bluuebunny/crossref_metadata_2025 huggingface dataset:
Parameters optimization for the generation of a keyhole weld pool during the start-up segment in variable-polarity plasma arc welding of aluminium alloys
Authors: Zheng B , Wang Q I , Kovacevic R
Published: October 2002

Stable weld formation is still one of the goals pursued in variable-polarity plasma arc welding (VPPAW) of aluminium alloys. Basically, VPPAW is divided into three segments: The start-up segment, during which the keyhole is generated, the main body segment, during which the keyhole is dynamically maintained, and the terminal segment, during which the keyhole collapses and the crater is filled. Very often, a smooth transition cannot be made from the start-up segment to the main body segment, and the weld easily fails because the keyhole weld pool is not properly generated. This paper explores four different combinations of plasma gas and welding current for generating a smooth transition from the start-up segment to the main body segment in VPPAW. The keyhole weld pool is categorized as one of three types: heat conduction mode, strong force mode or heat and force mode. The heat and force mode of the keyhole weld pool can be generated by raising the gas flowrate, raising the current or by raising both the gas and current. An increase in the plasma gas flowrate accompanied with an increase in the welding current is the best combination for generating a smooth transition during the start-up segment, which results in only a few double arcs and no short circuiting between the nozzle and the workpiece. The quality of the initial weld bead can be guaranteed using this approach.
Intelligent product manuals
Authors: Pham D T , Dimov S S , Peat B J
Published: October 2002

Intelligent product manuals are designed to allow product users to utilize a product as easily, effectively and with as little additional care as possible while minimizing support costs for manufacturers and suppliers. It is first shown how intelligent product manuals address these objectives by utilizing electronic, multimedia and knowledge-based technologies to provide active assistance to the user of the product during tasks such as installation, operation and maintenance. An architecture for the creation and deployment of an intelligent product manual is then proposed and general design considerations are outlined. Finally, four implementation approaches, based on XML, SGML, HTML and PDF technologies, are compared against a set of selection criteria. It is concluded that simple, low-cost solutions are available, which can provide significant benefits for appropriate businesses, including smaller companies.
Wavelet analysis of acoustic emission signals in boring
Authors: Li X , Wu J
Published: October 2002

Using acoustic emission (AE) signals to monitor tool wear states is one of the most effective methods used in metal cutting processes. As AE signals contain information on cutting processes, the problem of how to extract the features related to tool wear states from these signals needs to be solved. In this paper, a wavelet packet transform (WPT) method is used to decompose continuous AE signals during cutting; then the features related to tool wear states are extracted from decomposed AE signals. Experimental results verified the feasibility of using the WPT method to extract features related to tool wear states in boring.
Control of chip flow direction in high-pressure water jet-assisted orthogonal tube turning
Authors: Kaminski J , Ljungkrona O , Crafoord R , Lagerberg S
Published: October 2002

This paper shows the possibility of controlling the chip side-flow direction in water jet-assisted turning using flat-faced inserts without any chip formers. The experiments were performed under orthogonal cutting conditions of an end of a pipe with plain water jet assistance with a pressure up to 80 MPa and a flow up to 81/min. The jet was directed perpendicular to the cutting edge into the tool/chip interface. Experimental results show that the chip side-curl radius can be successfully controlled. A correlation between the jet momentum, jet diameter and side-curl radius is presented and widely discussed.
Surface alignment based on the moment of inertia and improved least-squares methods
Authors: Esat I I , Bahai H
Published: October 2002

As part of dimensional inspection and error analysis of components it is usually required to place the component in a fixture where its position can be related to its computer aided design (CAD) nominal coordinate axis and the coordinate frame of the measuring system. The fixturing can be expensive and does not completely eliminate the mathematical matching needed between measured and nominal surfaces.

Least-squares minimization is one of the most common methods employed in achieving the required alignment. This method, however, works only if the misalignment between two data sets is very small. Furthermore, there is no measure to establish whether this method is likely to converge or not before performing the actual iteration. The requirement for a small angle implies that this method is only suitable if fixturing is also used.

The other technique used in obtaining alignment is by consideration of the mass properties of surfaces. This method is more effective and works irrespective of the degree of alignment. The problem with the mass property approach is that its accuracy diminishes when the error is small.

