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ASME Conference No-Show Policy and Archival Proceedings

2011;():i. doi:10.1115/MSEC2011-NS2.
FREE TO VIEW

This online compilation of papers from the ASME 2011 International Manufacturing Science and Engineering Conference (MSEC2011) represents the archival version of the Conference Proceedings. According to ASME’s conference no-show policy, if a paper is not presented at the Conference, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in the ASME Digital Library and may not be cited as a published paper.

Commentary by Dr. Valentin Fuster

Materials

2011;():1-7. doi:10.1115/MSEC2011-50119.

This study investigates the potentiality of using atmospheric-pressure Direct Current (DC) plasma arc discharge as a surface treatment method of aluminum alloys in adhesively bonded joints in order to enhance adhesion. The surface morphology exposed to the arc for the current of 40 A (low intensity) and the plasma torch scanning speeds between 20 and 120 mm/s, exhibits a micro-scale surface roughness appropriate for adhesive bonding. The arc textured surfaces are characterized by using an optical profilometer. Additionally, the effect of modified surface on the stress distribution throughout the single-lap adhesively bonded joint in tension is explored by 2D FEM. The geometrical model for FE analysis of adhesively bonded structure is generated by including the surface texture coordinates obtained from the optical profilometer.

Commentary by Dr. Valentin Fuster
2011;():9-13. doi:10.1115/MSEC2011-50263.

Perovskite materials have been widely embedded in many consumer and industrial electronics, both for capacitor applications in the case of dielectric materials, and for actuator, transducer and sensor applications in the case of piezoelectric materials. Functional devices used in high temperature environments, such as deep oil well instrumentation, geothermal exploration, and devices for aerospace applications require the persistence of materials’ properties at high temperatures. In this paper, high potential capacitor and piezoelectric ceramics for high temperature applications are presented. High dielectric constant (K) materials based on 0.8BaTiO3 – 0.2Bi(Zn1/2 Ti1/2 )O3 solid solutions have been shown to have superior properties for high temperature capacitor applications. Studies of the temperature dependence of the dielectric properties have shown that the composition with Ba vacancies exhibits a high relative permittivity (εr > 1150) and a low dielectric loss (tan δ < 0.05) that persist up to a temperature of 460 °C. This composition also shows a high resistivity in excess of 7.0 × 1010 Ω-cm which remains unchanged up to a temperature of 270 °C as well as a large RC time constant (RC > 20 s). In the case of high temperature piezoelectric ceramics, solid solutions of PbTiO3 – BiScO3 – Bi(M1/2 Ti1/2 )O3 ternary systems were studied, where M is Mg and Zn. The ratio of BiScO3 to Bi(M1/2 Ti1/2 )O3 was kept at 1:1, while the concentration of PbTiO3 was varied. X-ray diffraction patterns showed that tetragonal symmetry was observed in compositions which contain a high concentration of PbTiO3 (> 60 mol%). Evidence of a morphotropic phase boundary (MPB) was observed with compositions containing PbTiO3 in the range of 52–56 mol%. At 70 mol% PbTiO3 compositions, high Curie temperatures (TC ) of 490 °C and 533 °C were observed for compositions containing Mg and Zn, respectively.

Commentary by Dr. Valentin Fuster

Properties, Applications and Systems

2011;():15-22. doi:10.1115/MSEC2011-50007.

A common practice in the manufacturing environment is to use different measuring tools for inspecting engineering products. These measuring tools range from hand held tools (manual) such as venire caliper, to manufactured inspection gages, and general purpose coordinate metrology based inspection tools such as: Coordinate Measuring Machine (CMM). Selecting the correct measuring tool is critical to measure the variation resulting from a manufacturing process. Three experiments have been conducted to evaluate the effect of this decision on the process capability index (Cpk ), and the Statistical Process Control (SPC) control limits. It was found that the data collected from the CMM tends to be clustered around the process mean, while it is more spread for the other inspection tools. This situation leads to higher process capability index when the data is collected from a CMM compared with the other measuring tools. It also leads to variation in the calculations of the SPC control limits. This may cause in-consistency, confusion, and may result in unnecessary false alarms. A standard deviation monitoring graph has been suggested to monitor the capability of the measuring system to ensure the integrity of the interpretation of the output of the SPC system.

Commentary by Dr. Valentin Fuster
2011;():23-32. doi:10.1115/MSEC2011-50029.

STEP-NC is the result of a ten-year international effort to replace the RS274D (ISO 6983) G and M code standard with a modern associative language. The new standard connects CAD design data to CAM process data so that smart applications can understand both the design requirements for a part and the manufacturing solutions developed to make that part. STEP-NC builds on a previous ten-year effort to develop the STEP standard for CAD to CAD and CAD to CAM data exchange, and uses the modern geometric constructs in that standard to specify device independent tool paths, and CAM independent volume removal features. This paper reviews a series of demonstrations carried out to test and validate the STEP-NC standard. These demonstrations were an international collaboration between industry, academia and research agencies. Each demonstration focused on testing and extending the STEP-NC data model for a different application.

Topics: Manufacturing
Commentary by Dr. Valentin Fuster
2011;():33-47. doi:10.1115/MSEC2011-50152.

The choice of fitting algorithm in CMM metrology has often been based on mathematical convenience rather than the fundamental GD&T principles dictated by the ASME Y14.5 standard. Algorithms based on the least squares technique are mostly used for GD&T inspection and this wrong choice of fitting algorithm results in errors that are often overlooked and leads to deficiency in the inspection process. The efforts by organizations such as NIST and NPL and many other researchers to evaluate commercial CMM software were concerned with the mathematical correctness of the algorithms and developing efficient and intelligent methods to overcome the inherent difficulties associated with the mathematics of these algorithms. None of these works evaluate the ramifications of the choice of a particular fitting algorithm for a particular tolerance type. To illustrate the errors that can arise out of a wrong choice of fitting algorithm, a case study was done on a simple prismatic part with intentional variations and the algorithms that were employed in the software were reverse engineered. Based on the results of the experiments, a standardization of fitting algorithms is proposed in light of the definition provided in the standard and an interpretation of manual inspection methods. The standardized fitting algorithms developed for substitute feature fitting are then used to develop Inspection maps (i-Maps) for size, orientation and form tolerances that apply to planar feature types. A methodology for Statistical Process Control (SPC) using these i-Maps is developed by fitting the i-Maps for a batch of parts into the parent Tolerance Maps (T-Maps). Different methods of computing the i-Maps for a batch are explored such as the mean, standard deviations, computing the convex hull and doing a principal component analysis of the distribution of the individual parts. The control limits for the process and the SPC and process capability metrics are computed from inspection samples and the resulting i-Maps. Thus, a framework for statistical control of the manufacturing process is developed.

Commentary by Dr. Valentin Fuster
2011;():49-56. doi:10.1115/MSEC2011-50267.

Statistical process monitoring and control has been popularized throughout the manufacturing industry as well as various other industries interested in improving product quality and reducing costs. Advances in this field have focused primarily on more efficient ways for diagnosing faults, reducing variation, developing robust design techniques, and increasing sensor capabilities. System level advances are largely dependent on the introduction of new techniques in the listed areas. A unique system level quality control approach is introduced in this paper as a means to integrate rapidly advancing computing technology and analysis methods in manufacturing systems. Inspired by biological systems, the developed framework utilizes immunological principles as a means of developing self-healing algorithms and techniques for manufacturing assembly systems. The principles and techniques attained through this bio-mimicking approach will be used for autonomous monitoring, detection, diagnosis, prognosis, and control of station and system level faults, contrary to traditional systems that largely rely on final product measurements and expert analysis to eliminate process faults.

Commentary by Dr. Valentin Fuster
2011;():57-64. doi:10.1115/MSEC2011-50018.

Machine tool covers are important parts of the machine. From the point of view of feed drives, a cover is an additional multi-body system that influences the dynamic properties of the feed drive and the positioning accuracy of the machine. The advantages of covers connected to the machine table with flexible elements are shown on simulation and experimental results. A mathematical model of the cover and its connection to the machine table is described. Optimization of the stiffness and damping ratio for the connection, using a model of the cover, is suggested. The optimal connection parameters cause decreasing of maximum reaction force acting from the cover to the feed drive. This phenomenon is presented on simulation example and also on the experiment results.

Topics: Machine tools
Commentary by Dr. Valentin Fuster
2011;():65-68. doi:10.1115/MSEC2011-50056.

