bluuebunny/crossref_metadata_2025 huggingface dataset:
An Integrated Decision Analysis for the Sustainable Product Design
Authors: Choi Jun-Ki , Ramani Karthik
Published: July 2009

Engineering designers consider many aspects surrounding a product’s life in order to meet safety, reliability, quality, manufacturing, and cost requirements. Most of the time this is done in an excellent way and the resulting products offers broad functionality with high quality and reasonable price. However serious considerations of integration of environmental requirements are often missed in the product development process. All products contribute to a range of environmental problems. These problems arise through the entire life cycle of products from the creation to the disposal of products. Design for environment (DfE) is the systematic consideration of design performance with respect to environmental, health, and safety objectives over the full product and process life-cycle. It takes place early in a product’s design or upgrade phase to ensure that the environmental consequences of a product’s life cycle are considered. The key issue to success is how to select the most appropriate and effective strategy for a particular product to reduce environmental impacts without disregarding the business strategies in the decision making process. In this paper, a general framework is proposed to integrate the life cycle assessment and decision analysis for prioritizing the design for environment strategy by considering uncertainty issues exist in the decision making process. A case study is illustrated focusing in the product upgrade phase. The ultimate goal is to provide a design advisory tool for product designers in the hopes of facilitating their complex decision making processes by considering the environmental issues in mind.
Identifying Correlations Between Independent Sets of Maintenance and Manufacturing Quality Data
Authors: El-Gheriani Hany , Guay Martin , Graton Guillaume , Arinez Jorge
Published: July 2009

Effective equipment maintenance is essential for a manufacturing plant seeking to produce high quality products. The impact of equipment reliability and quality on throughput have been well established, however, the relationship between maintenance and quality is not always clear or direct. This paper describes a statistical modeling method that makes use of a Kalman filter to identify correlations between independent sets of maintenance and quality data. With such a method, maintenance efforts can be better prioritized to satisfy both production and quality requirements. In addition, this method is used to compare results from the theoretical maintenance-quality model to data from an actual manufacturing system. Results of the analysis indicate the potential for this method to be applied to preventive as well as reactive maintenance decisions since ageing aspects of equipment are also considered in the model.
Discrete Microparts Production Using Through-Thickness Hot Embossing and Rubber-Assisted Ejection
Authors: Kuduva-Raman-Thanumoorthy Ramasubramani , Yao Donggang
Published: July 2009

The hot embossing process has so far been mainly developed for replication of surface structures on thermoplastic substrates. Because of the lack of a through-thickness action, fabrication of discrete microparts such as microgears is considered difficult. In this study, an embossing mold having 13 microcavities was used in a through-thickness embossing process with a rubber-assisted ejection mechanism. Microparts made of HDPE and ABS with each part weighing approximately 0.9 and 1.4 mg, respectively, were produced. When in the mold, embossed microparts were intermittently connected to each other through thin residual films of a thickness approximately 20–30 μm on one surface. The residual films were detached from the microparts during ejection. Because no resin delivery path, e.g., runner and gate, is needed for microcavities on the mold, this micropart fabrication process could replace micro injection molding in numerous applications.
Particle Distribution and Mechanical Properties of Silica-Filled PMMA Micro-Injection Moldings
Authors: Leong Yew Wei , Thumsorn Supaporn , Nakai Asami , Hamada Hiroyuki , Yoshinaga Kohji , Ito Hiroshi
Published: July 2009

Micro-injection moldings of poly(methyl methacrylate) filled with silica of various particle sizes ranging from 5 to 50 μm were fabricated. The distribution of the silica particles throughout the moldings was found to be significantly different, i.e. a more homogeneous distribution of fillers was evident as particle size decreases. Fracture properties, fracture surface appearance and transparency were significantly affected by the state of filler distribution.
Ultra-Precision Machining Technology of the Soft and Brittle Functional Crystal
Authors: Lu C. P. , Gao H. , Kang R. K. , Teng X. J. , Wang Q. G.
Published: July 2009

As an important branch of materials, soft and brittle functional crystals (SBFC) are widely used in the field of modern technology. However, the softness, brittleness, deliquescence, and strongly anisotropic natures of these materials present a challenge for their ultra-precision machining. The definition of SBFC is firstly given and their applications in many fields are also presented. For the ultra-precision machining technologies to satisfy the applied requirements, many methods such as single diamond turning, ultra-precision grinding, magnetorheological Finishing and so on, are successfully applied in SBFC materials, the challenges and difficulties occurred during machining these SBFC materials, such as KH2PO4, CdZnTe and CaF2, etc., are reviewed and the limits are also analyzed in detail. Moreover, many novel machining methods are suggested to achieve better surface quality and enhance machining efficiency.
Simulation of Crack Initiation at the Interface Edge Between Sub-Micron Thick Films Under Creep by Cohesive Zone Model
Authors: Truong Do Van
Published: July 2009

