bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of design dimensions on the driving force variation of a hybrid TRR’XY parallel kinematic machine tool
Authors: Chang T-H , Chen S-L , Chang Y-C
Published: October 2002

Using parallel-link mechanism as the basic structure of the parallel kinematic machine (PKM) tool is a new design concept and has become one of the most important research fields, attracting many previous researchers. Research on the actuator driving force variation of a PKM tool is essential for the applications of a PKM tool to real machining processes. For machining a component, the smaller actuator driving force required means that the PKM tool has a higher machining performance. To improve the machining performance, understanding of the required actuator driving is very important. A generalized force analysis of the developed system was obtained using the Denavit-Hartenberg (D-H) notation method. The force reactions on the joints and actuator driving forces are obtained on the basis of various cutter locations and a given external cutting force. The prediction of the cutter location with the singularity condition can be also obtained on the basis of the infinite force of the joints. The geometry relationship between the tool platform and the links is adopted to verify the singularity conditions of the system. The driving force variation of the hybrid TRR- XY five-degree-of-freedom machine tool is further investigated.
An intelligent system for performance measurement selection
Authors: Ahmed A M , Abdalla H S
Published: October 2002

The vital role of selecting the appropriate performance measurement has received widespread attention in industry and academia. This is due to the direct impact that these measures have in gaining competitive advantages. The use of a computer-based system to ease the complexity attached to this process has received no attention in the literature. This article briefly describes an intelligent system being developed as a step forward in this direction. The paper concentrates only on discussing the different models being adopted in this system and how they are integrated. One case study is discussed to demonstrate how a company can use and benefit from the developed system in rationalizing its performance measures.
A categorization of functional couplings in manufacturing systems
Authors: Almström P , Märtensson P
Published: October 2002

The axiomatic design theory as stated by Suh has proven useful when designing products, and this success has led to an increasing interest in applying the theory to manufacturing systems development. The theory states that functional couplings should be avoided in general. However, manufacturing systems are potentially coupled in many ways, the most obvious being that manufacturing operations usually are performed in a sequence. Functional coupling is defined as a dependence between functional requirements. The subject of couplings in manufacturing systems is not extensively explored or described in the literature, and specifically not in relation to the axiomatic design theory. Five different categories of couplings in manufacturing systems are described and exemplified in this paper. Couplings can be designed into the manufacturing system for a diverse range of reasons, e.g. selection of manufacturing processes or materials, but they may also be irrational, e.g. decisions based on political opinions.
An application of rough set theory to defect detection of automotive glass
Authors: Lee S , Vachtsevanos G
Published: October 2002

A technique based on rough set theory is investigated for identifying defects on a backlight (a rear window of a vehicle with a defrost circuit). Since replacement of defective backlights results in a significant financial loss, automobile manufacturers are trying to remove defective backlights during the manufacturing process. Therefore, an automated inspection system based on infrared (IR) imaging techniques has been developed to detect backlight defects such as missing lines or hotspots, where the most challenging task is identifying hotspots from their artefacts.

Feature selection techniques based on rough set theory are explored in this short communication and are used to extract a feature vector, which increases inspection accuracy as well as reduces computational complexity. The theory is also applied to generate decision rules, which can be simply added to existing inspection systems to assist the operators in their decision-making process. The proposed inspection system is expected to provide more reliable fault detection with low rate of false alarms than currently available systems.
A theory to support the high-speed computer numerical control machining of corner profiles
Authors: Loftus M , Wang D
Published: October 2002

This paper presents a new mathematical model for the motion of a milling cutter as it generates an obtuse corner profile. The model describes the different phases of cutter contact and can be used to optimize the speed of machining and to protect the cutters from adverse loading conditions in high-speed milling applications.
Improved production planning and control via low-cost prototype solutions
Authors: Dawes T B , Boughton N J
Published: October 2002

