bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructuring and Biofunctionalization of Alumina Surfaces to Enhance Abrasion Resistance and Suppress Bacterial Biofilm Growth
Authors: Treccani Laura , Rezwan Kurosch
Published: July 2009

The design and fabrication of alumina microstructured surfaces that simultaneously present high mechanical and chemical features and do not suffer biofouling are here reported. An aerosol based patterning technique was employed to fabricate alumina microstructures directly on alumina surfaces with the aim to enhance wear and chemical resistance. Microstructured alumina surfaces were subsequently biofunctionalised with antibacterial biomolecules to inhibit bacterial adhesion. Lysozyme, an antibacterial enzyme commonly found in body secretions, was used as antibacterial agent and directly deposited onto microstructured alumina surfaces. Lysozyme-biofunctionalised microstructured alumina surfaces were tested at flow condition using abrasive particles and viable bacteria. The very preliminary results showed that alumina microstructures presented high resistance against mechanical abrasion and that bacterial biofilm formation could be suppressed. In particular alumina microstructures protected lysozyme molecules from desorption and loss of enzymatic activity. Such biofunctionalised microstructures present a promising system for fundamental research in the field of biomolecule adsorption on surfaces and maybe a feasible alternative e. g. to protect surfaces of water transport systems where abrasive particles and microorganisms are present.
Material Characterization of Uncoated Boron Steel for Automotive Body Structure Applications
Authors: Koganti Ramakrishna , Angotti Sergio , Cooper Ron , Houston Dan , Waheed Asif , Topper T. H.
Published: July 2009

Use of Advanced High Strength Steels in automotive applications is increasing. One of these materials is boron steel, which is commercially available in coated and uncoated sheets. Automotive manufacturers are using boron steel in body structure applications to produce light weight parts and to address safety requirements. Boron steel is available in a non heat-treated condition (also referred to as “green state”) which typically has a yield strength around 350 MPa. The yield strength for a fully temperature hardened boron steel increases to above 1000 MPa, depending on heat treatment temperature and quenching methods used. In this report, the static and fatigue properties of uncoated boron steel were evaluated. One objective was to understand whether these properties varied with respect to the material rolling direction (longitudinal, transverse and diagonal). For static strength analysis three different gages (1.0 mm, 1.5 mm and 2.0 mm) were evaluated. For fatigue evaluation, 3.0 mm thickness boron steel was evaluated. Based on the mechanical test data, ultimate tensile strength was not statistically significant in all three directions (longitudinal, transverse and diagonal) among three gages chosen. However, within the same gage, ultimate tensile strength is statistically significant in all three directions. 0.2% offset Yield strength and total elongation are uniform in all gages as well as in all three directions within each gage. However, uniform elongation (at max. load condition) was significant among the gages as well as within the same gages. A comparison of the monotonic and cyclic stress strain curves indicates boron steel is a strain-softening material.
Comparison of Three Microstructure Fabrication Methods for Bone Cell Growth Studies
Authors: Große Holthaus Marzellus , Rezwan Kurosch
Published: July 2009

Different micropatterning techniques were applied to elucidate the potential for cell proliferation studies on calcium phosphate surfaces. Sintered hydroxyapatite (HA) platelets were microstructured by three different techniques: Aerosol jet printing (M3D®), laser ablation and microcontact printing via polydimethylsiloxane (PDMS) stamps. The microstructures were designed as channels between 1000 and 3000 micron in length, 10 to 220 micron in width and 5 to 110 micron in height. An optical profilometer, a Scanning Electron Microscope (SEM) and X-ray diffraction were used to characterize the microstructures. Cell proliferation tests were carried out by incubating the microstructured ceramic samples in complete cell media for a maximum of seven days. Osteoblast-like cells (MG-63) were used for testing. Each sample was immersed in media in which the cells were already seeded. Imaging was performed by SEM and Fluorescence Microscopy. The cells proliferated on all three differently fabricated microstructures. Cell growth was observed in the microchannels as well as on the microchannel walls or spacers. In particular it turned out, that the microtopology can provoke the cells to elongate aligned to the direction of the microchannels. Non-directional growth was observed on non-structured areas. All three differently fabricated hydroxyapatite microstructuring methods seem to be attractive and promising techniques for use in bone cell growth studies. The applied fabrication techniques show many advantages for fundamental research in the field of cell interaction with ceramic microstructures and may exhibit possible methods of structuring implant surfaces.
Definition of Cutting Conditions for Thin-to-Thin Milling of Aerospace Low Rigidity Parts
Authors: Campa F. J. , Lopez de Lacalle L. N. , Urbikain G. , Ruiz D.
Published: July 2009