This paper compares the two methods and demonstrates that both the r. m.s. minimization and the mass property methods can be expressed as eigenvalue problems, and both approaches produce identical eigenvectors despite having different eigenvalues (error measurements). A method is proposed to determine whether convergence is expected in the least-squares minimization at the first step of iteration. The proposed method may be used for accelerating the convergence operation.
Policy deployment: Modelling the CRISP process
Authors: Lee R G , Dale B G
Published: October 2002

This paper opens by making the point that there is little academic literature on policy deployment. Also highlighted are the different interpretations which Western writers place on policy deployment issues such as plans, targets, means, deployment and feedback and some of the interpretations fail to grasp some of the fundamentals of the process. It then goes on to describe a generic catch, reflect, improve, scrutinize and pass (CRISP) approach to policy deployment, based on the plan-do-check-act (PDCA) cycle, which it is claimed will enable an organization to deploy more effectively its vision, missions, goals, objectives, targets and means. It is also pointed out that more organizations should be using policy deployment to help to ensure that their continuous improvement activities are effective.
Improved positioning of a conical mill for machining ruled surfaces: Application to turbine blades
Authors: Monies F , Redonnet J-M , Rubio W , Lagarrigue P
Published: October 2002

For this short communication, side milling ruled surfaces using a conical milling cutter is studied. Conical mill machining is a field that has largely been ignored by research scientists but it is much used in industry especially to machine turbine blades. In this study, an ‘optimum’ positioning to respect the directrices of the ruled surface is suggested. In comparison with the methods already developed for the cylindrical tool, this positioning also enables interference between the milling cutter and the workpiece to be reduced. The work led to a development project for a computer aided manufacturing program in co-operation with the Sapex-Profor Company.
Collaborative virtual cutting verification and remote robot machining through the Internet
Authors: Lee R-S , Tsai J-P , Lee J-N , Kao Y-C , Lin G C I , Lu T-F
Published: October 2002

This paper presents the development of an international collaborative virtual multi-axis cutting verification system and the framework of a remote dual-robot machining system between the Centre for Advanced Manufacturing Research (CAMR), University of South Australia (UniSA), in Australia, and the Metal Forming Laboratory, (MFL) of the National Cheng Kung University (NCKU), in Taiwan, to establish computer-supported cooperative work (CSCW) through the Internet. Multi-media tools such as text, audio, images and a videoconference system are used to facilitate the communication between geographically distributed engineers. A remote control software is adopted in NCKU to remote control the dual-robot machining system in UniSA; it is also used to facilitate collaborative discussion on multi-axis cutting verification between Taiwan and Australia. A preliminary network analysis and evaluation is also achieved to serve as a reference prior to the execution of remote control. Several case studies for various connection types between campuses, universities and continents were tested through the Internet.
Continuous wave-CO2 laser power control process applied to welding
Authors: Deprez P , Vantomme P , Coutouly J F , Deffontaine A , Ramiere J F
Published: October 2002

The continuous control of the laser power during the welding operation would avert welding defects linked with objects in the optical path (dust) or with slow deterioration in the optical components. The use of a partially reflecting slide with a high reflection coefficient permitted the measurement of power variations of ±0.5 per cent during the welding process. Analysis of the signal obtained would allow a closed-loop power regulation by feedback to the laser power command input. To be suitable for short-duration laser welds, it would be necessary to lower the response time by using faster power detectors.
Estimation of the synthetic dynamic accuracy of the die and the press by considering the eccentric load in blanking
Authors: Sekine F
Published: October 2002

Manufacturing accuracy is ultimately decided by the synthetic dynamic accuracy of the die and the press in press working. In particular, blanking accuracy is determined by the relative mismatch of the upper die to the lower die in blanking. In this research, deformation of a die set and a press subjected to an eccentric load is analysed. Here, the moment of rotations M and the lateral force Q acting on the boundary between the upper die and the press slide are thought to be expressed by the inclination, Q, and the lateral displacement, Dx, of the upper die. In the blanking experiment, a die set is installed on a 600kN high-precision straight-sided press, and Q and Dx are measured under a dynamic eccentric loading of 50–600stroke/min. Then, estimation of the synthetic dynamic accuracy of the press and the die is examined. The effect of the stiffness of the press is discussed.