This paper describes prototype management information systems used to support the transformation of a job-orientated manufacturer into a preferred supplier to the Aerospace Industry. As a jobbing manufacturer the company excelled at reactive management, responding rapidly to short lead-time demands. This approach, however, was inappropriate for the increasingly competitive production of steady state orders (‘runners’) and spare parts orders (‘repeaters’). As a result, the company experienced falling delivery performances and increasing work-in-progress, inventory levels and overtime requirements. Furthermore, there was only a modest understanding of customer requirements due to the poor visibility of the order book. There was also little awareness of internal and supplier capabilities, and the planning and control systems were non-existent, relying heavily on senior management expertise. The company, however, was reluctant to invest in new management information systems, aware of the risk of expensive systems unsuited to the company requirements. Instead, prototype solutions were developed using low-cost and readily available software, which provided the stability and visibility that the company required and formed the basis of a more long-term understanding of planning and control requirements. This paper describes the iterative prototype developments to support the new company infrastructure and quantifies the benefits that were achieved through their introduction.
Two-dimensional and three-dimensional finite element models of external thread rolling
Authors: Domblesky J P , Feng F
Published: October 2002

In the present study, the DEFORM computer code was used to develop two-dimensional and three-dimensional finite element models for simulating external thread rolling. To simulate rolling in two dimensions, a plane strain model was used where the thread is assumed to form through progressive penetration of the blank surface using a parallel set of wedge-shaped indenters. To develop the three-dimensional model, a flat-die rolling process was simulated which incorporated blank rotation, die movement and pitch angle on the die faces. Based on a comparison of thread form and microhardness with as-rolled threads, the plane strain model was found to provide a reasonable approximation of thread-rolling behaviour. Results obtained from the initial pass of the three-dimensional model are promising although progress is currently limited by the excessive computational time needed, frequency of remeshing and sliding at the die-blank interface.
Assessment of a finite element model for plate shearing
Authors: Domblesky J P , Zhao L
Published: October 2002

A study was conducted to assess the robustness of a plane strain finite element model that was developed to simulate plate shearing using the Cockroft-Latham fracture criterion and element deletion. Model predictions for blade gap, ductility and edge wear were compared with published experimental results. Results showed that the model was able to simulate initiation and propagation of fracture lines at the punch and die corners and the resultant break angle along the edge was found to be close to values observed in practice. Simulated edge geometry and microhardness were found to be in reasonable agreement with published experimental results for the steel plate considered although the model was unable to simulate double cutting at 0.8 per cent clearance. Results also suggest that edge hardness is independent of the starting ductility in the plate and that increasing the edge radii does not effectively simulate edge wear. Based on the results obtained, it may be concluded that the plane strain model is able to simulate plate shearing with sufficient accuracy in the range of normal process conditions.
Investigation and utilization of the acoustic emission signal for monitoring the dressing process
Authors: Wehmeier M , Inasaki I
Published: October 2002

Improvement of monitoring techniques is essential to make the complex dressing process more reliable, economical and user friendly. A system utilizing data from acoustic emission (AE) sensors and a suitable algorithm combined with a graphical user interface has been applied with this aim. The influence of different grinding wheel types and dressing parameters on the AE signal has been investigated and a dressing monitoring system is proposed. The root mean square (r.m.s.) signal, or the low-frequency component of the AE signal, provides information that can be utilized to monitor the process. A reliable touch detection and cycle termination can be established. The spectrum of the raw signal has been investigated for cubic boron nitride (CBN) and conventional grinding wheels. Reliable data acquisition techniques, which make a continuous scanning of such wide bandwidth signals possible, have been applied.
Mechanically assisted droplet transfer process in gas metal arc welding
Authors: Wu Y , Kovacevic R
Published: October 2002