The main drawback of the high speed milling of monolithic parts for the aerospace industry is the high buy-to-fly ratio that leads to a huge material waste. This problem is caused by the need to stiffen the part during the machining in order to avoid chatter, excessive vibration and residual stresses. The present work proposes a methodology for the milling of compliant parts based on the selection of cutting conditions free of chatter. First, the modal parameters of the part in the most problematic stages of the machining are calculated by means of the finite elements method. Secondly, a three-dimensional stability model is used in each stage to calculate a three-dimensional stability lobes diagram dependent on the tool position along the whole tool path. Given the fact that the depth of cut is defined by the bulk of material, the three-dimensional stability diagram can be reduced to a two-dimensional one, which relates tool position during the machining and spindle speed, and indicates how to change the spindle speed in order to avoid the unstable areas. What is more, the proposed methodology can also be used to dimension the bulk of material, select the proper tool or improve the fixturing of the part. Finally, the methodology is validated experimentally on a test part.
Numerical Simulations of 3D Tool Geometry Effects on Deposition Stresses in Diamond Coated Cutting Tools
Authors: Renaud Anderson , Hu Jianwen , Qin Feng , Chou Kevin
Published: July 2009

Diamond-coated cutting tools are attractive alternatives to polycrystalline diamond tools for machining lightweight, high-strength components made of advanced materials such as composites. However, residual stresses induced by the diamond deposition process, due to thermal mismatch between diamond and the substrate, significantly impact the coating-substrate adhesion, and thus, the tool performance in machining. Moreover, the tool geometry, particularly at the very tip, complicates the stress fields because of the sharp geometry changes. The objective of this research is to investigate the effects of critical tool geometry parameters on the residual stress augmentations in diamond coated cutting tools. In this study, computer-aided design (CAD) software was used to create the solid model of various tool geometries. It was used to create an accurate model of the tool, which emulates each aspect of the tool geometry, e.g., as small as 5-micron edge radius on a 12.7-mm tool. The solid model was then exported to finite element analysis (FEA) software for 3D simulations of residual stresses generated in the tool with given deposition conditions. The obtained stress data was transformed to evaluate the interface stress profiles around the tool edges. To systematically investigate the tool geometry effects, a test matrix, determined using the design of experiments approach, includes 4 factors (edge radius, relief angle, corner radius, and corner angle) and 2 levels with a full factorial design. Analysis of variance was performed to quantitatively reveal the significant factors and interactions between the factors that dominate the stress concentrations. Results are summarized as follows. (1) The cutting edge radius is the most significant factor to the interface stresses. (2) For a 5 μm edge radius, the radial normal stress (σΓ) increases from 0 at the top uniform surface to about 1.5 GPa in tension, and the circumferential normal stress (σθ) increases from around 3.0 GPa in compression to over 3.7 GPa. (3) The corner radius is of secondary importance to σΓ, and the relief angle is of secondary importance to σθ.
E-Design Tool for Friction Stir Welding
Authors: Bagaitkar Harish , Allada Venkat
Published: July 2009

This paper describes efforts to develop a web-based E-Design tool for the Friction Stir Welding (FSW) technique. The input parameters to the E-Design tool are the joint specifications. The output parameters of the E-Design tool are process parameters such as tool geometry details, tool rpm, and plunge depth. The heart of the E-Design tool is the FSW database. The FSW database contains mappings of various input parameters and output parameters that are captured by referring to various experimental studies cited in the literature. The proposed E-Design tool deals with lap joints and butt joints between similar aluminum alloys.
Quality Monitoring and Fault Detection on Stamped Parts Using DCA and LDA Image Recognition Techniques
Authors: Zhao Qiangsheng , Camelio Jaime A.
Published: July 2009

New vision technologies provide an opportunity for fast detection and diagnosis of quality problems compared with traditional dimensional measurement techniques. This paper proposes a new use of image processing to detect quality faults using images traditionally obtained to guide manufacturing processes. The proposed method utilizes face recognition tools to eliminate the need of specific feature detection on determining out-of-specification parts. The algorithm is trained with previously classified images. New images are then classified into two groups, healthy and unhealthy. This paper proposes a method that combines Discrete Cosine Transform (DCT) with either Principal Component Analysis (PCA) or Linear Discriminant Analysis (LDA) to detect faults, such as cracks, directly from sheet metal parts.
Metrics for Sustainable Manufacturing
Authors: Reich-Weiser Corinne , Vijayaraghavan Athulan , Dornfeld David A.
Published: July 2009

A sustainable manufacturing strategy requires metrics for decision making at all levels of the enterprise. In this paper, a methodology is developed for designing sustainable manufacturing metrics given the specific concerns to be addressed. A top-down approach is suggested that follows the framework of goal and scope definition: (1) goal - what are the concerns addressed and what is the appropriate metric type to achieve the goal (2) scope - what is the appropriate geographic and manufacturing extent. In this methodology a distinction is made between environmental cost metrics and sustainability metrics. Utilizing this methodology, metrics focused on energy use, global climate change, non-renewable resource consumption, and water consumption are developed.
The Basic Relationship Between Machining Induced Residual Stress Profiles and Fatigue Life
Authors: Guo Y. B. , Warren A. W.
Published: July 2009

