bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite element modelling of local contact conditions in gear teeth
Authors: Dabnichki P , Crocombe A
Published: October 2002

The aim of the paper is to propose appropriate numerical methods and constitutive models for solution of the gear dynamic contact problem. This has been done through comparison with international gear standards. Such solution techniques are necessary for an accurate analysis of stress state and resultant design improvement of the complex gear configurations. This paper consists of two parts. The first part presents a solution of the general transient contact problem when the stress state of the tooth is studied. This has been carried out in two phases, initially using a coarse multiple-tooth finite element model to establish contact conditions and subsequently using a refined single-tooth-pair finite element model. Differences of up to 163 per cent were found between various international gear standards and the computed results. Various reasons for this have been discussed. The second part of the paper presents results from two types of local analysis which model viscoplasticity in the surface layer and defect generation respectively. These studies achieve a fuller understanding of the stress distribution in the contact zone, its deviation from the classical Hertzian closed-form solution and provide a firm basis for modelling the effect of gear dynamics on local damage, wear and failure. All the computations are made for single-tooth contact and procedures for optimizing the integration time step are used.
Fixtureless assembly of sheet metal parts for the aircraft industry
Authors: Walczyk D F , Raju V , Miller R
Published: October 2002

A method is presented for fixtureless assembly of simple sheet metal parts (i.e. consisting of flat patterns and simple bends) used in the aircraft industry. Current industry practice relies on manually intensive procedures and rigid fixtures for part assembly. The present method relies on carefully toleranced alignment holes that are computer numerical control (CNC) machined into the parts at fastener locations. Parts are temporarily fastened at these alignment holes for their proper alignment together into the assembly, and then permanently fastened at all rivet and bolt locations. A simple procedure is used to characterize empirically the CNC hole drilling process in sheet metal for this method. A simple experiment, involving the assembly of four parts with rivets, successfully demonstrates the potential of fixtureless assembly.
An intelligent fixture with a dynamic clamping scheme
Authors: Nee A Y C , Kumar A Senthil , Tao Z J
Published: October 2002

Both proper fixture design and optimum fixturing execution are crucial to workpiece quality assurance in manufacturing. This paper deals with an integrated approach to fixturing problems and, in particular, a ‘live’ fixture with sensory feedback and on-line fixturing control strategy to perform an optimal fixturing operation. The framework of an integrated fixture design procedure is first presented. The functions and structure of an intelligent fixture are proposed. The prototype intelligent fixture with dynamic clamps capable of delivering accurate but varying clamping intensity is developed. This novel set-up has been proven to be effective for workpiece quality improvement and productivity enhancement through machining experiments on thin-walled workpieces.
Fabrication of microcylindrical parts based on a novel grinding apparatus
Authors: Yeo S H , Balon S A P
Published: October 2002

This paper presents the newly developed grinding apparatus to fabricate microcylindrical parts made of ceramic material. Two major problems are encountered in the fabrication of miniature parts: firstly, the extremely small geometrical scale in the micrometre range and, secondly, the hard-to-machine ceramic materials. In order to machine such microcylindrical parts, a precision grinding apparatus has been developed. The novelty of this apparatus is adopted from dicing technology used in silicon wafers. The surface topology and ductility of the ground microcylindrical parts are presented.
A preliminary study of size reduction of powders in a single-vessel pharmaceutical processor
Authors: MacGregor S A , Newnes L B , Li M , Staniforth J N , Tobyn M J , Kay G R , Horrill M D , Lamming R C , Hajee D W , Wong D , Page T
Published: October 2002

The size reduction performance of a pneumatically driven single-vessel pharmaceutical processor is described. Two materials were considered, namely commercially available granular lactose (CAGL) and high-speed mixer granulator lactose (HSMGL). In both cases there is an initial phase in which the particle diameter is reduced rapidly. The rate at which the size reduction decreases is reduced with time. The final particle diameter was found to be dependent on the material being processed. In the case of CAGL, the minimum size achieved was 150 μm, while in the case of the HSMGL the final particle diameter was 100 μm.
Automatic tool selection for milling operations Part 2: Tool sorting and variety reduction
Authors: Carpenter I D , Maropoulos P G
Published: October 2002

The first part of this paper introduced a procedure for rapidly calculating optimized cutting data for all the feasible tools for a given milling operation. Having produced this list of tools with associated optimized cutting conditions, the preferred tool is selected by sorting the list by a composite objective function incorporating a combination of four desirable conditions: maximum metal removal rate, maximum tool life, minimum overall cost and minimum overall cutting time. These four criteria are normalized by a constant multiplier and prioritized by user-defined weighting coefficients. The tool selection procedure is implemented in software with a graphical user interface. The system includes material data for more than 750 ferrous alloys and specifications for 35988 possible holder/insert combinations. Several examples are presented to demonstrate the capability of the system and the subtle interplay of technological constraints that makes optimized tool selection a difficult process to perform manually. This automated procedure offers consistent selection of tools with efficient cutting data that can produce considerable reductions in machining cost when compared with non-optimal solutions.

