of micro tubes during the hydroforming process is desired. Being able to increase the formability is essential because as the tube diameters decrease in size, the required forming pressure increases. As a result, it is important to explore methods to decrease the yield stress during forming operations. Traditional methods for decreasing the materials yield stress typically involve heating either the sample or the process equipment. Using traditional methods typically sacrifice dimensional quality of the part, alter the mechanical properties and also raise the costs of the operations.

Electrically Assisted Manufacturing (EAM) is a non-traditional method that is gaining popularity by reducing the necessary forces and pressures required in metal forming operations.
Development of Statically Determinate Plate Rolling Mills Based on Micro-Scale Parameters
Authors: Shen Guangxian , Zheng Yongjiang , Li Ming
Published: July 2013

Contemporary plate rolling mills and pinch pass mills, which are unstable during the rolling process, are all statically indeterminate structures influenced by micro-scale parameters. The micro-scale parameters include bending deformations of the rolls and the side clearances between the chocks and the side surfaces of the housing window. All these are less than 1 mm, and they have an important effect on the skeletal structure of the roll systems of the mill. If the influence of micro-scale parameters is not considered in the design of the rolling mill, the skeletal structure of the roll system is incomplete and lacks kinematic links and pairs. The statically indeterminate nature of traditional rolling mills results in numerous disadvantages, including the frequent burning loss of the end-thrust bearing caused by excessive axial forces, the lateral movement of the strip owing to the deviation of the rolling load acting on the both ends of backup roll, the short service life of the four-row radial roller bearings on the back-up roll, and the quality of product tends to deteriorate due to the unstable operation of the control system, to mention a few. Because of the flattening effect between the rolls, the setting of the offset distance does not achieve the desired purpose and leads to the deviation of rolling load due to the asymmetric cross between the roll axes. To alleviate the above shortcomings, a new type of rolling mill with a statically determinate structure in which the horizontal offset distance between the roll axes is set to zero is thus proposed. In order to keep the rolls parallel and prevent cross between the rolls, a thrust device is designed, which also ensures sufficient free space to allow convenient roll replacement and allow for the thermal expansion of the chocks. In addition, back-up roll systems with component force bases as well as intermediate roll systems are designed in accordance with the theory of statically determinate characteristics with micro-scale parameters.
Robust Shearing Process for Improving AHSS Sheared Edge Stretchability
Authors: Shih Hua-Chu , Shi Ming F.
Published: July 2013

Results from a previous study have shown that a newly developed beveled shearing process is able to improve the quality of advanced high strength steel (AHSS) sheared edges and their edge stretchability. The objective of the current study is to further investigate and validate this phenomenon and to develop robust shearing conditions for improving the AHSS sheared edge stretchability. A straight edge shearing device with the capability of adjusting the shearing variables is used in this study. Two different advanced high strength steel grades, DP600 and DP980, with similar thicknesses are selected to assess the edge condition using various shearing variables. The edge stretchability of the straight edge sheared specimen is evaluated using the sheared edge tension test and a half specimen dome test. It was discovered that an optimal selection of the die clearance and other shearing variables would result in a less damaged sheared edge which would greatly delay edge fracture in the forming process and increase the edge stretchability of AHSS.
Experimental Measurement of Nano-Particle Emissions From Atomic Layer Deposition
Authors: Huo Jingwan , Lin Xiu , Yuan Chris
Published: July 2013

Atomic layer deposition (ALD) is a key enabling nanotechnology for a broad array of applications due to its ability to grow conformal and pinhole-free thin films and control layer growth at atomic scale. Like many nanotechnologies, the potential amount of nano-particle emissions from ALD nano-manufacturing system is a significant concern for both occupational and public health exposure. Here we report our preliminary investigations of nano-particle emissions at end-of-the-pipe of ALD nano-manufacturing system. Scanning Mobility Particle Sizer (SMPS) spectrometer is used for the nano-particle measurement during the ALD process of Al2O3 high-k dielectric gate materials using Trimethyl Aluminum (TMA) and H2O binary reactions. Under various experimental conditions tested in our project, the results demonstrate that the aerosol nanoparticle emissions from ALD nano-manufacturing system are averaged with a mean diameter of 201.28 nm and 940,850 particle concentrations at 200 °C reaction temperature.
Electro-Hydraulic Forming of Advanced High-Strength Steels: Deformation and Microstructural Characterization
Authors: Rohatgi Aashish , Stephens Elizabeth V. , Edwards Danny J. , Smith Mark T. , Davies Richard W.
Published: July 2013