The characteristics of residual stress (RS) profiles and their effects on rolling contact fatigue life for precision turned and ground surfaces with a white layer (WL) are very controversial. The key findings of this study are: (a) The basic RS profiles by a sharp tool can be fundamentally changed by a turned WL but not a ground WL; (b) The hook shaped RS profile of a turned surface may have about 40% more fatigue life than a ground one; (c) The white layer may reduce fatigue life as much as 7–8 times despite the deep compressive RS in the subsurface.
Characteristics of Residual Stress Profiles in Hard Turned Versus Ground Surfaces With and Without a White Layer
Authors: Warren A. W. , Guo Y. B.
Published: July 2009

Hard turning and grinding are competitive processes in many cases for manufacturing various mechanical products. Product performance is highly dependent on the process induced residual stresses. However, there exist some inconsistence regarding the true residual stress profiles generated by hard turning and grinding with and without the presence of a white layer. This study aims to clarify the pressing issues via an extensive residual stress measurement for five surface types: hard turned fresh (HTF), hard turned with a white layer (HTWL), ground fresh (GF), ground with a white layer (GWL), and as heat treated. The x-ray diffraction data revealed distinct differences in the residual stress profiles between the turned and ground surfaces. Specifically, the key findings are: (i) HTF surfaces generate a “hook” shaped residual stress profile characterized by surface compressive residual stress and maximum compressive residual stress in the subsurface, while GF surfaces only generate maximum compressive residual stress at the surface; (ii) HTWL surfaces generate a high tensile stress in the white layer, but has highly compressive residual stress in the deeper subsurface than the HTF surface; (iii) GWL surfaces only shift the residual stress to more tensile but does not affect the basic shape of the profile; (iv) Tensile residual stress in the HTWL surface is higher than that for the GWL one. However, the residual stress for the ground white layer does not become compressive and remains tensile in the subsurface; (v) Elliptical curve fitting is necessary for measuring residual stress for the HTWL surface due to the presence of shear stress induced severe Ψ splitting; (vi) Residual stresses by grinding show more scattering than those by hard turning; and (vii) Machining is the deterministic factor for the resulting residual stress magnitudes and profiles compared with the minor influence of initial residual stress by heat treatment.
Fabrication and Finite Element Analysis of Micro Dents Using μ-Laser Shock Peening
Authors: Sealy Michael P. , Guo Y. B. , Horstemeyer M. F.
Published: July 2009

Laser shock peening (LSP) is an innovative surface treatment developed to improve surface integrity. This study explores the feasibility using LSP to direct-write surface micro dents for lubricant retention. Since LSP is a highly transient process with a pulse duration of 10 – 100 ns, a real time in-situ measurement of laser/material interaction such as transient stresses/strains is challenging. Therefore, a 3D finite element simulation of micro-scale laser shock peening was developed to determine the effect of laser pulse duration and peak pressure on the transient material behaviors of titanium Ti-6Al-4V. The simulated dent geometry is similar to the measured dent geometry in terms of morphology. The results suggested there is an optimal peening time that produces the deepest dent. The maximum transient stress in peening direction occurred at a certain laser pulse time. However, the stress along the depth and radius were drastically affected by the peak pressures.
A Comparative Study on Hydraulic Bulge Testing and Analysis Methods
Authors: Billur Eren , Koc¸ Muammer
Published: July 2009

Hydraulic bulge testing is a material characterization method used as an alternative to tensile testing with the premise of accurately representing the material behavior to higher strain levels (∼70% as appeared to ∼30% in tensile test) in a biaxial stress mode. However, there are some major assumptions (such as continuous hemispherical bulge shape, thinnest point at apex) in hydraulic bulge analyses that lead to uncertainties in the resulting flow stress curves. In this paper, the effect of these assumptions on the accuracy and reliability of flow stress curves is investigated. The goal of this study is to determine the most accurate method for analyzing the data obtained from the bulge testing when continuous and in-line thickness measurement techniques are not available. Specifically, in this study the stress-strain relationships of two different materials (SS201 and Al5754) are obtained based on hydraulic bulge test data using various analysis methods for bulge radius and thickness predictions (e.g., Hill’s, Chakrabarty’s, Panknin’s theories, etc.). The flow stress curves are calculated using pressure and dome height measurements and compared to the actual 3-D strain measurement from a stereo optical and non-contact measurement system ARAMIS. In addition, the flow stress curves obtained from stepwise experiments are compared with the ones from above methods. Our findings indicate that Enikeev’s approach for thickness prediction and Panknin’s approach for bulge radius calculation result in the best agreement with both stepwise experiment results and 3D optical measurement results.
Numerical Study and Scale Analysis of Inner and Outer Diameters Prediction in Fabrication of Hollow Fiber Membranes for Nerve Regeneration
Authors: Yin Jun , Coutris Nicole , Huang Yong
Published: July 2009