Silicon nitride ceramics doped with rare-earth oxides exhibit excellent hardness, toughness, and strength at elevated temperatures making them attractive materials for replacing cemented carbides in a variety of manufacturing applications such as cutting and rolling tools. One recent example is the application of rolling of high strength alloy wires from steels and nickel-based super-alloys where cemented carbide rolls suffer wear and thermal fatigue cracking, leading to a degradation of wire quality. [1] Furthermore, it has been shown that under moderate loading silicon nitride rolls can give >10 times longer life and improved wire surface quality. [1] However, it has also been shown that the rolls can suffer fatigue failure at higher loadings, for example when rolling wires with high deformation resistance such as the super alloy wire Nicrofer S7020. [1–2] Accordingly the aim of this study is the develop a design tool for predicting the fatigue failure of silicon nitride ceramics. The silicon nitrides with favorable mechanical properties have microstructures with elongated β-phase grains and a glassy intergranular film. The weak film encourages intergranular fracture allowing the formation of grain bridges across the crack wake which helps to reduce the stress intensity felt at the crack tip, Ktip . [3]

Commentary by Dr. Valentin Fuster
2011;():69-78. doi:10.1115/MSEC2011-50155.

New, higher and challenging properties of new high-speed machines and high-performance machines bring up many questions connected to the design and properties of the main machine tool structures. Parameters like static stiffness, eigenfrequencies, modal damping and mass of parts may be identified as very important, and all these properties need to be improved. The most important material properties in the field of machine tools are presented in this paper. A case study based on a modification of a real horizontal machining centre is introduced. The modification consists in using a sandwich design concept in the main structural machine tool part. The sandwich concept, widely known and used in the aerospace industry and, more generally, the transportation industry, is not commonly used in machine tool design. A significant reduction of mass has been achieved by manufacturing a hybrid column with aluminum foam cores, while static stiffness has not been affected.

Commentary by Dr. Valentin Fuster
2011;():79-88. doi:10.1115/MSEC2011-50204.

A multidisciplinary design optimization (MDO) process of a large scale hybrid composite wind turbine blade is developed. Multiple objectives are considered in this design optimization: maximize length of blade, minimize weight and manufacturing cost. A wind turbine blade is divided into regions and the layup sequences for each region are considered as design variables. Applied load due to extreme wind condition for rotor rotation and rotor stop condition are considered for finite element analysis (FEA) to evaluate the structural strength. The structural stiffness is designed and illustrated so that the natural frequency of the blade does not coincidence with the excitation frequency of the wind turbine. A process of obtaining an optimum hybrid composite laminate layup and an optimum length of wind turbine blade is developed in this research.

Commentary by Dr. Valentin Fuster
2011;():89-98. doi:10.1115/MSEC2011-50220.

Recently, machining has been exploited as a means for producing ultra-fine grained (UFG) and nanocrystalline microstructures for various metal materials, such as aluminum alloys, copper, stainless steel, titanium and nickel-based super alloys, etc. However, no predictive, analytical or numerical work has ever been presented to quantitatively predict the change of grain sizes during machining. In this paper, a dislocation density-based viscoplastic model is adapted for modeling the grain size refinement mechanism during machining by means of a finite element based numerical framework. A novel Coupled Eulerian-Lagrangian (CEL) finite element model embedded with the dislocation density subroutine is developed to model the severe plastic deformation and grain refinement during a steady-state cutting process. The orthogonal cutting tests of a commercially pure titanium (CP Ti) material are simulated in order to assess the validity of the numerical solution through comparison with experiments. The dislocation density-based material model is calibrated to reproduce the observed material constitutive mechanical behavior of CP Ti under various strains, strain rates and temperatures in the cutting process. It is shown that the developed model captures the essential features of the material mechanical behavior and predicts a grain size of 100–160 nm in the chips of CP Ti at a cutting speed of 10 mm/s.

Commentary by Dr. Valentin Fuster
2011;():99-103. doi:10.1115/MSEC2011-50069.

Due to rapid consumption of world’s fossil fuel resources and impracticality of large-scale application and production of renewable energy, the significance of energy efficiency improvement of current available energy modes has been widely realized by both industry and academia. A great deal of research has been implemented to identify, model, estimate, and optimize energy efficiency of single-machine manufacturing system [1–5], but very little work has been done towards achieving the optimal energy efficiency for a typical manufacturing system with multiple machines. In this paper, we analyze the opportunity of energy saving on the system level and propose a new approach to improve energy efficiency for sustainable production systems considering the fact that more and more modern machines have multiple power states. Numerical case based on simulation model of an automotive assembly line is used to illustrate the effectiveness of the proposed approach.

Commentary by Dr. Valentin Fuster
2011;():105-110. doi:10.1115/MSEC2011-50071.

This study deals with some eco-indicators of cutting tools. Eco-indicators of cutting tools are classified into three categories, namely, material-, process-, and geometry-related eco-indicators. Material-related eco-indicators consist of density, price, embodied energy, CO2 footprint, NOX, SOX, water usage, material processing energy, and recycle fraction of tool materials. Process-related eco-indicators consist of material removal rate, cutting velocity, feed rate, spindle speed, and surface coating. Geometry-related eco-indictors consist of special geometric features of cutting tool that make the tool’s performance robust in terms of process-related eco-indicators. The general definitions and representations of these indicators are described. Giving examples of cutting tools made of tungsten carbide and HSS, it is shown that further research is needed to develop an ideal cutting tool that is equally preferable in terms of material-, process-, and geometry-related eco-indicators.

Topics: Cutting tools
Commentary by Dr. Valentin Fuster
2011;():111-118. doi:10.1115/MSEC2011-50089.

The need to cost effectively introduce new generations of product families within ever decreasing time frames have led manufacturers to seek product development strategies with a multigenerational outlook. Co-evolution of product families and assembly systems is a methodology that leads to the simultaneous design of several generations of product families and reconfigurable assembly systems that optimize life cycle costs. Two strategies that are necessary for the implementation of the co-evolution of product families and assembly systems methodology are: (1) The concurrent design of product families and assembly systems and (2) Assembly system reconfiguration planning (ASRP). ASRP is used for the determination of the assembly system reconfiguration plans that minimize the cost of producing several generations of product families. More specifically, the objective of ASRP is to minimize the net present cost of producing successive generations of products. This paper introduces a method for finding optimum solutions to the ASRP problem. The solution methodology involves the generation of a staged network of assembly system plans for all the generations that the product family is expected to be produced. Each stage in the network represents a generation that the product family is produced, while each state within a stage represents a potential assembly system configuration. A novel algorithm for generating the states (i.e. assembly system configurations) within each generation is also introduced. A dynamic program is used to find the cost minimizing path through the network. An example is used to demonstrate the implementation of the ASRP methodology.

Topics: Manufacturing
Commentary by Dr. Valentin Fuster
2011;():119-125. doi:10.1115/MSEC2011-50098.

Conventionally, improving production efficiency, flexibility and responsiveness has been the primary research focus of production management, while energy consumption has received relatively little attention. Energy consumption plays a more and more important role in manufacturing environment. This is mainly driven by energy cost and environmental concerns. When the energy system becomes complicated and coupled with ongoing production, it is very difficult to hunt the “hidden treasure” which affects the overall benefit of a manufacturing system. This paper provides a systematic method for energy management in a production system. We start from dynamic production transient analysis and provide quantitative analysis for energy saving opportunity in a system. Furthermore, energy saving is integrated into production system which includes downtime and throughput to provide integrated energy management framework for a production system. A case study is conducted to demonstrate its potential on energy savings in a multi-stage manufacturing system.

Commentary by Dr. Valentin Fuster
2011;():127-133. doi:10.1115/MSEC2011-50107.

The turbulent environment of dynamic job-shop operations affects shop-floor layout as well as manufacturing operations. Due to the dynamic nature of shop-floor layout changes, essential requirements such as adaptability and responsiveness to the changes need to be considered in addition to the cost issues for material handling and machine relocation when reconfiguring a shop floor’s layout. Here, based on the source of uncertainty, the shop floor layout problem is split into two sub-problems and dealt with by two modules: re-layout and find-route. Genetic algorithm is used where changes may cause a re-layout of the entire shop, while function blocks are utilised to find the best sequence of robots for the new conditions within the existing layout. This paper reports the latest development to the author’s previous work.

Commentary by Dr. Valentin Fuster
2011;():135-144. doi:10.1115/MSEC2011-50157.

With people becoming more individualistic in their choices they make in personalizing the goods and services they use, as resulted in major development that has been recorded in the customisation world. This individualism has resulted in the increase in demand of customized products in many industries especially in the footwear, kitchen and computer industries. However, little has been done when it comes to mechanically oriented products and little flexibility has been given to the consumers in the co-creation of customized products. The Hybrid system of classification is one way to satisfy the customers’ need for the products that are mechanically oriented in nature thereby meeting their desire needs. This paper presents a framework in which an Hybrid system of classification is used to integrates Customers into the design process by defining, configuring, matching, or modifying personal product that is mechanically oriented in nature and grouping the products into classes and sub-classes using a wide range of product parameters, products configuration which make it possible to add and/or change functionalities of a core product, a coding system for mechanical designs which is applicable to each product in the hierarchy, the use of a database for the products information. And the retrieval system to retrieve a similar product code from the database if the initial customer configuration data does not yield a feasible product code through the application of Analytic Hierarchy Process and finally modifying the existing similar product to suit the customers desire.