The analytical method proposed in this paper can be used in the selection of a press suitable for a given die set and an eccentric load. In precise press working, the selection of the optimum combination of die and press to make the lateral displacement of the punch as small as possible is facilitated by considering the above-mentioned conditions.
Correlation of cutting force features with tool wear in a metal turning operation
Authors: Snr D E Dimla
Published: October 2002

Interrupted turning has been conducted and the cutting forces recorded on-line while measurements of the cutting tool wear forms were made. The acquired data were analysed in the time and frequency domain for cutting tool wear correlation. The method employed was geared towards developing an understanding of the spectra energy content of the dynamic cutting force signals and how it could be used as an input sensor signal in the development of a tool wear monitoring system. Analysis of the data indicated that the spectra energy content correlated well with the measured tool wear at certain frequencies.
Evaluation of straightness and flatness using a hybrid approach—genetic algorithms and the geometric characterization method
Authors: Liu C-H , Chen C-K , Jywe W-Y
Published: October 2002

A heuristic approach is presented in this paper for efficient evaluation of exact straightness and flatness values using a hybrid approach combining genetic algorithms (GAs) with the geometric characterization method. The procedure of the hybrid approach begins with the evolution of GAs, and then the geometric characterization method, based on minimum zone criteria, is inserted into the process to improve the speed of convergence of the GAs. Numerical results indicate that the hybrid approach provides better accuracy and efficiency.
Using human line-of-sight to control equipment
Authors: Nishiuchi N , Kurihara K , Sakai S , Takada H
Published: October 2002

The human-machine interface is an important factor in computer systems. It is thought that line-of-sight (LOS) detection technology will allow significant advances in this field. The current study is intended to be a step in that direction. Two processes were established to fulfil the plan of this study. In process 1, a non-contact LOS detection method was developed that is able to be used freely and naturally using image processing. Markers or equipment worn by the user are no longer needed to detect LOS. In process 2, the new detection method was applied in developing an ON/OFF control equipment system using human LOS. Two key points are that the user is able to move freely and naturally and that only LOS is required to operate these systems.
Computer aided design of high-performance grinding tools
Authors: Jackson M J , Barlow N , Hon K K B
Published: October 2002

This paper considers computer aided design of high-performance cylindrical grinding wheels. The finite element method has been used as the numerical tool to examine the influence of geometric shape and size of abrasive elements on the safe design of high-speed grinding tools. Conventional cylindrical grinding wheels are limited to low peripheral speeds due to the strength of the abrasive body. By replacing the centre section of the wheel with a stronger material and bonding abrasive segments to it, it is shown that a substantial increase in maximum operating speed is possible while maintaining the required margin of safety. Optimization of the number and size of abrasive segments is considered as well as the material used for the reinforcing centre section. A new concept wheel is also presented that is used to increase the maximum operating speed even further.
A test rig for kite performance measurement
Authors: Alexander K , Stevenson J
Published: October 2002

Kite design has recently seen a revival as a result of the development of sports such as kite buggying and kite surfing. As a result, kites and their accessories have become significant business opportunities in many countries. Since the aerodynamics of kites has not been explored in much depth, research has been started to support a local kite development company. A key instrument in this research programme is a vehicle-mounted test rig, designed to measure the performance characteristics of two-line and four-line kites. This paper outlines the requirements, describes the design and operation and gives some results from the test rig. Future developments are discussed.
Process model based development of disassembly tools
Authors: Rebafka U , Seliger G , Stenzel A , Zuo B R
Published: October 2002

Disassembly processes require flexible tools for loosening and handling operations. Today, disassembly processes demand a great deal of manual labour and a vast variety of tools. Partly destructive tools which generate and use new acting surfaces are able to increase the economic viability owing to their flexibility and their promotion of the reuse of components. This article describes selected methods of acting surface generation and their application for prototypical tools.
Flexible disassembly systems-layouts and modules for processing obsolete products
Authors: Wiendahl H-P , Scholz-Reiter B , Bürkner S , Scharke H
Published: October 2002

Currently, a significant amount of worldwide research is dedicated to manual or automated disassembly. This field of application has progressed remarkably over the past few years because industry has been forced to consider new technologies for processing electronic waste. This is due to changing environmental legislation, increasing amounts of obsolete appliances, decreasing landfill space and a growing public awareness of environmental problems. These considerations lead to growing research, development and implementation of manual and automated disassembly systems which are able to process a wide range of obsolete electronic appliances.

