bluuebunny/crossref_metadata_2025 huggingface dataset:
First quantification of alpha‐Gal epitope in current glutaraldehyde‐fixed heart valve bioprostheses
Authors: Naso Filippo , Gandaglia Alessandro , Bottio Tomaso , Tarzia Vincenzo , Nottle Mark B. , d'Apice Anthony J. F. , Cowan Peter J. , Cozzi Emmanuele , Galli Cesare , Lagutina Irina , Lazzari Giovanna , Iop Laura , Spina Michele , Gerosa Gino
Published: July 2013

Background

Glutaraldehyde fixation does not guarantee complete tissue biocompatibility in current clinical bioprosthetic heart valves (BHVs). Particularly, circulating anti‐αGal human antibodies increase significantly from just 10 days after a BHV implantation. The inactivation of such epitope should be mandatory to meet the requirements for a perspectively safe clinical application; nevertheless, its quantitative assessment in commercially available BHVs has never been carried out.

Methods

In this investigation, seven different models of BHVs were tested. The number of epitopes was determined with reference to a standard αGal source by an ELISA test. The presence of xenoantigen was subsequently confirmed by immunofluorescence analysis. Porcine tissue, knockout for the αGal epitopes, was used as negative control.

Results

Epic™ valve was the only model among those tested, in which the αGal antigen appeared to be completely shielded. Composite Trifecta™ valve exhibited conflicting results: cusps of bovine pericardial tissue were devoid of reactive αGal epitopes, while the stent cover strip of porcine pericardium still maintained 30% of active antigens originally present in native tissue. All other tested BHVs express an αGal amount not significantly different from that exhibited by porcine Mosaic® valve (5.2 ± 0.6 × 1010 each 10 mg of tissue).

Conclusions

For the first time, the quantitative evaluation of the αGal epitope in heart valve bioprostheses, already in clinical practice for about 40 yrs, was finally determined. Such quantification might provide indications of biocompatibility relevant for the selection of bioprosthetic devices and an increase in the confidence of the patient. It might become a major quality control tool in the production and redirection of future investigation in the quest for αGal‐free long‐lasting substitutes.
Fast Trajectory Planning Via the B-Spline Augmented Virtual Motion Camouflage Approach
Authors: Basset Gareth , Xu Yunjun , Li Ni
Published: July 2013

The recently developed bio-inspired virtual motion camouflage (VMC) method can be used to rapidly solve nonlinear constrained optimal trajectory problems. However, the optimality of VMC solution is affected by the dimension reduced search space. Compared with the VMC method, the B-spline augmented VMC (BVMC) method studied in this paper improves the optimality of the solution, while the computational cost will not be significantly increased. Two simulation examples, the Snell's river problem and a robotic minimum time obstacle avoidance problem, are used to show the advantages of the algorithm.
Experimental Investigation of the Machinability of Epoxy Reinforced With Graphene Platelets
Authors: Arora Ishank , Samuel Johnson , Koratkar Nikhil
Published: July 2013

The objective of this research is to study the effect of graphene platelet (GPL) loading on the machinability of epoxy-based GPL composites. To this end, micro-milling experiments are conducted on composites with varying GPL content and their results are contrasted against that of plain epoxy. The material microstructure is characterized using transmission electron microscopy and scanning electron microscopy methods. Chip morphology, cutting force, machined surface morphology, and tool wear, are employed as the machinability measures for comparative purposes. At lower loadings of GPL (0.1% and 0.2% by weight) the deformation of the polymer phase plays a major role, whereas at a higher loading of 0.3% by weight, the GPL agglomerates and interface-dominated failure dictates the machining response. The minimum chip thickness value of the composites decreases with an increase in GPL loading. Overall, the 0.2% GPL composite has the highest cutting force and the lowest tool wear.
Microvia Formation for Multi-Layer PWB by Laser Direct Drilling: Improvement of Drilled Hole Quality of GFRP Plates
Authors: Ogawa Keiji , Hirogaki Toshiki , Aoyama Eiichi , Ayuzawa Tsukasa
Published: July 2013

Microvia formation technology using lasers has become the dominant method for drilling microvia that are called blind via-holes (BVHs) in printed wiring boards (PWBs). Laser direct drilling (LDD), which is direct drilling of the outer copper foil by laser, has attracted attention as a novel method. In particular, when copper and resin with different processing thresholds are simultaneously drilled, an overhang defect occurs on the drilled hole. On the other hand, aramid fiber reinforced plastics (AFRP) have been replaced by glass fiber reinforced plastics (GFRP) as the material used for the build-up layer because of its cost performance. Moreover, the PWB quality of the particle incrustations around the drilled holes has problems in the manufacturing process. However, the LDD process of such a composite has not been clarified. Therefore, we investigated it by detailed observation using a high-speed camera. We estimated the overhang length using the finite element method (FEM) and experimentally and analytically evaluated the effects of filler contented build-up layers. As a result, we improved drilled-hole quality by using prototype PWBs made of GFRP with filler in the build-up layer.
A New Approach to Predict Machining Force and Temperature With Minimum Quantity Lubrication
Authors: Ji Xia , Zhang Xueping , Liang Steven Y.
Published: July 2013