Commentary by Dr. Valentin Fuster
2011;():145-153. doi:10.1115/MSEC2011-50172.

This paper presents a case study for inventory management for an oilfield equipment company. The management encounters the problem of deciding which parts to manufacture in-house and which ones to subcontract. A decision support system (DSS) is developed which ranks component parts by integrating multi-criteria classification methods considering both quantitative (e.g., cost and demand) and qualitative (e.g., importance) factors. The focus on this research is to perform a sensitivity analysis on weight assignment for each criterion. This information is important in applications of inventory management since industries may not be able to manufacture all the necessary parts on time. Real world data from an oilfield equipment industry are used where inventory control problems have arisen because the company does not have the capacity to manufacture all the required parts to satisfy customer orders.

Commentary by Dr. Valentin Fuster
2011;():155-161. doi:10.1115/MSEC2011-50174.

Research efforts for energy consumption reduction in manufacturing systems have been centered at technology and process innovation. These projects, however, often involve major capital investment of new equipment and material. In this paper, we explore energy saving opportunities through improvement in factory floor operations. Specifically, in the framework of Bernoulli serial lines, we consider production systems with stripping operations. In such systems, the in-process buffers have to be depleted at the end of each shift to avoid quality deterioration during off-shift periods. Transient analysis of the systems are carried out and formulas to calculate the performance measures are derived. In addition, we investigate the effect of machine startup schedule on the system performances and develop optimal startup schedule which, as shown in the paper, can lead to significant improvement in energy utilization efficiency.

Commentary by Dr. Valentin Fuster
2011;():163-171. doi:10.1115/MSEC2011-50232.

As efforts continue to incorporate environmental sustainability into product design, struggles persist to concurrently consider the environmental impacts resulting from transportation planning and supply chain network design. In fact, the transportation sector is the second largest contributor to direct greenhouse gas (GHG) emissions in the United States, following electricity generation. To address these concerns and consider environmental issues more holistically during the development of products, Design for X (X: manufacturing, environment, etc.) methods, such as environmentally benign manufacturing (EBM) and life cycle assessment (LCA) continue to be advanced through research. In spite of improving environmental performance through design, supply chain related impacts are not well understood and can be impacted by decisions made during product design. Thus, the aim of this research is to explore how changes to the design of a product affect manufacturing supply chain configurations and, in turn, influence product environmental sustainability. The environmental impacts for producing several three-ring binder design variations are predicted by assuming a given set of suppliers that provide materials and components to the manufacturer. Supply chain transportation impacts are also accounted for in the analysis. Transportation impacts are found to be minor compared to materials and manufacturing impacts.

Commentary by Dr. Valentin Fuster
2011;():173-180. doi:10.1115/MSEC2011-50233.

With increasing production costs and constraints, demand has increased for manufacturers to minimize maintenance cost and product transport time. We address some aspects of this problem by examining how to choose the optimal layout of stations (machines or buffers) in a production facility based on how the station layout affects the maintenance and product transport times. Specifically, we consider how the location of the stations relative to the maintenance facility affects the overall maintenance time as well as how the location of the final station affects the product transport time. Hence, we can address maintenance cost during the design-phase of a production facility. By employing discrete-design optimization techniques, we generate and evaluate various station layouts to choose an optimal layout which satisfies all geometric and adjacency constraints. We focus on a single, serial production line including a set of n stations.

Commentary by Dr. Valentin Fuster
2011;():181-190. doi:10.1115/MSEC2011-50048.

Buckling of plates and tubes plays an important role in structural safety and energy absorption. Although buckling of plates and tubes has been studied theoretically and experimentally in the past, the effects of aspect ratio and side constraint on buckling of multi-wall structures and tubes has not been investigated systematically. In this work, finite element simulations have been carried out to investigate the buckling behavior of multi-wall structures and tubes. A series of one- to three-panel walls and square tubes with various aspect ratios were simulated. The critical aspect ratios causing buckling mode transition were obtained and compared with theoretical predictions available in the literature. Effects of wall angle and side constraint on buckling behavior were investigated. The relevance of research findings to honeycomb-like structures was discussed.

Topics: Buckling
Commentary by Dr. Valentin Fuster
2011;():191-198. doi:10.1115/MSEC2011-50209.

Warm forming is a manufacturing process in which a workpiece is formed into a desired shape at a temperature range between room temperature and material recrystallization temperature. Flow stress is expressed as a function of the strain, strain rate, and temperature. Based on such information, engineers can predict deformation behavior of material in the process. The majority of existing studies on flow stress mainly focus on the deformation and microstructure of alloys at temperature higher than their recrystallization temperatures or at room temperature. Not much works have been presented on flow stress at warm-forming temperatures. This study aimed to determine the flow stress of stainless steel AISI 316L and titanium TA2 using specially modified equipment. Comparing with the conventional method, the equipment developed for uniaxial compression tests has be verified to be an economical and feasible solution to accurately obtain flow stress data at warm-forming temperatures. With average strain rates of 0.01, 0.1, and 1 /s, the stainless steel was tested at degree 600, 650, 700, 750, and 800 °C and the titanium was tested at 500, 550, 600, 650, and 700 °C. Both materials softened at increasing temperatures. The overall flow stress of stainless steel was approximately 40 % more sensitive to the temperature compared to that of titanium. In order to increase the efficiency of forming process, it was suggested that the stainless steel should be formed at a higher warm-forming temperature, i.e. 800 °C. These findings are a practical reference that enables the industry to evaluate various process conditions in warm-forming without going through expensive and time consuming tests.

Commentary by Dr. Valentin Fuster
2011;():199-206. doi:10.1115/MSEC2011-50282.

Tool flank wear during hard milling adversely affects surface integrity and, therefore, fatigue strength of machined components. Surface integrity and machining accuracy deteriorate when tool wear progresses. In this paper, surface integrity and its impact on endurance limit of AISI H13 tool steel (50 ± 1 HRC) by milling using PVD coated tools are studied. The evolutions of surface integrity including surface roughness, microhardness and microstructure were characterized at three levels of tool flank wear (VB = 0, 0.1mm, 0.2mm). At each level of tool flank wear, the effects of cutting speed, feed, and radial depth-of-cut on surface integrity were investigated respectively. Fatigue endurance limits of the machined surfaces at different reliability levels were calculated and correlated with the experimentally determined fatigue life. The good surface finish and significant strain-hardening on the machined surfaces enhance endurance limit, which enables machined components have a fatigue life over 106 cycles.

Commentary by Dr. Valentin Fuster
2011;():207-214. doi:10.1115/MSEC2011-50019.

A typical manufacturing job shop comprises of legacy machine tools, new (modern) machine tools, material handling devices, and peripheral manufacturing equipments. Automated monitoring of legacy machine tools has been a long-standing issue for the manufacturing industry primarily because of the computer numeric controller (CNC) closed architecture and limited external communication functionality. This paper describes a non-invasive methodology and development of a software application to monitor real-time machine status, energy usage, and other machining parameters for a legacy machine tool using power signal analysis. State machine algorithm is implemented to detect tool changes and part count. The system architecture, implementation, benefits, limitations, and future work needed for the legacy machine tool monitoring application is explained in detail.

Topics: Machinery , Signals
Commentary by Dr. Valentin Fuster
2011;():215-224. doi:10.1115/MSEC2011-50041.

In semiconductor fabrication processes, reliable feature extraction and condition monitoring is critical to understanding equipment degradation and implementing the proper maintenance decisions. This paper presents an integrated feature extraction and equipment monitoring approach based on standard built-in sensors from a modern 300mm-technology industrial Plasma Enhanced Chemical Vapor Deposition (PECVD) tool. Linear Discriminant Analysis was utilized to determine the set of dynamic features that are the most sensitive to different tool conditions brought about by chamber cleaning. Gaussian Mixture Models of the dynamic feature distributions were used to statistically quantify changes of these features as the condition of the tool changed. Data was collected in the facilities of a well-known microelectronics manufacturer from a PECVD tool used for depositing various thin films on silicon wafers, which is one of the key steps in semiconductor manufacturing. Dynamic features coming from the radio frequency (RF) plasma power generator, matching capacitors, pedestal temperature, and chamber temperature sensors were shown to consistently have significant statistical changes as a consequence of repeated cleaning cycles, indicating physical connections to the chamber condition.

Topics: Thin films
Commentary by Dr. Valentin Fuster
2011;():225-233. doi:10.1115/MSEC2011-50059.