Recently the semi-permeable hollow fiber membrane (HFM) is finding promising applications in promoting axonal outgrowth for nerve repair and regeneration. It is of interest to model the phase inversion-based HFM fabrication process and control the fabricated HFM geometry. The effect of gravity and surface tension which is frequently ignored in general fiber spinning should be carefully addressed in HFM fabrication modeling. Both the volume of fluid (VOF) method and the scale analysis have been applied to appreciate the effect of gravity and surface tension on the HFM geometry profile. The VOF method-based simulation results reveal that both the gravity and/or surface tension significantly reduce the predicted radii/diameters, while the scale analysis reveals that the gravity or surface tension affects the HFM fabrication process dynamics. Both the approaches warrant the need of including the gravity and surface tension in HFM fabrication process modeling.
An Experimental Evaluation of Laser-Assisted Micromilling of Two Difficult to Machine Alloys
Authors: Shelton Jonathan A. , Shin Yung C.
Published: July 2009

Micro-milling can be difficult to apply to many engineering materials due to a variety of scaling induced factors including: low cutting speeds, high relative tool deflections and runout, and increased material strength at smaller size scales. Additionally, edge burrs which can easily be removed after macro scale milling must be avoided in micro-milling due to the lack of available finishing operations. Laser assisted machining (LAM) involves localized heating of the work material prior to the cutting tool. This localized heating thermally weakens the workpiece resulting in lower cutting forces, improved surface finish, and longer tool life. Applying this concept to micro-milling offers the opportunity for process improvements, especially with materials which are considered difficult to machine. Laser assisted micro-milling (LAMM) was evaluated on Ti-6Al-4V and 316 stainless steel alloys using 100 μm diameter endmills in slotting operations. Micro-scale laser-material interactions were first studied with bulk material absorptivity being determined experimentally through a novel technique utilizing several calibrated melting mediums. A three-dimensional transient finite volume based thermal model was then used to analytically predict appropriate process parameters on the basis of material removal temperatures. A thorough investigation of acoustic emissions (AE) during LAMM was performed. In particular, the effects of depth of cut, tool wear, and material removal temperature on the RMS of AE were studied. Additionally, the effect of LAMM on the machined surface was evaluated quantitatively.
Micromachining of Metals, Alloys and Ceramics by Picosecond Laser Ablation
Authors: Hu Wenqian , King Galen B. , Shin Yung C.
Published: July 2009

Microhole drilling and microstructure machining with a picosecond (ps) Nd:YVO4 laser (pulse duration of 10 ps) in metals, alloys and ceramics are reported. Blind and through microholes were drilled by percussion drilling as well as trepanning drilling. The diameters of the holes were in the range from 20 μm to 1000 μm. Microfeatures were machined and the flexibility of ps laser machining was demonstrated. The quality of drilled holes, e.g., recast layer, microcrack and conicity, and that of the microstructures, were investigated by optical microscope, surface profilometer, or scanning electron microscope (SEM). Ps laser ablation rate was investigated by experiments as well as a simplified laser ablation model.
Ink-Jet as a Manufacturing Method for Drug Delivery Applications
Authors: Antohe Bogdan V. , Wallace David B.
Published: July 2009

Recent drug delivery applications have stressed the need for precise dosage in the context of complex delivery vehicles. Ink-jet technology incorporates data-driven, non-contact techniques that enable precise, picoliter volumes of material to be deposited with high speed and accuracy at target sites (even onto non-planar surfaces) and thus has emerged as a front runner for drug delivery applications. Being data-driven, ink-jet dispensing is highly flexible and can be readily automated into manufacturing lines. Moreover, the ability to precisely target the delivery location reduces waste, an important factor when the active biological materials to be deposited are high value / high cost. Some of the applications that have made use of ink-jet methods for dosage and distribution of biologically active agents are: loading of active agents onto drug eluting stents (DES); generation of drug loaded microspheres; fabrication of polymeric nerve conduits loaded with nerve growth factor; and coating of the active components onto patches for transdermal delivery. This paper provides details on the manufacturing applications of ink-jet technology in drug delivery and discusses future potential uses and opportunities.
Analytical Model for the Characterization of the Guiding Zone Tribotest for Tube Hydroforming
Authors: Ngaile Gracious , Yang Chen
Published: July 2009

Common part failures in tube hydroforming include wrinkling, premature fracture, and unacceptable part surface quality. Some of these failures are attributed to the inability to optimize tribological conditions. There has been an increasing demand for the development of effective lubricants for tube hydroforming, due to widespread application of this process. This paper presents an analytical model of the guiding zone tribotest commonly used to evaluate lubricant performance for tube hydroforming. Through a mechanistic approach, a closed-form solution for the field variables contact pressure, effective stress/strain, longitudinal stress/strain, and hoop stress can be computed. The analytical model was validated by the finite element method. In addition to determining friction coefficient, the expression for local state of stress and strain on the tube provides an opportunity for in-depth study of the behavior of lubricant and associated lubrication mechanisms. The model can aid as a quick tool for iterating geometric variables in the design of a guiding zone, which is an integral part of tube hydroforming tooling.
Comparison of Free Abrasive Machining Processes in Wafer Manufacturing
Authors: Chung Chunhui , Kao Imin
Published: July 2009