The present paper investigates different prototypes of manual and automated disassembly cells at disassembly companies and research institutes. The approach, technology and architecture of these systems are described. Typical hardware components of flexible disassembly systems are then identified and explained. Furthermore, suggestions are made for modularization and standardization of these components, even if only at a very cursory level.
Eco-indicators in product development
Authors: Persson J-G
Published: October 2002

Industrial experience shows that many current eco-design methods, such as life cycle assessment (LCA), are very complex and cannot easily be used by designers. Such methods are primarily useful during detail design, when major design decisions have already been taken. Simplified, easy-to-use methods and tools for designers, such as eco-indicators, to be used during early design phases in product concept development, are therefore being developed. Examples of simple eco-indicators are recycling quotas, energy consumption, amount of material used and waste produced. Company-, business area- or product family-specific eco-indicators could be derived, using aggregations of commercially available and company-specific LCA data, combined with product user profiles and production process data. Irrelevant data can then be omitted. The reuse of eco-indicators should be justified in evolutionary product development, characterized by marginal improvements. The range of application and validity has to be specified carefully though. A generalized and simple set of eco-indicators would not be possible. Indicators for design should be defined for a specific purpose and several aspects must be considered. In this paper, a structured overview of various types of eco-indicator will be presented, in order to guide management, designers and other stakeholders in the selection of suitable eco-indicators to be used in product development.
Rough pocketing of multi-sculptured surface cavities
Authors: Vafaeesefat A , ElMaraghy H A
Published: October 2002

An algorithm for rough machining of multi-sculptured surfaces on milling machines is presented. The boundary contours are first created by decomposing the sculptured surfaces into a number of parallel cutting layers. These contours are defined using the Z buffer map created from the parallel projection of the triangles that approximate the surfaces. A set of offset curves is then generated inside the boundaries in each layer based on the proposed minimum distance approach. This algorithm efficiently creates boundary contours and inherently prevents the problem of loops, shocks and self-intersections that usually occur during the offset curve generation. One notable advantage of the proposed method is that the tool path generation is independent of the method used for surface description.
Agile manufacturing: A management and operational framework
Authors: Sharifi H , Colquhoun G , Barclay I , Dann Z
Published: October 2002

Manufacturing companies are now operating in fast-moving commercial environments where unanticipated threats and opportunities are the order of the day. Agile manufacturing in such environments means understanding the environment and being flexible, cost effective and productive with consistent high quality. Each company will respond in a different way to deploy its own agile characteristics. This paper describes research that tackles the problem of identifying what characteristics constitute agile manufacture and proposes a framework for evaluating and developing agile manufacturing. Manufacturing enterprises involve people, organization, technology, processes and information, and no commonly accepted practical reference framework exists to investigate, analyse and evaluate the ability to deal with change. The research is based on a wide-ranging review of agile manufacture and manufacturing architectures. From this review, a conceptual agile manufacturing model was developed and used in a study of 18 manufacturing companies. Subsequently, a framework for analysing and developing a company's agile characteristics is described. The paper concludes by discussing three case studies in detail and proposing the key characteristics of agile manufacturing.
Authoring environment for documentation development
Authors: Pham D T , Setchi R M
Published: October 2002

This paper presents a concurrent engineering (CE) approach to the authoring of technical documentation. This approach focuses on the development of a virtual environment (VE) for collaborative authoring that enables sharing and reuse of all available information sources during product and documentation development. The paper describes a VE for collaborative authoring using a product data management (PDM) system created to demonstrate the proposed approach.
Tool wear and surface integrity during high-speed turning of hardened steel with polycrystalline cubic boron nitride tools
Authors: Kishawy H A , Elbestawi M A
Published: October 2002

This paper examines the tool wear characteristics and surface integrity during high-speed turning of D2 tool steel. The effects of different process parameters, including tool wear and edge preparation, on the surface and subsurface damage were examined using a scanning electron microscope (SEM). Modes of tool wear were investigated under different cutting conditions. The X-ray diffraction technique was also employed to measure the residual stress distributions beneath the machined surface. Various forms of surface damage were observed under different cutting conditions. A wide range of residual stress distributions beneath the machined surface were obtained depending on the cutting conditions and edge preparation. The unfavourable tensile residual stresses were minimized at high cutting speeds and high depths of cut. This reveals the possibility of optimizing the cutting conditions for favourable residual stresses.
A novel eccentric lapping machine for finishing advanced ceramic balls
Authors: Kang J , Hadfield M
Published: October 2002

Advanced ceramic balls are used extensively in hybrid precision ball bearings and show advantages in high speed, high temperature, high load and hostile environment. Finishing these balls with high quality, good efficiency and low cost is critical to their widespread application. A brief review of the methods for finishing ceramic balls is presented. The design of a novel eccentric lapping machine for finishing advanced ceramic balls is described. The kinematics of eccentric lapping is analysed and discussed, the symbolic expressions for the ball spin angular speed, ωc, ball spin angle, β, and ball circulation angular speed, ωc, are derived and numerical solutions are plotted. Two kinds of hot isostatically pressed (HIPed) silicon nitride ball blanks (13.25–13.50mm in diameter) were lapped and polished to 12.700 mm using this machine. A maximum material removal rate of 68 μm/h was achieved at the lapping step, which is much higher than by the traditional concentric lapping method. The polished ball surface roughness, Ra, value is 0.003 μm, and the ball roundness is 0.08–0.09 μm, which is above grade 5 and close to grade 3 of the precision bearing ball specification. This machine can be used as a prototype to develop a larger-scale machine for production.
Contact probe radius compensation using computer aided design models
Authors: Ristic M , Ainsworth I , Brujic D
Published: October 2002

