bluuebunny/crossref_metadata_2025 huggingface dataset:
Microscale Oil-Covered Cell Array (MOCCA): A Droplet Array for High-Content Single-Cell Analysis and Imaging
Authors: Lin Liang-I , Chao Shih-Hui , Meldrum Deirdre R.
Published: September 2010

A simple, low-cost technique for high throughput single-cell analysis, Microscale Oil-Covered Cell Array (MOCCA), is presented in this paper. Corresponding to recent research on single cell analysis, simple devices for isolated cell chambers are urgently needed and long sought-after. Instead of using microfabricated solid structures to capture cells, MOCCA isolates cells in discrete aqueous droplets that are separated by oil on the patterned hydrophilic areas on a relatively more hydrophobic flat substrate. In our pioneer study, we created an array of 700-picoliter droplets. The randomly seeded E. coli cell number in each discrete droplet approaches single-cell levels. The total time needed for MOCCA fabrication was no more than 10 minutes. Compared to traditional micro-fabrication techniques, MOCCA dramatically lowers the cost and enhances the efficiency for the fabrication procedure, while producing a microscale array as in those made using traditional methods.
Prediction of Forced Convection Flow in a Parallel Plate Channel Filled With Porous Media
Authors: Ehyaei Dana , Honari Hamed , Rahimian M.
Published: September 2010

In this study the flow field and heat transfer properties of a steady, two-dimensional flow field in a porous domain between two parallel plates is investigated numerically by using a discretized numeric code. Analysis has been carried for Reynolds number based on particle sizes ranging from 60 to 1000. Numerical results are compared with different numerical methods used for predicting this kind of flow. Results are obtained for different regime, various Rep numbers and the effect of Particles size is also investigated. Solutions indicate that by increasing the Rep, the flow in the porous media remains laminar where the flow has turbulence characteristics for Rep <50. Moreover, by increasing Rep, the value of average Nusselt number increases. Also, reducing the particle size affects the Nusselt number and it increases while the porosity remains the same.
Simulation of Flow Control in Microchannels Using Ferrofluid Plugs
Authors: Gunde Akshay C. , Mitra Sushanta K.
Published: September 2010

Microfluidic devices have acquired an important position in the field of MEMS. While the usage of mechanical components for achieving electroosmosis and electrophoresis effects can prove to be impractical and costly, alternative methods for flow control have to be explored. This paper extends the concept of obtaining a superior flow control in microchannels by using ferrofluid plugs as barriers. These plugs occlude and discharge fluid flow, thereby functioning as valves and rendering the usage of mechanical components unnecessary. A numerical simulation of a ferrofluid plug blocking fluid flow in a microchannel due to the action of a magnetic field is carried out. The relationship between ferrofluid property and the capacity to block fluid flow is studied and analyzed. Thus a new concept of flow control in a microfluidic device by the proper variation of the external magnetic field and positioning of the ferrofluid plugs has been introduced.
Investigation of Water Distribution in a Polymer Electrolyte Fuel Cell Using X-Ray Imaging Technique
Authors: Kim Seung-Gon , Lee Sang-Joon
Published: September 2010

Water management in a polymer electrolyte fuel cell (PEFC) was experimentally investigated using an X-ray microscopy technique. Recently, fuel cell has been receiving large attention as an important renewable energy due to its efficiency, clearness and sustainability. Among various types of fuel cells, PEFC can be used as a power source of transport vehicles and home applications. In recent commercial development of PEFC, water management is one of the major problems to be solved. In fact, proper water management is vital to enhance performance and durability of PEFC. In this study, transport of water inside MEA (membrane electrode assembly) and GDL (gas diffusion layer) layers of an operating (in situ) fuel cell was observed using the synchrotron X-ray micro-imaging technique. As the synchrotron X-ray imaging technique has very high spatial and temporal resolutions, it is suitable for observing the dynamic movement and behavior of liquid layer and water distribution inside the PEFC. For this X-ray micro-imaging experiment, a single cell test kit of PEFC was specially designed for convenient capturing of X-ray images. Temporal variation of gray level in the PEFC components, such as MEA, GDL and endplate, was investigated with varying loading condition. As a result, X-ray images of the PEFC components were clearly distinguished by image pattern and gray level difference. The gray level shows roughly symmetric distribution with respect to MEA layer. The gray level at GDL decreases with lapse of time, indicating the increase of H2O concentration with time.
From High Performance Protein Micro Chip Toward Ultra High Sensitive Single Molecule Nano Array
Authors: Tseng Fan-Gang
Published: September 2010