A new model to predict cutting force and temperature is developed by incorporating the lubrication and cooling effects generated from minimum quantity lubrication (MQL) machining. The boundary lubrication theory is utilized to estimate the friction behavior in prediction model. The model is capable of predicting cutting force and temperature in MQL machining directly from given cutting conditions, as well as material properties. Subsequently, the response of temperature distributions to chip formation and MQL is quantified on the basis of a moving heat source/loss model which iterates with the initial cutting force to achieve the final predictions. The predicted cutting temperature and cutting force are validated by the experimental data for AISI 9310 steel and AISI 1045 steel, respectively. Results show that under cutting speeds of 223–483 m/min, feed rates 0.10–0.18 mm/rev, depth of cut 1.0mm, the predicted cutting temperature at the tool-chip interface are generally lower than experimental measurements by 2% to 19%. And the model provides an average error of 11% for temperature prediction. With respect to cutting force prediction, the model provides a prediction error of 13% on the average in the cutting direction and 12% in the thrust direction within the experimental test condition range (cutting speeds of 45.75–137.25m/min, feeds 0.0508–0.1016 mm/rev, and depth of cut 0.508–1.016mm). In actual machining, the effects of possible tool wear causing higher temperature and force can contribute to deviations from model predictions involving only sharp tools.
Effects of Water Soaking on Biomass Particle Size in Cellulosic Biofuel Manufacturing
Authors: Wu Hera , Zhang Pengfei , Zhang Qi , Pei Z. J.
Published: July 2013

Cellulosic biofuels are an alternative to petroleum-based liquid transportation fuels. However, manufacturing costs of cellulosic biofuels are high partially due to low density and sugar yield of cellulosic biomass. Previous studies show that UV-A pelleting can increase the density and sugar yield of cellulosic biomass. A hypothesis for UV-A pelleting to increase the density and sugar yield of cellulosic biomass is that UV-A pelleting can reduce biomass particle size. To test this hypothesis, biomass particle sizes before and after UV-A pelleting need to be compared. Soaking pellets in water is an efficient and non-invasive method to separate pellets into particles. However, water soaking itself might change biomass particle size. This paper reports an investigation on effects of water soaking on biomass particle size. The biomass particle sizes before and after water soaking are measured and compared. Results show that effects of water soaking on biomass particle size are dependent on the initial particle size (particle size before water soaking) and time period of water soaking.
Sugar Yield Comparison of Wheat Straw Processed by Two Pelleting Methods for Cellulosic Biofuel Manufacturing
Authors: Zhang Qi , Zhang Pengfei , Zhang Meng , Song Xiaoxu , Pei Z. J. , Siddiqui Obair , Fan Kangqi
Published: July 2013

Biofuels made from cellulosic biomass are an alternative to petroleum-based liquid transportation fuels. However, low density of cellulosic biomass causes high costs in biomass transportation and handling in cellulosic biofuel manufacturing. Such costs can be reduced by pelleting processes that can densify cellulosic biomass. Ultrasonic vibration-assisted (UV-A) pelleting and ring-die pelleting are two pelleting methods. A previous study has compared the two pelleting methods in terms of pellet quality and pelleting power consumption. This paper reports an experimental comparison on sugar yields of wheat straw processed by the two pelleting methods under different combinations of pretreatment variables. Results show that wheat straw processed by UV-A pelleting has higher sugar yield than that processed by ring-die pelleting when the higher temperature and longer time are applied in pretreatment. Under other combinations of pretreatment variables, wheat straw processed by UV-A pelleting has lower sugar yield than that processed by ring-die pelleting.
Modeling Mechanical Behavior of Materials Processed by Accumulative Roll Bonding
Authors: Milner Justin L. , Bunget Cristina J. , Kurfess Thomas R. , Hammond Vincent H.
Published: July 2013

Nanostructured materials are a relatively new class of materials that exhibit high strength and toughness, thus improving performance and capabilities of products, with potential applications to automotive, aerospace and defense industries. Among the severe plastic deformation (SPD) methods currently used for achieving nanoscale structure of a material, accumulative roll bonding (ARB) is the most favorable method to produce grain refinement for continuous production of metallic sheets at a bulk scale. ARB is a deformation technique where metallic sheets are repeatedly prepared, stacked and rolled together, usually to a reduction of 50% in thickness.