Probe radius compensation is necessary in metrology applications that employ contact probes, but it can be a significant source of systematic measurement errors when dealing with free-form part geometry. The paper presents implementation and performance analysis of a proposed new compensation technique based on the nominal computer aided design (CAD) model, which is assumed to be defined using non-uniform rational B-splines (NURBS). Errors associated with the conventional compensation approach are assessed on the basis of experiments using a modern coordinate measuring machine (CMM), providing clear motivation for this work. The proposed method consists of a number of steps, including measurement, generation of offset nominal surfaces, registration, surface fitting, data smoothing and calculation of compensating offsets. Critical steps include registration and NURBS surface fitting and their implementation is presented. Simulation studies are used to analyse the registration accuracy and the accuracy of the overall method in comparison with the conventional one. The proposed method is shown to produce superior results in situations involving non-uniform measurement distribution, measurement noise, free-form geometry with no clear datums, deformation relative to the nominal shape and component misalignment.
Task sequence optimization for a dual-robot assembly system using evolutionary algorithms
Authors: Park J-H , Ryu S-H
Published: October 2002

For the purpose of improving assembly task productivity, a multirobot assembly system has been introduced. In this system, multirobots operate simultaneously and transfer parts from the part feeders to the printed circuit boards (PCBs) moving at a constant speed on the conveyor line. To exploit the capacity of this system to the full, the system should be set up with an optimal conveyor line speed and each robot should be operated along a proper assembly sequence. In this paper, a dual-robot assembly system is considered, and an efficient algorithm for concurrent optimization of conveyor line speed and assembly sequence is developed. Various evolution algorithms are tried as an optimization method, and, based on the results, the optimal conveyor line speed and assembly sequence are obtained. When using the optimized conveyor line speed and assembly sequence, the operation time can be reduced by up to 22.8 per cent compared with the initial set-up.
Investigation into a new incremental forming process using an adjustable punch set for the manufacture of a doubly curved sheet metal
Authors: Yoon S J , Yang D Y
Published: October 2002

For flexible manufacture of a doubly curved sheet metal, a new sheet metal forming process is proposed that uses a movable punch set composed of two pairs of lower support punches and one upper centre punch. The process is characterized by flexibility compared with the existing conventional processes because it does not require any complex-shaped die and the loss of material is minimized by unconstrained forming. The process involves very little thickness. strain by applying the principle of bending deformation instead of stretching. In the preliminary finite element method (FEM) simulation it is found that the curvature of the formed sheet metal is determined by the distance between the supporting punches working in pairs and the forming depth of the centre punch. In the experiments using sheets of aluminium, a method with edge forming is proposed for producing sheet metal in the desired shape. The equation using process variables such as the distance between supporting punches in pairs and the forming depth of the centre punch is proposed for the prediction of curvature of the formed shape. The equation is revised by the experimental results and the FEM simulation results containing springback information. It is then shown that the radius of curvature for the formed sheet metal can be predicted by the revised equation unless a very large amount of springback occurs.
Concurrent modelling of components and realization systems to support proactive design for manufacture/assembly
Authors: Yan X-T , Borg J C , Juster N P
Published: October 2002

Increasing market pressure is forcing manufacturing companies to improve product lead times and quality at reduced cost. An important approach aimed at tackling these problems is to generate manufacturing/assembly system models concurrently with the design solutions of a component. A designer can therefore make product design decisions while having access to, and interacting with, the evolving ‘virtual’ manufacturing system models. This allows designers to foresee any potential manufacturing problems caused by design decisions. This paper presents an approach that proactively supports designers in making informed design decisions, through the timely revelation of knowledge about manufacturing and assembly processes. Such knowledge, when provided early in the design process, allows designers to avoid negative implications and to use positive ones. Based on this approach, a knowledge-intensive computer aided design (KICAD) prototype tool, named FORESEE, has been developed. FORESEE is a proof-of-concept system and allows designers to foresee and explore manufacturing and assembly consequences caused by design decisions, as the design of a mechanical component evolves. The paper presents an outline of the KICAD approach, together with a brief description of FORESEE's architecture and implementation. The application of FORESEE is demonstrated through a thermoplastic component design case study. FORESEE has been evaluated by practising designers. Evaluation results indicate that the approach has the potential proactively to support component design.
Indicators for performance measurement in small and medium-sized enterprises
Authors: Hvolby H-H , Thorstenson A
Published: October 2002