The deformation behavior and texture evolution during forming of an advanced high-strength steel (DP600 grade) were characterized. The deformation history of DP600 during electro-hydraulic forming (EHF) was quantified using a unique experimental capability developed at PNNL. The texture evolution during quasi-static and high-strain-rate deformation was determined using the electron backscatter diffraction (EBSD) technique. The deformation history of EHF formed steel sheets shows an amplification of the strain-rate, relative to free-forming conditions, when the forming was carried out inside a conical-die. This strain-rate amplification was attributed to the focusing action of the conical die. The undeformed DP600 sheet was found to possess a {111} fiber texture in the sheet-normal direction. Quasi-static deformation was found to strengthen the pre-existing texture whereas high-rate forming using EHF had a lesser influence. The results of this work demonstrate the unique capability to correlate deformation history during high-strain-rate metal forming processes with the corresponding microstructural evolution. It is expected that results of this work can help fill-in the gaps in our understanding of high-rate forming processes, leading to development of accurate and validated numerical models.
Microfluidic Channel Fabrication With Tailored Wall Roughness
Authors: Ren Jing , Sundararajan Sriram
Published: July 2013

Realistic random roughness of channel surfaces is known to affect the fluid flow behavior in microscale fluidic devices. This has relevance particularly for applications involving non-Newtonian fluids, such as biomedical lab-on-chip devices. In this study, a surface texturing process was developed and integrated into microfluidic channel fabrication. The process combines colloidal masking and Reactive Ion Etching (RIE) for generating random surfaces with desired roughness parameters on the micro/nanoscale. The surface texturing process was shown to be able to tailor the random surface roughness on quartz. A Large range of particle coverage (around 6% to 67%) was achieved using dip coating and drop casting methods using a polystyrene colloidal solution. A relation between the amplitude roughness, autocorrelation length, etch depth and particle coverage of the processed surface was built. Experimental results agreed reasonably well with model predictions. The processed substrate was further incorporated into microchannel fabrication. Final device with designed wall roughness was tested and proved a satisfying sealing performance.
Sensitivities When Modeling Electrically-Assisted Forming
Authors: Bunget Cristina J. , Salandro Wesley A. , Mears Laine
Published: July 2013

Recent research by the authors has resulted in the conception of several methods of accounting for direct electrical effects during an Electrically-Assisted Manufacturing (EAM) process, where electricity is applied to a conductive workpiece to enhance its formability characteristics. The modeling and analysis strategy accounts for both mechanical effects and heat transfer effects due to the applied electrical power.

This work presents a sensitivity analysis and explanation of several key material and process inputs during an Electrically-Assisted Forming (EAF) test on Stainless Steel 304 and Titanium Grades 2 and 5 specimens. First, the effect that the specific heat (Cp) value has on the model will be discussed and compared with another lightweight material. Second, the significance of all three heat transfer modes (conduction, convection, and radiation) will be noted, and any possible simplifications to the existing heat transfer model will be highlighted. Third, the general electroplastic effect coefficient (EEC) profile shape for the Stainless Steel 304 material will be compared to that of Titanium alloys. Fourth, a frequency analysis will be done on the data taken during the experiments, by way of a Fast Fourier Transform (FFT), and the variation of frequency response with the electric input is studied.

Overall, this work provides insight into several factors affecting a material’s EEC profile, and also compares resulting EEC profiles of various materials.
Dissimilarity Measures for ICA-Based Source Number Estimation
Authors: Cheng Wei , Lee Seungchul , Zhang Zhousuo , He Zhengjia
Published: July 2013

Most of blind source separation problems are carried out with a priori knowledge of the source numbers. However, for source separation-based machinery condition monitoring and fault diagnosis, it is a challenge work to determine the number of sources for a well source separation due to complex structures and nonlinear mixing mode. Therefore, source number estimation is a necessary and important procedure prior to source separation and further diagnosis work. In this paper, we focus on a novel source number estimation method based on independent component analysis (ICA) and clustering evaluation analysis, and investigate the performances of different dissimilarity measures of ICA-based source number estimations with typical mechanical vibration signals. Our work contributes to find an effective solution of source number estimation for source separation-based machinery condition monitoring and fault diagnosis.
Extension of Maintenance Opportunity Windows to General Manufacturing Systems
Authors: Gu Xi , Lee Seungchul , Liang Xinran , Ni Jun
Published: July 2013