This paper describes the dynamic characteristics of a newly-designed force sensor comprised of carbon nanoparticles embedded in a polyphenylene sulfide matrix and operating on the principle of contact resistance change with pressure. Sensor performance was investigated for frequencies ranging from 1 to 1,000 Hz using two testing setups: a load frame for low frequency characterization and a piezo-electric stack for describing higher-frequency behavior. Bode magnitude and phase response plots were developed and it was determined that the sensor under study can be modeled as a first order system up to 600 Hz. The −3 dB bandwidth was found to be 90 Hz and the sensor’s time constant was determined to be 0.0018 seconds. A dynamic model of the sensor is constructed and compared against performance data. The sensor was found to have non-linear spring properties, allowing for two damping coefficients, one for each spring constant range, to be calculated. The damping coefficient was calculated to be 619 lb-s/in for loadings under 600 lbs and 1928 lb-s/in for loadings greater than 600 lbs. The sensor’s time response was also found to be more similar in shape to the input loading waveform when it was compared to piezoelectric load transducers.

Commentary by Dr. Valentin Fuster
2011;():235-242. doi:10.1115/MSEC2011-50099.

An experienced technician can usually identify the cutting condition by hearing the sound generated during the cutting and the sound signal can be expected to detect the features closely related to the tool condition. However, the background noise always contaminates the signal obtained by microphone system during cutting and reduces the chance of applying the sound based micro tool condition monitoring system in industry. In order to reduce the noise effect and improve the system performance, a microphone array integrated with Wiener filter was designed and implemented in this study to enhance the noise reduction capability for monitoring system. The experimental results show that the microphone array integrated with Wiener filter provides a better solution than single microphone integrated with Wiener filter or the microphone array without the post filter design in reducing the broadband background noise.

Commentary by Dr. Valentin Fuster
2011;():243-251. doi:10.1115/MSEC2011-50132.

Condition based maintenance (CBM) of machine tools is an important maintenance strategy to invoke for a manufacturing company to run as lean as possible. CBM does this by indicating, in advance, the failure of the machine tool components or system, thus reducing the machine downtime. In this paper, the development of such a system is sought. A background review of the need and structure of such a system has been provided as well as the design considerations for the system are discussed. Having those considerations as the target requirements for a CBM system, discussion of a demonstrative system is presented, being implemented on an OKUMA LB 3000EX CNC lathe. Leveraging the Open Architecture Control (OAC) technology built into OKUMA CNC systems, the proposed system shall enhance machine monitoring by integrating the internal and external sensors aboard the machine tool. This work lays the foundation for the framework of a proposed CBM system. Coolant temperatures and spindle vibration signals are acquired and processed using a high speed data acquisition system. Towards the end of the paper, descriptions of how to best use this data and integrate it with the machine tool CNC system have been provided.

Commentary by Dr. Valentin Fuster
2011;():253-262. doi:10.1115/MSEC2011-50133.

New approaches for fast surface quality estimation in Milling are presented. Dimensional Error, Surface Roughness, and the 3D topological plots of the surfaces are generated. Calculation speed is improved by methods of structural organization and numerical optimizations. Structural organization enables program division into initialization and program-run segments for faster runs. Numerical optimizations are used to help further reduce the run time by reducing variable volume and avoiding unnecessary estimations. Experimental evaluation of the methods for Dimensional Error, Surface roughness and profiles are performed using three different cutting tool types (flat-end, ball-end and insert mills) in order to reveal strengths and weaknesses of the proposed approaches. Comparison of experimental and estimated surface profiles show good correlation. Typical surface profile estimation for one tool rotation takes between 0.04–4.1 seconds depending on the cut and whether or not the tool deflection is included in the algorithm. Surface quality estimation is done quickly enough to be promising for use in feedrate scheduling. Further improvement in the tool deflection model is expected to increase accuracy and further reduce the computational time.

Commentary by Dr. Valentin Fuster
2011;():263-271. doi:10.1115/MSEC2011-50154.

Model based control of machining processes is aimed at improving the performance of CNC systems by using the knowledge of machining process to reduce cost, improving machining accuracy and improving overall productivity. In this paper, real time control of the machining process to maintain dimensional quality when turning a slender bar is addressed. The goal is to actively control the machining feed rate to maintain constant and predicable deflection through a combined force-stiffness model integrated to the process controller. A brief review is presented on manufacturing process models, process monitoring, and model based control strategies such as Model Predictive Control (MPC). The main objective of this paper is to outline a method for deploying such models to process control. To demonstrate this, model of the deflection of the workpiece under tool cutting forces is developed. Unknown process parameters have been calculated using series of FEA simulations and verified with basic experimental data. A simple but effective control strategy has been formulated and simulated. In the initial results, the diameter of bar is maintained within 1.04% error with controller as opposed to up to 4% error without controller. Ultimately, the goal is to deploy such control strategies in the industrial control system. With the continual development in physical understanding of machining processes and affordable computing technology (both software and hardware) coupled with Open Architecture Control (OAC) applied to CNC machine tools, such approaches are now computationally feasible. This will be an enabling factor to deploy model based control in an industrial environment. The last section discusses the proposed hardware architecture to achieve this. The paper concludes with a brief plan for the future work and a summary.

Commentary by Dr. Valentin Fuster
2011;():273-280. doi:10.1115/MSEC2011-50168.

The introduction of multi-axis CNC machining has reduced machining time and increased production rates. However, optimizing simultaneous operations to produce quality parts and prolong tool life still possesses a challenge to engineers due to the mutual interactions of two tools removing material and the amount of factors and noise in a production environment. Since there are multiple factors and the sources of error are unknown, we use a statistical approach to obtain and organize information. A design of experiment study was implemented across twelve sensor responses to optimize the spindle speed, feed rate, inner diameter (ID) depth of cut and outer diameter (OD) depth of cut for simultaneous turning and boring roughing operations. The optimal machining conditions were obtained by a response optimizer from Minitab 16 statistical software. The optimized settings result in 13% reduced cutting and 10% reduced total power consumption for a 3% increase of average power. Future studies will cross correlate different responses to reduce the number of sensors in developing a robust adaptive controller for chatter detection and tool condition monitoring.

Commentary by Dr. Valentin Fuster
2011;():281-288. doi:10.1115/MSEC2011-50178.

In this paper, three basic lighting geometries are compared quantitatively in an inspection task that checks for the presence of J-clips on an aluminum carrier. Two independent LabVIEW® machine vision algorithms were used to evaluate backlight, bright field and dark field illumination on their ability to minimize variations within a pass (clip present) or fail (clip absent) sample set, as well as maximize the separation between sample sets. Results showed that there were clear differences in performance with the different lighting geometries, with over a 30% change in performance. Although it is widely acknowledged that the choice of lighting is not a trivial exercise for machine vision systems, this paper provides a case study of the quantitative performance of different lighting geometries.

Topics: Machinery , Inspection
Commentary by Dr. Valentin Fuster
2011;():289-296. doi:10.1115/MSEC2011-50211.

Solutions for machinery anomaly detection and diagnosis are typically designed on an ad hoc, custom basis, and previous studies have shown limited success in automating or generalizing these solutions. Reusing and maintaining the analysis software, especially when the machine usage pattern or operating condition changes, remains a challenge. This paper outlines a strategy to make use of operational data obtained from the machine’s controller and signals obtained from external sensors to provide an accurate analysis within each operating condition. Operational data collected from the controller is used both for labeling datasets into different operating conditions and for analysis. Principal component analysis (PCA) is adopted to identify critical sensors that can provide useful information. Self-organizing map (SOM)-based anomaly detection and diagnosis methods are used to automatically convert data to easily understandable machine health information for operators. Experiment trials conducted on a feed-axis test-bed demonstrated the effectiveness of incorporating operational data for anomaly detection and diagnosis.

Commentary by Dr. Valentin Fuster
2011;():297-306. doi:10.1115/MSEC2011-50297.

This paper presents a novel approach for obtaining thermomechanical data from the close vicinity (i.e., 10s of micrometers) of the tool-workpiece interface while machining hardened steel. Arrays of micro thin film C-type thermocouples with a junction size of 5 μm × 5 μm were fabricated by standard microfabrication methods and have been successfully embedded into polycrystalline cubic boron nitride (PCBN) using a diffusion bonding technique. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were performed to examine material interactions at the bonding interface and to determine optimal bonding parameters. Static and dynamic sensor performances have been characterized. The sensors exhibit excellent linearity up to 1300 °C, fast rise time of 150 ns, and good sensitivity. The PCBN inserts instrumented with embedded thin film C-type thermocouples were successfully applied to measure internal tool temperatures as close as 70 μm to the cutting edge while machining hardened steel workpieces at industrially relevant cutting parameters. Acquired temperature data followed theoretical trends very well. Correlations between temperature and cutting parameters have been established. The embedded micro thin film sensor array provided unprecedented temporal and spatial resolution as well as high accuracy for micro-scale transient tool-internal temperature field measurements. Tool internal temperature maps were generated from acquired data. In the frequency domain, obtained thermal data indicated the onset of regenerative machining chatter earlier and more effective than conventional force measurement by dynamometer.