In small and medium-sized enterprises (SMEs), resources and knowledge bases are usually strongly restricted. Therefore, it is of particular importance for these companies to be able to select and utilize only the most critical performance indicators. This could point towards a focused approach to performance measurement such as, for example, advocated in quick response manufacturing (QRM). Results from a recently conducted empirical survey of SMEs in northern Denmark are used to illustrate the present focus of performance measurement in these companies.
On-line sensing and estimation of laser surface modification by computer vision
Authors: Hu D , Labudovic M , Kovacevic R
Published: October 2002

Laser surface modification with alloying or remelting often yields unstable results. To achieve on-line control, process sensing and estimation are the key technologies. This paper introduces molten pool imaging as laser processing feedback. Well-contrasted molten pool images are acquired in experiments by eliminating the strong light from spatter and plasma. An algorithm for real-time image processing is developed that shows robust and high-speed performance. Analytical models of laser surface modification are studied using moving heat source models. The simplified analytical model shows a roughly linear relationship between laser power and depth of modified surface (molten depth). Based on key feature analysis in analytical models, an on-line estimation model of molten depth is built using a neural network, which applies a time- series of widths of the molten pools as an input vector. By controlling laser power, the neural network model is trained for different heat inputs in a transient process. The testing results by another group of experiments show that the on-line estimation model can predict the depth of the modified surface accurately.
Process improvement planning using path modelling and simulation
Authors: van Voorthuysen E J , Platfoot R A
Published: October 2002

A process improvement methodology based on path modelling and simulation is proposed. Benefits from using path modelling include the ability to model direct and indirect relationships between process variables and to convert the calculated coefficients into a process state matrix that can be used in process simulation. By identifying critical process variables, a correlation matrix can be constructed and used as input for library procedures incorporated in off-the-shelf statistical analysis software. The system equations may be inverted and solved for the unknown inputs as a function of desired outputs on the basis of the inverted state matrix. The results are indicative of the degree of control and improvement required to avoid intractable process problems and can be used to specify and select new process technology.
Determination of the critical modification coefficient for a cylindrical worm gear drive with the worm generated by a surface of revolution
Authors: Lee C-K , Chen C-K
Published: October 2002

This paper presents a general method to determine the critical modification coefficient (CMC) for a cylindrical worm gear drive with the worm generated by a surface of revolution. Unlike the existing methods for the determination of the first boundary points, to avoid tedious partial derivatives the curvature information of generating surface and relative motion parameters is directly applied to the worm and the concept of equivalent generation is applied to obtain an explicit form of the equation of meshing; thus it is a very efficient way to determine the first boundary points on the worm gear tooth surface. By solving a system of non-linear equations, the CMC can be obtained and the gear undercutting can be avoided. On the basis of the proposed method, a computer program is created and applied to four commonly used worm gear drives: ZK1, ZK2, F-I and F-II.
Modelling of integrated, distributed and cooperative process planning system using an agent-based approach
Authors: Chan F T S , Zhang J , Li P
Published: October 2002

This paper describes a conceptual framework for applying a multi-agent system to process planning for integrating design, process planning and shop floor scheduling so that a distributed, cooperative and integrated process planning system is constructed. The problem in process planning has been mapped onto a multi-agent architecture based on multistage cooperation. The multi-agent system has some common characteristics, such as distribution, autonomy, interaction and openness, which are helpful for the traditional architecture to be transferred to the distributed, cooperative architecture for process planning system. An agent-based framework for an integrated, distributed and cooperative process planning system (IDCPPS) integrates all the activities of process planning into a distributed intelligent open environment. Agents in the agent-based framework for the IDCPPS can be organized dynamically and cooperate with each other to perform an appointed task flexibly. In addition, using CORBA technology, a prototype system of the IDCPPS is implemented.
What limits the ability of design organizations to predict failure?
Authors: Busby J S , Strutt J E
Published: October 2002