This tool selection procedure is designed to select tools and associated cutting conditions for single milling operations. As many machining centres have a limited number of tool positions available for automated tool changing, it is possible that the optimal set of tools for a given component is not the set of tools that are optimal for each operation considered singly. A post-processing method is presented which rationalizes a set of tools so as to reduce the number of unique tools with the minimal decrease in performance when compared with the set of individually optimized tools.
Triangulation of unordered data using trimmed NURBS computer aided design models
Authors: Ristic M , Brujic D , Handayani S
Published: October 2002

Computer aided design (CAD) models of many complex engineering parts, typically in the aerospace and the automotive industries, are defined using trimmed NURBS. The shape of the finished part can be captured by measuring a sufficiently large number of points. Triangulation of those points is a frequent requirement in the analysis of that shape as part of the quality assessment and of the product and manufacturing process development. The paper proposes a new method for efficient and robust triangulation of large sets of unordered three-dimensional points, based on the available CAD model. Unlike many other methods, it is not constrained by certain types of measurement distribution or object shapes. Examples involving real engineering parts are presented, with the conclusion that the method was well suited for the perceived applications in engineering manufacture.
Management system standards: The key integration issues
Authors: Wilkinson G , Dale B G
Published: October 2002

This paper has identified five key issues and four major questions regarding the integration of quality, environmental and occupational health and safety management systems and standards. These issues and questions were tested, using four distinct methods, in order to assess their relevance and to determine their importance. One of the major findings is that what organizations mean by integration depends to a great extent on what they want it to mean. However, if the culture and climate do not match their aims then the resulting integrated management system is likely to be no more than a merging of system documentation. The findings have also revealed two approaches to integration which reflect both the differences in culture and the needs of organizations. They are a merging of the documentation (the aligned approach), and implementation of an integrated management system (IMS) through a total quality approach.
Conditions for the successful implementation of finite capacity/MRPII hybrid control systems
Authors: Petty D J , Stirling M D , Travis L C , Bennett R
Published: October 2002

Manufacturing resource planning II (MRPII) is the most widely employed methodology for production planning and control. Many authors, however, have stated that the fundamental basis of MRPII is flawed: that is to say, scheduling is based on fixed manufacturing lead times/lot sizes with infinite capacity. There has also been great interest in alternative methodologies such as optimized production technology (OPT) which plans to finite capacity. As a result, there are now several software houses who offer finite capacity scheduling (FCS) tools designed to operate alongside MRPII packages. These provide detailed finite capacity planning while retaining the database infrastructure of MRPII. Such hybrids claim to give the benefits of FCS to established MRPII users without the need for re-implementation. This paper describes the operation of such hybrids. Based on a case study drawn from the automotive components industry, it discusses the pitfalls that might be experienced without careful consideration of planning methods in relation to Bill of Material (BOM) structures. In particular, it shows that for a hybrid to be successful, it is necessary to consider the system as a whole, rather than considering FCS as a simple addition to MRPII.
An image-based fast three-dimensional modelling method for virtual manufacturing
Authors: Peng Q , Loftus M
Published: October 2002

This paper focuses on a quick way to extract geometric information from an object and transfer the information into a virtual reality (VR) system. Considering the problems associated with the construction of VR environments, different three-dimensional modelling methods are analysed in this paper, and the authors report an effective methodology to construct virtual manufacturing environments. A three-dimensional surface reconstruction system, based on image analysis, forms a new approach to data acquisition and promises to be a competitive technique for VR applications. This three-dimensional surface reconstruction system integrates the binocular stereo principle and the shape from shading technique. Experimental results are encouraging and the performance of the system has been evaluated by simulation procedures.
Recognition of overlapping machining features based on hybrid artificial intelligent techniques
Authors: Li W D , Ong S K , Nee A Y C
Published: October 2002