The main objective of this paper is to create a model that relates the process parameters and number of ARB cycles to the mechanical properties of the resultant material. The model established in this study can be a useful tool in designing the process and establishing the number of cycles needed in order to achieve the desired properties. Accumulative roll bonding experiments of various materials are analyzed and the resultant materials strength, at the corresponding ARB cycles, is modeled with good agreement.
Pulse Electrochemical Micromachining of Tungsten Carbide
Authors: Kamaraj Abishek Balsamy , Dyer Rachael , Sundaram Murali M.
Published: July 2013

Pulse electrochemical micromachining (PECMM) is a non-conventional manufacturing method suitable for the production of micro-sized components on a wide range of conductive materials. PECMM improves dimensional accuracy and simplifies tool design in machining hard, high strength, and heat resistant materials into complex shapes. Extremely small interelectrode gaps are required in PECMM for better dimensional accuracy. However, excessively small interelectrode gaps may lead to complications like short-circuiting. This imposes the need for better control of the PECMM process. In this study a feedback controlled PECMM system was developed for the electrochemical micromachining of tungsten carbide. It was noticed that while, higher ratios of return velocity to feed rate is preferred as it reduces the number of current spikes, very high value of this ratio results in poor machining rates due to increased interelectrode gap. Therefore, this ratio of return velocity to feed rate may be used to optimize the PECMM process.
Modeling the Electroplastic Effect During Electrically-Assisted Forming of 304 Stainless Steel
Authors: Salandro Wesley A. , Bunget Cristina , Mears Laine
Published: July 2013

Over the last decade, the Electrically-Assisted Manufacturing (EAM) technique, where electricity is applied to a metal during deformation, has been experimentally proven to increase the workability of many lightweight alloys which are highly desirable to the automotive industry. Recent research by the authors has led to ways of accounting for the formability increases due to the applied electricity, by way of an Electroplastic Effect Coefficient (EEC), and by utilizing this coefficient, simple EAM forming tests can ultimately be modeled.

This work provides insight into the authors’ EAM modeling methodology and how it differs from previous EAM modeling attempts. Additionally, from the Electrically-Assisted Forming (EAF) experiments, two methods of accounting for the electroplastic effect will be discussed and compared. Ultimately, these methods will be integrated into the thermo-mechanical model to predict compressive stress-strain profiles for electrically-assisted forming tests under various current densities and die speeds. Finally, the efficiency of applying electricity to the deformation process will be discussed.
Simulation-Based Energy Efficiency Improvement for Sustainable Manufacturing Systems
Authors: Li Lin , Sun Zeyi , Yang Haoxiang , Gu Fangming
Published: July 2013

Energy efficiency improvement as well as carbon footprint reduction in the manufacturing industry becomes increasingly important for a green world from the point of sustainability. However, because of the complexity of modern manufacturing systems, most of the existing research efforts in energy efficiency improvement only focus on either single-machine system or process level. Seldom work has been performed to study the potential of energy consumption reduction for typical manufacturing systems with multiple machines and buffers. In this paper, a simulation-based method is proposed to study various strategies for energy efficiency improvement of complex manufacturing systems. This study provides an initial framework to study the real time energy control of multi-machine manufacturing systems, and demonstrates the energy efficiency improvement and energy saving potentials by adjusting the machines’ power level according to their operation states while maintaining the system throughput. Comparison between the results with and without power level adjustment is performed to illustrate the effectiveness of the proposed method.
Modeling and Optimization of Kerf Taper in Pulsed Laser Cutting of Duralumin Sheet
Authors: Pandey Arun Kumar , Dubey Avanish Kumar
Published: July 2013

Duralumin sheets are strong, hard, light weight and heat treated alloy of Aluminum, widely used by different sectors such as automobile, marine, aircraft and satellites. Many a times those applications demand complex shapes and intricate profiles with stringent design requirements which are not completely achieved by conventional sheet cutting methods. Laser cutting has capability of quality cutting with above requirements in thin sheetmetals. But highly reflective and thermally conductive sheetmetals like Duralumin pose difficulty in achieving quality cuts by laser beam. The kerf taper always occurs in laser cut specimen due to inherent converging-diverging profile of laser beam. The optimization of kerf taper and other cut qualities such as surface roughness, heat affected zone and recast layer formation in difficult-to-laser-cut sheetmetals like Duralumin or Aluminium alloy has become recent research interests. The aim of present research is to optimize kerf taper in pulsed laser cutting of Duralumin sheet using hybrid approach of ‘design of experiment (DOE)’ and ‘artificial intelligence tool’ such as genetic algorithm. The empirical model for kerf taper has also been proposed with the discussion on parametric effect.
Thermal Modeling of Electron Beam Additive Manufacturing Process: Powder Sintering Effects
Authors: Shen Ninggang , Chou Kevin
Published: July 2013

In recently developed Additive Manufacturing (AM) technologies, high-energy sources have been used to fabricate metallic parts, in a layer by layer fashion, by sintering and/or melting metal powders. In particular, Electron Beam Additive Manufacturing (EBAM) utilizes a high-energy electron beam to melt and fuse metal powders to build solid parts. EBAM is one of a few AM technologies capable of making full-density metallic parts and has dramatically extended their applications. Heat transport is the center of the process physics in EBAM, involving a high-intensity, localized moving heat source and rapid self-cooling, and is critically correlated to the part quality and process efficiency.