Protein microarrays have been employed to screen tens to thousands of proteins simultaneously for the observation of the biochemical activities in the protein-protein, protein-nucleic acid and small molecule interactions. This technology allows high throughput analysis and holds great potential for basic molecular biology research, disease marker identification, toxicological response profiling and pharmaceutical target screening. However, proteins easily malfunction in harsh environments so that they are hardly preserved before the application because of their complex and fragile structures. On the other hand, identify scarce amount of proteins less than fM range is very important and challenge for disease diagnosis at very early stage. As a result, the procedures for protein micro array formation are very important for preserving protein functionality to ensure useful protein assays, as well as the improvement of the detection sensitivity up to single molecule event but with high dynamic range for disease early detection. Therefore, this paper provides a novel view from the preparation of high efficient protein micro chip toward ultra high sensitive single protein nano array through the technology integration of BioMEMS and Bio-Nanotechnology.
Modeling of Transport Phenomena in the Laser Multilayered Cladding
Authors: Kong Fanrong , Kovacevic Radovan
Published: September 2010

The present work studies the heat and mass transfer process in the laser multilayered cladding of H13 tool steel powder by numerical modeling and experimental validation. A solid-liquid-gas unified transient model was developed to investigate the evolution of temperature distribution and flow velocity of the liquid phase in the molten pool. In this model, an enthalpy-porosity approach was applied to deal with the solidification and melting occurring in the clad, and a level-set method was used to track the evolution of the molten pool free surface. Moreover, heat loss due to forced convection and heat radiation and laser heat input occurring on the top surface of deposited layer and substrate have been incorporated into the source term of governing equations. The effects of laser power, scanning speed, and powder feed rate on the dilution and height of the multilayered clad are investigated based on the numerical model and experimental measurement. The results show that increasing the laser power and powder feed rate, or reducing the scanning speed, can increase the clad height and directly influence the remelted depth of each layer of deposition. The numerical results have a qualitative agreement with the experimental measurements.
Optimization of Laser Hardening Processes for Industrial Parts With Complex Geometry via Predictive Modeling
Authors: Bailey Neil S. , Shin Yung C.
Published: September 2010

A predictive laser hardening model for industrial parts with complex geometric features has been developed and used for optimization of hardening processes. A transient three-dimensional thermal model is combined with a three-dimensional kinetic model for steel phase transformation and solved in order to predict the temperature history and solid phase history of the workpiece while considering latent heat of phase transformation. Further, back-tempering is also added to the model to determine the phase transformation during multitrack laser hardening. The integrated model is designed to accurately predict temperature, phase distributions and hardness inside complex geometric domains. The laser hardening parameters for two industrial workpieces are optimized for two different industrial laser systems using this model. Experimental results confirm the validity of predicted results.
Study on Loading Path Influences on the Thickness Distribution of TRIP Steels During Sheet Metal Forming
Authors: Dan W. J. , Zhang W. G. , Li S. H.
Published: September 2010

Loading path is one of key factors that influence the formability of sheet metal forming processes. In this study, the effect of several kinds of loading paths on the thickness distribution of TRIP steel is investigated in a deep drawing process based on a constitutive model accompanying the strain-induced martensite transformation. A kinetic model of transformation, that describes the relationship between the thickness distribution of a deep drawing process and the martensite transformation, is used to calculate the martensite volume fraction. The influences of loading path on the martensite transformation are also evaluated through the change in the stress-strain state, the forming temperature, the transformation driving force, the nucleation site probability and the shear-band intersection controlled by the stress-strain state and forming temperature at the minimum thickness location in the formed part.
Diamond Disc Pad Conditioning in Chemical Mechanical Polishing: A Literature Review of Process Modeling
Authors: Baisie Emmanuel A. , Li Z. C. , Zhang X. H.
Published: September 2010

Chemical Mechanical Polishing (CMP) is a major manufacturing step extensively used to planarize semiconductor wafers. In CMP, the polishing pad surface is glazed by residues. A diamond disc conditioner is used to dress the pad to regenerate new pad profile and asperity in order to maintain favorable process conditions. This paper presents a review on process modeling of diamond disc pad conditioning in CMP. Following the introduction, the paper briefly introduces a technical background of the conditioning process and process control. It then summarizes research work on the various analytical process models proposed and ends with conclusions and topics for future research.
Stochastic Modeling and Analysis of Rotary Ultrasonic Machining
Authors: Wu Jiaqing , Cong Weilong , Williams Robert E. , Pei Z. J.
Published: September 2010

Rotary Ultrasonic Machining (RUM) is a hybrid machining approach that combines two material removal mechanisms, namely diamond grinding and ultrasonic machining. Currently available literature mainly focuses on static parametric relationships. This paper presents preliminary results of an experimental study on some aspects of the RUM process performance, surface integrity, and dynamic process modeling. A stochastic modeling and analysis technique called Data Dependent Systems (DDS) was used to study RUM generated surface profiles and cutting force signals. The DDS wavelength decomposition of the surface profiles suggested that the major characteristic root wavelength had a positive correlation with feed rate, and the wavelength magnitude may be linked to the grain size of the workpiece material. In addition, the difference of the major wavelength between the surface profiles for machined holes and that for machined rods was investigated. The surface variation between the entrance and exit segments of both holes and rods were also studied. Moreover, the DDS modeling approach was applied to cutting force signals collected during RUM and comparisons were made to the surface profiles results.
Cutting Simulation of Laser Assisted Milling of Silicon Nitride Ceramics Using PFC2D
Authors: Shen Xinwei , Lei Shuting
Published: September 2010