Delamination between sub-micron thick films is initiated at an interface edge due to creep deformation, and leads to the malfunction of microelectronic devices. In this study, the cohesive zone model approach with a cohesive law based on damage mechanics was developed to simulate crack initiation process at an interface edge between film layers under creep. Delamination experiments using a micro-cantilever bend specimen with a Sn/Si interface were conducted. The parameters charactering the cohesive law were calibrated by fitting displacement-time curves obtained by experiments and simulations. In addition, the order of the stress singularity, which increases with time and has a significant jump in its value at the crack initiation, was investigated.
Dimensional Variation Analysis of T-Node Joints Using Aluminum 6063-T52 Extrusion Material in Gas Metal Arc Welding (GMAW) Joining Process
Authors: Koganti Ramakrishna , Joaquin Armando , Karas Chris
Published: July 2009

The development of manufacturing processes for joining and assembling of lightweight aluminum vehicles requires detailed process capability studies as well as dimensional variation analysis studies to ensure process controls are in place. These manufacturing processes not only have to provide cycle time viability but also need to maintain or surpass product safety and quality. T-Nodes joint designs are an integral of aluminum architectures based on hybrid designs, i.e those fabricated from mixed aluminum products consisting of castings, stampings and extrusions. The purpose of this study was to find optimum parameters for minimum distortion for the gas metal arc welding (GMAW) of 6063-T52 T-Nodes. The welding factors considered were locators (4-way and 2-way pins verses net surfaces), the welding equiment process factors (power input, pulse frequency, gas flow rate, torch angle and arc intensity), the use of simultaneous welding, and welding sequence order. A partial factorial design of experiment (DOE) was conducted to understand the effects of these factors on T-node joint distortions. A total of 14 points were considered for dimensional distortion measurements. Results showed power (heat) input is the only statiscally significant factor on joint distortion. Locators type as well as welding sequence and simultaneous welding also had a measurable affect on part deviation during welding.
Effect of Tool Wear on Rolling Contact Fatigue Performance of Superfinish Hard Machined Surfaces
Authors: Choi Youngsik , Liu C. Richard
Published: July 2009

This study investigates the effect of tool wear on the rolling contact fatigue performance of superfinish hard machined surfaces. Specimens were machined at two different cutting tool conditions: new and worn tools. The condition of a new tool is defined as the state of an unused tool, while that of a worn tool is defined as the state of a tool after being used for machining 150 identical specimens at the same machining conditions. It is noted that tool wear induces less compressive residual stresses for the specimens machined by square tools, while tool wear induces more compressive residual stresses in a deeper region for the specimens machined by round tools, which have a relatively large tool nose radius. In the micro-hardness distribution, the specimen machined by a worn tool typically shows a more softened layer than the specimen machined by a new tool. The rolling contact fatigue test results indicate that the rolling contact fatigue life of the specimen machined by a new tool is generally longer than that of the specimen machined by a worn tool.
Modeling Machining at High Speeds as a Fluid Mechanics Problem
Authors: Kazban Roman V. , Mason James J.
Published: July 2009

Even though many models for machining exist, most of them are for low-speed machining, where momentum is negligible and material behavior is well approximated by quasi-static plastic constitutive laws. In machining at high speeds, momentum can be important and the strain rate can be exceedingly high. For these reasons, a fluid mechanics approach to understanding high-speed, very high-speed, and ultra-high-speed machining is attempted here. Namely, a potential flow solution is used to model the behavior of the material around a sharp tool tip during machining at high speeds. It is carefully argued that the potential flow solution is relevant and can be used as a first approximation to model the behavior of a metal during high-speed, very high-speed, or ultra-high-speed machining events; and at a minimum, the potential flow solution is qualitatively useful in understanding mechanics of machining at high speeds and above. Interestingly, the flow solution predicts that there is a stagnation point on the rake face, not at the tool tip as is usually assumed. Because the stagnation point is not at the tool tip, the flow solution predicts a significant amount of deformation in the workpiece resulting in large residual strains that may lead to a temperature rise on the finished surface.
A Comparative Assessment of Austempered Ductile Iron as a Substitute in Weight Reduction Applications
Authors: Polishetty Ashwin , Singamneni Sarat , Littlefair Guy
Published: July 2009

Manufacturing engineering has had to undergo drastic changes in the approach to material selection in order to meet new design challenges. In the automotive industry, researchers in their effort to reduce emissions and satisfy environmental regulations, have shifted their focus to new emerging materials such as high-strength aluminium alloys, metal matrix composites, plastics, polymers and of late, Austempered Ductile Iron (ADI). ADI is a good choice for design where the criterion is high performance at reduced weight and cost. The unique, ausferrite microstructure gives the material desirable material properties and an edge over other materials. A comparative study of ADI in terms of materials properties and machining characteristics with other materials is desirable to highlight the potential of the material. This paper focuses on a comparative assessment of material and machining characteristics of ADI for different applications. The properties under consideration are machinability, weight and cost savings and versatility. ADI has a higher strength-to-weight ratio than aluminium making it a ready alternative for material selection. In terms of machinability, there are some problems associated with machining of ADI due to its work hardening nature. This paper attempts to identify the possible potential applications of ADI, by critically reviewing specific applications such as machinability, overall economics and service.
Effect of Tooling Surface Roughness in Micro-Injection Molding
Authors: Yoon Sung-Hwan , Lee Jun S. , Im Ji-Sun , Xiong Xugang , Cha Nam-Goo , Mead Joey L. , Barry Carol M. F.
Published: July 2009