In this study, a finite element model was developed to simulate the transient heat transfer in a part during EBAM subject to a moving heat source with a Gaussian volumetric distribution. The developed model was first examined against literature data. The model was then used to evaluate the powder porosity and the beam size effects on the high temperature penetration volume (melt pool size). The major findings include the following. (1) For the powder layer case, the melt pool size is larger with a higher maximum temperature compared to a solid layer, indicating the importance of considering powders for the model accuracy. (2) With the increase of the porosity, temperatures are higher in the melt pool and the molten pool sizes increase in the depth, but decrease along the beam moving direction. Furthermore, both the heating and cooling rates are higher for a lower porosity level. (3) A larger electron-beam diameter will reduce the maximum temperature in the melt pool and temperature gradients could be much smaller, giving a lower cooling rate. However, for the tested electron beam-power level, the beam diameter around 0.4 mm could be an adequate choice.
An Analysis of Polishing Forces in Magnetic Field Assisted Finishing
Authors: Ganguly Vasishta , Schmitz Tony , Graziano Arthur A. , Yamaguchi Hitomi
Published: July 2013

Magnetic field assisted finishing (MAF) is used to polish free-form surfaces. The material removal mechanism can be described as a flexible “magnetic brush” that consists of ferromagnetic particles and abrasives that arrange themselves in the working gap between the magnet and the work piece. Relative motion between the brush and the work piece causes micro-cutting and improves surface finish. In this study, the contributions of the magnetic and polishing force components to the total force were evaluated. The effect of varying the polishing conditions, such as the working gap and the size of the ferromagnetic iron particles, on polishing forces and surface roughness was also analyzed. It was observed that the polishing forces varied considerably with working gap. Also, the iron particle size was found to have a strong relation to the rate at which the surface roughness decreased. Surface area roughness of 2–3 nm was achieved.
Observations During Vortex Machining Process Development
Authors: Howard Stephen C. , Chesna Jacob W. , Mullany Brigid , Smith Stuart T.
Published: July 2013

Vortex machining is a newly developed process that utilizes vortices generated by oscillating a micrometer sized fiber in colloidal abrasive slurry to remove material in highly localized regions [1]. Typical material removal footprints produced by our current machining process have micrometer sized lateral dimensions and nanometer depths with volumetric removal rates near 20 μm3 per hour. The carbon fiber attached to the tuning fork oscillator is approximately 7 μm in diameter and 4 mm in length. Resonant frequencies of the probe (fiber and tuning fork) are in the order of 30 kHz and oscillate with amplitudes of the fiber tip up to 50 μm. For these initial tests a silicon substrate has been machined using 0.05 μm alumina colloidal slurry and the resulting footprints were measured by a scanning white light interferometer. This paper provides details of the developed machining process, observations from initial test results, process metrology, and a short discussion of future process challenges.
Design and Analysis of Helical Needle Tip Grinding Process
Authors: Che Demeng , Guo Ping , Ehmann Kornel F.
Published: July 2013

A generalized helical needle tip geometry model, which can describe many typical needle tip geometries, including conical, bevel, blunt and helical shapes with proper geometric parameters, is presented based on analogy to the helical point drill geometry. The generality of this model offers a general way for manufacturing various needle tip geometries. A mathematical model of the helical needle tip geometry is provided along with the formulation of the kinematic model of the tip grinding process. The control strategy on a 5-axis grinding machine system is also developed to implement the designed kinematic model. The needle tip’s motions in the grinding process are simulated to characterize the effects of grinding parameters on needle tip properties and to predict the trajectory of the needle tip point during the grinding process. Finally, several types of needle geometries have been manufactured by the developed grinding process to verify the newly formulated models.
Chacterization of Cutting Force Induced Surface Shape Variation Using High-Definition Metrology
Authors: Nguyen Hai Trong , Wang Hui , Hu S. Jack
Published: July 2013

High-definition metrology (HDM) systems with fine lateral resolution are capable of capturing the surface shape on a machined part that is beyond the scope of measurement systems employed in manufacturing plants today. Such surface shapes can precisely reflect the impact of cutting processes on surface quality. Understanding the cutting processes and the resultant surface shape is vital to identifying opportunities for high-precision machining process monitoring and control. This paper presents modeling and experiments of a face milling process to extract surface patterns from measured HDM data and correlate these patterns with cutting force variation. A relation is established between instantaneous cutting forces and the observed dominant patterns along the feed and circumferential directions. Potential applications of such relationship in process monitoring, diagnosis, and control are also discussed.
Machining Process Power Monitoring: Bayesian Update of Machining Power Model
Authors: Mehta Parikshit , Kuttolamadom Mathew , Mears Laine
Published: July 2013

Monitoring the CNC machine tool power provides valuable information that aids condition based maintenance, machine efficiency and machining process monitoring. Cutting force in machining process is an interesting variable to measure from monitoring and control point of view. Although the direct methods of measuring the cutting force exist, prohibitive costs do not allow deployment in industrial environment. In the indirect methods of measuring force, measuring the spindle motor current to estimate the cutting power and consequently the cutting force is popular.

