bluuebunny/crossref_metadata_2025 huggingface dataset:
Strategies for Polymer Welding with High-Power Diode Lasers
Authors: Horn Wolfgang
Published: September 2010

Diode lasers have become an important tool for polymer welding in automotive industries, in medical and electronics manufacturing. High efficiency and well fitting beam quality make them a perfect tool for industrial applications. With adapted optics it is possible to fit the laser spot shape to the geometry of the work piece. Galvo scanners are the most flexible tool to apply local and precise dose of heat to the work piece. If this flexibility is not needed, the laser spot can be customized by optics to line, circular or arbitrary shaped geometries. For joining transparent parts either an absorbing layer or diode lasers with a wavelength of 1940 nm can be used.
Automatic Manufacturing Feature Extraction of CAD Models for Machining
Authors: Narabu Yusuke , Zhu Jiang , Tanaka Tomohisa , Saito Yoshio
Published: September 2010

Currently CAD/CAM systems have become more common in automated manufacturing to enhance accuracy and efficiency. However, machining efficiency and accuracy are mainly relied on the experience of the engineer. Therefore, in this research the main aim is to propose the system which automatically analyzes the characteristics of a CAD model and to extract manufacturing features. The method for analyzing shapes of a CAD model represented by triangle mesh is studied. The system can extract planar, spherical, cylindrical, hole, arc, and other curved regions. This research will improve the integration of CAD, CAM system, and is supposed to have a great potential in the application of manufacturing and other engineering fields.
Towards Smart and Competitive Sustainable Machining
Authors: Liu Pei Ling
Published: September 2010

Computer Numeric Control (CNC) revolutionized the machining technology and has been the cutting edge of digital manufacturing since 1950s. CNC machining model, simulation, verification, and optimization have been a vivid research topic of Smart Machining that automated the CNC programming (CAM) and cutting process, hence greatly increased machining productivity since 1990s. This paper traces back the history of CNC simulation, analysis the different CNC machining models, tested with application examples, and listed different CNC verification industry applications for the last 20 years. The new challenge comes from sustainable manufacturing. Towards smart and competitive sustainable machining, CNC model and simulation will be used to optimize the machining process, where the raw material could be saved through First Part Correct technology, the energy could be saved through cutting speed optimization, and used parts could be saved by remanufacturing.
Tool Path Planning Assist System for Freeform Surface Machining
Authors: Zhu Jiang , Nomura Keisuke , Tanaka Tomohisa , Saito Yoshio
Published: September 2010

With the rapid development of CG technology and 3D scanning technology, it is easy to design the freeform surface more complexly, but it also makes it difficult to machine such complex freeform surface rapidly and accurately. In this paper, a tool path planning assist system for freeform surface machining is presented. Differing from general CAM systems, in this developed tool path planning assist system, the tool path is generated based on the features of the CAD model, and focus on the applicability of material removal process. New machining strategies for both rough cutting process and finish cutting process are presented. With the assisting of this developed system, freeform surface could be machined efficiently and accurately.
Planning and Optimizing Projects for MRO
Authors: Zhang Allan N. , Lye Kong Wei , Ma Bin , Loke Dominic , Kumar Shiva , Chan Ying Yip
Published: September 2010

This paper addresses some difficulties common in planning and scheduling work in the MRO industries. We present a solution developed based on Microsoft Project Server for managing and optimizing the deployment of critical resources so as to maximize the project profits. We discuss the methods for managing of multiple projects based on enterprise shared resources, identifying the critical chain for multiple projects, and optimizing their makespans and costs with constrained resources using overtime and outsourcing strategies. We present some results to show the viability and efficiency of the solution in an MRO environment. Several potential research issues are identified and discussed for future research.
Study on Precise Stamping under Eccentric Load Using a Multi-Point Die-Support Structure
Authors: Ohashi Takahiro , Lian Hong Ji , Saito Susumu
Published: September 2010

In this study, the authors employ a multi-point die-support structure to hold the punch plate of a stamping die in order to intercept useless force from the slide of a press machine. The developed multi-point support structure has 12 support cells (support units) between the punch plate and the slide of the press machine; the cells are metal cylinders working as springs. The support unit has a ball contact at the interface of the punch plate, and the interface freely for rotates and slides horizontally. The support unit has strain gauges on the side surface, and we can determine the bearing load at each unit, as well as elastic deformation. We can observe the bearing load distribution and then relocate the support units to better distribute the supporting points. The authors discuss the relocation of support units and demonstrate the efficiency of the proposed structure for reducing the jolt of a stamping die set. The range of jolt between the punch plate and the die plate of the experimental die is 0.711mm with normal support for piercing a 30mm-diameter hole on a 1.2mm-thick JSC980Y sheet. However, it is 0.355mm with the proposed die-support structure after several relocations of the support units.
Investigation of Microstructure and Hardness in Microfoming of Pure Copper Pins
Authors: Ghassemali Ehsan , Jarfors Anders W.E. , Tan Ming Jen , Lim Samuel C.V. , Chew Mei Qian
Published: September 2010