Quality of tooling surface has been considered as one of the important factors defining the injection molded part quality. Therefore, surface polishing has been an important and relatively expensive step in conventional mold making process. Although the poor surface quality impacts the product quality when molding macroscale parts, it becomes more significant with sub-micrometer features. Previous micro injection molding research result has indicated that rough tooling surface may cause polymer adhesion on the tooling surface. To evaluate the effect of roughness, optical grade polycarbonate was molded using silicon inserts with artificially generated surface roughness (root-mean-square roughness: 3∼143 nm) by dry etching. The silicon and molded parts surface were characterized using atomic force and scanning electron microscopy. Filling and ejection of the parts as well as residual polymer on the tooling correlated surface roughness of the tooling.
The Influence of the Chemical Composition of Welding Material Used in Semi-Automatic Welding for Pipeline Steel on Mechanical Properties
Authors: Bai Lu , Tong Lige , Ding Hongsheng , Wang Li , Kang Qilan , Bai Shiwu
Published: July 2009

The mechanical properties of welding material is correlative with the chemical composition Artificial neural network (ANN) program to predict mechanical properties — yield strength, tensile strength, elongation and average Charpy impact toughness — of welding material is established by Visual C + + 6.0 based on improved BP arithmetic with momentum factor, in which one input layer with 13 nodes, one hidden layer with 23 nodes, one output layer with 4 nodes, and Sigmoid activation function are included. The 20 samples are from the experimental data of semi-automatic welding material of X70. The average maximum relative error of the 4 mechanical properties is less than 0.5%. Based on the program, the influence of the chemical composition, such as C, S, P, Si, Mn, Cr, Ni and Al on the mechanical properties is analyzed. The results show that the different element has different influence on the mechanical properties. For non-metallic elements, the mechanical properties are becoming worse with the increase of composition, in which the influence of C is primary, then P and then S. For metallic elements, the influence is greater and more complex than that of non-metallic ones.
Experimental Study on Submersed Gas-Jetting EDM
Authors: Kang X. M. , Zhao W. S. , Tang C. J. , Ding L. S.
Published: July 2009

A new method called submersed gas-jetting EDM was proposed, in which the high-pressure gas working as the dielectric medium, is blown throughout the inner hole of a tubular electrode, and machining liquid around the gas plays significant roles of helping cooling and debris evacuation but doesn’t involve in the discharge directly. Experiments were conducted to investigate the influence of polarity, pulse duration, peak current, gas pressure and different gas/machining liquid combination. The comparison of submersed gas-jetting EDM and dry EDM indicated that this new method revealed higher material removal rate (MRR), better surface quality and equivalently minute electrode wear.
Wear Signal Measurement of Micro-End Mill Using Wavelet Analysis
Authors: Park Jeong-Bin , Hong Yeong-Seon , Kim Jin-Woong , Yeo Jun-Cheol , Lee Kyung-Tae , Park Jae-Seuk , Cho Young-Man , Ahn Sung-Hoon
Published: July 2009

Tool breakage poses a major problem for mechanical micro-tools. Although the prediction of tool wear is important in the scheduling of tool change and maintaining productivity, the life of micro-tools is generally predicted statistically based on data from experimental machining trials. In this study, force signals were observed during machining using a micro-end mill. The relationship between these signals and the wear of the micro-end mill was investigated using wavelet analysis. Printed Circuit Board (PCB) substrate materials were used as a workpiece, and cutting forces were measured with a dynamometer. To determine the difference between worn and unused tool conditions, the continuous wavelet transform was applied to the force signals that were measured by the dynamometer. The signals from the worn and unused tools had a different dominant frequency or scale. As the machining cutting length increased, the variation in dominant frequency could be identified by wavelet analysis.
Influence of Metal Inert Gas (MIG) Welding Factors Wire Feed Rate and Weld Travel Speed on Aluminum Weld Joint Strength
Authors: Koganti Ramakrishna , Joaquin Armando , Zaluzec Matthew , Karas Chris
Published: July 2009