Gas metal arc welding has been generally accepted as the preferred joining technique due to its advantages in high production and automated welding applications. Separate control of arc energy and arc force is an essential way to improve the welding quality and to obtain the projected metal transfer mode. One of the most effective methods for obtaining separate control is to exert an additional force on the metal transfer process. In this paper, the droplet transfer process with additional mechanical force is studied. The welding system is composed of an oscillating wire feeder. The images of molten metal droplets are captured by a high-speed digital camera, and both the macroscopic appearance and the cross-sectional profiles of the weld beads are analysed. It is shown that the droplet transfer process can be significantly improved by wire electrode oscillation, and a projected spray transfer mode can be established at much lower currents. By increasing the oscillation frequency, the droplet transfer rate increases while the droplet size decreases. In addition, the improvement in the droplet transfer process with wire oscillation leads to an enhancement of the surface quality and a modification of the geometry of the weld beads that could be of importance for overlay cladding and rapid prototyping based on deposition by welding.
Minimizing angular backlash of a multistage gear train
Authors: Hsu Y-L , Wang S-G
Published: October 2002

An optimization model is constructed to select the optimum reduction ratios that minimize the total angular backlash of a gear train, under constraints on the total reduction ratio and available space. It is found that a proper layout of reduction ratios has a major effect on the total angular backlash of a gear train.
An intelligent system for optimal selection of dies and tools for sheet metal operations
Authors: Singh R , Sekhon G S
Published: October 2002

This paper describes an intelligent system for assisting process planning staff working in small and medium sheet metal industries for optimal selection of type of die, jig, fixture and inspection gauge for a given job. The problem is tackled through the expert system approach. Knowledge in the form of data, facts, rules of thumb and judgements gathered from product designers, process planners, die designers, process planning handbooks, catalogues and brochures has been analysed, tabulated and incorporated into a set of production rules of the IF-THEN variety. The system is coded in the AutoLISP language and loaded into the prompt area of AutoCAD. This arrangement facilitates interfacing of process design with drafting and can be operated on a PC/AT. For consultation, the system generates friendly prompts eliciting from the user data pertaining to the job. The system output includes recommendations on optimal type of die, jig, fixture and inspection gauge suitable for the job at hand. Illustrative examples have been included for demonstrating the usefulness of the proposed system. The knowledge base of the proposed system can be modified depending upon the capabilities of a specific shop-floor. The low cost of the system makes it affordable for planners working in small- and medium-sized enterprises.
The effects of cryogenic cooling on chips and cutting forces in turning AISI 1040 and AISI 4320 steels
Authors: Dhar N R , Kishore Nanda S V , Paul S , Chattopadhyay A B
Published: October 2002

Application of conventional cutting fluids often cannot control the high cutting temperatures, especially in high production machining. In addition, they are a major source of pollution in machining industries. Cryogenic cooling is a potential environmentally friendly clean technology for desirable control of the cutting temperature.

The present work deals with experimental investigations on the role of cryogenic cooling by liquid nitrogen jets on chip formation and cutting forces in turning AISI 1040 steel and AISI 4320 steel at industrial speed—feed combinations by two types of carbide inserts of different geometrical configurations. The experimental results indicate the possibility of a substantial reduction in cutting forces by cryogenic cooling, which enabled a reduction in cutting forces by favourable chip formation, chip—tool interaction and also retention of tool sharpness due to reduced cutting temperature. Thus cryogenic cooling, if properly employed, is not only environmentally friendly but can also improve machinability characteristics.
Study using position silicon detectors for performance testing of computer numerically controlled machine tools
Authors: Jywe W
Published: October 2002

In this paper, various contouring test systems for computer numerically controlled (CNC) machine tools are reviewed. It is the first time a laser diode and a quadrant sensor have been employed to build a simple contouring measuring system for testing dynamic performance of a CNC machine tool. The experimental work on a CNC machine tool with a Fanuc OM controller for various contouring paths under specified feed rates is carried out. Then, the compensation work is executed with the assistance of this developed contouring system. After the compensation, the contouring error, especially at a high feed rate and small radius, is reduced significantly.
Uncertainty analysis of multijet modelling processes for rapid prototyping of parts
Authors: Pérez C J Luis , Calvet J Vivancos
Published: October 2002