In manufacturing systems, many maintenance tasks require equipment to be stopped in order to safely perform them. However, such tasks cannot last for a long time since the stoppage of machines might directly result in production losses. In this paper, we investigate how long we can perform maintenance during scheduled operations by strategically shutting down equipment without bringing extra production losses to the system. Using the concept of maintenance opportunity window (MOW) we calculate such time intervals with given information of manufacturing systems. MOWs are analytically derived with various system configurations. Simulations are used to deal with uncertainties in production lines such as random machine failures, starvations, blockages, etc. Moreover, the proposed MOW algorithms are demonstrated through numerical case studies.
A Two-Parameter Method to Monitor and Characterize Tool Wear in End Milling Inconel 718
Authors: Li W. , Guo Y. B.
Published: July 2013

Inconel 718 is among the most widely used superalloys in many industries. It is often used in very harsh conditions such as jet engines, combustors and nuclear reactors due to its high strength at elevated temperatures, high oxidation and corrosion resistance. Machining superalloy Inconel 718 has always been a challenging task due to its poor machinability including rapid work hardening, low thermal conductivity, and relatively short cutting tool life. The fast tool wear during cutting Inconel 718 results in longer production time, deteriorated surface integrity, and higher manufacturing cost. In this paper, an on-line optical tool monitoring system integrated with a CNC machine tool has been developed to examine tool wear evolutions in end milling Inconel 718 with PVD (Ti, Al) N/TiN-coated carbide insert. Three basic types of tool wear: flank wear, nose wear, and crater wear were examined and analyzed. A two-parameter method has been proposed to evaluate both flank wear and nose wear vs. cutting time.
Residual Stress and Fatigue Properties of AISI H13 Steel by Sustainable Dry Milling
Authors: Li W. , Guo Y. B.
Published: July 2013

Dry machining is a cluster of sustainable manufacturing processes to eliminate the negative environmental effect of machining coolants. It is critical to ensure that product quality cannot be sacrificed for achieving sustainability. The progress of tool flank wear during hard milling adversely affects surface integrity and, therefore, fatigue life of machined components. This paper focuses on the influence of tool flank wear on residual stress and fatigue properties in dry end milling AISI H13 tool steel (50 ± 1 HRC) using PVD coated tools. The effects of flank wear (VB = 0, 0.1, and 0.2 mm) on residual stresses at three different feeds were studied. Four-point bending fatigue tests were performed on the samples machined at five levels of tool flank wears (VB = 0, 0.05, 0.10, 0.15, 0.20 mm) and surface fatigue initiations of the fatigued samples were identified by the fractographic method.
Laser Micromachining Modeling and Laser Machined Surface Errors Prediction for Biomedical Applications
Authors: Wongwiwat Plawut , Narayan Roger J. , Lee Yuan-Shin
Published: July 2013

This paper presents an analytical modeling and laser micromachining technique of microchannel and micro-structures for bio-devices manufacturing and biomedical applications. The ablation of the laser micromachining with direct-write method has been modeled and simulated for micro-channels or microstructures in bio-devices microfabrication. In this paper, the analytical model was adapted from the linear function for beam propagation in our previous research by using the Gaussian function to improve modeling accuracy. Basically, the new laser ablation model based on Gaussian distribution, beam propagation modeling and Beer’s law were used to formulate and model the laser ablation phenomenon. After the simulation with MATLAB programming, the actual experiment on laser micromachining has been conducted to compare the simulated results with the actual ones. Finally, the purposed modeling technique can be applied in the surface error analysis and biomedical applications. The example case in this paper showed how the modeling could solve the complex phenomenon of the overlapping in laser micromachining.
Enhanced Laser Shock by an Active Liquid Confinement
Authors: Liao Yiliang , Cheng Gary J.
Published: July 2013

This letter investigates a unique process to generate the enhanced laser shock with a higher pressure by applying an active liquid confinement — hydrogen peroxide (H2O2). The mechanism of fast chemical etching-assisted laser ablation is proposed. As a result, comparing with utilizing water as confinement, the efficiency of underwater laser shock peening of aluminum alloy 6061 is improved by 150%, and the ablation rate of pulse laser ablation of zinc is enhanced by 300%. This method breaks the major limitation of underwater pulsed laser processing caused by the breakdown plasma.