The purpose of the study was to understand effects of weld travel speed and wire feed rate in metal inert gas (MIG) welding on the aluminum materials joint strength. Initial experiments indicated a noticeable positive effect of travel speed on weld strength with an over 95% statistical significance. Nonetheless further experimentation at a significantly lower wire feed rate proved the opposite with similar statistical significance. A negative effect of welding travel speed on joint strength was measured at lower wire feed rates. In order to understand the weld travel and wire feed rate on the joint strength, a Design of Experiment (DOE) was conducted. For this experiment, weld system process factors were set constant (wave control, gas flow rate, torch angle, trim and wave type) except for travel speed and wire feed rate. A two-factor two-level full factorial design of experiment (DOE) was conducted in order to understand the effects of these two factors on weld strength. Additional welding at higher wire feed rates were conducted in order to confirmed the trend found. Results showed travel speed effects on joint strength as a result of its direct interaction with wire feed rate. This occurrence can have significant economic implications if proven to be repeatable and will be the subject of this and future MIG welding studies as they relate to aluminum structures.
Viscoelasticity Effects of Polymeric Material in Micro Injection Molding
Authors: Mosaddegh Peiman , Angstadt David C.
Published: July 2009

An experimental study has been carried out to determine the effect of viscoelasticity in comparison to viscosity on micro-injection molded parts. In this study, two different polymeric materials — Polystyrene (PS) as a viscous material and High Density Poly-Ethylene (HDPE) as a viscoelastic material — have been selected to observe the effect of melt elasticity on the filling phase of micro molding based on cavity pressure of molded part. All process parameters except temperature are the same for both polymers. Process temperatures have been selected in order to match the viscosity for both polymers used. Polymer viscosity was characterized at different shear rate and temperature. Viscoelasticity of both polymers were investigated using rotational rheometry in the oscillation mode. The mold geometry with high aspect ratio has been used and the effect of viscoelasticity on cavity pressure has been discussed. It was observed that there is retardation on the response of pressure because of elastic response of material during filling. Despite the differences in slope, peak value, area, and cycle time between two curves, they share similar trends. The only difference is their response during solidifying because of material property.
An Economic Model for the Maintenance of a Device Submitted to Minor and Major Repairs
Authors: Phadke Hrishikesh , Bao Han P. , Dean Anthony W.
Published: July 2009

Preventive maintenance has been a mainstream strategy to keep equipment and machinery going. In this paper a Markov model is used to characterize the performance of a continuously operating device that is subject to random failure as well as failure generated by deterioration. The optimum preventive maintenance of this device is based not only on its maximum availability but also on the consideration of the total cost of operation and maintenance against a backdrop of replacement cost. The economic model proposed in this paper provides a more complete decision process to determine when to replace it even while the device is maintained optimally.
Study of Structured Porogen Method for Bone Scaffold Fabrication
Authors: Lu Lin , Wootton David , Lelkes Peter I. , Zhou Jack
Published: July 2009

The increasing demand on bone scaffolds has promoted the development of tissue engineering fabrication technique for manufacturing bone scaffold. In this study, a novel structured porogen method for bone scaffold fabrication has been explored. This method has demonstrated highly efficient and reproducible fabrication of structured bone scaffolds which mimics the bone structure. By using commercially available Drop on Demand (DDP) system and three dimensional printer (3-DP) system, at first designed structured porogens can be manufactured, and then bone scaffolds can be fabricated by injecting the biocomposite materials into the porogens. The mechanical properties of the fabricated scaffolds using DDP system have been characterized. The biocompatibility of our fabricated scaffolds using 3-DP has been examined. With incorporating of bioactive calcium phosphate into the composite materials, the mechanical strength and bioactivity of the scaffolds made by the structured porogen method can be improved significantly. This structured porogen method has a potential to be used on various Solid Freeform Fabrication systems which allows each system to use a single ubiquitous building material to fabricate multiple biomaterial scaffolds with sufficient mechanical integrity.
Microscale Flanging Using Quasi-Static and Electromagnetic Forming Processes
Authors: VanBenthysen Reid , Michaud Jonathan , DiSalvo Peter , Kinsey Brad L. , Blakely Michael , Shang Jianhui
Published: July 2009

Past research has shown that scatter in material properties and springback (i.e., the elastic recovery of material after the tooling is extracted) increase as components are miniaturized to the microscale. At the macroscale, electromagnetic forming (EMF) has been shown to completely eliminate or at least decrease springback by varying the deformation mechanism. In EMF, a capacitor bank is charged and then quickly dissipated into a specially designed magnetic coil. A transient magnetic field is produced which induces eddy currents in the workpiece, and any other conductive material nearby. The magnetic fields in the coil and the workpiece are repulsive; thus, the workpiece is launched at a high velocity away from the coil. EMF at the macroscale requires a significant amount of stored energy. However at the microscale, EMF may be a viable process due to the reduced energy and force requirements and thus is being investigated in this work.
The Effect of Model Parameters on Predicted Stress Based Failure Criterion for Sheet Metal
Authors: Derov Matthew J. , Kinsey Brad L. , Tsukrov Igor
Published: July 2009