A hybrid feature recognition system using feature hints, graph manipulations and artificial neural networks for the recognition of overlapping machining features is presented. Based on the enhanced attributed adjacency graph (EAAG) representation and the virtual link graph (VLG) of a designed part, the face loops (F-loops) are defined as the generalized feature hints. They are then extracted from the EAAG using vector calculations, and the relationships between the F-loops are established. Next, the F-loops are manipulated according to the six types of the relationship between F-loops to build the F-loop subgraphs (FLGs), which are potential features. Finally, these FLGs are presented to a trained artificial neural network using various overlapping feature cases to be classified into different types of feature. By utilizing the characteristics of three intelligent techniques in the different subtasks of the feature recognition process, the system can recognize complex overlapping machining features with planar faces and quadric surfaces efficiently. The system is open and has the capability to recognize new types of overlapping feature from the learning ability of the artificial neural networks.
Assessment of machining features for tool condition monitoring in face milling using an artificial neural network
Authors: Dutta R K , Kiran G , Paul S , Chattopadhyay A B
Published: October 2002

Because of a wide scatter in the tool lives of face milling inserts and limitations of conventional methods for predicting the same, artificial neural systems have become advantageous for their ability to learn input-output mappings. Process parameters coupled with machining responses and experimental observations provide a basis for monitoring the tool wear in face milling. Chip characteristics such as shape and colour together with features of force and vibration are potential candidates for wear prediction in the field of tool condition monitoring.
Finite element simulation of the railway coach shell assembly process
Authors: Kumaran M Senthil , Kumar R Krishna , Sriraman R
Published: October 2002

Thin sheets covering the skeleton of the railway coach shell undergo severe deformations during the manufacturing process. A comprehensive three-dimensional finite element model has been developed to simulate the manufacture of the complete coach shell assembly. The analysis has been extended by varying the camber, the self-weight of the coach shell and the thickness of the side panel sheet, to identify the exact cause for the coach shell deformation. Camber, a positive deflection given intentionally to compensate for the sagging of the coach, is one of the very important design parameters in the manufacture of railway coaches. A three-step analysis is suggested to calculate the correct camber. It has been demonstrated that the camber value arrived at by the conventional method is not accurate and a correction factor is required. The welding of the side panel to the underframe is a crucial determinant of camber. This issue is addressed through a comprehensive finite element analysis.
The development of an active computer vision system for reverse engineering
Authors: Armstrong P J , Antonis J
Published: October 2002

A research project is described on the development of an active computer vision system for automatically producing three-dimensional models of physical objects. The objective is to meet the increasing demand for such models for reverse engineering and computer graphics purposes. The system under development uses a camera mounted on a gantry robot arm to view an object placed on a turntable from any desired angle or position. An occluding contour technique is described which is employed by the system to generate three-dimensional data. Examples are presented of the type of model that the system can produce and current work that will further enhance the performance of the system is reviewed.
Impact strength measurement of spot welds
Authors: Zhang H , Zhou M , Hu S J
Published: October 2002

The impact strength of spot welds is a very important quality index in the automotive industry. However, impact testing is not routinely performed for weld quality testing because of its complexity, cost and relatively low reliability and repeatability. In this paper, the impact strength of steel spot welds was measured using a newly designed impact tester. Besides the impact energy of the welds, detailed impact process characteristics, such as impact force and displacement profiles, which may be important to understanding the impact performance of a weld for vehicle design and analysis, were also recorded. A brief description of the new impact tester and experimental results on welded joints using this device are presented. A sensitivity study of testing results to specimen size has been conducted, prior to experiments on the influence of weld size, shape and orientation on the impact strength of resistance spot-welded joints. Results of impact testing were also compared with those of static tensile shear tests. The correlation between weld attributes and impact performance also provides important information for the quality definition of spot welds. Initial tests using this impact tester show promise that it can be used to measure impact strength of a large variety of welds (spot welded, laser welded, brazed, etc.), and other joints (such as mechanical fasteners and adhesion).
Effects of grain-size gradients on thinning in superplastic gas-blow forming
Authors: Cheong B H , Lin J , Ball A A
Published: October 2002

This paper shows that the mechanical response of superplastic materials is related to their microstructure and that the use of a microstructural gradient approach can improve the evenness in straining during superplastic gas-blow forming. Finite element simulations of the forming process are carried out to investigate the effect of initial grain-size gradients on the non-uniform thinning of a formed structural component.
Turning particulate metal matrix composites: Experimental study of the evolution of the cutting forces, tool wear and workpiece surface roughness with the cutting time
Authors: Davim J P
Published: October 2002