Commentary by Dr. Valentin Fuster
2011;():307-311. doi:10.1115/MSEC2011-50035.

Carbon nanotubes (CNTs) reinforced Al matrix composites were prepared by friction stir processing (FSP). The effect of CNTs content on the wearing performance and hardness of Al matrix composites was studied. Results show that CNTs reinforced Al matrix composites by FSP are to create a good dispersion of the CNTs in the matrix and to achieve a good combination with the matrix. The interface of CNTs and pure aluminum matrix is smooth, no defects and is one kind of mechanical bonding interface. There are a large number of dislocations. CNTs can strengthen the matrix composites effectively and obviously improve the hardness of the composites. With increasing CNTs content, CNTs can also improve the wear performance of the matrix composites.

Commentary by Dr. Valentin Fuster
2011;():313-322. doi:10.1115/MSEC2011-50278.

The objective of this paper is to qualitatively assess the inadequacies of the current manner of tool wear quantification and consequently to suggest/develop a more comprehensive approach to machining tool wear characterization. Traditional parameters used for tool wear representation such as flank and crater wear are no longer self-sufficient to satisfactorily represent the wear of the complex geometric profiles of more recent cutting tools. These complexities in tool geometries are all the more pronounced when catering to difficult-to-machine materials such as titanium and its alloys. Hence, alternatives to traditional tool wear assessment parameters are briefly explored and a suitable one is selected, that will help understand the very nature of the evolving wear profile itself from a three dimensional standpoint. The assessment methodology is further developed and standardized and suggestions for future use and development provided. The measurement system is evaluated using a gauge repeatability and reproducibility (R&R) study as well. The method is deployed for assessing tool wear during the machining of Ti-6Al-4V at selected process conditions for validation purposes. Further, concepts such as the M-ratio and its derivatives are developed to quantify the efficiency of the cutting tool during each pass as a function of time at a theoretically constant material removal rate (MRR).

Topics: Wear , Machining
Commentary by Dr. Valentin Fuster
2011;():323-329. doi:10.1115/MSEC2011-50295.

This paper investigates the application of atmospheric arc (the same arc that is used for welding) for surface texturing of aluminum alloy in micro scale. This research shows that micro-texturing of metallic surfaces is feasible with an arc-based, inexpensive, environment-friendly method. In this paper, fundamental phenomena occurring during surface texturing process using cathode spots of arc are introduced. The surface texturing process is experimentally studied using surface microscopy and high-speed real-time monitoring by a machine-vision system. The advantages of the process and the potential applications are discussed.

Commentary by Dr. Valentin Fuster

Micro and Nano Technologies

2011;():331-338. doi:10.1115/MSEC2011-50026.

This paper presents the findings of an experimental study on lathe turning operations on Hard-to-Cut Materials based on 55RC samples using Carbide inserts coated with Titanium Nitride fitted on a self-propelling rotary tool, and compares the results with simulated conventional tools with fixed inserts. Tool performance is assessed based on cutting force, surface quality of the machined workpiece, and tool wear. Findings indicate better tool life and overall performance of rotary tools due to the self-propelled motion of the inserts. The self-propelled motion of the inserts provides a self-cooling effect, improving tribological properties and lowering Thrust Force as a result of the decrease of contact time at the tool-work surface interface. Wear is observed to be evenly distributed with no evidence of diffusion-type wear. Finally, the machined surface quality is at par or better than one resulting from using a conventional fixed tool. The above characteristics translate into a more cost-efficient cutting operation.

Topics: Turning
Commentary by Dr. Valentin Fuster
2011;():339-348. doi:10.1115/MSEC2011-50076.

In an earlier paper, a high-speed micro-groove cutting process that makes use of a flexible single-point cutting tool was presented. In this paper, 3D finite element modeling of this cutting process is used to better understand process mechanics. The development of the model, including parameter estimation and validation, is described. Validation experiments show that on average the model predicts side burr height to within 2.8%, chip curl radius to within 4.1%, and chip thickness to within 25.4%. The model is used to examine chip formation, side burr formation, exit burr formation, and the potential for delamination of a workpiece consisting of a thin film on a substrate. Side burr formation is shown to primarily occur ahead of a tool and is caused by expansion of material compressed after starting to flow around a tool rather than becoming part of a chip. Exit burr formation is shown to occur when a thin membrane of material forms ahead of a tool and splits into two side segments and one bottom segment as the tool exits a workpiece. Lastly, examination of the stresses below a workpiece surface shows that film delamination can occur when the depth of a groove cut into a thin film is large relative to the film thickness.

Topics: Cutting
Commentary by Dr. Valentin Fuster
2011;():349-358. doi:10.1115/MSEC2011-50122.

The objective of this paper is to study the time-evolution of the process mechanics for micro-electrical discharge machining (MEDM) and reverse-micro-electrical discharge machining (R-MEDM), as a function of key system parameters, viz., voltage, capacitance, and threshold of the spark circuit. Full factorial experiments have been performed to quantify the aforementioned system parameters on the MEDM and R-MEDM processes. The process monitoring voltage and current signals, material erosion rate and the surface roughness values are the machining responses of interest. The voltage and current (V-I) signals reveal information about the material erosion rate and the extent of debris-interference associated with the corresponding process. Analysis of the V-I signals shows that R-MEDM is more stable than MEDM and can therefore be operated at aggressive conditions of capacitance and voltage. R-MEDM also results in higher material erosion rates but the resulting surface has a higher surface roughness value than that generated by MEDM. A debris deposition mechanism is proposed for R-MEDM that suggests debris entrapment and subsequent welding to the machined feature to be the reason for the increased surface roughness.

Commentary by Dr. Valentin Fuster
2011;():359-364. doi:10.1115/MSEC2011-50143.

Dry machining is considered as a green manufacturing process because the use of cutting fluids has concerns about environmental contamination and health hazards. However, in grinding, the use of cutting fluids is a common strategy to improve the cutting performance and the product surface finish due to the transportation of heat away from the cutting zone. Vibration-assisted machining is a novel technology which is an efficient technique for high quality surface finish in dry cutting. The purpose of this paper is to investigate the feasibility of vibration-assisted grinding of SKD61 steels, where the amplitude about 1 μm with a frequency about 10 KHz is applied. This study compares the machined surface finish in vibration-assisted grinding to that in conventional machining based on experimental measurements. The effects of the grinding and vibrating conditions on the ground surface finish are studied. A near mirror surface (Ra = 0.05 μm) is achieved at the vibration frequency of 11.4 KHz in this paper. It is also found that the best surface finish in vibration-assisted grinding is affected both by the feed and the vibration frequencies. The experimental results show that proper combination of grinding and vibration parameters should be carefully chosen to prevent instability in grinding.

Commentary by Dr. Valentin Fuster
2011;():365-372. doi:10.1115/MSEC2011-50144.

This paper presents a multi-objective optimization study for the micro-milling process with adaptive data modeling based on the process simulation. A micro-milling machining process model was developed and verified through our previous study. Based on the model, a set of simulation data was generated from a factorial design. The data was converted into a surrogate model with adaptive data modeling method. The model has three input variables: axial depth of cut, feed rate and spindle speed. It has two conflictive objectives: minimization of surface location error (which affects surface accuracy) and minimization of total tooling cost. The surrogate model is used in a multi-objective optimization study to obtain the Pareto optimal sets of machining parameters. The visual display of the non-dominated solution frontier allows an engineer to select a preferred machining parameter in order to get a lowest cost solution given the requirement from tolerance and accuracy. The contribution of this study is to provide a streamlined methodology to identify the preferred best machining parameters for micro-milling.

Commentary by Dr. Valentin Fuster
2011;():373-386. doi:10.1115/MSEC2011-50244.

This study is focused on experimental evaluation and numerical modeling of micro-milling of hardened H13 tool steels. Multiple tool wear tests are performed in a micro side cutting condition with 100 μm diameter endmills. The machined surface integrity, part dimension control, size effect and tool wear progression in micromachining of hardened tool steels are experimentally investigated. A strain gradient plasticity model is developed for micromachining of hardened H13 tool steel. Novel 2D FE models are developed in software ABAQUS to simulate the continuous chip formation with varying chip thickness in complete micro-milling cycles under two configurations: micro slotting and micro side cutting. The steady-state cutting temperature is investigated by a heat transfer analysis of multi micro-milling cycles. The FE model with the material strain gradient plasticity is validated by comparing the model predictions of the specific cutting forces with the measured data. The FE model results are discussed in chip formation, stress, temperature, and velocity fields to great details. It is shown that the developed FE model is capable of modeling a continuous chip formation in a complete micro-milling cycle, including the size effect. It is also shown that built-up edge in micromachining can be predicted with the FE model.