The present study focuses on aspects of the surface qualities of prototypes obtained by multijet modelling (MJM) techniques. The surface finish and dimensional precision of parts obtained through these manufacturing processes are often highly important, especially in those cases where the manufactured prototypes are used as functional parts, as in the case of lost wax casting. Moreover, it is important to obtain an estimate of the average surface roughness in order to select the appropriate manufacturing parameters. Although there are many different techniques for evaluating surface roughness, one of the most commonly employed methods involves the assessment of the average surface roughness by means of stylus instruments. Prototypes were manufactured using two different MJM systems under different conditions for each prototype. After the parts were obtained, an experimental study of effective roughness was carried out. A comparative study using the same MJM systems with different accuracies was also performed in order to evaluate the capability of these rapid prototyping techniques to manufacture parts.
Evaluation of existing and new feature recognition algorithms: Part 1: Theory and implementation
Authors: Owodunni O , Hinduja S
Published: October 2002

This is the first of two papers evaluating the performance of general-purpose feature detection techniques for geometric models. In this paper, six different methods are described to identify sets of faces that bound depression and protrusion faces. Each algorithm has been implemented and tested on eight components from the National Design Repository. The algorithms studied include previously published general-purpose feature detection algorithms such as the single-face inner-loop and concavity techniques. Others are improvements to existing algorithms such as extensions of the two-dimensional convex hull method to handle curved faces as well as protrusions. Lastly, new algorithms based on the three-dimensional convex hull, minimum concave, visible and multiple-face inner-loop face sets are described. These algorithms provide a basis for the comparative analysis that is the subject of the second paper.
WebCAD: A computer aided design tool constrained with explicit ‘design for manufacturability’ rules for computer numerical control milling
Authors: Mohole A , Wright P , Séquin C
Published: October 2002

A key element in the overall efficiency of a manufacturing enterprise is the compatibility between the features that have been created in a newly designed part, and the capabilities of the downstream manufacturing processes. With this in mind, a process-aware computer aided design (CAD) system called WebCAD has been developed. The system restricts the freedom of the designer in such a way that the designed parts can be manufactured on a three-axis computer numerical control milling machine. This paper discusses the vision of WebCAD and explains the rationale for its development in comparison with commercial CAD/CAM (computer aided design/manufacture) systems. The paper then goes on to describe the implementation issues that enforce the manufacturability rules. Finally, certain design tools are described that aid a user during the design process. Some examples are given of the parts designed and manufactured with WebCAD.
A study on an automatic seam tracking system by using an electromagnetic sensor for sheet metal arc welding of butt joints
Authors: You B-H , Kim J-W
Published: October 2002

Many sensors, such as the vision sensor and the laser displacement sensor, have been developed to automate the arc welding process. However, these sensors have some problems due to the effects of arc light, fumes and spatter. An electromagnetic sensor, which utilizes the generation of an eddy current, was developed for detecting the weld line of a butt joint in which the root gap size was zero. An automatic seam tracking system designed for sheet metal arc welding was constructed with a sensor. Through experiments, it was revealed that the system had an excellent seam tracking accuracy of the order of ±0.2mm.
A fuzzy logic approach to accommodate thermal stress and improve the start-up phase in combined cycle power plants
Authors: Boulos A M , Burnham K J
Published: October 2002

Use of combined cycle power generation plant has increased dramatically over the last decade. A supervisory control approach based on a dynamic model is developed, which makes use of proportional-integral-derivative (PID), fuzzy logic and fuzzy PID schemes. The aim is to minimize the steam turbine plant start-up time, without violating maximum thermal stress limits. An existing start-up schedule provides the benchmark by which the performance of candidate controllers is assessed. Improvements regarding possible reduced start-up times and satisfaction of maximum thermal stress restrictions have been realized using the proposed control scheme.
Optimization of the aluminium die casting process based on the Taguchi method
Authors: Anastasiou K S
Published: October 2002