Free abrasive machining (FAM) processes, such as slicing using slurry wiresaws, lapping, and polishing, are very important manufacturing processes in wafer production for microelectronics fabrication. Since the materials in semiconductor industry are usually brittle, such as silicon, gallium arsenide, ... etc., the FAM processed can provide more gentle machining than the bonded abrasive machining process. Various machining theories and models have been developed to understand those processes. In this paper, the free abrasive machining processes in wafer manufacturing will be discussed in conjunction with the brittle material cracking theory. The modern slurry wire-saw slicing process and lapping process in wafer production will be presented with comparison to abrasive grits, manufacturing process models, characterization of manufacturing mechanisms, and properties of processes.
Tensile and Micro Stretch Bending Experiments for Studying Stainless Steel 304 Foil for Micro Sheet Forming
Authors: Chen Chi-Han , Gau Jenn-Terng , Lee Rong-Shean
Published: July 2009

Tensile test and a micro stretch bending test were conducted to study the behavior of the stainless steel 304 foils for micro sheet forming. In this study, 4 different thicknesses stainless steel 304 foils were used as specimens while 5 micro deep draw dies were used for micro stretch bending experiments. By observing the tensile test results, it can be found that the stainless steel 304 foils with T/D (thickness/average grain diameter: the numbers of grains throughout the metal thickness) <10 has less formability than those with T/D>10. By observing the results of the micro stretch bending experiments, it can be concluded that the stainless steel foils with T/D>10 have less springback amount and smaller springback deviation in comparison with those with T/D<10. In order to have a better formability and less springback, it is recommend having the stainless steel 304 foils with T/D>10 for micro sheet forming application.
Shifting Secondary Discharge as the Expulsion Mechanism in EDM
Authors: Luo Y. F. , Tao Jia
Published: July 2009

A new understanding of the expulsion mechanism in electrical discharge machining (EDM) is discussed in this investigation. The shifting secondary discharge inside a cathodic root is revealed as the major driving force for metal expulsion in EDM. A typical electrode couple of steel for cathode and copper for anode is used in all the experiments and discussions. Micro graphs of discharge craters are taken from the complex surface directly after a continual discharging process while either normal or reversed polarity is applied. The apparent difference in crater morphologies on anode and cathode indicates the unique expulsion mechanism, namely secondary discharges, which only take place inside the cathodic root. The compliance of secondary discharges with long-disputed phenomena, such as the discrepancy between energy distribution and metal removal, is demonstrated through the applications of the mechanism to the phenomena. The applied methods and results are more realistic since single pulse discharge among other process changes is prohibited. Such a more reliable understanding can correlate the complex metal removal mechanisms to better future process developments.
Experimental Study on a New Method of Double Side Incremental Forming
Authors: Wang Yongjun , Huang Ying , Cao Jian , Reddy N. Venkata
Published: July 2009

This paper presents a new configuration for sheet metal incremental forming using DSIF (Double Sided Incremental Forming) to overcome the limitation of single point incremental forming (SPIF). The new process can produce geometrical features on either side of the initial plane of the sheet without changing setup. A component having such challenging features is selected to demonstrate the capabilities of the proposed method and a contour tool path is generated using UniGraphics (UG) surface machining module and formed by mounting the new setup on a CNC milling machine. The final formed shape was scanned and compared to the designed profile. In addition, two more components having cylindrical and spherical geometries are formed to study the effect of geometry on the accuracy of the component that can be produced by using the proposed method. A simple analysis model has been developed to explain the effect of squeezing and stretching to the part elongation during the DSIF process.
Experiment, Thermal Simulation and Characterizations on Transmission Laser Coating of Hydroxyapatite on Metal Implant
Authors: Cheng Gary J. , Ye Chang
Published: July 2009

Coating of bioceramic material — Hydroxyapatite (HAp) — on metal implant has attracted many attentions in biomedical industry recently because its combination of good mechanical property and biocompatibility. However, most of current HAp coatings are lack of coating/substrate interfacial strength, and/or biocompatibility. The cell-tissue attachment is affected by the degraded biocompatibility due to decomposition of HAp during high temperature processing. In this paper, an innovative method — transmission laser coating is investigated to coat HAp on Ti substrate with low temperature processing. This process enhances the HAp/Metal interfacial property of current coatings, while maintaining good biocompatibility. Experiments are conducted using a continuous Nd-YAG laser. Multiphysics simulation is conducted to simulate the temperature distribution in coatings and substrates during TLC processing. X-ray energy dispersion spectrum is used to measure the chemical composition of HAp coatings after TLC process. Pull-out tests are conducted to measure the interfacial strength between the HAp coating and Ti substrate. Cell culture study is conducted to qualitatively evaluate the biocompatibility after TLC of HAp particles. These results show that TLC processing will open new ways of producing biocompatible bioceramic coatings with controlled thickness, and at low processing temperature.
Interface Effects on Coating Failure of Diamond Coated Cutting Tools
Authors: Hu Jianwen , Chou Kevin , Thompson Raymond G.
Published: July 2009