Commentary by Dr. Valentin Fuster
2011;():387-392. doi:10.1115/MSEC2011-50248.

This paper presents two basic experimental studies of a micro-drilling process with nanofluid minimum quantity lubrication (MQL) in terms of machining and environmental characteristics. By using a miniaturized desktop machine tool system, a series of micro drilling experiments were conducted in the cases of dry, compressed air and nanofluid MQL. The experimental results imply that nanofluid MQL significantly reduces the adhesion of chips when compared with the cases of dry and compressed air micro-drilling. As a result, it is observed that the magnitudes of average drilling torque and thrust force are decreased and the tool life of micro drills is extended in the case of nanofluid MQL micro-drilling process. In addition, the empirical study on environmental characteristics of MQL micro-drilling process is conducted by measuring MQL oil mist with the oil sampling method. The results show that remaining MQL oil mist is tiny enough not to have a detrimental effect on human health.

Commentary by Dr. Valentin Fuster
2011;():393-402. doi:10.1115/MSEC2011-50256.

With a broader intention of producing thin sheet embossing molds, results from investigations in orthogonal cutting of thin workpieces are presented here. Challenges in machining thin workpieces are many: residual stress effects, fixturing challenges, and substrate effects. Aluminum alloy Al6061-T6 workpiece fixture using an adhesive is orthogonally cut with a single crystal diamond tool. We study trends in cutting forces, understand to what level of thickness we can machine the workpiece down to and in what the form the adhesive fails. Two types of workpiese-adhesive anomalies were noticed. One is the detachment of the thin workpiece by peel-off and the other one is where the workpiece did not get detached but the final width of the workpiece was non-uniform. We then use a validated finite element machining model to understand the stresses in the workpiece when it is thick and when machined to thin condition, effect of the adhesive itself and also the effect of adhesive thickness. Simulations show that the stress induced by the cutting process at the bottom of the workpiece is higher for the thinner workpiece (40 μm) compare to a thicker workpiece (400 μm) especially at the tool entrance region for adhesive thicknesses of 30 μm and 100 μm. Hence a thinner workpiece is more susceptible to failure by adhesive peeling.

Topics: Cutting
Commentary by Dr. Valentin Fuster
2011;():403-407. doi:10.1115/MSEC2011-50285.

In micromachining, when the undeformed chip thickness becomes comparable to the edge radius of the cutting tool, the effective rake angle becomes to be negative and has significant effect on the determination of the minimum uncut chip thickness. The determination of the minimum uncut chip thickness is essential in micro machining in order to achieve desired surface integrity and accuracy. In this paper, an Arbitrary Lagrangian Eulerian (ALE)-based numerical modeling is proposed to determine the minimum uncut chip thickness for Copper by changing the cutting tool’s nominal rake angle. According to the relationship between the minimum uncut chip thickness and the effective rake angle, a mathematical model that reflects the relationship between the effective rake angle and the nominal rake angle is established.

Commentary by Dr. Valentin Fuster
2011;():409-417. doi:10.1115/MSEC2011-50180.

This project is focused on developing physics based models to predict the outcome of pulsed laser micro polishing (PLμP). Perry et al. [1–3] have modeled PLμP as oscillations of capillary waves with damping resulting from the forces of surface tension and viscosity. They have proposed a critical spatial frequency, fcr , above which a significant reduction in the amplitude of the spatial Fourier components is expected. The current work extends the concept of critical spatial frequency to the prediction of the spatial frequency content and average surface roughness after polishing, given the features of the original surface, the material properties, and laser parameters used for PLμP. The proposed prediction methodology was tested using PLμP results for Nickel, Ti6Al4V, and stainless steel 316L with initial average surface roughnesses from 70 nm to 190 nm. The predicted average surface roughnesses were within 10% to 15% of the values measured on the polished surfaces. The results show that the critical frequency continues to be a useful predictor of polishing results in the spatial frequency domain. The laser processing parameters, as represented by the critical frequency and the initial surface texture therefore can be used to predict the final surface roughness before actually implementing PLμP.

Topics: Lasers , Polishing , Finishes
Commentary by Dr. Valentin Fuster
2011;():419-428. doi:10.1115/MSEC2011-50222.

Microvia formation technology using lasers has become the dominant method for drilling microvia called blind via-holes (BVHs) in printed wiring boards (PWBs). Laser direct drilling (LDD), drilling directly outer copper foil by laser, has attracted attention as a novel method. In particular, when copper and resin with different processing thresholds are drilled at the same time, an overhang defect occurs on the drilled hole. However, the overhang generation mechanism has not been clarified. Therefore, we investigated it by detailed observation of the drilled-hole section. Moreover, the overhang length was estimated using the finite element method (FEM). Influences of surface treatment of outer copper foil and thermal properties of the build-up layer were evaluated experimentally and analytically. Consequently, an experiment with a prototype PWB with silica filler added in the build-up layer was carried out. Using the prototype PWBs, the overhang was reduced as shown in FEM analysis results.

Commentary by Dr. Valentin Fuster
2011;():429-442. doi:10.1115/MSEC2011-50260.

The paper introduces the LIP-MM process and compares its micro-machining capabilities with micro-EDM in the machining of micro-channels. While, micro-EDM is a well-established micro-manufacturing process and has been at the center of research for the last 15 years, the LIP-MM is a newly developed micro-machining process. Although both processes utilize plasma to perform micro-machining, differences in their plasma generation mechanism and hence differences in their plasma characteristics lead to differences in their micro-machining capabilities. For comparative assessment of their micro-machining capabilities, micro-channels were machined by the two processes at similar pulse energy levels, while other process parameters were maintained at their optimal values, depending on the respective experimental setups used. The comparative assessment was based on the geometric characteristics of the micro-channels, material removal rate (MRR), productivity in the machining of micro-channels, effect of tool wear, and the range of machinable materials for the two processes.

Commentary by Dr. Valentin Fuster
2011;():443-448. doi:10.1115/MSEC2011-50294.

In this paper, partial amorphization of NiTi alloys by laser shock peening (LSP) is reported. The microstructure of NiTi after LSP was characterized by transmission electron microscopy (TEM). The amorphization mechanism was discussed in light of the high strain rate deformation characteristics of LSP. With subsequent controlled annealing after LSP, nanostructure with different grain size distribution was achieved.

Commentary by Dr. Valentin Fuster
2011;():449-461. doi:10.1115/MSEC2011-50296.

Nanoscale size effects on pulsed laser coating of hydroxyapatite/titanium nanoparticles on metal substrate is discussed in this article. Laser coating method has recently been developed to coat bioceramics material on Ti-6Al-4V substrate. Laser-coated bioceramics implants have several advantages due to the use of nanosized materials: strong interfacial bonding strength, good biocompatibility and potentially longer lifetime cycle. These advantages benefit from intrinsic properties of nanoparticles. Size effects on melting point, heat capacity, thermal and electrical conductivities have been discussed. Multiphysics model is built to reveal the mechanism of laser coating process. Two sub-modules are included in the model: electromagnetic module to represent the laser-nanoparticle interactions and heat transfer module to simulate the heat conduction. Both simulation and experimental results showed that nanoTi, functioning as nanoheaters, effectively enhances the laser coating sinterability. For large nanoTi (>100 nm), sinterability enhancement mainly attributes to the stronger laser-particle interactions due to higher plasmon resonance; for small nanoparticles (<100 nm), not only stronger laser-nanoparticle interactions, reduction on melting point also contributes to sinterability enhancement.

Commentary by Dr. Valentin Fuster
2011;():463-470. doi:10.1115/MSEC2011-50301.

One-dimensional nanomaterials have attracted a great deal of research interest in the past few decades due to their unique mechanical, electrical and optical properties. Changing the shape of nanowires is a big challenge, but remains key for realistic applications of nanowires. Here we report a general technique to flexibly form nanowires into different shapes by making use of laser shock pressure. Controllable deformation is induced into nanowires in a similar manner as traditional metal forming. Shaping of silver nanowires is demonstrated, during which the Ag nanowires exhibit very good ductility (strain to failure is larger than 1). The microstructure observation indicates that the main deformation mechanism in Ag nanowires under dynamic loading is controlled by twinning and stacking fault formation. Dislocation motion and pile-up is still operative but less important. Our method provides a simple, unique, and one-step approach in massive forming and machining nanowires.

Commentary by Dr. Valentin Fuster
2011;():471-478. doi:10.1115/MSEC2011-50070.