This work discusses the calibration of spindle current based torque sensor for the estimation of the cutting force in turning operation. The work undertakes handling uncertainty in measurement of the cutting torque measurement. Considering the steady state value, the cutting torque is represented as a polynomial function of the speed and measured power. Though the identification of the unknown coefficients can be done based on the offline tests, in current work, the Bayesian update of coefficients is proposed. This method allows online learning of these coefficients. The cutting torque value based on the model has some variability due to variation in the coefficients and unmodeled dynamics. The iterative learning happens in three stages, namely — Prior belief, likelihood function establishment and update in prior belief with observed data producing posterior belief. The establishment of the priors is done through some offline tests. The likelihood function accounts for noise in the measurement of torque. And finally, Markov Chain Monte Carlo (MCMC) simulations help sampling from unknown posterior distribution. This scheme has ability to sample from any distribution. A single update cycle shows high reduction in the variability of the torque. Experimental data is produced to verify the effectiveness of method; the Bayesian update scheme outperforms least-square polynomial fit method consistently for different cutting speeds and cutting load values.
High Speed Non-Linear Micro-Milling Dynamics
Authors: Halfmann Eric B. , Suh C. Steve
Published: July 2013

The efficiency of the milling process is limited due to excessive vibrations that negatively impact the tool and work-piece quality. This becomes even more of a concern in micro-milling where sudden tool breakage occurs before the operator can adjust cutting parameters. Due to different chip formation mechanisms in micro-milling, an increased tool-radius to feed-rate ratio, and higher spindle speeds, micro-milling is a highly non-linear process which can produce multiple and broadband frequencies which increase the probability of tool failure. This paper investigates micro-milling through the development and analysis of a 3-D nonlinear micro-milling dynamic model. A lumped mass, spring, damper system is assumed for modeling the dynamic properties of the tool. The force mechanism utilized is a slip-line field model that provides the advantages of being highly dynamic by accounting for the constantly changing effective rake angle and slip-line variables. Accurate prediction of the chip thickness is important in correctly predicting the dynamics of the system since the force mechanism and its variables are a function of the chip thickness. A novel approach for calculating the instantaneous chip thickness which accounts for the tool jumping out of the cut and elastic recovery of the work-piece is presented. The derivation for the effective rake angle is given and the helical angle is accounted for resulting in a 3-D micro-milling model. The results of simulating the model demonstrate its capability of producing the high frequency force components that are seen in experimental data available in literature. The advantages of using this approach over the constant empirical force coefficient approach when studying micro-milling dynamics is discussed and the instability of the system is investigated utilizing instantaneous frequency.
Tribological Investigation of Deep-Drawing Processes Using Servo Presses
Authors: Groche Peter , Möller Norman
Published: July 2013

Deep-drawing is one of the most important processes for the economic production of sheet metal parts, especially for high quantities. The forming forces during the process are a limiting factor for the producible shapes. A particular importance is associated with the tribology, because the percentage of friction forces on the total forces is relatively high. The friction between sheet metal and tool is influenced by several factors, such as surface characteristics of the work piece and the tool, lubrication conditions and process parameters, like the contact pressure and the sliding speed. Controlling these parameters will expand the process window for deep-drawing. Lately, servo presses provide the possibility of controlling the process speed in dependency of the process progress. The subject of this paper is the tribological investigation of deep-drawing processes. The friction coefficient decreases with an increasing sliding speed. Investigating this correlation and utilizing it for the application with modern servo technology for industrial use is the main objective of the presented research works.

First of all the dependency of the friction coefficient on the sliding speed is investigated by the use of the strip drawing tests, which allows the control of every parameter independently. The dependencies are implemented in a FEM-simulation, evaluating the potential for real deep-drawing processes. Deep-drawing experiments are then used to validate the results of the simulation with a speed-dependent friction coefficient as well as for the verification of the force reduction due to the influencing of process speed. In the end, the numerical simulated results in comparisons to the experimental measured results are discussed.
Synthesis of Manufacturing and Facility Data for Sustainability Analysis
Authors: Michaloski John , Shao Goudong , Riddick Frank , Leong Swee , Berglund Jonatan , Arinez Jorge , Biller Stephan
Published: July 2013