Since laser assisted milling (LAMill) exhibits complicated characteristics in ceramic machining, this paper applies a distinct-element code, PFC2D (Particle Flow Code in Two-Dimensions), to conduct cutting simulation of laser assisted slab milling and explore its machining mechanism. The microstructure of a β-type silicon nitride ceramic (β-Si3N4) is modeled at grain scale. Clusters are used to simulate the rod-like grains of β-Si3N4. Parallel bonds are employed to represent the connection between intergranular glass phase and grains. A temperature-dependent PFC specimen is created for simulation of LAMill. A special milling cutter is designed for improving the computing efficiency. Simulation results show that the cutting force is strongly related to crack formation and propagation. The specific cutting energy decreases as the cutting temperature increases.
Product Family Design to Minimize Manufacturing Complexity in Mixed-Model Assembly Systems
Authors: Wang He , Zhu Xiaowei , Hu S. Jack , Lin Zhongqin , Chen Guanlong
Published: September 2010

The number of product varieties offered by manufacturers has increased drastically as a result of the paradigm change from mass production to mass customization. High product variety introduces complexity in manufacturing. In this paper, we discuss product family design to minimize manufacturing complexity in manual, mixed-model assembly systems. A concept of relative complexity is proposed to help system designers making decisions on product family selection. Based on the relative complexity, a model for product variety selection is then proposed to find the best combination of product variants to be provided to the market in order to maximize market share and minimize manufacturing complexity. A numerical example is provided to demonstrate the approach.
Numerical Simulations and Analysis of the Thermal Effects on Silicon Carbide During Ductile Mode Micro-Laser Assisted Machining
Authors: Virkar Saurabh R. , Patten John A.
Published: September 2010

Various 2-D numerical simulations were carried out using the commercial software AdvantEdge Versions 5.2 and 5.3 to model ductile mode micro-Laser Assisted Machining (μ-LAM) of Silicon Carbide (4H-SiC). The cutting tool is a single point diamond. The workpiece material (SiC) is heated locally by a laser beam, which passes through the diamond tool tip. The workpiece is heated beyond the thermal softening point in order to study the effect of increased temperature. The cutting and thrust forces are reduced when machining is done above the thermal softening temperature. The simulations were carried out for two cases at different temperatures above and below the thermal softening point to study the effect of μ-LAM on the cutting and thrust forces. In the first case both the tool and workpiece material were heated to study the behavior at elevated temperatures. In the second case, a thermal boundary condition was provided on the top surface of the workpiece to simulate the laser heating effect keeping the tool at room temperature (20° C). In both cases the chip formation was observed and the changes in cutting and thrust forces were evaluated. The simulation results indicate a significant decrease in machining forces if Silicon Carbide is heated beyond the thermal softening temperature thus demonstrating the benefits of μ-LAM process.
Modeling of the Effect of Path Planning on Deposition of Metal-Ceramic Composite With Laser Powder Deposition Process
Authors: Foroozmehr Ehsan , Kovacevic Radovan
Published: September 2010

A finite element model, coupled with a thermo-kinetic model is developed to simulate the heat transfer and microstructural evolution in laser deposition of a metal-matrix composite powder. The model is used to predict the final hardness and the effect of process parameters on a metal matrix. A defined area is covered by H13-WC powder with three different deposition patterns: one-section, two-section, and three-section. The one-section pattern is the normal deposition pattern in which the deposition area is covered with zigzag patterns and in one step. In the two- and three-section patterns, the deposition area is divided to two and three sections, respectively, and is covered in two and three steps. The finite element model is used to determine the temperature history of the process used in the kinetic model to analyze the tempering effect of the heating and cooling cycles of the deposition process on the composite matrix. The results show that dividing the area under deposition into smaller areas can influence the phase transformation kinetics of the process and, consequently, change the final hardness of the metal matrix. The two-section pattern shows a higher average hardness than the one-section pattern, and the three-section pattern shows a fully hardened surface without significant tempered zones with low hardness. The simulation results are in very good agreement with the experimental ones.
Achievement of High Flatness of Large Diameter Silicon Wafer in Double-Sided Polishing: Optimization of Polishing Conditions Considering Relative Motion Direction
Authors: Hirose Kenji , Enomoto Toshiyuki
Published: September 2010