This paper presents a novel method to achieve high yield assembly of millimeter-scale thin silicon chips from an air-water interface. Surface functionalized silicon parts (1×1 mm2 with 100 μm thickness) assemble in preprogrammed hydrophilic locations on a wafer substrate with self-alignment. We optimize the process and design factors systematically using DOE (Design of Experiment) that leads to high yield (close to 100 %). This paper also presents an experimental and theoretical study of a high yield self-assembly process with programmable template. An analysis of the method is presented with an emphasis on the combined effect of substrate tilting angle and part size on fluidic assembly at an air-water interface. For 1×1, 3×3 and 5×5 mm2 parts with 100 μm thickness, the maximum substrate tilting angles are experimentally determined and the surface tension induced torques are calculated based on the developed model. The result indicates that there is a limit on the lateral size of the parts that can be assembled when we use one substrate tilting angle. Based on our analysis, we propose a novel method that is capable of assembling parts of higher lateral dimensions using parametric changes in substrate tilting angle.

Topics: Self-assembly
Commentary by Dr. Valentin Fuster
2011;():479-485. doi:10.1115/MSEC2011-50160.

In this paper, we present an approach to design MOEMS based on Reconfigurable Free Space Micro-Optical Benches (RFS-MOB). The proposed concept enables to design modular and reconfigurable MOEMS by using a generic structure of silicon holders and non defined position in the substrate. Various micro-optical elements, e.g. microlenses or micromirrors, can be integrated within holders. Their assembly is achieved with an active microgripper, after high precision alignement within guiding rails of silicon substrate. Flexible parts are used to maintain a final position. The concept is validated by successful assembly of holders. A characterization method of assembled holders is proposed and provides an accuracy better than ± 0.04° for an angle measurement.

Commentary by Dr. Valentin Fuster
2011;():487-492. doi:10.1115/MSEC2011-50171.

Magnetotactic bacteria (MTB) can be used in a coordinated fashion to assemble micro-objects in an orderly manner. To perform micro-assembly tasks, magnetotaxis-based control is used where a directional magnetic field is generated to induce a torque on an embedded chain of membrane-based magnetic nanoparticles (MNP) named magnetosomes. Such chain acts like a nano-compass or a nano-steering system embedded in each bacterium. Such magnetotaxis-based control is then used to orient the MTB in such a way that the laminar flow created by their flagella bundles provides a displacement force on the micro-objects being assembled. Since the force is generated by the bacteria, relatively large micro-objects can be moved with no requirement for electrical energy except for a relatively small value required for inducing a directional torque on the chain of magnetosomes in the cells. Because the energy required to generate the directional torque is independent on the population of MTB being involved but the displacement force can be scaled up with the use of a larger swarm while the total workspace would typically be at microscale dimensions, the energy required for the coils configuration around such workspace and responsible for generating the directional torque can be reduced further to a very low level and hence, makes the implementation of mass-scale bacterial micro-assembly systems, a viable approach. Based on these findings, we propose a corresponding mass-scale system based on many workspaces, each relying on a swarm of MTB to perform micro-assembly tasks in parallel.

Commentary by Dr. Valentin Fuster
2011;():493-506. doi:10.1115/MSEC2011-50045.

The scanning probe microscope (SPM), in particular the atomic force microscope (AFM), is widely used as a metrology tool at the nanoscale. Recently, the instrument has shown tremendous potential to perform various nanoscale fabrication processes (e.g. nanolithography, atomic deposition, nanomachining, etc.) with high resolution (< 10 nm). However, use of SPMs for fabrication have a low throughput and require frequent manual replacement of the SPM tips due to damage or wear. Manual switching of tips for multiple operations, is relatively time consuming. Thus these issues hinder the throughput, quality, reliability, and scalability of SPM as a practical tool for nanofabrication. To address these issues, this paper presents the design, analysis, and fabrication of a novel nano tool-tip exchanger that automatically loads and unloads SPM tool-tips. The ability to provide fully automated on-demand tool-tip exchange would enable SPM as a scalable tool for nanomanufacturing. In this work, an active SPM cantilever is designed with an electrothermally actuated microgripper capable of locating, loading, and unloading tool-tips automatically. The microgripper has been designed to provide adequate range of actuation, gripping force, stiffness, and dynamic response required for securely holding the tool-tip and for functioning within existing SPM-based systems. The design has been validated by finite element analysis. Experiments have been conducted to establish the micro-electro-mechanical systems (MEMS) fabrication processes for successful fabrication of the prototype.

Commentary by Dr. Valentin Fuster
2011;():507-513. doi:10.1115/MSEC2011-50067.

An attempt has been made to synthesize SrFeO3-δ powder by sol-gel process involving oxalate formation, its digestion for 4h, drying at 150°C for 24h, and decomposition at 800°C for 10h. The resulting powder is shown to a) exhibit a single phase with a perovskite-type cubic structure and lattice parameter a = 3.862±0.002Å, b) contain irregular shape particles, and c) display optical absorption peaks corresponding to charge transfer from oxygen to iron (3.73 and 3.41eV), t2g to eg transition of Fe3+ (1.57eV), and crystal field (3d-3d) charge transfer of Fe3+ (1.25eV). Impedance over a wide frequency range of 20Hz-2MHz at 118–318K has contributions from two parallel ‘RC’ circuits belonging to bulk and grain boundaries with the later displaying significant space charge polarization. The relaxation time of polarization follows an Arrhenius behaviour (τ = τo exp[Ea /kB T]) with τo as ∼10−8 s and activation energy Ea as ∼50meV. Further, the sample having magnetic character with transition temperature as 853K, coercivity (Hc ) = 3748Oe and magnetization 0.09 μB per iron atom (at 17kOe). The zero field cooled and field cooled magnetization versus temperature data in conjunction with constricted hysteresis loops near the origin suggest core-shell morphology for the particles, core being antiferromagnetic with net uncompensated moment and shell conforming to disordered disposition of spins.

Commentary by Dr. Valentin Fuster
2011;():515-523. doi:10.1115/MSEC2011-50115.

This experimental study investigated the machinability of polymethylmethacrylate (PMMA)/multi-walled carbon nanotube (MWCNT) nanocomposites with 20 wt% MWCNTs in focused ion beam (FIB) micromachining. PMMA/MWCNT nanocomposites were fabricated using a solution casting method, in which PMMA and MWCNTs were dispersed in a solvent by ultrasonication. Microscale rectangular pockets were created on the PMMA/MWCNT nanocomposites to study the material removal mechanism in FIB. Effects of FIB input current and the ion beam overlap parameter (overlap %) on the material removal rate and geometric accuracy were studied. It was observed that the material removal rate increased with increasing input current and decreasing overlap %. Soft lithography was used to translate the ion-milled pockets on PMMA/MWCNT nanocomposites into microscale posts on polydimethylsiloxane (PDMS) for accurate measurement of the pocket geometries. A Scanning Electron Microscope (SEM) was used to investigate the characteristics of the micromachined features, nanocomposite surfaces, and replicated PDMS patterns. Our results demonstrated an effective method to produce microscale patterns on MWCNT-based nanocomposites.

Commentary by Dr. Valentin Fuster
2011;():525-536. doi:10.1115/MSEC2011-50170.

Magnesium Metal Matrix Composites (Mg-MMCs) with nano-sized reinforcements exhibit better mechanical properties comparing to pure Magnesium (Mg) and its alloys. However, it is challenging to improve the machinability of this kind of composites. An analytical cutting force model for the micro-milling process was developed and validated to analyze the micro-machinability of the SiC nanoparticles reinforced Mg-MMCs. This model is different from the previous ones because it encompasses the behaviors of the reinforcement nanoparticles in the three cutting regimes, i.e., shearing, ploughing and elastic recovery. The volume fraction of particles and particle size are considered as two significant factors affecting the cutting forces in this model. The effects of the reinforcement nanoparticles on cutting forces were studied through modeling and experimental validation. The simulated cutting forces show a good agreement with the experimental data. Moreover, it is indicated that the amplitude and profile of cutting forces vary with the reinforcement particle’s volume fraction. This mainly arises from the strengthening effect of SiC nanoparticles.

Commentary by Dr. Valentin Fuster
2011;():537-544. doi:10.1115/MSEC2011-50268.

A magnetic field-assisted finishing (MAF) process has been developed to reduce the sidewall surface roughness of the 5–20 μm wide curvilinear pores of microelectromechanical systems micropore X-ray optics. Although the feasibility of this process has been demonstrated on these optics, a clear understanding of the MAF process material removal mechanisms has not been attained. To discover these mechanisms, the MAF process is applied to a flat workpiece, allowing for direct observation and tracking of changes to distinctive surface features before and after MAF. Atomic force microscopy, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy are used to analyze the surface morphology and composition with respect to polishing time. These observations suggest that the MAF process removes surface material, improving surface roughness (to 0.1 nm Rq on silicon) without significantly changing the shape of existing surface features. Moreover, the MAF process appears to remove material by mechanical means.