Tearing failure in sheet metal forming has traditionally been predicted based on the strain state of the material. However, a concern with this failure prediction method is that the strain based forming limit curve exhibits significant strain path dependence. A stress based failure criterion has been proposed and shown to be less sensitive to the strain path through numerical simulations and by analytically converting strain based data to stress space. However, a means to predict this stress based failure criterion without prior knowledge of the strain based forming limit curve for sheet metal is required. In this paper, an analytical prediction of the stress based forming limit curve is derived and compared to experimental and numerical results. The effects of model parameters are also investigated.
Investigation of Fatigue Properties for Welded Aluminum Forging Preforms
Authors: Harris W. P. , Domblesky J. P.
Published: July 2009

While welded forging preforms offer potential benefits for producing forged parts, work to date has mainly been concentrated on assessing static mechanical properties. As dynamic properties are an important consideration, the objective in the current study was to assess the high cycle fatigue properties of 6061-T6 aluminum forging performs which were prepared using friction welding. Monolithic and friction welded specimens were prepared and hot worked using a laboratory press. Fatigue data was then generated using a rotating beam test machine and a metallurgical evaluation of the weld zone performed. The results showed that, in general, forged preforms demonstrated superior fatigue life when compared to as-friction welded preforms in the same temper condition. Fatigue performance was also found to be comparable to that obtained from monolithic forging preforms which had an identical processing history.
Improving the Surface Roughness of a CVD Coated Silicon Carbide Disk by Performing Ductile Regime Single Point Diamond Turning
Authors: Ravindra Deepak , Patten John
Published: July 2009

Silicon carbide (SiC) is one of the advanced engineered ceramics materials designed to operate in extreme environments. One of the main reasons for the choice of this material is due to its excellent electrical, mechanical and optical properties that benefit the semiconductor, MEMS and optoelectronic industry respectively. Manufacture of this material is extremely challenging due to its high hardness, brittle characteristics and poor machinability. Severe fracture can result when trying to machine SiC due to its low fracture toughness. However, from past experience it has been proven that ductile regime machining of silicon carbide is possible. The main goal of the subject research is to improve the surface quality of a chemically vapor deposited (CVD) polycrystalline SiC material to be used in an optics device such as a mirror. Besides improving the surface roughness of the material, the research also emphasized increasing the material removal rate (MRR) and minimizing the diamond tool wear. The surface quality was improved using a Single Point Diamond Turning (SPDT) machining operation from 1158nm to 88nm (Ra) and from 8.49μm to 0.53μm (Rz; peak-to-valley).
Application of Nickel Nanoparticles in Diffusion Bonding of Stainless Steel Surfaces
Authors: Tiwari Santosh K. , Paul Brian K.
Published: July 2009

In this study, the effect of nickel nanoparticles (NiNPs) interlayer application to transient liquid-phase diffusion brazing was investigated. The primary focus was to bond stainless steel 316L laminae in a stack using a Nickel nanoparticles interlayer and to compare the bond line of the sample with the conventionally bonded and nickel-phosphorous interlayer (NiP) brazed samples for microstructure evolution and bond strength. The bonding was carried out in a vacuum hot press and the bonding parameters were kept same for all the samples: bonding temperatures 1000°C, bonding pressure 1000 psi, heating rate 10°C/min and dwell time of 2 hrs. The cross sections of the bonded samples were investigated for microstructure evolution using optical microscopy and scanning electron microscopy (SEM). The inter-diffusion of the diffusing species across the bond line (interface) was evaluated by wavelength dispersive spectroscopy (WDS). X-ray diffraction technique (XRD) is proposed to determine the formation of any brittle intermetallic phases along the bond line and transmission electron microscopy (TEM) to confirm the same. Bond strength will be measured with the help of samples bonded according to ASTM standards.
Application of an Accuracy Enhancement Module for Precision Machine Tools by Spatial Error Compensation
Authors: Hsu Fu-Chuan , Chiu Cheng-Chang , Lyu Yu-Ting , Chang Wen-Long , Wang Junz J.-J. , Liao Yung-Yuan , Liang Steven Y.
Published: July 2009

A PC-based precision promotion module named “Precimatics” is presented in this study, which uses a spatial error compensation algorithm to modify the G/M code of coordinates of a CNC machine tool. The spatial errors of three axes machine tools were measured by two kinds of laser interferometers (Renishaw Inc. & Optodyne Inc.) According to the American standard (ASME B 5.54) and the laser vector method with sequential step diagonal path (LDDM™), the spatial errors of machine tools, such as linear position error, horizontal straightness error, vertical straightness error, and squareness error, were obtained without time consuming. A spatial error map of machine tools was created and embedded into the “Precimatics” for error compensation. The compensated results were simulated and verified by the coordinates of numerical control (NC) code. Integrating a CAD/CAM system with the “Precimatics”, the position accuracy of micro/meso machine tools (mMTs) can be improved by spatial error compensation without changing the configuration of CNC controller.
Estimation of Temperature Distribution in Silicon During Micro Laser Assisted Machining
Authors: Suthar Kamlesh J. , Patten John , Dong Lei , Abdel-Aal Hisham
Published: July 2009