Despite the superior tribological and mechanical properties, the advantages of diamond coated tools have been largely compromised by the insufficient adhesion. Interface characteristics play a vital role in the failure and performance of diamond coated tools. Thus, quantitative modeling of the coating-substrate interface is important to the design and usage of diamond coating tools. In this study, a cohesive zone model was incorporated to investigate the diamond coating on a tungsten carbide substrate. The cohesive zone model is based on the traction-separation law, and is represented by four parameters, determined from the tungsten-carbide fracture properties. The cohesive zone model was implemented in finite element codes to simulate the indentation process, using a spherical diamond indenter. The model was applied to examine the interface effects during indentation and the coating property effects on different coating failure modes. The simulation results are summarized as follows. (1) Normal mode delamination is the dominant mechanism of interface failure and takes place during unloading if the substrate yielding occurs during the loading stage. (2) The cohesive zone interface does not affect the critical load for coating surface tensile cracking, but affects the plastic strain during loading. In addition, for thin coatings, the maximum stress location changes between the perfect interface and cohesive zone interface cases. (3) Elasticity has a complex effect on coating failure. As the coating elasticity increases, the critical load for coating cracking decreases, but the critical load for substrate yielding increases slightly. Moreover, the interface delamination size will decrease with increasing coating elasticity.
A Geometrically Comprehensive Approach to Modeling Dynamic Cutting Forces in Turning: Application to Regenerative Chatter
Authors: Cardi Adam A. , Bement Matthew T. , Liang Steven Y.
Published: July 2009

Present chatter models in turning lack physical insight because they do not model the process in a geometrically rigorous manner. Many of the models are linear and produce unrealistic, unbounded vibration amplitude growth after the onset of chatter. Those that are nonlinear are typically reverse engineered in order to predict bounded vibration. The current approach models the forces in machining due to chip formation, plowing, and interference between the flank of the cutting tool and the machined workpiece surface in a geometrically comprehensive fashion. Additionally the effects of strain, strain rate and temperature on the chip formation process are captured. In doing so, accurate predictions can be made for both the occurrence of chatter and its vibration amplitude growth over time. The proposed model is validated with machining experiments on a compliant workpiece to explore the effect of tool nose radius on chatter.
Modeling Machinability Parameters of Turning Al-SiC (10p) MMC by Artificial Neural Network
Authors: Muthukrishnan N. , Mohan Ravi , Thiagarajan M. S. , Venugopal J.
Published: July 2009

The paper presents the results of an experimental investigation on the machinability of fabricated Aluminum metal matrix composite (A356/SiC/10p) during continuous turning of composite rods using medium grade Polycrystalline Diamond (PCD 1500) inserts. Metal Matrix Composites (MMC’s) are very difficult to machine and PCD tools are considered by far, the best choice for the machining of these materials. Experiments were conducted at LMW-CNC-LAL-2 production lathe using PCD 1500 grade insert at various cutting conditions and parameters such as surface roughness and specific powers consumed were measured. The present results reaffirm the suitability of PCD for machining MMCs. Though BUE formation was observed at low cutting speeds, at high cutting speeds very good surface finish and low specific power consumption could be achieved. An Artificial Neural Network (ANN) model has been developed for prediction of machinability parameters of MMC using feed forward back propagation algorithm. The various stages in the development of ANN models VIZ. selection of network type, input and output of the network, arriving at a suitable network configuration, training of the network, validation of the resulting network has been taken up. A 2-9-9-2 feed forward neural network has been successfully trained and validated to act as a model for predicting the machining parameters of Al-SiC (10p) -MMC. The ANN models after successful training are able to predict the surface quality; and specific power consumption for a given set of input values of cutting speed and machining time.
Force/Velocity Control of a Pneumatic Gantry Robot for Contour Tracking With Neural Network Compensation
Authors: Abu-Mallouh Mohammed , Surgenor Brian
Published: July 2009

In this paper, the application of a pneumatic gantry robot to contour tracking is examined. A hybrid controller is structured to control the contact force and the tangential velocity, simultaneously. A previous study provided controller tuning and model validation results for a fixed gain PI-based force/velocity controller. Performance was limited by system lag and Coulomb friction. New results demonstrate that even with perfect friction compensation, the limiting factor is the system lag. A neural network (NN) compensator was subsequently developed to counter both effects. Results for straight and curved edged workpieces are presented to demonstrate the effectiveness of the NN compensator and the capabilities of a pneumatic gantry robot.
Meso-Macro Simulations of Textile Composite Forming
Authors: Hamila Nahiene , Boisse Philippe , Chatel Sylvain
Published: July 2009