Porosity in the die casting process causes costly scrap loss and limits the use of die-cast parts in critical high-strength applications. The amount of porosity is closely related to the die casting process parameters. Consequently, the mechanisms of porosity formation in relation to die casting parameters have to be studied in detail. A considerable reduction in porosity formation can be obtained by Taguchi technique implementation in the die casting process. Through simple multifactorial experiments in the foundry, controllable factors can be isolated to provide centring and variance control for a process variable. The primary objective of this paper is to investigate the effects of process parameters on porosity formation in the pressure die casting process to improve casting quality. Examples of the off-line technique used in a Greek aluminium die casting company are given for the purpose of illustrating the practicality and ease of use by industry engineers and managers.
Layer-based machining: Recent development and support structure design
Authors: Yang Z Y , Chen Y G , Sze W S
Published: October 2002

There is growing interest in additive and subtractive shaping theories that are synthesized to integrate the layered manufacturing process and material removal process. Recently, layer-based machining has emerged as a promising method for integrated additive and subtractive shaping theory. In this paper, major layer-based machining systems are reviewed and compared according to characteristics of stock layers, numerical control machining configurations, stacking operations, input format and raw materials. Support structure, a major issue in machining-based systems which has seldom been addressed in previous research, will be investigated in this paper with considerations of four situations: floating overhang, cantilever, vaulted overhang and ceiling. Except for the floating overhang where a support structure should not be overlooked, the necessity for support structures for the other three situations is determined by stress and deflection analysis. This will be demonstrated by the machining of a large castle model.
Innovative manufacture of impulse turbine blades for wave energy power conversion
Authors: Thakker A , Sheahan C , Frawley P , Khaleeq H B
Published: October 2002

An innovative approach to the manufacture of impulse turbine blades using rapid prototyping, fused decomposition modelling (FDM), is presented in this paper. These blades were designed and manufactured by the Wave Energy Research Team (WERT) at the University of Limerick for the experimental analysis of a 0.6m impulse turbine with fixed guide vanes for wave energy power conversion. The computer aided design/manufacture (CAD/CAM) package Pro-Engineer 2000i was used for three-dimensional solid modelling of the individual blades. A detailed finite element analysis (FEA) of the blades under centrifugal loads was performed using Pro-Mechanica. Based on this analysis and FDM machine capabilities, blades were redesigned. Finally, Pro-E data were transferred to an FDM machine for the manufacture of turbine blades. The objective of this paper is to present the innovative method used to design, modify and manufacture blades in a time and cost effective manner using a concurrent engineering approach.
Three-dimensional optimum design of the cooling lines of injection moulds based on boundary element design sensitivity analysis
Authors: Zhou H , Li D , Cui S
Published: October 2002

A three-dimensional numerical simulation using the boundary element method is proposed, which can predict the cavity temperature distributions in the cooling stage of injection moulding. Then, choosing the radii and positions of cooling lines as design variables, the boundary integral sensitivity formulations are deduced. For the optimum design of cooling lines, the squared difference between the objective temperature and the temperature of the cavity is taken as the objective function. Based on the optimization techniques with design sensitivity analysis, an iterative algorithm to reach the minimum value of the objective function is introduced, which leads to the optimum design of cooling lines at the same time.
A numerical investigation of diffuse images for effective defect detection
Authors: Parker J M , Hou Z
Published: October 2002

Numerical simulation is a flexible, practical tool for efficiently investigating machine vision hardware/software configurations for myriad industrial applications and can significantly reduce the engineering time necessary to design and implement a system. In this paper, physically accurate image synthesis is used to investigate the ability of diffuse angle images to detect topographical defects reliably in smooth, highly specular coatings; a specular-plus-diffuse reflectance model provides the scientific underpinning for this hypothesis. The specific results presented in this study show that diffuse images of topographical defects yield high-contrast grey-scale images compared with diffuse images of similar coatings without topographical defects, facilitating effective defect detection and providing a foundation for characterizing the severity of defects present in a given region.
Computer aided optimum design of machine tool spindle systems with hydrostatic bearings
Authors: Montusiewicz J , Osyczka A
Published: October 2002