This paper presents an experimental study of the evolution of the cutting forces, tool wear and surface roughness during the turning of the particulate metal matrix composite A356/20/SiCp-T6. The experimental work was developed through the continuous measurement of the cutting forces with an appropriate piezoelectric dynamometer. The wear type was identified and its evolution with cutting time was measured. Inserts with polycrystalline diamond (PCD) were tested. The surface roughness was evaluated with a profilometer.
Temperature case studies in grinding including an inclined heat source model
Authors: Rowe W B
Published: October 2002

Previous analytical models of heat transfer in grinding have been based on the sliding heat source analysed by Jaeger and Carslaw in 1942. It is now shown that for deep grinding processes, and particularly for high efficiency deep grinding (HEDG), the sliding model overestimates the temperatures experienced by the finished workpiece surface. These situations are re-analysed using sliding sources and inclined sources to estimate contact surface temperatures and subsurface temperatures in grinding. Convection in the abrasive contact region to the process fluid, to the grinding wheel and to the chip material removed is taken into account. It is shown that each of these effects can predominate under different process conditions. Case studies illustrate the importance of thermal processes in achieving efficient material removal. The results for HEDG are particularly interesting and suggest that under the right conditions specific energy may be self-limiting. This is offered as a possible explanation for the efficiency of the process.
Exploration of contact conditions in machining
Authors: Ackroyd B , Akcan N S , Chhabra P , Krishnamurthy K , Madhavan V , Chandrasekar S , Compton W D , Farris T N
Published: October 2002

The contact conditions along the tool-chip and tool-work interfaces in the machining of metals are analysed and discussed. The principal experimental techniques used are direct optical measurements of the interfaces at visible and infrared wavelengths using transparent tools, measurements of the variation of forces with flank wear and microstructural changes produced in steel surfaces during machining and perturbation of the tool-chip interface using low-frequency modulation. The application of these techniques has provided new insights into the motion of the chip relative to the tool along the rake face, enabled measurement of the full-field temperature along the rake face and suggested avenues for modifying friction conditions along the tool rake and flank faces. It is shown that important differences as well as similarities exist between the rake face and flank face boundary conditions. The implications of these results for the theoretical analysis of machining are discussed.
Using the grey level histogram to distinguish between roughness of surfaces
Authors: Gadelmawla E S , Koura M M , Maksoud T M A , Elewa I M , Soliman H H
Published: October 2002

In recent years, the advent of high-speed general-purpose digital computers and vision systems has made image analysis easier and more flexible. Images of surfaces captured using vision systems can be used to identify surface texture. In this paper, a new method, called the best grey level histogram (BGLH), is introduced to get the most accurate image of a surface for the purpose of surface texture assessment. A program was written using MS Visual C++ to calculate and display the grey level histogram for any grey image. The software is capable of converting the colour images to grey images. The program is capable of reading six different image file formats; these are BMP, TIFF, GIF, PCX, JPG and WMF. The conversion method depends on calculating three items from the grey levels of the image. These items are the minimum non-zero grey level, the maximum non-zero grey level and the number of used grey levels for the captured image. Many factors affect the quality of the captured image such as the brightness, contrast, saturation and hue. The BGLH method, introduced here, is used to select the best values for these factors to obtain the most accurate image for the surface using vision systems. The BGLH is also used to distinguish between roughness of different surfaces.
An analysis of plastic deformation processes for twist-assisted upset forging of cylindrical billets
Authors: Kim Y H , Park J H , Jin Y E
Published: October 2002

An investigation has been performed into the effect of the die and deformation pattern on twist-assisted upset forging. Rotation of the lower flat die accompanied by axial compression of the punch plays a distinct role in saving axial force. In this study, an upper bound analysis considering bulge formation, finite element method simulations (DEFORM 3D) and experimental research were carried out. A simple kinematically admissible velocity field for three-dimensional deformation is presented for twist-assisted upset forging of a cylindrical billet. An analytical expression for the upset force and torque is obtained from several process parameters. An increase in the friction factor and rotation speed was found to favour decreases in the magnitude of the upset force, dead metal zone and non-homogeneous deformation. Plasticine model experiments were performed where the lower die was rotated against the workpiece using a 5 ton model press.
Investigation of electrodischarge micromachining controllable factors on machined silicon surface quality
Authors: Yeo S H , Nachiappan R
Published: October 2002