Microforming is defined as the process of production of metallic micro-parts with sub-millimeter dimension. There is as strong interaction between the scale of the microstructure and the size of the part affecting material flow, the so-called “size effect” in microforming processes. Conventional forming rules cannot be directly applied to the micro-scale forming. To better understand the implications for part geometry and properties, further investigation of the material flow related events is necessary. The aim of this work is to investigate microstructural evolution of pure copper during a micro-extrusion process - for production of micro-pins with diameters varying from 300 to 800µm - by means of optical microscope (OM). Qualitative strain gradient distribution could be observed by those pictures. The results showed that change of micro-pins diameter and die angle affect the microstructure and strain distribution of the final product remarkably, that affect the mechanical properties of the pin formed. Furthermore, microhardness results were consistent with the microstructural observations.
Fabrication and Molding Testing of the Blazed Gratings for Microoptics Applications
Authors: Lee Cha Bum , Lee Sun Kyu
Published: September 2010

This paper presents the experimental investigation of the optimal hot embossing replication to prevent the nanoscale thermal deformation of microstructures replicated from the electroless Ni mold fabricated by the diamond tool-interfered scribing process. The fabricated microstructures have the blazed profile with a period of 2.0 ㎛ and a depth of 0.2 ㎛ and a thermoplastic material PMMA as the replica was used. The hot embossing molding was carried out under the several experimental conditions. In terms of a quality of surface smoothness, profile, sharp blaze edge, surface roughness, peak to valley Ry and optical performance of the replica, the PMMA microstructures replicated under the optimal conditions, were ideally identical with those in the mold in dimension, and it was found that the demolding temperature is the most important factor for replication. From optical testing, diffraction efficiency of the replica was measured, 87.6%, similar to that of the calculated value 89.6%, and the replica molded in other conditions showed the noticeable efficiency drop due to molding error.
FEM Investigation of Particle Behavior in Particulate Reinforced Metal-Matrix Composites during Micro-Extrusion
Authors: Zhang Xin Ping , Castagne Sylvie
Published: September 2010

This paper is concerned with the deformation and the redistribution process of particles in SnO2/Ag particulate reinforced metal-matrix composites during micro-extrusion. The effects of the extrusion angle, the extrusion ratio and the ram speed on the deformation and redistribution of particles during the forming process were studied by finite element methods using Deform software. The deformation behavior and redistribution pattern are explained based on the non-uniform flow of the billet and the non-uniform stress distribution.
Experimental Investigation of Flaring in the Warm Flow-Forming of AZ31 Magnesium Cups
Authors: Fong Kai Soon , Wong Chow Cher , Atsushi Danno
Published: September 2010

The effect of forming temperature and feed rate on the flaring of AZ31 magnesium cups was investigated in the warm flow-forming process. Flaring is a common phenomenon in flow-forming process whereby the diameter of the work-piece is observed to increase gradually along the flow-formed path. In this study, forward flow-forming process was performed on a cup-shaped work-piece by using two diametrically opposite rollers (approach angle of 20) at a constant thickness reduction. To study the effects on flaring, experiments were performed at feed rates of 0.2mm/rev, 0.4mm/rev, and 0.8mm/rev and at forming temperatures between 50~300°C. Experimental results indicated that feed rate was the most significant parameter influencing flaring while temperature mainly improve the formability of the material. It is believed that a higher feed rate resulted in an increase in metal flow in the circumferential direction because of higher mean circumferential strain and hence increases flaring. Flaring was also observed to be most severe at forming temperature of 300°C and feed rate of 0.8 mm/rev due to the excessive metal flow in the cirucmferential direction of the test-piece. This study clarifies the relationship between feed rate and the extend of flaring and that forming temperature has little influence on flaring from temperature range of 50°C to 250°C.
Automatic Egg-Cell Gathering by Two Versatile Miniature Robots and a Miniature Pump on an Inverted Microscopy
Authors: Fuchiwaki Ohmi , Ichikawa Tatsuya , Yamagiwa Tsubasa
Published: September 2010

In this paper, we have described automatic gathering with visual feedback of egg-cells by 2 miniature robots. Generating a transgenic mouse is one of the most important operations in the bio-medical field. Sometimes scientists need several hundreds of egg-cells for only 1 experiment. However, conventional manipulators are designed for only DNA-injecting, and they are not useful devices for gathering egg-cells. To support the DNA-injecting operation, we have proposed the automatic gathering of egg-cells by 2 miniature robots and a miniature pump. In several experiments, we have checked the efficiency and confirmed that our device has good feasibility to support egg-cell processing. We have also proposed a 5 pipettes’ egg-cell processing method using miniature robots to realize multi-functional and flexible egg-cell processing.
Micro Machining of Metal Injection Mould with Micro Channel Features of Tens Micro Meters for Polymer Microfluidic Devices Manufacturing
Authors: Liu Kui , Zhao Jian Hong , Shaw Kah Chuan , Wu Hu , Ng Fern Lan
Published: September 2010