This paper discusses data synthesis of production and facility knowledge for sustainability analysis by applying the ISA–95 “Activity Models of Manufacturing Operations Management” (MOM) model. Presently, production and facility management basically function independently of each other. This paper presents the addition of facility activities to the MOM model, in accordance with the needs for attaining a holistic view of sustainability analysis. Historically, production and facility data are represented in various forms, e.g., data bases, CAD, and spread-sheets, without a common unifying representation. Based on this combination of incompatible modeling tools, the use of Core Manufacturing Simulation Data (CMSD) is proposed as a standard framework for integrating the broad range of technology. A case study of the data synthesis for a precision sand casting production facility is explored.
A Metallo-Thermo-Mechanically Coupled Analysis of Orthogonal Cutting of AISI 1045 Steel
Authors: Ding Hongtao , Shin Yung C.
Published: July 2013

Materials often behave in a complicated manner involving deeply coupled effects among stress/stain, temperature and microstructure during a machining process. This paper is concerned with prediction of the phase change effect on orthogonal cutting of AISI 1045 steel based on a true metallo-thermo-mechanical coupled analysis. A metallo-thermo-mechanical coupled material model is developed, and a finite element model is used to solve the evolution of phase constituents, cutting temperature, chip morphology, and cutting force simultaneously using ABAQUS. The model validity is assessed using the experimental data for orthogonal cutting of AISI 1045 steel under various conditions, with cutting speeds ranging from 198 to 879 m/min, feeds from 0.1 to 0.3 mm, and tool rake angles from −7° to 5°. A good agreement is achieved in chip formation, cutting force and cutting temperature between the model predictions and the experimental data.
Discovering Material Recovery Scenarios for Industrial Machinery: A Case-Based Approach
Authors: Bernstein William Z. , Ramanujan Devarajan , Koho Mikko , Zhao Fu , Ramani Karthik
Published: July 2013

Decision-making methodologies for evaluating a product’s end-of-life options have become a significant area of research. Extensive work has been carried out in the area of product recovery, e.g. module-based disassemblability, reverse logistics, remanufacturing, material recyclability, among others. Some of these methods use graphical representations in the form of disassembly trees and/or networks to find feasible solutions with computational approaches, but have not been made applicable to larger, more complex electrohydraulic mechanical systems. The work presented in this paper aims to apply a disassembly assessment technique by comparing a component’s disassembly effort to a reward such as recycling value or energy recovery from recycling. First, the disassembly network is represented by a directed graph where weighted edges represent reward/cost. Next, an implementation of Dijkstra’s algorithm is used to compute the optimal disassembly path that minimizes the sum of the edge weights. Lastly, the optimal disassembly paths for each individual reward are compared to discover the globally optimal disassembly scenario. This method is applied to a real-world case study of an underground mining drill rig with direct contributions from engineers involved in the development of the machine itself. Specific component recovery options are recommended based on the methodology and alternative design practices are suggested to improve product recyclability.
Enabling Machining Vision Using STEP-NC
Authors: Hardwick Martin , Proctor Frederick M. , Loffredo David , Venkatesh Sid
Published: July 2013

STEP-NC is a new data format for manufacturing control. One of its applications is to enable integrated on machine measurement of machining processes using vision systems and other sensors. In this paper we describe the manufacturing process and manufacturing resource models in STEP-NC that can be used to enable this type of measurement. These descriptions include the machine setup so that the configuration of the part can be identified and corrected, the machine kinematics so that the actions of a machine while adding or subtracting material can be verified, and the product tolerances so that the quality of the final part can be predicted and corrected during the machining.
Numerical and Experimental Investigations of Key Assumptions of Analytical Failure Models in Sheet Metal Forming
Authors: Hasan Raed , Kasikci Tugce , Tsukrov Igor , Kinsey Brad L.
Published: July 2013

In this paper, the key assumptions in the M-K and effective stress ratio models are investigated for AISI 1018 steel specimens with a thickness of 0.78 mm using experimental and numerical data from Marciniak tests. The experimental procedure included Digital Imaging Correlation (DIC) to measure the major and minor in-plane strains. Strain components were obtained at points inside (i.e., the defect region) and adjacent (i.e., the safe regions) to the high strain concentrations for four different strain paths. In the numerical analysis, FEA simulations with Marc Mentat were performed with shell elements to investigate the four specimen geometries. The key assumptions of interest are the incremental major strain ratio from M-K model and the critical stress concentration factor from effective stress ratio model. Thus, the mechanics- and material-based failure phenomena in these two analytical models are examined in this paper to provide insight into the material behavior at failure.
Studying the Temperature Effect During the High-Pressure Phase Transformation of Silicon via Indentations
Authors: Ravindra Deepak , Patten John , Ghantasala Muralidhar K.
Published: July 2013

Micro-laser assisted machining (μ-LAM) is a novel micro/nano machining technique developed for ductile mode machining of ceramics and semiconductors. Ductile mode material removal is possible in a nominally brittle material due to the high-pressure phase transformation (HPPT) phenomenon during the machining process. This study isolates the pressure and temperature effect in the μ-LAM process. The μ-LAM process is unique whereby the pressure and temperature effect occur concurrently leading to the material removal process. The effect of temperature and thermal softening is studied via indentation tests using a cutting tool. In the precisely controlled indentation tests, laser heating is applied at various stages to determine the phase (i.e. atmospheric Si-I phase or high pressure phases that benefits most from the thermal softening effect. The indentation depths are measured and compared for each condition to identify the enhanced ductility of the nominally brittle material caused by the laser irradiation.
Tool-Workpiece Interface Temperature Measurement in Friction Stir Welding
Authors: Fehrenbacher Axel , Schmale Joshua R. , Zinn Michael R. , Pfefferkorn Frank E.
Published: July 2013

The objectives of this work are to develop an improved temperature measurement system for Friction Stir Welding (FSW). FSW is a novel joining technology enabling welds with excellent metallurgical and mechanical properties, as well as significant energy consumption and cost savings compared to traditional fusion welding processes.