A study was conducted of the factors that limited the ability of design organizations to forestall equipment failures in subsea systems. Group interviews were conducted in four suppliers of mechanical and electromechanical subsystems, and the impediments to effective prediction and elimination of failure were identified. Many of the impediments arose from constraints over which the design organizations, individually, had little influence. Some arose from intrinsic limits to the availability of failure data and intrinsic limits to the possible informativeness of different kinds of failure analysis. Several impediments arose from organizational practices in various stages of the design process, and some of these reflected basic organizational attitudes to risk. Ironically, the desire to limit risk by keeping open the possibility of intervening in the operation of a product (by replacement or repair) also limited the organizations' ability to design for very high reliability.
The influence of gender and individual differences on risks of injury due to layout in assembly work
Authors: O'Sullivan L W , Gallwey T J
Published: October 2002

This paper examines variation in elbow and shoulder joint angles between genders for a simulated light assembly task within normal reach at three bin distances. Joint angle ranges were estimated for 5th, 50th and 95th percentile values pooled from males and females for each of the 17 task elements. Large differences in risk levels were found between the 5th and 95th percentile estimates. Male elbow angles were smaller than the females', but the male shoulder angles were greater than the females', on average. These results have important implications for workplace design.
Effect of process parameters on the kerf width during the laser cutting process
Authors: Yilbas B S
Published: October 2002

One of the deficiencies in laser cutting quality is the large size of striation formed at the cut edges. Striation formation is related to the slow drifts and disturbances in various parameters during the laser cutting process. In the present study, the effects of laser power, cutting speed and energy coupling factor on the kerf size are investigated. A simplified formulation based on the lumped parameter approach is considered for the kerf width analysis. An experiment is carried out to verify the present predictions. In addition, a kerf width formulation developed in a previous study is used to compare the predictions of the present analysis and the previous results. It is found that increasing laser power and energy coupling factor increase the kerf width size. Slight variations in laser power, cutting speed and energy coupling factor modify the kerf width size considerably, in which case the striation size increases or the striation initiates during the cutting process.
Techniques for rapid characterization of grinding wheel-workpiece combinations
Authors: Kompella S , Farris T N , Chandrasekar S
Published: October 2002

A study has been made of a technique called taper grinding, which offers considerable potential as a test procedure for the rapid acquisition and analysis of grinding output data. On the basis of a comparison of results pertaining to forces, specific energy and workpiece residual stress from taper grinding with those obtained from conventional slot grinding tests on cast iron, it is shown that taper grinding is a robust and efficient method for the analysis of grinding data. Analysis of the taper and slot grinding test results has also shown that equivalent chip thickness and average workpiece temperature are excellent universal parameters for the assessment and prediction of forces and residual stress respectively.
A systems approach to electronic assembly optimization
Authors: Newnes L B , Mileham A R , Doniavi A
Published: October 2002

There are many complex problems in the optimization of an electronics manufacturing environment, and it is the view of the authors that these problems should not be solved and optimized in isolation but analysed in the framework of a system. A systems approach offers an overall approach for solving problems, optimizing the whole of the system rather than discrete subsystems. The research introduced in this paper integrates several techniques, namely integrated computer aided manufacturing definition, experimental design and response surface methods for the analysis, control and optimization of electronic manufacturing processes. Electronics manufacturing includes three major processes: printed circuit board manufacturing, semiconductor device manufacturing and electronics assembly. This paper describes a generic systematic model for optimizing electronic assembly. Computer aided systems engineering methodology is introduced and a description of how this was applied to optimize electronic assembly within a manufacturing company using historical data is given together with a process map for electronic assembly. An analysis of the overall assembly operation is then used to generate the relationship between overall yield and yield of the subprocesses.
A form of deviation-based method for coordinate measuring machine sampling optimization in an assessment of roundness
Authors: Rossi A
Published: October 2002

A method for minimizing coordinate measuring machine (CMM) inspection time in the accuracy measurement of roundness is described. The peculiar feature of the method is to employ a presampling with a strategic distribution of the points, in order to decrease the sample size in point-by-point acquisition. Point distribution is derived from a method for detecting two of the most frequent categories of deviation in the profile: waviness and random deviation. Depending on the actual category of deviation, a subsequent sampling, which locates points near the main features of the profile, is performed to refine the error of roundness. The main goal of the system is to detect an exact roundness error by means of a method for minimizing inspection time for wavy deviation with a fixed level of noisy band superimposed.
Study on acoustic emission in machining hardened steels Part 1: Acoustic emission during saw-tooth chip formation
Authors: Barry J , Byrne G
Published: October 2002