Composite textile reinforcement draping simulations aid in determining the processing conditions for a quality part and in finding the positions of the fibers after forming. This last point is essential for the structural computations of the composite part and for resin injection analyses in the case of LCM processes. Because the textile composite reinforcements are multiscale materials, continuous (macro) approaches and discrete (meso) approaches that model the yarns have been developed. The finite element that is proposed in this paper for textile fabric forming is composed of woven unit cells. The mechanical behaviour of these is analyzed by 3D computations at the mesoscale. The warp and weft directions of the woven fabric can be in an arbitrary direction with respect to the direction of the element side. This is very important in the case of multi-ply deep drawing and when using remeshing. The element is efficient because it is close to the physics of the woven cell while avoiding the very large number of unknowns in the discrete approach. A set of validation tests and forming simulations on single-ply and multi-ply fabrics is presented and shows the efficiency of the approach.
Methods for Improving Chucking Accuracy
Authors: Byun Jeongmin , Liu C. R.
Published: July 2009

Since recent studies have demonstrated the benefits of hard turning over other abrasive machining processes as a finishing process in terms of surface integrity, a strong need has existed to improve the performance of chucking. It is because the poor repeatability and accuracy in the positioning of chucked workpieces became the major bottleneck in the implementation of finish hard turning for precision mechanical components. However, the understanding of chucking has not been adequate, nor has any systematic method been reported for improving chucking accuracy. In this paper, all the major factors that affect the positioning accuracy and repeatability of a chucked workpiece have been identified by error budgeting and systematic measurements. In addition, the characteristics of these factors, as well as their effect on chucking accuracy, were investigated. From the results, a chucking error map that summarizes the relations between these factors and the positioning error of a chucked workpiece was developed. Then, a series of experiments were carried out, based on the results of the earlier works to test the effectiveness of the error budget. The results demonstrated that the knowledge on these factors was accurate and it could be effectively used to improve the positioning accuracy and repeatability of a range of cylindrical workpieces chucked for machining. It was also shown that hard turning alone, without any extra machining process, could satisfy the same level of concentricity which is currently achieved by finish grinding in the machining of different types of cylindrical workpieces. Even if this study was originally intended for the implementation of finish hard turning that can replace finish grinding, the methods developed can be used to improve the final form accuracy of cylindrical workpieces in other finishing processes including grinding if any workholding devices similar to chucks are used to hold the workpieces. The methodology and the procedures for improving chucking accuracy are covered in a pending patent by the authors.
Finite Element Analysis of Deformed Geometry in Three-Roller Plate Bending Process
Authors: Tailor V. K. , Gandhi A. H. , Moliya R. D. , Raval H. K.
Published: July 2009

In pyramid type three-roller bending process, it is difficult to deform the plate perfectly to the required circular shape and it mainly depends on the skill of the operator. Presented work shows the finite element (FE) simulations of three-roller plate bending process to study the influence of different parameters, such as roller position, rolling speed, plate material, plate length and friction (at roller plate interfaces) on the bending quality of the deformed plate. FE simulations were performed based on the elastic–plastic explicit dynamic finite element method under the Hyperform LS-DYNA environment. FE simulation results were verified with the experimental results. Parametric studies were carried out to investigate the effect of various parameters on the quality of the final shape. Reported work will be helpful to process engineers in predicting the final radius of curvature and deviation of plate prior to manufacturing. This will reduce the trail and error in achieving the final geometry.
Effect of Bias Voltage on Fatigue Behavior of CrN Film Deposited on Ti-6Al-4V Alloy
Authors: Rahman Md. Shamimur , Yonekura Daisuke , Katsuma Takeshi , Murakami Ri-Ichi
Published: July 2009

PVD technique incorporating CrN coating was applied to the titanium alloy (Ti-6Al-4V) and its effects on the fatigue life and fatigue strength were studied in this paper to explore the fatigue behavior of Ti-6Al-4V specimens. A CrN film deposited by arc ion plating (AIP) improved the mechanical properties; specially hardness and fatigue life of Ti-6Al-4V specimens. The properties were studied using XRD, hardness and fatigue testers. The fatigue life of CrN-coated Ti-6Al-4V specimens was improved significantly compared to those of uncoated specimens. The enhanced fatigue life can be attributed to the improved hardness of CrN film due to change of bias voltage during the film deposition. The initiation of fatigue cracks is likely to be retarded by the presence of hard and strong layers on the substrate surface. It has been determined that the fatigue fracture of the substrate-coating composite is dominated by the fracture of the CrN film since fatigue cracks have been observed to form first at the surface of the film and subsequently to propagate towards the substrate. It has also been concluded that the increase in fatigue properties of the coated substrate is associated mainly with the changing of bias voltage during the coating observed in most of the maximum alternating stress range explored in this work.
Allocation of Flexible Tooling for Optimal Stochastic Multistation Manufacturing Process Quality Control
Authors: Jiao Yibo , Djurdjanovic Dragan
Published: July 2009