There are increasing demands for polymer based microfluidic devices as polymer devices can be mass produced using the injection molding process for disposable analytical applications. However, fabrication of precision injection molds with micro features down to tens of micro meters is a challenging task. The most efficient manufacturing method for this type of high precision micro mold is the tool-based micro machining. In this paper, studies have been conducted to develop metal injection mould manufacturing technologies for polymer microfluidic device fabrication. An injection mould with a micro feature of 29m wall thickness, 20m height and 9.8mm length has been successfully achieved on brass with very precise dimensional accuracy and surface quality for molding process of polymer microfluidic devices. Polymer microfluidic chips with micro channels of 30m width have been successfully produced using the machined metal injection mould.
Screw-Driven Multi-Channel Peristaltic Pump for Pneumatic Micro Actuator System
Authors: Rhie Wonsei , Higuchi Toshiro
Published: September 2010

The authors have developed a miniaturized peristaltic pump which is characterized by multi-channel, low pulsation, high pressure resistance and portability. The pump mainly consists of a disposable pumping channel unit and reusable actuating parts. The pumping channel unit, made of silicone elastomers, has eight pumping channels. The operation principle is based on the peristaltic motion of pumping channels that are occluded by the screw shaft. The shaft rotating inside the pumping channel unit has a spirally arranged projection which deforms and closes down the channels. While the shaft rotates, the pinched locations in the channels move either way according to direction of rotation, squeezing out the air inside. The maximum discharge pressure generated was about 160 kPa at rotating speeds of 30 ~ 180 rpm. A micro pneumatic actuator was fabricated to demonstrate the performance of the pump. The validity of the pump for pneumatic actuation was reported.
Micro-Object Orientation Control by Using Different Vibration Modes of Board Stage
Authors: Tateno Toshitake , Kakuta Akira , Okui Kotaro
Published: September 2010

This paper deals with an orientation control method for micro objects, which have a size in the order of 100 micro meters, by using a board stage that is vibrated in the natural frequencies of various vibration modes. Orientation control is important for manufacturing processes, such as the assembling of small parts. Since it is difficult to grip and to manipulate micro objects, a simple and reliable method is desired. In this paper, the vibration mode is used for generating different motions of the stage and for controlling the orientation of the objects on the stage. Since each vibration mode has a unique vibration motion, different motions can be selected by choosing the vibration frequency. In order to design the stage so that the objects turn toward target direction, Finite Element Method (FEM) analysis was applied. And, the designed vibration stage was fabricated using a stainless steel thin plate. Experimental results showed that the actual vibration is similar with the simulation results. As an example of the orientation control of the micro objects, some small electronics parts were tested and they could be turned toward the target directions.
Development of a Linear-Motor-Driven Table Supported by Hydrostatic Water Bearings: Effect of Air Volume Contained in Water-Supply Tube on Pitching Motion of Table Slider
Authors: Yui Akinori , Okahata Go , Okuyama Shigeki , Kobayashi Hisashi , Slocum Alexander Henry
Published: September 2010

A linear-motor-driven table supported by hydrostatic-water bearings had been developed. The table slider is supported by a single-sided recess type bearing system and preloaded by attractive force using a linear-motor magnet. Since eccentric excitation force is applied to the table slider due to the change of attractive force according to the magnet track position of the linear-motor, pitching motion of the table occurs. This paper investigates the effect of air volume contained in a water-supply tube on the pitching motion. Larger air volume results in lower natural pitching frequency of the table slider, lower logarithmic decrement of the pitching motion and larger pitching angle. When the natural pitching frequency corresponds to the frequency of the eccentric excitation force during table feed, pitching angle grows by resonation.
Effects of Insert Nose Radius and Processing Cutting Parameter on the Surface Roughness of Aisi 316 Stainless Steel
Authors: Abdullah Mohd Fazuri , Chua Abdullah Muhammad Ilman Hakimi , Sulong Abu Bakar , Ghani Jaharah A.
Published: September 2010

The effects of different cutting parameters, insert nose radius, cutting speed and feed rates on the surface quality of the stainless steel to be use in medical application. Stainless steel AISI 316 had been machined with three different nose radiuses (0.4 mm 0.8 mm, and 1.2mm), three different cutting speeds (100, 130, 170 m/min) and feed rates (0.1, 0.125, 0.16 mm/rev) while depth of cut keep constant at (0.4 mm). It is seen that the insert nose radius, feed rates, and cutting speed have different effect on the surface roughness. The minimum average surface roughness (0.225µm) has been measured using the nose radius insert (1.2 mm) at lowest feed rate (0.1 mm/rev). The highest surface roughness (1.838µm) has been measured with nose radius insert (0.4 mm) at highest feed rate (0.16 mm/rev). The analysis of ANOVA showed the cutting speed is not dominant in processing for the fine surface finish compared with feed rate and nose radius. Conclusion, surface roughness is decreasing with decreasing of the feed rate. High nose radius produce better surface finish than small nose radius because of the maximum uncut chip thickness decreases with increase of nose radius.
Nanoindentation of Multi-Wall CNT Reinforced Al Composites
Authors: Liao Jin Zhi , Pang Jian Jun , Tan Ming Jen
Published: September 2010