The measurement of temperatures during FSW is employed for process monitoring, heat transfer model verification and process control, but current methods have limitations due to their restricted spatial and temporal resolution and have found only few industrial applications so far. Thermocouples, which are most commonly used, are either placed too far away from the weld zone or are destructively embedded into the weld path, and therefore fail to provide suitable data about the dynamic thermal phenomena at the tool-workpiece interface.

Previous work showed that temperatures at the tool shoulder-workpiece interface can be measured and utilized for closed-loop control of temperature. The method is improved by adding an additional thermocouple at the tool pin-workpiece interface to gain better insight into the temperature distribution in the weld zone. Both thermocouples were placed in through holes right at the interface of tool and workpiece so that the sheaths are in contact with the workpiece material. This measurement strategy reveals dynamic temperature variations at the shoulder and the pin within a single rotation of the tool in real-time.

Due to the thermocouple’s limited response time and inherent delays due to physical heat conduction, the temperature response is experiencing attenuation in magnitude and a phase lag. Heat transfer models were constructed to correct for this issue. It was found that the highest temperatures are between the advancing side and the trailing edge of the tool. Further work is needed to increase the accuracy of the correction. Experimental results show that the weld quality is sensitive to the measured interface temperatures, but that temperature is not the only factor influencing the weld quality.

The dynamic temperature measurements obtained with the current system are of unmatched resolution, fast and reliable and are likely to be of interest for both fundamental studies and process control of FSW.
Wettability Enhancement of Aluminum Alloys via Plasma Arc Discharge
Authors: Asgharifar Mehdi , Abramovitch Joshua , Kong Fanrong , Carlson Blair , Kovacevic Radovan
Published: July 2013

The aim of this study is to determine the wettability-enhancing effects of an atmospheric-pressure, direct current (DC) plasma arc discharge on aluminum alloys. Wettability is a critical factor in engineering applications such as biomedical implants, painting, and adhesive bonding. For example, in the realm of adhesive bonding, greater wettability improves a metal substrate’s attraction to an adhesive material, which results in higher bond quality. In this study, the contact angle is determined and compared as a measure of the wettability using two different techniques, the sessile drop and ballistic deposition methods, with water as a test liquid. Additionally, this paper analyzes the impact of different arc discharge parameters, including arc current and plasma torch velocity, on the wettability.
Evidence of Phase Dependent Tool Wear in Ti-6Al-4V Turning Experiments Using PCD and Carbide Inserts
Authors: Schrock David J. , Kwon Patrick
Published: July 2013

This paper presents evidence of phase transformation in turning titanium work material and discusses its impact on tool wear. Tool wear of polycrystalline diamond inserts was studied in turning experiments on Ti-6Al-4V. Confocal laser scanning microscopy was conducted to analyze the rake face of the turning inserts. At cutting speeds of 61m/min, the rake face exhibited scalloped-shaped, fractured, uneven, and rough wear. This is characteristic of attrition wear. At cutting speeds of 122m/min, wear was smooth and even in nature, which is a typical characteristic of diffusion/dissolution wear. At a cutting speed of 91m/min, the wear was a combination of those observed at speeds of 61m/m and 122m/m. A comparison of the wear on the PCD tools to that of WC-6Co from earlier work is also discussed. A significant difference in wear existed between the two different cutting tool materials at the low cutting speed. This difference in wear was linked to a transition from alpha to beta phase in the titanium work material. Temperature estimates on the rake face of the tool previously extracted from FEM support the possibility of phase transformation at the cutting data tested.
Remote Tool Health Monitoring Using Wireless Sensors on Rotational Machinery
Authors: Rynders Mark D. , Loker David R. , Roth John T.
Published: July 2013