Silicon (Si) wafers are the most commonly used substrates for manufacturing semiconductor devices. The design rule is miniaturized, and the chip size is increasing to improve the degree of the device integration. Then Si wafer is required to be manufactured with the higher flatness and larger diameter to meet above demands. The double-sided polishing is widely adopted as the finishing process of the wafer manufacturing, because the wafers with the good surface quality and flatness can be obtained economically. However, the polishing technology has serious problems: It is very difficult to set the appropriate conditions for stably polishing the Si wafer and wearing the pad to the high flatness. In our previous work, the optimization of the polishing conditions with the theoretical calculation was conducted, however, the calculation did not consider the relative motion direction having large influence on polishing behaviours. In this study, the optimizing method considering the relative motion direction was newly developed, and it was revealed that the calculation results corresponded well with the experimental results. Furthermore, it was found that the time-fluctuation of the wafer flatness was larger in the case of the wafer having taper shape, compared to that having convex shape in the calculation.
Thermal Error Compensation for a High Precision Lathe to Improve Machining Accuracy
Authors: Kim Byung-Sub , Song Young-Chan , Park Chun-Hong , Park Jong-Kweon
Published: September 2010

High precision machines require very stable operational environment: temperature control and vibration isolation. Tight temperature control for machines usually demand high cost to operate air conditioners. Some of high precision machines require the ambient temperature changes to maintain within ±0.1 degrees. In this paper, we present a thermal error compensation scheme and experimental results for improving machining accuracy of a high precision lathe. The testbed lathe has X- and Z-axes and they are driven by linear motors and hydrostatic oil bearing. Due to the temperature changes of the ambient air and supplied oil to the hydrostatic bearing, thermal deformation is generated and measured to be as much as 200–300 nanometers. To identify the dynamic relations between the temperature changes and the thermal drift, a state-space model is used in which state variables are constructed from the input measured temperatures and the output thermal drift data. The identified model is implemented in a servo control loop and the predicted thermal error is compensated by subtracting the predicted thermal drift from the servo command. In our simulation, a thermal error of 97 nanometers RMS over 3 hours is reduced to 55 nanometers RMS. Experimental results show an average of 24% reduction in thermal drift and support the validity of our approach.
The Edge Roll Off Generation Mechanism in Polishing by Considering the Viscoelasticity of Polishing Pads
Authors: Miyake Takahiro , Enomoto Toshiyuki , Hirose Kenji
Published: September 2010

Recently, the achievement of further high flatness of workpiece edge shape is strongly required in mirror finishing. Especially, the edge roll off of silicon wafers as the substrates of semiconductor devices is demanded to decrease in the polishing process for raising the yield of IC chips. Many theoretical and experimental analyses of the edge roll off generation have been already done and the polishing methods for suppressing the roll off have been proposed to meet the demand. The analyses, however, cannot fully account for the obtained edge shape in actual polishing and the problem about the roll off remains. In this study, the generation mechanism of the edge roll off based on the viscoelasticity of polishing pad was newly proposed. The mechanism considered the horizontal and vertical relative static and dynamic motion between the pad and the workpiece. Moreover, the non-contact viscoelasticity measurement instrument was originally developed to evaluate the viscoelasticity of the polishing pad precisely. A series of polishing experiments for silicon wafers revealed that the edge shape, which was induced from the edge roll off generation mechanism and the measured viscoelasticity of the polishing pad, corresponded well with the obtained edge shape.
Developing a Durability by Design Process
Authors: Draper John
Published: September 2010

Modern fatigue analysis is providing analytical solutions to problems that could previously be addressed only by methods that were highly empirical and often inaccurate. We can now focus on five crucial steps to successful fatigue analysis. Working from elastic finite element models, the five steps are: 1) the calculation of elastic-plastic stresses and strains for complex loading and biaxial stress states; 2) modification of the endurance limit to allow for the interaction between small and larger cycles; 3) the calculation of the life to crack initiation; 4) critical plane searching to determine the orientation of a potential crack; 5) and an assessment of whether the crack will propagate to failure. The paper describes these steps and the underlying theories, and gives industrial examples of their application to real components.
Unit Process Life Cycle Inventory for Product Manufacturing Operations
Authors: Overcash Michael , Twomey Janet , Kalla Devi
Published: September 2010

Rapid access to or generation of life cycle information is a potentially valuable tool for the design of products to meet the needs of sustainability improvement. A new approach is developed to use the manufacturing unit process, commonly outlined in manufacturing process taxonomy systems, as the basis for life cycle inventory. This will initially involve 50–70 unit processes from the taxonomy and will generate energy and mass profiles for each unit process life cycle (uplci). These uplci can be adjusted for each case to include the major variables affecting such operations as related to any specific product. The sum of the performance of a sequence of uplci thus provides the life cycle of the specific product from a defined set of plant process inputs.
Modeling and Simulation of Process and Structure Interactions Considering Turning Operations
Authors: Zaeh Michael F. , Schwarz Florian
Published: September 2010