This work used nanoindentation to characterize the local mechanical properties of the multi-wall carbon nanotube (MWCNT) reinforced aluminum (Al) composites. The Al-MWCNT (0.5, 1.0 and 2.0 wt.%) specimens were fabricated by spark plasma sintering (SPS) followed by hot extrusion. Different local regions of the as-extruded and tensile-fractured specimen over the longitudinal and transverse section were studied by nanoindentation. The nanoindentation results were compared with the conventional macro- and mircoscopic mechanical tests, and were found in good agreement. The values of hardness (H) and elastic modulus (E) obtained reached maximum at the 0.5 wt.% MWCNT adding Al samples. E was highest in the necking region then decreased with increasing distance from the localized deformed region; while H varied in different regions. In the same region, H and V were higher in the longitudinal than those in the transverse direction, due to the texture hardening and alignment of CNT.
Review on Serpentine Flow Field Design for PEM Fuel Cell System
Authors: Erni Misran , Wan Daud Wan Ramli , Majlan Edy Herianto
Published: September 2010

Flow field design has several functions that should perform simultaneously. Therefore, specific plate materials and channel designs are needed to enhance the performance of proton exchange membrane (PEM) fuel cell. Serpentine flow field design is one of the most popular channel configurations for PEM fuel cell system. Some configurations have been developed to improve the cell performance. This paper presents a review on serpentine flow field (SFF) design and its influence to PEM fuel cell performance based on some indicators of performance. The comparisons of SFF with other flow field designs are summarized. The results of some experimental and numerical investigations are also presented.
Optical Sensing Based on Localized Surface Plasmon Resonance
Authors: Zhu Shao Li , Zhou Wei
Published: September 2010

Localized surface plasmon resonance (LSPR)-based nano-biosensors are of great interest in various applications such as environmental protection, biotechnology, and food safety. It is well known that types of materials and shapes of the nanostructures have significant influence on the sensitivity and the resolution in nanobiosensor application field. The conventional nanostructure array used for nanobiosensor is fabricated by chemical method, so it is difficult to control the shape and the inter-particle space. Focused ion beam (FIB) can be used to produce any shapes with a very high level of regularity and reproducibility. This makes it possible to optimize the shape of nanostructures and the inter-particle distance to achieve the full potential application in nanobiosensor. Using focused ion beam (FIB) nanofabrication method, we have fabricated the regularly shaped hybrid Ag-Au nanostructures distributed on the surface of the glass substrate. Gold-coating was used to tuning the optical characteristics of the silver nanostructure array. Discrete dipole approximation (DDA) method was used to optimize geometrical parameters of the hybrid Ag-Au nanostructures. The design and experiment results show that the sensitivity and resolution have been improved considerably compared to the chemically synthesized nanostructures. The nano-biosensor demonstrates the potential applications in monitoring, detection and identiﬁcation of biological agents, and characterization of intermolecular interactions.
A Multi-Probe Measurement Method to Evaluate the Yaw and Straightness Errors of XY Stage on High Precision CMM
Authors: Yang Ping , Shibata Shusaku , Takahashi Satoru , Takamasu Kiyoshi , Sato Osamu , Osawa Sonko , Takatsuji Toshiyuki
Published: September 2010

To develop a high precision Micro Coordinate Measuring Machine (Micro-CMM), it is important to evaluate an X-Y stage on the Micro-CMM. A precision multi-probe measurement system has been designed and developed for simultaneously measuring the yaw and straightness errors of the X-Y stage. In the system, an autocollimator measures the yaw error of the stage, and two laser interferometers measure the profile of a standard mirror which is fixed on the X-Y stage. The straightness error is reconstructed by the application of simultaneous equation and least-squares methods, and the uncertainty associated with the multi-probe method is simulated. When the interval of the laser interferometers equals 10 mm, the standard deviation of multi-probe method using the high accuracy autocollimator and the laser interferometers is about 10 nm. The simulation results satisfy our purpose for the uncertainty of 50 nm, and practical considerations are discussed.
Profile Measurement of Large Aspheric Optical Surface by Scanning Deflectometry with Rotatable Optical Devices - Error Analysis and Pre-Experiment-
Authors: Xiao Mu Zheng , Jujo Satomi , Takahashi Satoru , Takamasu Kiyoshi
Published: September 2010

Large aspheric mirrors with diameter over 300 millimeters with high surface accuracy are wildly used in many areas such as astronomical telescopes. Interferometers are widely used in profile measurement of optical flat and sphere. However, standard reference aspheric surface which is necessary for this method is difficult to make. Scanning defletometry based on ESAD (Extended Shear Angle Difference) is used to measure ultra-precise large near-flat and slight curved optical surface with the accuracy of sub-nanometer. However, it is not possible for it to measure aspheric surface because of the limitation of the measuring range of autocollimators. We proposed a new measuring method to scan the surface of a large aspheric optical surface using autocollimator with rotatable optical devices fixed on linear motion stage. To eliminate the influence of the pitching error of the scanning stage, we use two mirrors reflecting laser comes from autocollimator, which have the same effect with a pentaprism used in ESAD. To enlarge the measuring range of the autocollimator, we use a rotatable mirror to fit the changes of the slope of the mirror surface under measurement. The error analysis of the method is done. Measurement of an optical flat mirror and a sphere mirror with diameter of 50 mm and biggest slope of 6000 arc-second are done. The rotatable optical devices that we designed are proved effective on eliminating the pitching error of the moving stage.
Laser-Pointer Rangefinder between Mobile Robot and Obstacles via Webcam Based
Authors: Shojaeipour Shahed , Parhizkar Behrang , Hosseinmemar Amirhossein , Shojaeipour Ali , Esfandiari Hamed , Mobasheri Esmaeil , Binti Gebril Zahra Mohana
Published: September 2010