Electrodischarge micromachining (micro-EDM) is a prospective technology for the micromachining of conductive and even semi-conductive materials. However, there remain a number of application problems, particularly in relation to the understanding and control of the effect of micro-EDM controllable factor interaction on surface integrity in machining silicon. This study investigates the effect of the interaction of micro-EDM parameters, such as the rotary action of the tool electrode and discharge energy levels, on the surface integrity of a p-type boron-doped silicon wafer. Empirical models are formulated that adequately describe the effects of discharge energy on the average surface roughness and the area fraction voids. Subsequently, the nature and causes of micro-EDM surface and subsurface characteristics are discussed on the basis of scanning electron microscope and X-ray energy dispersive spectrometer analysis. This provides useful information for controlling the input process parameters to obtain smooth finished surfaces.
Development of the continuous shear deformation process
Authors: Utsunomiya H , Saito Y , Suzuki H , Sakai T
Published: October 2002

The equal channel angular extrusion (ECAE) process has been successfully used as an intense straining process to obtain ultrafine-grained metals. However, the process is essentially discontinuous and the productivity is quite low for industrial purposes. The authors have proposed a novel continuous shear deformation process called ‘conshearing’ to solve this problem. This process can also be used as a novel texture control method for long coiled strips by introducing shear textures. In this paper, the principle of the process is described and analysed mechanically. Commercial purity aluminium annealed strips are successfully consheared at room temperature. The whole process is repeated up to four passes. The changes in structure, texture and mechanical properties in the conshearing and in subsequent annealing are investigated. It is found that the r value, i.e. deep drawability, is remarkably improved by the development of shear texture. It is concluded that conshearing is an effective process for texture control as well as for microstructure control.
Dynamic measurement accuracy evaluation of coordinate measuring machines
Authors: Lin S-W
Published: October 2002

The coordinate measuring machine (CMM) is one of the most flexible and versatile inspection machines in the manufacturing industry. Used around the world, the CMM has become a symbol of industrialization. However, there is still no reliable method for evaluating the accuracy of a CMM. The current commonly used method—the static evaluation method—may result in an incorrect assessment owing to the very dynamic nature of the CMM.

In order to evaluate CMM dynamic accuracy, in this paper an error separation method for dynamic measuring data is presented to obtain their accuracy evaluation indices. Referring to international evaluating principles of measurement uncertainty, this method was derived through the analysis of dynamic measuring data and dynamic measuring error. To verify the validity of the proposed method, the dynamic accuracy of a CMM was evaluated and was found to be much better than that of the current static evaluation method.
On precision droplet-based net-form manufacturing technology
Authors: Liu Q , Orme M
Published: October 2002

High-precision droplet-based net-form manufacturing of structural components is gaining considerable academic and industrial interest owing to the promise of improved component quality resulting from rapid solidification processing and the economic benefits associated with fabricating a structural component in one integrated operation. A droplet-based net-form manufacturing technique is under development by the authors which is termed precision droplet-based net-form manufacturing (PDM). As the technique exploits the capillary instability phenomenon of liquid jets for producing uniform liquid metal droplets, it allows for a greater control of the thermal state and mass flux of the droplets and thus the microstructure of the deposit can be readily tailored. The principle and the associated technical issues are described and discussed in detail in this paper. Recent progress in the development of PDM is also presented. The preliminary results demonstrated the following four important facts: (a) molten aluminium droplet streams can be generated on a repeatable basis and travel 50.0cm in an inert environment with little degradation in stream stability, (b) components of significant size can be fabricated (i.e. the horizontal square tube is 11.0cm in height), (c) fully dense components can be fabricated with no post-treatment and (d) measured hardness is consistently higher than the raw stock.
Intelligent control of fibre optic components assembly
Authors: Pham D T , Castellani M
Published: October 2002

This paper presents an ‘intelligent’ automatic alignment system for use in the assembly of optical fibre components. The system optimizes the light output from a fibre by applying a gradient-based algorithm enhanced with momentum information. The algorithm parameters are adjusted on-line by a fuzzy controller according to the progress of the alignment process. Using past experience, a neuron-like element directs the starting point of the search for the optimum alignment towards the most favourable position. The automatic alignment system yielded 100 per cent success in a test involving 100 different samples of components. The system achieved significant reductions in alignment times compared with manual or conventional automatic methods. The system was also almost twice as fast as an alternative based on simulated annealing. Moreover, the use of fuzzy logic facilitated the design of the controller and provided noise rejection capabilities.
Mathematical modelling of geometric tolerance propagation, considering effects of datums
Authors: Park S , Lee K
Published: October 2002