A consideration of the dynamic interaction between the machine tool structure and the cutting process is required for the prediction and optimization of machining tasks through simulation. This paper outlines a modular, analytical cutting force model applicable to common turning processes. It takes into account the dynamic material behavior and nonlinear friction ratios on the rake face as well as heat transfer phenomena in the deformation zones. In order to overcome simplifying assumptions in analytical cutting force descriptions and to incorporate the chip formation process into the analysis, specific input variables are determined in a metal cutting simulation based on the Finite Element Method (FEM). On the machine tool structure side, the setup of a parametric FEM model is presented. The accuracy of both the machine tool and cutting force models was verified experimentally on a turning center.
Experimental Study on Shear Fracture of Advanced High Strength Steels: Part II
Authors: Shih Hua-Chu , Shi Ming F. , Xia Z. Cedric , Zeng Danielle
Published: September 2010

Developing a proper local formability failure criterion is the key to the successful prediction of the local formability of Advanced High Strength Steels (AHSS) in computer simulations. Shear fracture, which refers to the fracture occurred in the die radius when a sheet metal is drawn over a small die radius, often occurs earlier than predicted by the conventional forming limit curve (FLC). As shown in a previous study using a laboratory Stretch-Forming Simulator (SFS), shear fracture depends not only on the radius-to-thickness (R/T) ratio but also on the tension/stretch level applied to the sheet during stretching or drawing. In the SFS test, a flat sheet is first clamped at the both ends then gradually is wrapped around the die radius as the punch moves downward. This process simulates the early stage of stamping when a sheet metal is initially stretched or drawn over a die/punch radius. However, shear fracture may not occur in this stage if the stretch/tension level is not high enough. In this study, the Bending under Tension (BUT) tester is used to evaluate shear fracture occurring in the later stage of stamping, after the sheet metal is totally wrapped around the die radius. It is demonstrated that shear fracture does occur in this deformation mode when a sufficient tension level is applied. Effects of forming conditions, such as forming speeds and lubrication on shear fracture, are also investigated. When compared to the results from the SFS, the data points failing at the die radius tangent point agree very well. It is observed that all data points above the tangent point failure line show shear fracture, while data points below this line show tensile failure (localized necking) regardless of the test methods used. This indicates that the tangent point fracture line can be used as the shear fracture failure limit. This failure criterion can be used in a computer simulation to simulate the shear fracture phenomenon in the entire deformation process involved in a sheet metal stretching or drawing over a die radius.
An Economic Study on Chemical Mechanical Polishing of Silicon Wafers
Authors: Baisie Emmanuel A. , Yang Man , Kaware Ravindra , Hooker Maria , Li Z. C. , Sun Wangping , Zhang X. H.
Published: September 2010

Chemical mechanical polishing (CMP) is used to remove irregularities on the silicon wafer surface. The importance of CMP is the achievement of both local and global planarity of wafer surface. This paper presents an economic study on CMP of silicon wafers. A cost model is developed to predict the total cost for CMP of silicon wafers. An input-output model is developed to analyze parameters relevant to the fixed cost and variable cost. The labor cost is investigated through a flow chart of the labor operation. Based on the cost model, a hypothetical case study is conducted to show the model’s capability of performing sensitivity analysis and identifying critical factors for the total cost for strategic management purposes.
An Innovative Indoor Coordinate Measuring System for Large-Scale Metrology Based on a Distributed IR Sensor Network
Authors: Galetto Maurizio , Mastrogiacomo Luca , Pralio Barbara
Published: September 2010

The aim of this paper is to describe the architecture and the working principles of a novel InfraRed (IR) optical-based distributed system, designed to perform low-cost indoor coordinate measurements of large-size objects. The hardware/software architecture and system functionalities are discussed, focusing the attention on the integration of methods for distributed network configuration, sensors self-calibration, 3D point localization, and data processing. A preliminary performance evaluation of the sensor devices as well as of the overall measuring system is carried out by discussing the experimental results obtained with a system prototype.
Noise Reduction During Acoustic Monitoring of Laser Welding of High-Strength Steels
Authors: Huang Wei , Kovacevic Radovan
Published: September 2010

During the laser welding process of high-strength steels, different defects, such as a partial weld penetration, spatters, and blow-through holes could be present. In order to detect the presence of defects and achieve a quality control, acoustic monitoring based on microphones is applied to the welding process. As an effective sensor to monitor the laser welding process, however, the microphone is greatly limited by intensive noise existing in the complex industrial environment. In this paper, in order to acquire a clean acoustic signal from the laser welding process, two noise reduction methods are proposed: one is the spectral subtraction method based on one microphone and the other one is the beamforming based on a microphone array. By applying these two noise reduction methods, the quality of the acoustic signal is enhanced, and the acoustic signatures are extracted both in the time domain and frequency domain. The analysis results show that the extracted acoustic signatures can well indicate the different weld penetration states and they can also be used to study the internal mechanisms of the laser-material interaction.
Integrated Production and Preventive Maintenance Decision Making Using Option-Based Cost Model
Authors: Jin Xiaoning , Li Lin , Ni Jun
Published: September 2010