In this paper, we present a method to measurement a distance using a laser-pointer. This method calculated the distance from obstacles for the robot to transverse to its target location, while avoiding obstacles along the way. The environment is first captured as an image using a webcam. Image processing are then calculate to identify the existence of obstacles within the environment. Using the laser-pointer, ditance locations with obstacles are identified which laser-pointer consist of the webcam and the laser-pointer. It measure the distace mobile robot to the obstacles is identified. The program is written in MATLAB with the Image processing toolbox.
Basic Characteristics of a Simultaneous Double-Side CMP Machine, Housed in a Sealed, Pressure-Resistant Container
Authors: Kitamura Kei , Doi Toshiro K. , Kurokawa Syuhei , Umezaki Yoji , Matsukawa Yoji , Ooki Yota , Hasegawa Tadashi , Koshiyama Isamu , Ichikawa Koichiro , Nakamura Yoshio
Published: September 2010

We designed and manufactured a prototype of a unique CMP machine, which can perform double-side CMP simultaneously in a sealed and pressure container as regarding effective action of the processing atmosphere around workpieces as important. Polishing experiments with single crystal silicon (Si) wafers (100) are performed by charging the container with various gases. As a result, the removal rates increased by up to 25% under high pressure oxygen gas atmosphere.
Effects of Molecular Weight and Annealing on Electrical Conductivity of Multi-Walled Carbon Nanotube/Polypropylene Composites
Authors: Pan Yong Zheng , Li Lin , Chan Siew Hwa , Zhao Jian Hong
Published: September 2010

Composites of polypropylene (PP) and multi-walled carbon nanotubes (MWCNTs) were prepared by a micro melt mixing process. The molecular weight of PP was varied from 190,000 to 340,000 to examine its effects on the electrical conductivity. It has been discovered that a significant enhancement of electrical conductivity could be achieved by a thermal post annealing process above the melting temperature of PP. Factors such as annealing time, temperature, viscosity of PP, and content of MWCNTs all affected the enhancement of electrical conductivity. Re-aggregation of MWCNTs and the subsequent formation of MWCNT networks during annealing are considered to be the main reasons for the quick enhancement of electrical conductivity. The observed effect of molecular weight of PP on the enhancement of electrical conductivity suggested that the enhancement process could be controlled by diffusion of MWCNTs.
Drilling of Titanium/CFRP/Aluminium Stacks
Authors: Shyha Islam , Soo Sein Leung , Aspinwall David K. , Bradley Sam , Dawson Stuart , Pretorius Cornelius J.
Published: September 2010

Following a review on the machinability of CFRP composites and multilayer stacks typically comprising metallic and composite material elements, the paper details experimental results when drilling 30 mm thick titanium/CFRP/aluminium workpiece stacks. Testing utilised a modified fractional factorial design based on an L18 Taguchi orthogonal array. This comprised four factors, three of which were at three levels and one at two levels and involved tool coating, cutting speed, feed rate and machining environment. Tools evaluated involved hardmetal and diamond coated carbide in addition to uncoated tungsten carbide drills. Response variables were principally tool wear and cutting force/torque with an end of test criteria of 300m flank wear. Peeling of the CVD diamond coating occurred within the first several holes drilled however this was not a limiting factor in terms of tool life. Principal damage occurred when drilling through the titanium (Ti-6Al-4V) rather than the aluminium (Al 7050) or CFRP (unidirectional “UD” laminates) sections. Best tool life/performance (310 drilled holes) was obtained with the more conventional uncoated carbide drills at lower cutting speed and feed rate. Typically thrust forces increased from 300 N for the first hole to ~2200 N for last hole drilled while torque values were generally below 600 N.cm for worn tools.
Achieving High Flatness of Workpiece Edge Shape by Considering Polishing Pressure
Authors: Miyake Takahiro , Enomoto Toshiyuki
Published: September 2010

In recent years, the achievement of further high flatness of workpiece edge shape is strongly required in mirror finishing. Especially, the edge roll off of silicon wafers as the substrates of semiconductor devices is demanded to decrease in the polishing process for raising the yield of IC chips. Many theoretical and experimental analyses for the edge roll off generation have been already done to meet the demand. The analyses, however, cannot fully account for the obtained edge shape in actual polishing. Concretely, the influence of the polishing pressure as one of the key polishing conditions on the edge roll off has not been clarified. In this study, the influence of the polishing pressure on the edge shape was investigated by the polishing experiments and the edge roll off generation analyses using the model based on the viscoelasticity of the polishing pad, which was proposed in the previous study. And it was revealed that an appropriate polishing pressure is needed to be set for achieving high flatness of workpiece edge shape with the consideration of the properties of applied polishing pads.
Characterization of Silicon Wafer Surface Irradiated with Fiber Laser
Authors: Farrokhi Hamid , Zhou Wei , Zheng Hong Yu , Li Zhong Li
Published: September 2010