Every mechanical part is fabricated with variations in size and shape in the real world. Thus, tolerances are assigned to specify the tolerance zone corresponding to the allowable range of variation in the design shape within which the entire shape element must lie after the manufacturing process. Geometric tolerances constrain the size and the thickness of an individual shape element or its relative position and orientation with respect to the related datums. The effect of the tolerances given to the datums should be propagated to the orientation and the location tolerances in the proper order of precedence. This paper proposes a mathematical foundation for representing the propagation of geometric tolerances while considering the order of precedence of the datums. The effect caused by the tolerances of the datum can also be mathematically handled while considering the datum order of precedence.
A study of an arc sensor model for gas metal arc welding with rotating arc Part 1: Dynamic simulation of wire melting
Authors: Kim G-H , Na S-J
Published: October 2002

A dynamic wire melting phenomenon is found in rotating arc welding since self-regulation of the arc length is not fully performed. Consequently welding current and electrode extension vary rapidly in high speed rotating arc operation. This paper presents the dynamic simulation of wire melting by using the variable space network method and by modelling the heat flux from the molten end of the wire into the electrode. The simulations are compared with experimental results from other references to show a fairly good agreement. By using simulation analyses, it is clarified how the characteristics of the welding power source affect the sensitivity of the arc sensor.
Improving wheel—workpiece contact detection using a hybrid neural network
Authors: Maksoud T M A , Ahmed M R , Koura M
Published: October 2002

Eliminating the gap between the grinding wheel and workpiece is a major time-wasting step during grinding operations. Reducing the time of this step has attracted many investigations. Several researchers have investigated the variation in some process parameters during the wheel-workpiece contact. These parameters include grinding force, grinding power and acoustic emission. During the approach of the grinding wheel to the workpiece, there are three primary stages which have an effect on these parameters: hydrodynamic stage, grit contact stage and wheel contact stage. A few researchers introduced a method to identify the start of the wheel contact stage, which is the practical contact stage. Most of these methods depend on predefined threshold values for some measured parameters. This paper introduces a new methodology to identify the wheel-workpiece contact event in surface grinding operations. A hybrid neural network with supervised learning is used to extract the contact event from the measured parameters. It consists of two neural nets. The first is a self-organizing map neural network with unsupervised learning and the second is a feedforward neural network with supervised learning. Using this hybrid network produces first self-organized clusters for the input data at the first network and then the second network recognizes these clusters. This results in the detection and classification of the contact events automatically from the measured data. This presents a very important step towards the full control of grinding operations in a computer numerically controlled (CNC) environment.
Micromachining of assembled liquid crystal displays
Authors: Yeo S H , Tan E C
Published: October 2002

Lasers have come into wide use for the repair of liquid crystal displays (LCDs). As displays have become larger, more complex and thus increasingly more expensive, repair has become indispensable. Lasers are used to remove the ‘short’ (unwanted materials) as a form of laser repair. Currently, there are many lasers being used for this application, but they are not able to perform the process efficiently. Green yttrium aluminium garnet (YAG) and xenon lasers are not capable of removing indium tin oxide (ITO) in thin-film transistor (TFT) LCDs. Excimer lasers are capable of removing the ITO, but due to their opacity to glass substrates, the removal of the materials is not possible once the LCD is assembled. Therefore, there is a need to study another laser-based micromachining technique to remove the ITO in the assembled LCD.

With the unique features of the ultrafast lasers, the femtosecond laser is introduced in this work to perform micromachining of ITO in the assembled LCD. The results clearly show that a femtosecond laser beam is able to penetrate through the glass substrate and polarizer to remove the ITO without damaging the LCD panel.
Web-based metal forming advisory system for the finite element analysis of sheet metal bending
Authors: Ling Y E , Lee H P , Cheok B T
Published: October 2002

In the metal stamping industry, one of the major problems is getting the sheet metal to conform exactly to the shape of the die. Because of the effects of springback, die designs are usually finalized only after the fabrication and testing of multiple prototypes. The design of a die for a given part may undergo many iterations in the debugging stage before a satisfactory geometry is obtained. In order to reduce time spent on such manual corrections of the die, a parametric study is conducted on how the inclusion of a step in the die may reduce springback. The results provide a better understanding of how certain die parameters affect springback. In addition, a Web-based advisory system is developed to enable a user to study bending of sheet metal using finite element analysis. Through the system, the user may conduct simulations on line, retrieve results or search for die configurations from a database of numerical results that have been computed earlier. The intricate details of finite element analysis, such as mesh generation and refinement, or the finite element software itself, remain transparent to the user, who may not be a specialist in this field.
Dynamic stiffness evaluation for reconfigurable machine tools including weakly non-linear joint characteristics
Authors: Yigit A S , Ulsoy A G
Published: October 2002