Silicon is machined using a diamond tool and the process is assisted with an IR Laser for the purpose of heating and thermal softening the work piece material. The laser beam passes through the tool and into the work piece, where the material is both thermally heated (by the laser) and mechanically deformed (by the tool). The laser is used to increase the work piece temperature (up to the softening temperature of silicon, about 500–800°C [10]), while the tool deforms and cuts the heated and softened silicon in the ductile regime, without producing cracks. This hybrid laser assisted machining process results in a smooth plastically deformed surface and extends the life of the diamond tool when cutting a hard and abrasive material, e.g. silicon. Scratch tests were done using the micro laser assisted machining method with diamond tools, which demonstrated enhancement in the depth of cut from 60 nm to 120 nm with (a 2x increase in depth of cut, at a constant load) while the cutting speed varied from 0.305 mm/sec to 0.002 mm/s. An analytical and numerical method was used to estimate the temperature rise in the vicinity of the diamond tool due to laser irradiation and absorption by the silicon work piece. It is assumed that the layer of silicon that absorbs the heat from the laser radiation is silicon II. Silicon II is a metallic phase of silicon, commonly referred to as the beta-tin structure, formed by a high pressure phase transformation (HPPT). In this context, the analytical and numerical models are solved using the heat conduction equation for semi-infinite solid over time with a Gaussian laser beam intensity distribution. The temperature rise for different cases (laser intensity, depth of cut, cutting speed, etc.) was modeled using point, and plane heat source method with Gaussian intensity distribution. These results are discussed in detail to estimate the temperature distribution while machining.
Numerical and Experimental Study on the Injection Moulding of a Thin-Wall Complex Part
Authors: Fetecau Catalin , Postolache Ion , Stan Felicia
Published: July 2009

The research presented in this paper involves numerical and experimental efforts to investigate the relative thin-wall injection molding process in order to obtain high dimensional quality complex parts. To better understand the effects of various processing parameters (the filling time, injection pressure, the melting temperature, the mold temperature) on the injection molding of a thin-wall complex part, the molding experiments are regenerated into the computer model using the Moldflow Plastics Insight (MPI) 6.1 software. The computer visualization of the filling phase allows accurate prediction of the location of the flow front, welding lines and air traps. Furthermore, in order to optimize the injection molding process, the effects of the geometry of the runner system on the filling and packing phases are also investigated. It is shown that computational modeling could be used to help the process and mold designer to produce accurate parts.
Design and Fabrication of a Roller Imprinting Device for Microfluidic Device Manufacturing
Authors: Vijayaraghavan Athulan , Jayanathan Stephen V. , Helu Moneer M. , Dornfeld David A.
Published: July 2009

Microfluidic devices are gaining popularity in a variety of applications, ranging from molecular biology to bio-defense. However, the widespread adoption of this technology is constrained by the lack of efficient and cost-effective manufacturing processes. This paper focuses on the roller imprinting process, which is being developed to rapidly and inexpensively fabricate micro-fluidic devices. In this process, a cylindrical roll with raised features on its surface creates imprints by rolling over a fixed workpiece substrate and mechanically deforming it. Roller imprinting aims to replace processes that were developed for laboratory scale prototyping which tend to not be scalable and have high equipment requirements and overheads. We discuss the limitations of PDMS soft lithography in large-scale manufacture of microfluidic devices. We also discuss the design, fabrication, and testing of a simple roller imprinting device. This imprinter has been developed based on the principles of precision machine design and is implemented using a three-axis machine tool for actuation and position measurement. A framework for the micro-machining of precision imprint rolls is also presented.
Modeling and Analysis of the Thread Milling Operation in the Combined Drilling/Thread Milling Process
Authors: Jun Martin B. G. , Araujo Anna Carla
Published: July 2009

This paper investigates a thread making process called thrilling, which performs both drilling and thread milling with one tool. A chip thickness and mechanistic cutting force model has been developed for a thread milling operation with a thrilling tool. The model considers the complex geometry of a thrilling tool and the unique tool paths associated with the thread milling operation. Calibration experiments have been conducted to estimate the cutting coefficients associated with specific cutting energies. Experiments have been conducted to validate the developed model. Comparison of the average torque and forces between experiment and simulation results shows that the model predicts the experimental results within 12% error. The model has also been used to analyze the effects of helix angle and number of engaged threads on the cutting forces.
Structural Modification of Amorphous Fused Silica Under Femtosecond Laser Irradiation
Authors: Vukelic S. , Gao B. , Ryu S. , Yao Y. L.
Published: July 2009