Stream of Variance (SoV) modeling of multi-station manufacturing process has been studied for the past 15 years and was used for identification of root causes of manufacturing errors, characterization and optimal allocation of measurements in multi-station manufacturing processes, process-oriented tolerance allocation, and most recently, for optimal in-process adaptations of programmable, flexible tooling (flexible fixtures, CNC machines) for autonomous minimization of errors in dimensional product quality. However, due to the high cost of flexible tooling, it is plausible to strategically position such devices across a manufacturing system in a way that one’s ability to mitigate quality problems is maximized. In this paper, a distributed stochastic feed-forward control method is devised which gives the optimal (in least square sense) reduction of the variance-covariance matrix of errors in dimensional workpiece quality in a multi-station manufacturing process with a limited number of flexible tooling components. Genetic Algorithm is proposed to enable optimal allocation of flexible tooling devices. Theoretical results have been evaluated and demonstrated using the SoV model of a real industrial process.
Mathematical Modelling and Finite Element Simulation of Pre-Bending Stage of Three-Roller Plate Bending Process
Authors: Gandhi A. H. , Gajjar H. V. , Raval H. K.
Published: July 2009

Continuous three roller bending process is widely used in practice to bend the plates into cylinders. Bending load for plate material under bending is affected by plate thickness, width and shell diameter combinations. Maximum top roller load is encountered during the edge pre-bending stage as top roller is set at an offset distance from its mid position. Shell diameter, thickness and material for cylindrical structural element to be produced are fixed by design. Width of the plate for roller bending decides number of cylindrical segments required to achieve the designed shell length. Maximum pre-bending width depends on maximum top roller load imparting capacity. Looking to the above considerations, maximum width which can be pre-bend at limiting top roller load (for designed shell diameter, thickness and material combinations) specifies the capacity. Presented work aims at developing the mathematical model of top roller load for pre-bending. Top roller offset for pre-bending were calculated based on practical top roller pre-bending load data, for different grades of C-Mn steel plates (as per ASME sec II part-A). Based on these top roller offsets, finite element analysis (FEA) of pre-bending stage were performed using Hyperform LS-DYNA. Effect of co-efficient of friction at roller plate interfaces was analyzed. FE simulation of pre-bending of cladded plate (54 mm thick C-Mn steel plate of material grade SA-387Gr11Cl2 having 3 mm thick layer of stain less steel material grade SS-308) was performed. FEA load results were found in good agreement with the practical load results and can be used for capacity assessment and analysis of roller bending machines.
Dynamic Mold Temperature Control Using Gas-Assisted Heating and Its Effect on the Molding Replication Qualities of Micro Channels
Authors: Chen Shia-Chung , Chang Yaw-Jen , Chang Jen-An , Peng Hsin-Shu , Wang Ying-Chieh
Published: July 2009

Dynamic mold surface temperature control (DMTC) has the advantage of improving molded part qualities without significant increases in cycle time. A gas-assisted heating system combined with water cooling was developed to achieve DMTC for injection molding. With gas-assisted heating, it takes 2s for the mold surface temperature to vary from 60 °C to 120 °C whereas it requires 186s using water heating. Further, it takes 21s and 84s for the mold surface to cool to 60 °C under gas heating and water heating, respectively. The gas-assisted heating system also shows excellent efficiency for micro injection molding of biochips to achieve high replication accuracy of the micro channels.
Enhancing Safety in Manufacturing Systems by Integrating Diagnostic Information
Authors: Schroeder Kyle , Khan Aftab A. , Moyne James , Tilbury Dawn
Published: July 2009

Integrating traditionally separate industrial control systems can derive factory-wide benefits by leveraging more information about the ongoing process. This paper shows that connecting a networked safety system and a process control system leads to an extension of the individual benefits provided by each system. A safety system gains the ability to protect not only the machines and workers but also the product that is being built. A diagnostic system can also raise safety alarms when a process variable is outside the expected range of safe operation. This connection is explored to determine the practical impact of different methods of integration on machining and system processes. Three integration methods are possible depending on which portions of the system can be classified as “safe”. A case study integrating a diagnostics system as a non-safe sensor proves that this connection, when it is implemented on an industrial testbed, provides all of the benefits described and does not require significant changes to control software.
Investigation on Operating Temperature in Laser Assisted Milling of Silicon Nitride Ceramics
Authors: Shen Xinwei , Lei Shuting
Published: July 2009

This paper discusses the operating temperature in laser assisted milling (LAMill) of silicon nitride ceramics. Experimental investigation shows that the laser parameters including laser power, laser beam diameter, laser translating speed and preheat time affect the temperatures at the cutting zone. Especially, laser intensity plays an important role in the heat absorption of silicon nitride ceramics. In LAM, high laser intensity is desired. In addition, laser interaction mechanism with silicon nitride shows that high operating temperature may cause the material at the thin top layer of the workpiece to oxidize and thereby forming silica bubbles. With high operating temperature the machined surface of the workpiece has good finish and less edge chipping.
Dry Machining Using Vortex-Tube Generated Cold Air as Coolant: A Literature Review
Authors: Cong Weilong , Pei Z. J.
Published: July 2009

This paper reviews the literature on dry machining with VT cooling (using vortex-tube generated cold air as coolant). It presents reported experimental results on effects of VT cooling on cutting force, cutting temperature, tool wear, surface roughness, and residual stress. It also points out areas where VT cooling applications have not been reported and potential directions for future research.