A systematic procedure is proposed to evaluate the dynamic characteristics of design alternatives for a reconfigurable machine tool (RMT). The procedure is intended to be used in an automated design environment where various design alternatives are generated by kinematic synthesis based on a given task and specification. The evaluation procedure makes use of a substructuring method called non-linear receptance coupling. The coupling method includes the effects of weakly non-linear compliant joints through the use of describing functions for the non-linearities involved. Experimental data obtained from a prototype RMT are used to show the validity of the coupling method. To demonstrate the utility of the proposed evaluation procedure design alternatives are generated based on a lumped parameter model of the RMT and examined with respect to the proposed criteria. It is shown that joint non-linearities may affect dynamic stiffness considerably. It is also shown that the suggested criteria can distinguish various design alternatives with respect to their expected dynamic behaviour.
Temporary network of enterprises: Managing complexity by a multi-agent architecture
Authors: Villa A
Published: October 2002

Present evolution of manufacturing systems is characterized by multi-firm enterprises, often organized in multi-site networks where each firm can be managed with large autonomy. As the system complexity and the number of local decision makers grow, the uncertainty of the production management seems to grow also. This paper first aims to verify whether the increasing complexity of actual manufacturing systems is going to allow an increasingly greater autonomy to local decision makers (also called ‘agents’). The scope is to show when and how local decentralized decision makers could apply efficient controls without degrading global efficiency. Then, taking into account that the final aim of an enterprise is profit, a positive relation between global system efficiency and local agents autonomy is proved.
Uniaxial compression tests of aluminium foams
Authors: Haag F C , Galio A F , Schaeffer L
Published: October 2002

Some cellular aluminium materials have been extensively developed and investigated in recent years. The potential for applying aluminium foams in lightweight construction is mainly based on the stiffness and impact absorption. Because of these characteristics, this work is based mainly on the uniaxial compression resistance of aluminium foam. The aluminium foam was formed with three different compaction presses to verify the influence on density and, subsequently, crushing resistance.
Development of the machining producibility evaluation method: Quantitative machining producibility evaluation for various processes
Authors: Ohashi T , Arimoto S , Miyakawa S
Published: October 2002

The machining producibility evaluation model (MEM) was developed to assess design quality quantitatively for easier processing of parts and products. It is constructed on the basis of product and process modelling and covers cutting and grinding, metal working, welding, moulding, die-casting and casting. The main features of the MEM are

Quantitative evaluation is carried out by means of an easy-to-understand 100-point scale, and processing cost is estimated within a ±15 per cent error. It is an easy method to both learn and use, employing approximately 20 basic symbols and five supplementary elements.

This paper provides a description of the theory, the evaluation procedure and the accuracy of the method, and gives application examples.
Image synthesis methodology for algorithm testing and vision system design
Authors: Parker J M , Lee K-M
Published: October 2002

Although it is well-recognized and widely accepted that vision adds considerable flexibility, and it has also been shown that numerical simulation can aid in image understanding and vision system design (significantly reducing the engineering time to design and implement such systems), the utilization of image synthesis as an aid in algorithm and system design still remains a largely underexplored area. In machine vision applications, accuracy of the image generally outweighs image appearance. Unfortunately, the focus of most commercially available simulation methods is on photorealistic image synthesis; this is insufficient to design vision systems or evaluate and compare image-processing algorithms for part-presentation tasks: physically accurate, rather than photo-realistic, synthesis methods are necessary to sufficiently simulate captured image grey-scale values.

This paper presents a methodology to generate physically accurate synthetic images efficiently in order to provide an accurate, flexible and practical means of evaluating the performance of image-processing algorithms for numerous hardware/software configuration combinations and a wide range of parts. While the synthesis methodology cannot fully compensate for the real environment, it can be used efficiently to study the effects of vision system design parameters on image accuracy. This provides an insight into the efficacy of the design and the ability of suggested image-processing algorithms to perform adequately for specific applications; furthermore, it may provide a means for correcting apparent errors in image-processing results.
Tool path error prediction of a five-axis machine tool with geometric errors
Authors: Mir Y A , Mayer J R R , Fortin C
Published: October 2002