We studied the feasibility of micromachining of silicon wafer using 200 W fiber laser of 1090 nm in wavelength. Irradiated area was observed and analyzed using scanning electron microscope and surface profiler. It was found that micromachining of silicon could not be carried out efficiently. Careful analyses revealed possible causes for the poor machinability: first, very weak plasma formed during the fiber laser-material interaction, leading to low evaporation or melt ejection; second, formation of large amounts of SiO2 resulted in expansion of volume. It is further demonstrated that the surface oxidation can be made use of for the purpose of surface texturing.
Micro-Laser Welding of Plastics for the Applications in Micro-Fluidic Devices
Authors: Bi Gui Jun , Ng Sum Huan , May Khin Thet , Chan Cong Zhi
Published: September 2010

This study aims to investigate laser welding process for the bonding of micro-fluidic devices. PMMA was selected for the investigation. The devices consist of an opaque substrate with micro-channels and a transparent cover. The welding process was optimized according to laser power, welding speed and clamping pressure. The cross-sectional analysis, flow and pressure tests, as well as the lap-shear test were conducted on the samples welded with the optimized process parameters. The results show that the laser welding can meet the requirements for bonding the plastic micro-fluidic devices.
Study Effect of Stress in the Electrical Contact Resistance of Bipolar Plate and Membrane Electrode Assembly in Proton Exchange Membrane Fuel Cell: A Review
Authors: Miftah Kurniawan , Wan Daud Wan Ramli , Majlan Edy Herianto
Published: September 2010

Stress applying in the stack of Proton Exchange Membrane Fuel Cell (PEMFC) effects the performance of PEMFC. High pressure in the Membrane Electrode Assembly (MEA) can reduce electrical contact resistance between bipolar plate and MEA. Nevertheless, too high pressure in the PEMFC can destroy MEA. Performance of PEMFC can be optimized by make proportional stress in the assembly of PEMFC. Finite element analysis (FEA) is one of method that can be used for analysis of stress in the PEMFC stack. However, setting of parameter in the analysis using FEA still became one of problem if realistic result must be desired. This paper reports setting of parameters in the stress analysis of PEMFC assembly using FEA method and study relationship of stress analysis with electrical contact resistance.
Surface Integrity in MQL Drilling Nickel-Based Superalloy
Authors: Rahim Erween Abdul , Sasahara Hiroyuki
Published: September 2010

Nickel-based superalloys remain the most widely used of all materials in aerospace industry, contributed over 50 % of the weight of a jet engine. In machining of any jet engine components, it is necessary to satisfy the surface quality or surface integrity requirements to facilitate high reliability components. In the present study, surface integrity of Inconel 718 was studied when drilling under different lubricants. The holes were drilled individually using indexable AlTiN coated carbide drill under minimum quantity of lubricant (MQL) conditions. The results demonstrated that the machining conditions and lubricants strongly influence the surface integrity. The surface roughness decreases with the increase in cutting speed and increases with the increase in feed rate. Microhardness profiles indicated that the subsurface deformation extends up to a 100 and 150 μm for palm oil and synthetic ester, respectively underneath the machined surface. Pit holes, cavities, grooves, microcracks and surface smearing were the dominant surface damages criteria for all cases.
Investigation on the Cutting Process of Plasma Sprayed Iron Base Alloys
Authors: Ding Kan , Sasahara Hiroyuki , Adachi Syuji , Nishimura Kimio
Published: September 2010

In the recent years, the current technology enables only the molten iron base alloys, sprayed on the aluminum alloy engine block thus it can function as a cylinder bore. However, the machinability performance of plasma spray coated cylinder bore in boring process is poor because of severe tool wear compared with the previous cast iron cylinder bore. This paper deals with the results obtained at boring process of plasma sprayed iron base alloys coating to clarify the root cause of tool wear. Preliminary fine boring and turning experiments are conducted on the plasma sprayed cylinder bore, and tool wear, tool failure modes and cutting force were also investigated. The result shows plasma spray coated cylinder bore recorded larger cutting force than the cast iron cylinder bore. Also, this work shows that abrasive effect by the hard oxide particles on the cross-sectioned of machined layer is superior when fine boring plasma spraying iron base alloys coating.
Effect of Rapid-Feed Step-Drilling Cycle and Super-High-Speed Spindle for High-Speed Micro Drilling in Printed Wiring Boards
Authors: Aoyama Eiichi , Hirogaki Toshiki , Ogawa Keiji , Nojiri Satoshi , Takeda Yutaka
Published: September 2010