This paper presents an analytical, option-based cost model for an integrated production and preventive maintenance decision making with stochastic demand. The determination of preventive maintenance times and their schedule during a production period is converted to an option problem through maximizing the profit of the production per unit time. The optimal number of preventive maintenance actions is obtained and some further discussions on how the cost parameters affect the optimal results are also derived. The resulting option-based model is found to add flexibility to the production system and thus reduce the risk of shortage when the production system is faced with stochastic demand. A comparisons between the basic model (without option) and the option-based preventive maintenance model has shown that the option model is a more flexible under demand uncertainty and results in at least as much profit as the basic one.
Experimental Investigations Into the Carbide Cracking Phenomenon on Inconel 718 Superalloy Material
Authors: Ranganath Santosh , Guo Changsheng , Holt Sean
Published: September 2010

Inconel 718 (IN718) presents significant challenges in machining due to its high strength properties at high temperature, attributable to the hard niobium and titanium carbide phases. Machined surfaces (oblique turning) at conventional conditions of speeds and feeds, typically show a tendency of those carbides to crack, drag and smear under the machining stresses and deformation. Such behavior can severely debilitate the fatigue strength of the material, and cause accelerated damage. This paper describes the experimental investigations as well as the qualitative and quantitative studies undertaken to study and mitigate the impact of process variables and tool geometry parameters on the carbide surface cracking phenomenon. SEM observations showed the feed rate (or chip thickness), nose radius, and insert grade-edge geometry to have significant influences on the behavior of these surface carbides.
Multilayer Laser Sintering of HAp/Ti Nanoparticles Onto Metallic Implants
Authors: Zhang Yi , Cheng Gary J.
Published: September 2010

Novel methodology of laser sintering of mixture of mixture of bio-ceramics and metallic nanoparticles on metallic implants is introduced in current work. Feasibility of this method is demonstrated using a multiphysics numerical simulation. Treating laser beam as electromagnetic (EM) wave, EM module is coupled with heat transfer (HT) module. The EMHT scheme analyzes the interaction between laser-nanoparticles which ends up with temperature raise within the sample. As a demonstration, HAp and Ti nanoparticles are employed to be sintered on titanium substrate. Processing parameters such as laser power, beam radius, scan speed, and layer thickness are studied, and correlation between these parameters and final temperature is presented. Effects of mixing ratio and nanoparticle size are also examined. Considering effects of mixing ratios and particle sizes, the following coating scheme is proposed for future experiments: varying HAp concentration from 100% to 0% at 10% intervals from coating surface to coating/substrate interface, and meanwhile, varying particle diameters from 500 nm to 100 nm at 100 nm intervals.
Precision XY Positioning Stage With Coupled Flexures and Piezo Actuators for Avoiding Parasitic Tilt Error
Authors: Hwang Donghyun , Lee Moon G. , Kim Hyun-Uk , Lee Soo-Hun , Jeong Jaehwa
Published: September 2010

In the field of scanning probe microscopes (SPMs), a precision positioning stage has become an important component as the requirement of the SPMs has been extended from high resolution to high accuracy. The stages used in SPMs plays a role of transferring a specimen or a probe in multiple directions. The stage should satisfy the requirements for small parasitic motion and compactness. Therefore a coupled flexure leaf spring is used as a guide mechanism at recently developed multi-directional nano positioning stage with piezo actuator. Using the coupled flexure leaf spring mechanism, a compact and symmetric stage can be embodied. However, in this case, there are some problems caused by assembly process of piezo actuators. The first is that piezo actuator can be broken because of bending force when another axis is working. Commercially stack type piezo actuators are composed some ceramic materials, so they are brittle. This problem causes the durability weakening of ultra precision positioning stage. The second is unnecessary parasitic tilt error. When an actuator of one axis is acting, the other non-acting actuator works as constraint force. As a consequence, the accuracy of each axis gets lower and the control to compensate parasitic motion becomes difficult. In this research, we will propose a precision positioning stage with coupled flexures and piezo actuator to withstand bending force and avoid a parasitic tilt error. This research includes performance analysis and parametric design of the stage. The stage is designed for motion of two degree of freedom using a flexure leaf spring. Design optimization based on a finite element method (FEM) is also covered in this study. Simulation results show that the optimally designed stage decreases a tilt error less than 25% compared to the stage without concerning the bending and constraint.
Design of Compact 6-DOF Precision Aligner for Micro-Assembly
Authors: Yoo Yong-Hwan , Sung Yeon wook , Lee Soo-Hun , Hong Min-Sung , Lee Moon G. , Lee Chang-Woo , Ha Tae Ho , Song Jun-Yeob
Published: September 2010

This work will develop a 6 Degrees Of Freedom (DOF) precision aligner with a small size and a high resolution for the assembly of the micro-scale parts used in mobile electronics. The arrangement of actuators in the aligner is symmetrical, based on kinematic design. A VCM (Voice Coil Motor) actuator that is small and reliable will be applied to this aligner system. This paper presents the combination of two modules to form the mechanism for the 6-DOF precision aligner. The first is a stage that can control XY θZ motion, while the second can control Z motion, i.e. Z tilt motion. According to its specifications, it is expected to satisfy precision requirements. Several tests will be carried out to confirm the specifications with PID control.
Fuel Cell ASAP: Two Iterations of an Automated Stack Assembly Process and Ramifications for Fuel Cell Design-for-Manufacture Considerations
Authors: Laskowski Christina , Derby Stephen
Published: September 2010