Predicting the actual tool path of a machine tool prior to machining a part provides useful data in order to ensure or improve the dimensional accuracy of the part. The actual tool path can be estimated by accounting for the effect of the machine tool geometric error parameters. In computer aided design/computer aided manufacture (CAD/CAM) systems, the nominal tool path [or CL (cutter location) data] is directly generated from the curves and surfaces to be machined and the errors of the machine tool are not considered. In order to take these errors into consideration, they must first be identified and then used in the machine tool forward kinematic model. In this paper a method is presented to identify the geometric errors of machine tools and predict their effect on the tool-tip position. Both the link errors (position-independent geometric error parameters) and the motion errors (position-dependent geometric error parameters) are considered. The nominal and predicted tool paths are compared and an assessment is made of the resulting surfaces with respect to the desired part profile tolerance. A methodology is also suggested to integrate this tool within a CAD/CAPP (computer aided process planning)/CAM environment.
Optimal blank shape design by the iterative sensitivity method
Authors: Shim H , Son K
Published: October 2002

In order to realize net shape manufacturing of drawn parts, determination of the optimal blank shape plays a key role in the process development stage. The sensitivity method has many successful applications of the optimal blank design. In the method, the undeformed blank shape is modified iteratively by moving boundary nodes in the initial moving direction until the deformed shape satisfies a target shape. To determine the magnitude of the movement of the nodes, both the shape error measured at the deformed shape and the shape sensitivity defined by the effect of initial shape change on the final shape are utilized. To obtain shape sensitivity for each boundary node numerically, a couple of deformation processes has been analysed at each design stage with an original blank and offset blank. Drawings of the trapezoidal cup, cross-shaped cup and oil pan have been chosen as examples to verify the sensitivity method. Both the cross-shaped cup and oil pan are examples of complicated material flow during forming while the trapezoidal cup is of a simple flow. For every case the optimal blank shape has been obtained after only a few modifications without any predetermined deformation path. With the predicted optimal blank, a corresponding experiment has been carried out. The deformed shapes of the experiment almost exactly coincide with the desired target shape in every case. Through the investigation, the sensitivity method is found to be excellent in the blank design of arbitrary shaped drawing products.
A design to cost system for innovative product development
Authors: Shehab E M , Abdalla H S
Published: October 2002

This research paper presents a prototype object-oriented and rule-based system for product cost modelling and design for automation at an early design stage. The developed system comprises a computer aided design (CAD) solid modelling system, a material selection module, a knowledge-based system (KBS), a process optimization module, a design for assembly module, a cost estimation module and a user interface. The system development process has passed through four major steps: constructing the knowledge-based and process optimization system; developing a design for assembly module; integrating the KBS with both a material selection database and the CAD system; developing and implementing a fuzzy logic approach to generate reliable estimation of cost and to handle the uncertainty in the cost estimation model that cannot be addressed by traditional analytical methods. Two manufacturing processes, namely machining and injection moulding processes, were considered in the developed system.

The main function of the system, besides estimating the product cost, is to generate initial process planning, including the generation and selection of machining processes, their sequence and their machining parameters, and to recommend the most economical assembly technique for a product and provide design improvement suggestions based on a design feasibility technique. In addition, a feature-by-feature cost estimation report is generated using the proposed system to highlight the features of high manufacturing cost. Two case studies were used to validate the developed system.
Managing safety and strategic stocks to improve materials requirements planning performance
Authors: Caridi M , Cigolini R
Published: October 2002

This paper provides a methodology for managing safety and strategic stocks in materials requirements planning (MRP) environments to face uncertainty in market demand. A set of recommended guidelines suggest where to position, how to dimension and when to replenish both safety and strategic stocks. Trade-offs between stock positioning and dimensioning and between stock positioning and replenishment order triggering are outlined. The study reveals also that most of the decisions are system specific, so that they should be evaluated in a quantitative manner through simulation. A case study is reported, where the benefits from adopting the new proposed methodology lie in achieving the target service level even under peak demand conditions, with the value of safety stocks as a whole growing only by about 20 per cent.
On-line wear estimation using neural networks
Authors: Ghasempoor A , Moore T N , Jeswiet J
Published: October 2002

In this paper, a neural network based system for ‘on-line’ estimation of tool wear in turning operations is introduced. The system monitors the cutting force components and extracts the tool wear information from the changes occurring over the cutting process. A hierarchical structure using multilayered feedforward static and dynamic neural networks is used as a specialized subsystem, for each wear component to be monitored. These subsystems share information about the tool wear components they are monitoring and their error in estimating the cutting force components is used to update the dynamic neural networks. The adaptability property of neural networks ensures that changes in machining parameters can be accommodated. Simulation studies are undertaken using experimental data available from manufacturing literature. The results are promising and show good estimation ability.