Non-linear absorption of femtosecond laser pulses enables the induction of structural changes in the interior of bulk transparent materials without affecting their surface. This property can be exploited for the transmission welding of transparent dielectrics, three dimensional optical data storages and waveguides. In the present study, femtosecond laser pulses were tightly focused within the interior of bulk fused silica specimen. Localized plasma was formed, initiating rearrangement of the network structure. The change in material properties were studied through employment of spatially resolved Raman spectroscopy, atomic force microscopy and optical microscopy. The nature of the physical mechanisms responsible for the alteration of material properties as a function of process parameters is discussed.
Dynamic Optimization of the Grinding Process in Batch Production
Authors: Lee Cheol W.
Published: July 2009

This paper presents a novel dynamic optimization framework for the grinding process in batch production. The grinding process exhibits time-varying characteristics due to the progressive wear of the grinding wheel. Nevertheless, many existing frameworks for the grinding process can optimize only one cycle at a time, thereby generating suboptimal solutions. Moreover, a dynamic scheduling of dressing operations in response to process feedback would require significant human intervention with existing methods. We propose a unique dynamic programming - evolution strategy (DP-ES) framework to optimize a series of grinding cycles depending on the wheel condition and batch size. In the proposed framework, a dynamic programming module dynamically determines the frequency and parameter of wheel dressing while the evolution strategy (ES) locates the optimal operating parameters of each cycle subject to the constraints on the operating ranges and part quality. A case study based on experimental data is conducted to demonstrate the advantages of the proposed method over conventional approaches.
Damped Vibration Response at Different Speeds of Wire in Slurry Wiresaw Manufacturing Operations
Authors: Chung Chunhui , Kao Imin
Published: July 2009

Wiresaw has become a standard slicing tool especially for large ingots in the wafer preparation industry since late 1990s. To meet the requirements of the surface finish and topology, it is critical to control the process parameters to render good surface finish and to minimize kerf loss. The vibration of moving wire in the wiresaw manufacturing operation affects the wafer surface finish and kerf loss; therefore, the study and analysis of vibration of moving wire become very important and relevant to this manufacturing process. Built on the previous research, the free vibration response of axially moving wire with damping is a combination of infinite sets of response solutions, with trigonometric functions due to end constraints. The apparent damping due to the increase of speed on the first several components of responses will be presented and discussed in this paper. The results also show that the increase in speed will excite components of response except the dominating one. Since the free vibration response is a combination of infinite sets of solutions, it is not possible for the system to be completely critically-damped or over-damped because of the existence of under-damped modes at higher order. Therefore, a damped index is introduced to help in understanding the behavior of such system. When the physical damping is increased (for example, by using a more viscous carrier fluid in slurry), all components are more damped accordingly. However, in addition to the physical damping, the apparent damping caused by the increase of wire speed will also damp out the response. These two parameters, physical damping and apparent damping, control the behavior of an axially moving wire. This is a new finding in vibration analysis of moving wire that, to our best knowledge, has not been reported in the previous literature.
Dimensional Error Compensation in Compliant Assembly Processes Using Virtual Assembly Training
Authors: Xie Kang , Camelio Jaime A. , Izquierdo L. Eduardo
Published: July 2009

Dimensional variation propagation and accumulation in multistage manufacturing processes are among the most important issues that affect quality. Although robust design and statistical process quality control help to reduce the effects of these problems, neither of these two methods can be used for instant variation reduction during assembly operations. This paper introduces a complete methodology for error compensation in compliant sheet metal assembly processes. The proposed methodology can be divided in two steps: (1) an off-line error control-learning module using virtual assembly models, and (2), an in-line control implementation using a feedforward control strategy. The off-line learning method focuses on determining the optimal control actions or corrections to a set of predefined deviations. Specifically, it utilizes a newly developed iterative sampling method based on Kriging fitting to efficiently determine an optimal control action. The in-line feedforward control uses measurements of incoming assembly components to select an appropriate pre-learned control action. Two case studies are presented; first, a mathematical case study is used as the empirical proof for the feasibility of the iterative sampling and fitting algorithm. Second, a simulation-based case study is used to illustrate the effectiveness of the proposed methodology to improve dimensional quality in assembly operations of compliant sheet metal parts.
A New Position Feedback Method for Manufacturing Equipment
Authors: Wong Chan , Montes Carlos , Mears Laine , Ziegert John
Published: July 2009

This paper presents an innovative real time 2-dimensional position feedback method, which processes visual input data from a target image on an actively-controlled planar pixel matrix. The objective is to demonstrate the ability to position an X-Y stage with high resolution, using direct position sensing of a dynamically controlled image. In order to achieve high spatial resolution using a pixel array as a target, an algorithm that processes both the geometric shape and the grayscale intensities of the image is implemented. The test platform consists of an X-Y stage carrying a Liquid Crystal Display (LCD) screen that is imaged by a stationary digital camera. The pixel intensities on the LCD screen are modified dynamically to provide 2-dimensional position command inputs that translate to the desired stage motion. The digital images acquired by the camera are used to provide position error feedback to the controller. Experimental results show that direct position sensing is possible to a certain degree of accuracy. However, in order to match today’s CNC machines’ accuracy levels further processing of the digital images is required. A noise reduction algorithm to filter the fluctuations of the measurements in the digital images is proposed as future work, as well as other considerations.
Monitoring of the Spatter Formation in Laser Welding of Galvanized Steels in Lap Joint Configuration by the Measurement of the Acoustic Emission
Authors: Yang Shanglu , Huang Wei , Lin Dechao , Kong Fanrong , Kovacevic Radovan
Published: July 2009