A drilling technique using micro-drills of 0.2 mm or less in diameter and a super-high-speed spindle of 160000 rpm or more has been developed for drilling ultra-micro holes in printed wiring boards (PWBs). The drilling process requires higher reliability and quality to maintain the reliability of the electrical connection between circuit layers. On the other hand, higher processing efficiency is also required in PWBs manufacturing. To maintain high productivity, drilling is normally performed using a non-step method, but heat damage called B-RING occurs around the drilled holes with this method. To solve these problems without the loss of processing efficiency, we applied the rapid-feed step-drilling cycle method. We investigated the B-RING for drilling quality and evaluated the drilling time for processing efficiency under various drilling conditions. We found that using a rapid-feed step-drilling cycle with an appropriate number of steps and feed rates ensures a higher level of hole quality and processing efficiency compared with the conventional non-step drilling.
The Application of Nanotechnology for Mechanical Manufacturing
Authors: Gu Li Zhi , Hong Qi , Xiang Chun Jiang
Published: September 2010

Nanoscience and nanotechnology is one of the most important researches in the 21st century. This paper took the application of nanotechnology for mechanical manufacturing as a point of departure, discussed the nano-material technology, nano-processing technology, nano-assembly technology and nano-measurement technology in mechanical manufacturing, and described the resulting theory nano-mechanics which was different from the traditional mechanics. Moreover the important role of nano-technology for the development of mechanical manufacturing was pointed out at the end of the paper.
The Effects of UIT in the Fatigue Life of Al 2024-T3
Authors: Castillo-Morales Martin , Salas-Zamarripa A.
Published: September 2010

The Ultrasonic Impact Treatment (UIT) has been used in different materials to reduce residual welding tensile stresses and improve the fatigue life of welded joints, and also to increase the fatigue resistance at low temperatures. The main aim of this research was to explore the effects of UIT in the fatigue life of a 2024-T3 aluminium alloy. Load controlled fatigue tests were carried out at high and low cycle fatigue, and three UIT parameters at a carrier frequency of 36 kHz were evaluated. These parameters were feed rate, amplitude under load and impact frequency. The results revealed an increase in compressive residual stress and microhardness, as well as some evidence of porosity. However, the fatigue life was reduced drastically. The possible causes of this decrease are still under discussion.
Numerical Formulation to Study Fluid-Solid Interfaces Excited by Elastic Waves
Authors: Rodríguez-Castellanos Alejandro , Flores Mendez Esteban , Sánchez-Sesma Francisco José , Rodríguez-Sánchez José Efraín
Published: September 2010

In this paper, the scattering of elastic waves in a fluid-solid interface is researched. The Indirect Boundary Element Method (IBEM) was used to study this wave propagation phenomenon in a 2D fluid-solid model. The source, represented by a Hankel´s function of the second kind, is always applied in the fluid. This approximate boundary integral technique is based upon the integral representation for scattered elastic waves using single-layer boundary sources. The approach presented is usually called IBEM as the sources’ strengths should be obtained as an intermediate step. This indirect formulation can give a deep physical insight to the analyst on the generated diffracted waves, because it is closer to the physical reality and can be regarded as a realization of Huygens’ Principle, which mathematically is fully equivalent to the classical Somigliana’s representation theorem. In order to gauge accuracy, the method was tested by comparing it to an analytical solution. A near interface pulse generates scattered waves that can be registered by sensors located in the fluid. Results are presented in time domain, where several aspects related to the different wave types that emerge from this kind of problems are pointed out.
Corrosion Degradation of Pipeline Carbon Steels Subject to Geothermal Plant Conditions
Authors: Miranda-Herrera Carlos , Sauceda Israel , González-Sánchez J. , Acuña-González Narciso
Published: September 2010

The electrochemical behaviour of two carbon steels exposed to the acidic solutions and their resistance to hydrogen induced cracking (HIC) is evaluated in order to determine the effect of hydrogen damage on the failure process of the steels used in line pipe and casing at a geothermal plant. MethodologyApproach: Samples of two different steels, ASTM A-53 grade B (line pipe) and API L-80 (casing) were immersed during 96 hours in the electrolyte proposed by NACE to evaluate the susceptibility to HIC. Samples of the two steels embedded in non-conducting bakelite were exposed to potentiodynamic polarisation at room temperature using brines obtained from different wells at Cerro Prieto geothermal plant as electrolyte. Hardness tests were performed before and after the HIC test on samples in order to determine hardness changes induced by hydrogen penetration, as field results indicated embrittlement of the steels after 4 months of service. Findings: The steels, ASTM A-53 grade B and API L-80 did not present cracking sensitivity, as no cracks were observed in the tests specimens, although they showed an increase in hardness. The steels presented high corrosion rate in the brine media at room temperature (3.3 mm/year), which is expected to increase at high temperatures. Originality: This work revealed that carbon steels used at line pipes and casing at geothermal plants present high resistance to hydrogen induced cracking; however they corrode at high rates and present embrittlement. It is suggested that due to the high operation temperature the damage induced by hydrogen results in hardness increase but was not sufficient to crack development.
Mechanical Behavior of Ceramic and Polymer Composites Reinforced with Volcanic Ashes
Authors: Soto Trinidad José Luis , Vite Jaime , Franco Araceli , Mendoza Nuñez Maribel , Gutiérrez Torres Claudia del Carmen
Published: September 2010