Commentary by Dr. Valentin Fuster
2011;():545-554. doi:10.1115/MSEC2011-50270.

Recently, atomic force microscopy (AFM) has been widely used for nanomachining and fabrication of micro/ nanodevices. This paper describes the development and validation of computational models for AFM-based nanomachining (nanoindentation and nanoscratching). The Molecular Dynamics (MD) technique is used to model and simulate mechanical indentation and scratching at the nanoscale in the case of gold and silicon. The simulation allows for the prediction of indentation forces and the friction force at the interface between an indenter and a substrate. The effects of tip curvature and speed on indentation force and friction coefficient are investigated. The material deformation and indentation geometry are extracted based on the final locations of atoms, which are displaced by the rigid tool. In addition to modeling, an AFM was used to conduct actual indentation at the nanoscale, and provide measurements to validate the predictions from the MD simulation. The AFM provides resolution on nanometer (lateral) and angstrom (vertical) scales. A three-sided pyramid indenter (with a radius of curvature ∼ 50 nm) is raster scanned on top of the surface and in contact with it. It can be observed from the MD simulation results that the indentation force increases as the depth of indentation increases, but decreases as the scratching speed increases. On the other hand, the friction coefficient is found to be independent of scratching speed.

Commentary by Dr. Valentin Fuster
2011;():555-562. doi:10.1115/MSEC2011-50288.

In this study, a preliminary investigation about the grain size effect in machining of polycrystalline copper structures at atomistic scale is carried out using molecular dynamics simulation. Four copper structures with different grain sizes are chosen for simulation. The four structures consist of 16, 64, 128, and 256 grains, and the corresponding equivalent grain sizes are 13.6, 8.6, 6.8, and 5.4 nm, respectively. The results show that significant smaller forces are required to machine the copper workpiece in both the tangential and thrust directions as the grain size decreases. The magnitude of equivalent stress distribution also becomes smaller with the decrease of grain size. It disagrees with the commonly accepted strengthening effect (i.e., the Hall-Petch relation) for polycrystalline materials as a result of grain size reduction. This phenomenon can be explained by the inverse Hall-Petch relation proposed in literature in recent years. According to the new relation, the polycrystalline material strength decreases as the grain size decreases within a threshold value. This can be further attributed to the fact that the dominant deformation mode is changed from dislocation movement to other mechanisms such as grain boundary sliding with very fine nano-structured polycrystalline.

Topics: Copper , Machining
Commentary by Dr. Valentin Fuster
2011;():563-567. doi:10.1115/MSEC2011-50302.

In this study, synthesized Wurtzite-structured ZnS nanobelts was investigated using high resolution transmission electron microscope, atomic force microscope, and scanning electron microscope for structural and morphology analyses. Results show that ZnS nanobelts are tens of microns in length, mostly ∼40×50 nm2 in width and thickness. The nanobelts grow along direction [001] and are dislocation free. The distance spacing for (001) plane is 3.19Å. The capillary force was found strong enough to deform the ZnS nanobeam down to the substrate. Theoretical analysis on small strain elastic deformation was conducted. It was found that as the maximum beam deflection increases, beam elastic energy increases; in the meantime, the surface energy decreases. The net increase in elastic beam energy is less than the net decrease in the surface energy, resulting in total energy decrease. In addition, as the volume of liquid increases, for a certain maximum beam deflection, the total energy increases, this is result of the increase of the surface energy. Furthermore, for a specific nanobeam to be deflected to the underlying surface, the amount of liquid can be calculated.

Topics: Force , Deformation
Commentary by Dr. Valentin Fuster
2011;():569-575. doi:10.1115/MSEC2011-50057.

Electronics manufacturing technology has been advancing at an increasing rate for the past few decades and has forced related industries to do the same. One related industry involves the packaging technology used to enclose chips for power electronics. As demands of electronics manufacturers continue to increase in terms of cost, performance, and environmental impacts, so do demands on the packaging technologies involved. A variety of packaging materials have been used and proposed. The performance of each material varies in terms of ease of manufacturing, as well as its heat transfer properties. This study addresses performance, cost, and environmental impact measures to assist in selecting the most appropriate electronics packaging material. A performance study identified epoxy, aluminum nitride (AlN), and silicon carbide (SiC) to be the most viable options. Further analysis then found that epoxy outperforms the other options in terms of cost and environmental impact on a per-part basis, with AlN shown to be slightly better than SiC according to both metrics. Since it is known that AlN and SiC have superior material performance to epoxy packaging, further investigation is warranted to elucidate these relative differences, which will result in a more representative functional unit for comparative analysis.

Commentary by Dr. Valentin Fuster
2011;():577-584. doi:10.1115/MSEC2011-50246.

Computational fluid dynamics is used to refine the operating parameters of a Reverse Oscillatory Flow (ROF) microreaction system for the synthesis of uniformly-sized nanoparticles. The ROF mixing system uses highly advective flow regions to achieve high quality mixing over short mixing lengths. The mixing system is further enhanced by sinusoidal inlet flow conditions which create plugs having reduced diffusional lengths. Flow conditions leading to plug creation were found to be chiefly responsible for shorter mixing times. Residence time distributions (of simulated inert particles) were found to decrease with increasing pump displacement. It is expected that these conditions will lead to smaller particle size distributions. Mixing quality and residence time distribution are not captured well by Reynolds or Strouhal numbers; however the maximum inlet Reynolds number does correlate well with mixing time trends. Implications for flow conditions are discussed.

Commentary by Dr. Valentin Fuster
2011;():585-590. doi:10.1115/MSEC2011-50271.

Nanomaterials and nanomanufacturing is one of the fast growing and interesting fields in recent research and industries, and gaining huge interest around the world. As the nanomaterials has a higher physical and mechanical properties compared to their metal counterparts, it is expected that significant amount (15–20%) of nanomaterials will be put into use in less than five years periods almost in all fields of manufacturing. As the nanomaterial manufacturing is new, it is essential to establish an optimal method so as to reduce wastages and to increase the ratio of output to input materials used. It’s important to use the minimal energy, water and other raw materials. Thus, this review will more concentrate on the sustainability of inputs, need to improve or optimize the production methods or sustainable manufacturing and green gas production and its global effects. Suitability of both top-down and bottom-up processing for nanoparticles will be addressed. Need of life cycle analysis to understand feasibility of recyclable at the end of the life with least possible wastage and reduced energy. Current research on environmental benefits and risk of potential toxicity and health effects of nanoproducts will be discussed.

Topics: Sustainability
Commentary by Dr. Valentin Fuster
2011;():591-598. doi:10.1115/MSEC2011-50276.

Microchannel mixers enable faster mixing times compared with batch stir mixing leading to the promise of higher throughput, better yields and less solvent usage for the solution-phase reactive precipitation of inorganic nanoparticles. However, reliance on diffusive transport for subsecond mixing requires channel dimensions in the tens of micrometers. These channel dimensions make diffusive micromixers vulnerable to clogging. In this paper, an oscillatory flow mixing strategy is explored to increase the contact area between reagents within larger microchannels. Forward and reverse oscillatory signals are designed to pump reactants through a 450 μm high serpentine microchannel to increase advection within the flow. Computational fluid dynamics simulations are performed to provide insight into flow behavior and nanoparticle morphology. Quantification of mixing performance is proposed using mixing quality and particle residence time metrics. Experimental validation is pursued through the reactive precipitation of CdS quantum dots using a reverse oscillatory mixing setup. Transmission electron microscopy provides insights into the particle size distribution and particle crystallinity.

Commentary by Dr. Valentin Fuster
2011;():599-619. doi:10.1115/MSEC2011-50300.

Sustainable manufacturing has been defined by the U.S. Department of Commerce as the creation of manufactured products using processes that minimize negative environmental impacts, conserve energy and natural resources, are safe for employees, communities, and consumers, and are economically sound. Thus, it requires simultaneous consideration of economic, environmental, and social implications associated with production and delivery of goods. Research in sustainable manufacturing is an important activity that informs product development from a life cycle perspective. At the process level, sustainable manufacturing research addresses issues related to planning, analysis and improvement, and the development of processes. At a systems level, sustainable manufacturing research addresses challenges relating to supply chain design, facility design and operations, and production planning. Though economically vital, manufacturing processes and systems have retained the negative image of being inefficient, polluting, and dangerous. Through strategic activities focused on sustainable processes and systems, industrial and academic engineering researchers are re-imagining manufacturing as a source of innovation to meet society’s future needs. Recent research into concepts, methods, and tools for sustainable manufacturing are highlighted at the systems level, and explored more deeply as they relate to discrete manufacturing process development and analysis. Despite recent developments in decision making, and process- and systems-level research, many challenges and opportunities remain. Several of these in manufacturing research, development, implementation, and education are highlighted.

Commentary by Dr. Valentin Fuster

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