Polymer-electrode membrane (PEM) fuel cell technology will need to progress from low-volume production to high-volume within the course of the next decade. To successfully achieve this transition, a fully-functional fuel cell automatic stack assembly robotic station is being developed. This document outlines both iterations of the robotic fuel cell assembly stations, other work to date, DFM and DFA lessons learned, and the anticipated future progression of automatic fuel cell stack assembly stations. Two individual robotic fuel cell assembly stations were constructed, including custom-built end effectors and parts feeders. The second station incorporated numerous improvements, including overlapping work envelopes, elimination of a shuttle cart, software synchronization, fewer axes, and a better end effector. Consequentially, the second workcell achieved a four-fold improvement in cycle time over the previous iteration. Future improvements will focus in part upon improving the reliability of the overall system. As the stack assembly workcell continues to improve, research will focus upon the ramifications and interplay of tolerances, stack failure modes, sealing, reliability, and the potential for component redesign specifically to optimize fuel cell manufacturing throughput.
Dynamic Thermal Thin Film Processing of Large Areas With High Power Laser Sources
Authors: Kubacki Frank , Hauschild Dirk , Ivanenko Mikhail , Meinschien Jens , Bayer Andreas , Lissotschenko Vitalij
Published: September 2010

High power laser sources are used in various production tools for cutting, welding and hardening of metal parts and patterning, annealing and lithography of flat panel displays, solar cells and microelectronic devices. Beside the right choice of the laser source suitable high performance optical beam delivery and shaping systems are needed for generating the appropriate beam profile and intensity distribution are of high importance for the right processing speed, quality and yield. In addition to the typical laser processes with circular beam shapes LIMO has developed laser sources with line shaped beams for large area processing for e.g. crystallization and tempering of conducting and semi-conducting films on glass for FPD, PV and thermal processing of semiconductor wafer, coated float glass and sheet metal. Due to the high power density of several 100kW/cm2 and line length up to several hundred millimetres a treatment capacity of several m2 per minute and processing speeds up to 1 m/s can be achieved per laser head with typical scan & repeat processes. The use of multiple laser heads in one machine scales the productivity to the individual needs. The high scanning speed together with line widths of 0,01mm to 0,1mm is the basis for heating only a few microns of the surfaces layers and no costly cooling time is needed like with regular heating technologies. With this controlled surface heating even more sensitive materials can be processes like inks on polymers and paper for RFIDs, printed solar absorbers and coatings. For industrial applications equally important is an adequate understanding of the physics of the light-matter interaction behind the process. In advance simulations of the tool performance can minimize technical and financial risk as well as lead times for prototyping and introduction into series production. Based on this knowledge together with a unique free-form micro-lens array production technology and patented micro-optics beam shaping designs a number of novel production tool sub-systems have been built by LIMO: 1. a multi-kilowatt direct diode illumination modules for solar cell annealing, and crystallization; 2. a novel green laser beam line for the annealing of silicon thin films on glass; 3. a novel wavefront shaping optics that generates a top hat beam profile from a TEM00 high-power laser source for accurate thin film structuring. For each of these sub-system basic functionalities, design principles and performance results are presented with a special emphasis on resilience, cost reduction and process reliability.
Modeling of Ceramic Microgrinding by Cohesive Zone Based Finite Element Method
Authors: Feng Jie , Kim Bongsuk , Ni Jun
Published: September 2010

This study investigates modeling of microgrinding of ceramic materials by cohesive zone method (CZM) and Finite element analysis (FEA). A maximum grinding chip thickness model, which considers detail diamond profile and tool deflection, is developed in this study. The chip thickness model is then implemented in FEA to predict peak grinding force in grinding alumina. The simulation result is compared with experimental result for a specific diamond on the microgrinding tool. The feasibility of modeling ceramic microgrinding by CZM based FEA is then discussed.
Single Point Diamond Turning Effects on Surface Quality and Subsurface Damage in Ceramics
Authors: Ravindra Deepak , Patten John A. , Qu Jun
Published: September 2010