The generation of acoustic emission (AE) in the machining of hardened steels is investigated. It is shown that, in ‘hard machining’, the energy of the AE signal may be up to two orders of magnitude greater than in the machining of softer pearlitic steels, depending on work material hardness and cutting parameters. This is a result of the transition from continuous to saw-tooth chip formation and, specifically, the periodic, rapid release of elastic strain energy during catastrophic failure within the primary shear zone. Of the parameters which influence the transition from continuous to saw-tooth chip formation, flank land width may be considered unique. In contrast to work material hardness, cutting speed, undeformed chip thickness and tool rake angle, when the transition in chip morphology is effected by an increase in flank land width, there is not necessarily an increase in AERMS. Also, within the continuous chip domain, there is no clear relationship between flank land width, feed and AERMS. As such and as is shown, AERMS may increase or decrease with cutting tool wear.
Quality assurance of milling cutters—a contribution to multicomponent tolerancing
Authors: Chen C-K , Jywe W-Y , Liu C-H
Published: October 2002

This paper presents evaluation methods for the precision assessment of milling cutters. The geometric shapes of milling cutters comprise various revolving portions which may include: a cylindrical surface, a conical surface, a circular arc-type surface, a toroidal surface, a spherical head and/or other helicoidal surfaces. In actual operation, the shank of a milling cutter is held by the spindle head holder and rotated about an axis. The axis of the minimum enveloped shank can thus be used as the common central line of the entire tool surfaces. A heuristic approach is presented to model form errors for quality assessment on milling cutters using genetic algorithms (GAs). The proposed GA-based models systematically compute the exact turning envelopes of individual revolving surfaces separately, and then combined together, using the central line of the minimum enveloped shank as a common axis. Numerical examples are employed to illustrate the effectiveness of the proposed modelling approaches. The results indicate that the proposed models are simple, sensible and accurate for the quality assessment of various complicated cutters.
Suppression of chatter in grinding using high-viscosity coolants
Authors: Maksoud T M A , Mokbel A A
Published: October 2002

Contact area deformation between grinding wheel and workpiece is one of the major parameters that affect the susceptibility of the grinding process to chatter. Introducing an artificial damping to this area is one way to improve the process stability. Damping can be introduced by creating a high hydrodynamic pressure in the contact zone wedge between the wheel and the workpiece. Using high viscosity coolant with an impervious grinding wheel such as a diamond grit wheel will produce this pressure. This paper presents a theoretical and experimental model which confirms the favourable effect of the induced hydrodynamic pressure on the stability and hence the chatter that may be present in the grinding process.
Towards deflection prediction and compensation in machining of low-rigidity parts
Authors: Ratchev S , Govender E , Nikov S
Published: October 2002

Producing the right profile in machining low-rigidity complex parts increasingly depends on specialized computer aided manufacture (CAM) packages for defining appropriate cutting strategies and tool paths. Despite the significant developments in numerically controlled (NC) simulation and verification there are still gaps between the theoretically predicted surfaces and the measured surfaces owing to a relatively small percentage of machining error types that could be detected and interpreted by the existing software systems. This paper reports on a new methodology for simulation and prediction of the deflection of thin wall parts during machining. It aims to increase the understanding of the causes of poor geometric accuracy by considering the impact of the machining forces on the deflection of thin-walled structures. The proposed approach is based on identifying and modelling key processing characteristics that influence part deflection, modelling the material removal process using ‘voxels’ and predicting and correcting the deflection of the parts. The reported work is part of ongoing research on developing an adaptive machining planning environment for modelling, prediction and selection of process and tool path parameters for rapid machining of complex low-rigidity high-accuracy parts.
A study of design management in the telecommunications industry
Authors: Whybrew K , Raine J K , Dallas T P , Erasmuson L
Published: October 2002

This paper presents an account of a study undertaken jointly by the University of Canterbury and Tait Electronics Limited, a leading New Zealand manufacturer of high-technology radio communications equipment. The project was part of a wider research programme exploring design management and the uptake of computer aided engineering tools in New Zealand industry, funded by the New Zealand Foundation for Research Science and Technology. The study reported in this paper investigated techniques by which the product development cycle may be reduced, and in particular, the practical implementation of concurrent engineering principles in the company's product development environment. The research methodology involved the application of design phase diagrams and the recording of instances of communication between intracompany groups and departments, and organizations external to the company. The study highlighted strengths and weaknesses in the company's design management. Particular weaknesses were the level of communications between engineering and marketing functions, and recurrences of task clarification and conceptual design activity late in the overall product development process because of incomplete definition of customer design requirements at the design proposal stage. It was concluded that, with automated data gathering, design phase diagrams could provide a valuable design management tool to evaluate ongoing project progress, and to identify weaknesses in communication or design team effectiveness.