Galvanized steels have been widely used in the different industries such as automotive, aerospace and marine industry, due to their high corrosion resistance and excellent mechanical properties. However, the zinc coating on the metal sheet offers a big challenge to the welding operation, specifically in the high-power laser welding process of the lap joint if the metal sheets are installed in a gap-free configuration. Spatters, one of the critical problems for the weld quality, is readily generated by the high-pressurized zinc vapor developed at the interface of two metal sheets. It takes extra procedures to clean the weld surface or repair the blowholes generated by the spatters. The on-line process monitoring is critical to assure the achievement of the high quality welds. Therefore, it is necessary to develop an on-line efficient monitoring system for the welding of galvanized steels. In the past few years, acoustic emission (AE) technique has been applied to monitor different manufacturing processes. This paper will highlight its application in the laser welding of galvanized steels. An AE signal acquisition system is used to real-time monitor the welding process. The results of the investigation show that the amplitude of AE signals varies with the welding process status. When the welding process is stable, the amplitudes of AE signals are almost constant and with the low intensity compared to the AE emission signals when the weld defects are presented. When the spatter is formed, a sharp spike with the high amplitude is shown in the collected acoustic emission signal. In order to extract the features of the AE signals in frequency domain, the acquired signal in time domain is further processed using Short-time Fourier Transformation (STFT). The STFT processed results indicated that the spatter-induced AE signals cover a wide range of frequencies and the background noise is mainly presented in the range below 100 Hz.
Active Fixturing for Mesoscale Manufacturing Systems: Fixel Design Alternatives
Authors: Wiens Gloria J. , Rao Koustubh J. , Rippere Troy B.
Published: July 2009

This paper presents an investigation of fixel design alternatives for active (dynamic) fixturing to be incorporated into mesoscale manufacturing systems. Using simple compliant mechanisms and components (e.g., monolithic four-bar mechanisms and/or cantilever beams), fixels exhibiting mechanically adjustable stiffness characteristics are achievable. Manually or automating the stiffness adjustments, these fixels provide a functionality for enabling greater control of the dynamic response of the workpiece due to vibrations and variation in contact forces at the tool-workpiece-fixture interface. To quantify the fixel functionality and its dynamic range, this paper presents the theoretical models of the stiffness characteristics expressed as a function of each fixel design’s mechanical variables. Upon establishing a common stiffness range for the different fixel designs, a metric is formed based on the sensitivity of stiffness expressed as a function of slenderness ratio and an operation range, bounded by a maximum possible stiffness value shared by all fixture models. Using this metric, results are generated to delineate the advantages and disadvantages of each design and their potential impact on fixturing and material handling in the creation of micron features on micro and macro parts.
A Comparative Study on the Effect of Surface Topography by Hard Turning vs. Grinding on Frictional Performance at Dry and Lubricated Sliding Contact
Authors: Waikar R. A. , Guo Y. B.
Published: July 2009

Machining-induced surface topography has a significant effect on tribological performance of machined components in sliding contact. However, the effect of different surface topography by turning versus grinding on tribological performance has received very little attention. In this study four types of surface topography by turning and grinding AISI 52100 bearing steel (62 HRc) were prepared and characterized to study its effect on friction and wear in sliding contact. Dry and lubricated reciprocating sliding wear tests with an on-line acoustic emission (AE) sensor were carried out using a ball-on-disk tribometer. The experimental results have shown that: (i) the turned surfaces, regardless of the presence of a white layer, yield smaller friction of coefficients in sliding along feed marks than across sliding at both dry and lubricated conditions. However, the opposite hold true for the ground surfaces; (ii) friction of coefficients (0.6∼0.8) at dry conditions is higher for both turned and ground fresh surfaces than their white layer counterparts regardless of sliding direction. At lubricated conditions, Friction of coefficients (0.1∼0.12) are smaller for the both turned and ground fresh surfaces than the white layer surfaces in along sliding, while it is equivalent in across sliding; (iii) the trends of acoustic amplitude amplitude are consistent with those of frictional coefficients for the turned or ground surfaces at dry conditions. Similar trends are also true for the turned surfaces at lubricated conditions, but not for the ground surfaces; and (iv) the wear debris on the track may act as solid lubricants to reduce the sliding frictional coefficient. Machining induced white layers leads to a better wear resistance than the fresh surfaces in either along or across sliding.