A study of the mechanical behavior of three composite materials under compressive, flexural, hardness and impact stress is presented in this research. The experimental work consisted on manufacturing and characterizing the composites. Firstly, the volcanic ashes, clay, water and other adherent ingredients were mixed. Then, this mixture was winterized and vitrified to obtain the ceramic matrix composite. On the other hand, the ashes were mixed with epoxy resin and polyester resin, individually, to origin two polymer matrix composites. Next, physical and mechanical tests were done to determine their physical and mechanical properties. The hardness, compressive, flexural, and impact stresses were determined and analyzed to know the mechanical behavior of the materials and to study their failure. Due to the fact that the mechanical properties of these composites are strongly affected by characteristics of their microstructure, their physical properties such as density, porosity and water absorption were evaluated. Also, an analysis of the materials’ microstructures in the scanning electron microscope and X-ray diffractometer was made. Finally, it could be observed that finer grain size helped reduce the volumes of open pores and stresses that develop at grain boundaries due to anisotropic expansion and contraction in the microstructures. Ceramic composites failed because of their low fracture toughness. However, this mechanism of failure in the polymer matrix composites was different, as the materials were subject to stresses. Considerable heating occurred near some pores and the inter-relationships between fatigue and creep. The results indicate that these products can be used like an added value in the industrial sector.
Effect of Air Humidity on the Mechanical Properties of In Situ Polymerized Cyclic Butylene Terephtalate Matrix Composites
Authors: Balogh Gabor , Czigány Tibor
Published: September 2010

Composite sheets were made of cyclic butylene terephthalate as matrix and carbon fibers as reinforcing material.Hot press method was used at different temperatures for composite processing. The mechanical properties of these materials and the effect of processing temperature were tested. The samples were kept in a climate chamber, and the effect of air humidity was examined through the change of the mechanical properties. Pictures were taken by a scanning electron microscope of the broken surfaces of the specimens. The results give conclusions about the outdoor application of these composites.
Development of Multifunctional Silicon Nitride Based Nanocomposites
Authors: Balázsi Csaba
Published: September 2010

Silicon nitride based composites with 3 wt% different carbon additives (multiwall carbon nanotubes, graphene and carbon black) have been prepared. Optimisation of the manufacturing processes has been conducted to preserve the carbon nanotubes in composites and to avoid damaging during high temperature processing. The results show that carbon additives have a good contact to the surface of silicon nitride grains. It was found that the different carbon additions have significant effect to the electrical, mechanical, tribological and thermophysical properties of silicon nitride based composites in comparison with pure silicon nitride.
Hot Ductility Variations of ST52-3 Continuously Cast Steel within the Cast Strand
Authors: Gonda Viktor , Csepeli Zsolt , Kardos Ibolya , Verő Balázs , Csizmadia József
Published: September 2010

Along the metallurgical length at continuous casting, the temperature within the strand ranges from above melt temperature (>1500) to about 900 oC. In this range, mechanical properties drastically drop at above the zero deformation temperature (ZDT) and the zero strength temperature (ZST), therefore crack susceptibility increases. These temperatures depend on (local) chemical and microstructural properties. We investigated the change in ZDT and ZST for ST52-3 steel grade by taking samples from the as-cast strand from positions of the columnar grains and from the centreline segregated zone. We found more than 100 oC drop in ZDT due to segregations in the centreline compared to the columnar zone within the strand.
Flame Retardant Polyethylene Terephthalate Fibers Added with Melamine Based FR Additive
Authors: Czél György , Kelemen A. , Solyom D.
Published: September 2010

Polyethylene terephtalate (PET) was modified with a melamine derivative additive in order to obtain flame resistance of fiber products. The effect of flame retardant (FR) agent was determined by measuring rheological and combustion properties of PET linear polyester. The solubility of additive was investigated using a torque-rheometer. In course of the rheological investigation, the rate of solution was determined. The effect of FR additive on the melt rheology could well be traced by using a torque-rheometer and its evaluation method. After preparation of polyethylene terephtalat and melamine mixture melt, fibers were made by coextrusion centrifugal apparatus. The flame retardancy of fibers were determined by standard combustion tests. These tests were performed in order to determine the oxygen index of fiber products. It was proven that a favourable degree of combustibility of PET can be obtained under the influece of adding melamine-derivative additive.
Development of Polymer Coatings for Coronary Stents
Authors: Domján Dániel , Molnár Lászlo Milán , Bognár Eszter , Balázs Tibor
Published: September 2010

The aim of this study is to examine some key properties of medical polyurethane coatings on coronary stents such as thickness and size of pores on the surface of austenitic stainless steel (316L). Plates were used as carrier instead of real stents, because they are too expensive and difficult to work with. The carriers were dipped into the solution of polyurethane and tetrahydrofuran. Solutions of 1 to 5 wt % were prepared for the experiments and the numbers of the dipping were changed. The coatings were examined with Atomic Force Microscope (AFM). In contact mode detailed images with good contrast were made about the coatings. These images were processed with image processing algorithms in MATLAB and with the image analysis software belonging to the AFM instrument.