A key concern in modern day manufacturing is developing a reliable method for monitoring tool health. This involves not only establishing a mathematical method for deriving tool failure, but also developing a reliable method for collecting and transmitting this information. This paper presents a reliable wireless network for collecting, analyzing, and predicting tool failure. The wireless network consists of three remote nodes and one coordinator node. Each remote node is mounted on a 1″ R8 mill tool holder and consists of three major components: an accelerometer, microcontroller, and wireless transceiver. These wireless nodes transmit the Z-axis acceleration (the machines vertical Z-axis) as seen by the tool holder back to a central computer. This computer utilizes LabVIEW in order to collect and analyze the acceleration data. The LabVIEW program also acts as a simple user interface for indicating states of tool failure, along with providing a means for publishing the information to the internet for process monitoring by remote users. The wireless network discussed in this paper is robust, inexpensive, and was found to reliably monitor and predict tool health conditions. The innovative aspect of this work is the ability to use commercial-off-the-shelf wireless sensors to remotely monitor multiple rotational machines from a single location on site and over the internet to off-site locations.
Extension of a Microscale Indentation Fracture Model to Nanoscale Contact in Purview of Mechanical Nanofabrication Processes
Authors: Hann Jared N. , Riveros Raul E. , Yamaguchi Hitomi , Taylor Curtis R.
Published: July 2013

In this work, we investigate the extension of the Lawn and Evans indentation fracture model, developed primarily for microscale contact, to nanoscale contacts. Systematic nanoindentation fracture experiments are performed on Si (100) using a sharp diamond cube corner (radius, r = 32 nm) indenter as a function of load, load cycles, contact dimension, and contact separation. Atomic force microscopy is used to image and measure contact deformation and fracture. The experimental results show that the threshold load for fracture was 290 μN, which is lower than previously reported. Adjacent indents separated by less than three times the radius of each indent were observed to interact with each other, such that second indents were consistently deeper than the first at the same loads. There was an increase in crack length for pairs of indents that were separated by equally small distances (<3 indentation radii). These results have clear implications for nanofabrication where stress field interactions impose limits on the closeness (resolution) to which features can be generated and to free abrasive machining where stress field interactions enhance the ability to machine below the threshold load.
The Correlation of Volumetric Tool Wear and Wear Rate of Machining Tools With the Material Removal Rate of Titanium Alloys
Authors: Kuttolamadom Mathew , Mehta Parikshit , Mears Laine , Kurfess Thomas
Published: July 2013

The objective of this paper is to assess the correlation of volumetric tool wear (VTW) and wear rate of carbide tools on the material removal rate (MRR) of titanium alloys. A previously developed methodology for assessing the worn tool material volume is utilized for quantifying the VTW of carbide tools when machining Ti-6Al-4V. To capture the tool substrate response, controlled milling experiments are conducted at suitable corner points of the feed-speed design space for constant stock material removal volumes. For each case, the tool material volumes worn away, as well as the corresponding volumetric wear profile evolution in terms of a set of geometric coefficients are quantified — these are then related to the MRR. Further, the volumetric wear rate and the M-ratio (volume of stock removed to VTW), which is a measure of the cutting tool efficiency, are related to the MRR — these provide a tool-centered optimal MRR in terms of profitability. This work not only elevates tool wear from a 1-D to 3-D concept, but helps in assessing machining economics from a stock material removal efficiency perspective as well.
Process Monitoring During Micro-Drilling via Acoustic Emission, Ultrasonic Sound, and Spindle Load Sensors
Authors: Bourne Keith A. , Kapoor Shiv G.
Published: July 2013

Careful monitoring of conditions during micro-drilling is important for insuring production of consistent high-quality holes. In this study, acoustic emission, ultrasonic sound, and electric spindle load were used to monitor micro-drilling performed using a micro-scale machine tool (mMT). Experiments were conducted where 0.508 mm diameter holes were drilled in polyetheretherketone (PEEK) polymer and 316 stainless steel. It was found that spindle load significantly increased when tool gumming occurred during drilling of PEEK. Increased spindle load when cutting 316 stainless steel was found to correspond to increased incidences of tool breakage, and a large reduction in spindle load was present during additional drilling operations following a breakage event. It was found that elevated acoustic emission levels were always present during drilling and that a lack of sufficient acoustic emission generation during retraction of a tool indicated tool breakage. The ultrasonic sound spectra were found to change in a manner that is a function of depth of cut and hence a function of depth of cut dependent tool dynamics.
Scheduling of Machine Startup and Shutdown to Reduce Energy Consumption in Bernoulli Production Lines
Authors: Chen Guorong , Zhang Liang , Arinez Jorge , Biller Stephan
Published: July 2013

Effective control of production operations usually leads to improved energy efficiency in manufacturing systems. In this paper, we investigate energy consumption reduction in production systems by scheduling of machine startup and shutdown. Specifically, we consider serial production lines with finite buffers and machines having Bernoulli reliability model. This machine reliability model is applicable in production situations, where the downtime is relatively short and comparable to machine cycle time (e.g., automotive paint shops and general assembly). Using transient analysis of the systems at hand, an analytical performance evaluation technique is developed for Bernoulli serial lines with time-dependent machine efficiencies. In addition, trade-off between productivity and energy-efficiency in production systems is discussed and the energy-efficient production problem is formulated as a constrained optimization problem. The effects and practical implications of operations schedule are demonstrated using a numerical study on automotive paint shop operations.