Advanced ceramics, such as Silicon Carbide (SiC) and Quartz, are increasingly being used for industrial applications. These ceramics are hard, strong, inert, and light weight. This combination of properties makes them ideal candidates for tribological, semiconductor, MEMS and optoelectronic applications respectively. Manufacturing these materials without causing surface and subsurface damage is extremely challenging due to their high hardness, brittle characteristics and poor machinability. Often times, severe fracture can result when trying to achieve high material removal rates during machining of SiC or quartz due to their low fracture toughness. This research demonstrates that ductile regime Single Point Diamond Turning (SPDT) is possible on these materials to improve its surface quality without imparting subsurface damage. Machining parameters, such as depth of cut and feed, used to carry out ductile regime machining will be discussed. Subsurface damage analysis was carried out on the machined samples using non-destructive methods such as Optical Microscopy, Raman Spectroscopy and Scanning Acoustic Microscopy to show evidence that the chosen material removal method leaves a damage-free surface and subsurface. Optical microscopy was used to image the improvements in surface finish whereas Raman spectroscopy and scanning acoustic microscopy was used to observe the formation of amorphous layer and subsurface imaging in the machined regions. All three techniques complement the initial hypothesis of being able to remove a nominally brittle material in the ductile regime.
Lapping of Semiconductor Wafers: An Experimental Investigation on Subsurface Damage
Authors: Zhang P. F. , Pei Z. J.
Published: September 2010

Semiconductor substrate wafers are used to manufacture a variety of semiconductor devices. Lapping is an important process to obtain flat wafer surfaces. Subsurface damage, however, is unavoidably generated during the lapping process and has vital effects on wafer quality. Experiments were conducted to study the effects of several lapping parameters on subsurface damage in semiconductor substrate wafers, such as abrasive grain size, abrasive material, lapping pressure, and slurry concentration. It was found that abrasive grain size and abrasive material have significant effects on subsurface damage. Effects of lapping pressure and slurry concentration on subsurface damage were less significant.
Formation of 5052 Aluminum Channels Using Electrically-Assisted Manufacturing (EAM)
Authors: Salandro Wesley A. , Roth John T.
Published: September 2010

In recent years, the industrial demand for strong, lightweight metal alloys, such as 5052 Aluminum, has increased. Previous research has shown that the Electrically-Assisted Manufacturing (EAM) technique, where electricity is applied to a material during deformation, improves the material behavior of most metals. By applying electricity continuously or by applying electrical pulses during deformation, the technique reduces the material’s flow stress and increases its achievable elongation. Considering this, the research presented herein investigates applying pulsed EAM when fabricating channels from Al 5052. To fully determine the technique’s influence on the manufacturing process, the effects of current density, pulse duration, pulse period, and die speed are examined. The results demonstrate that the channel formation process is improved using EAM. The improvements include reduced force/energy requirements and increased achievable channel depth.
RFID Product and Part Tracking for the Preventive Maintenance
Authors: Ostojic Gordana , Jovanovic Vukica , Stankovski Stevan , Lazarevic Milovan
Published: September 2010

RFID technology can be applied during the different phases of a product realization, material handling, packaging, but also during the disassembly. Recently, environmental issues have posed certain challenges in a way that products are being handled after the end of their lifecycle. Nowadays, the products are being designed for assembly but also for a disassembly. Whatever the selected strategy for products or parts of products is at the end of their life cycle, it is necessary to design an appropriate production system as well as a disassembly system. Reflection about the final stages in a product overall lifecycle early in the process has enabled focus on a sustainable design. In this paper, one such system is going to be described. Managing of product related data and product identification could be more efficient if some new technologies are used. One of them is the use In-mould labeling (IML) technology. The molded plastic items are being labeled before they are formed by different kinds of robots or manipulators. Labels are caught into the mould of plastic injection molding machines (IMM). Our intention is to present an automated system that enables tracking of product throughout the different stages of its lifecycle. Writing and updating information about the states of the IML robot and its basic robot components (e.g. cylinders), on the RFID tag and in database, could be done only by an authorized user. The user can get the information about the momentary status of a particular product or part during different phases during the life cycle. Information placed in the database about a product can describe the components that can be used for spare parts, information about the services (dates and descriptions), number of working cycles, etc. Such information can be used for product or part tracking for preventive maintenance.
Study of Machining-Induced Microstructure Variations of ECAE-Processed Ultrafine-Grained Copper
Authors: Huang Yong , Morehead Mason
Published: September 2010

Various methods for production of bulk ultrafine-grained (UFG)/nanostructured materials have been developed. Recently, a top-down approach named equal channel angular extrusion (ECAE), a form of severe plastic deformation (SPD), has gained increasing attention in making bulk UFG materials. Such bulk materials are favored for their high strength, wear resistance, ductility, and high strain-rate superplasticity, which makes them suitable for light weight engineering and medical applications. Further precision machining work is normally indispensable for structural applications after bulk ultrafine grained materials are manufactured from any SPD processes. Unfortunately, the microstructure stability issues in precision machining such materials are frequently ignored. Using an ECAE copper bar as an example, this study has investigated its machining-induced workpiece microstructure variation. It has been found that there was a small increase in the size parameter median and the average arithmetic and area weighted grain sizes when comparing those of machined and unmachined bars, and the measured grain sizes oscillated slightly in the radial direction of the machined bar. Dislocation density was shown to have the most reduction at the outer radius location of the machined ECAE bar where more heat and/or higher pressure were experienced.