A general model of the spindle system with hydrostatic bearings is presented. In this model the whole system is divided into subsystems. Each of these subsystems is modelled in order to obtain an optimization considering the global criteria of the system. A four-stage multicriterion optimization strategy is applied to solve the problem. On the basis of this strategy, which has a heuristic character, a computer aided optimum design software package for spindle systems for grinding and lathe machine tools is developed. The software is supported by computer graphics. An example of designing a grinding machine spindle system is given.
An analytical solution for transient temperature distribution in fillet arc welding including the effect of molten metal
Authors: Jeong S. K. , Cho H. S.
Published: October 2002

This paper presents an analytical solution to predict the transient temperature distribution in fillet arc welding, including the effect of the molten metal generated from the electrode. The analytical solution is obtained by solving a transient three-dimensional heat conduction equation with convection boundary conditions on the surfaces of an infinite plate with finite thickness, and mapping an infinite plate on to the fillet weld geometry, including the molten metal with energy equation. The electric arc heat input on the fillet weld and on the infinite plate is assumed to have a travelling bivariate Gaussian distribution.

To check the validity of the solution, flux cored arc (FCA) welding experiments were performed under various welding conditions. The actual isotherms of the weldment cross-sections at various distances from the arc start point are compared with those of the simulation result. As the result shows a good accuracy, this analytical solution can be used to predict the transient temperature distribution in the fillet weld of finite thickness under a moving bivariate Gaussian distributed heat source.

The simplicity and short calculation time of the analytical solution provides the rationale for using the analytical solution to model the welding control systems or to obtain an optimization tool for welding process parameters.
Development of the new-type indexable inserts with helical rake faces
Authors: Fang N , Wang M , Nedeß C
Published: October 2002

A kind of new-type indexable insert with a three-dimensionally shaped rake face, namely the helical rake face, is developed in this present work, contributing to the formation of short conical helical chips acceptable for modern automated and unattended machining systems. The geometric parameters of the helical rake face consist of the helical gradient, the helical length, the beginning rake angle at the tool nose and the end rake angle on the cutting edge. The influences of these parameters on the side-curling of the chip and on the chip breakability are investigated. Under the cutting conditions employed in this paper, the cutting force measuring results show that the cutting component of the resultant tool force and the radial force when using the tool insert with the helical rake face are less than those when using the type CNMG120408-ZF tool insert, a kind of commercially available insert widely used.
Characteristics of organizations not committed to total quality management
Authors: Dale B G
Published: October 2002

The focus of the paper is to examine the characteristics and behaviour of organizations that are not committed to the ideals of total quality management (TQM). In the five cases presented a number of conditions have helped to stifle the TQM initiative including: the lack of a plan, inadequate understanding of TQM, TQM seen as a necessary evil by senior management, inappropriate management style, poor channels of communication, no attempt to understand the needs and requirements of customers, proposals for improvement blocked by senior management, lack of integration between the ‘soft’ and ‘hard’ issues of quality management, a failure to understand the basics and linkages between concepts such as business process re-engineering, people empowerment and TQM, emphasis on quick-fix solutions and fire-fighting, and extending employee responsibility without adequate training. In turn these types of conditions have resulted in a lack of willingness by employees to participate in improvement initiatives and quality is seen as an added cost and something to be avoided.
Analysing the natural resting aspect of a complex shaped part on a hard surface for automated parts feeding
Authors: Ngoi K A , Lye S W , Chen J
Published: October 2002

This paper presents a new approach to analysing the natural resting behaviour of a non-regular prism on a hard surface. The methods proposed by Boothroyd, Redford, Poli and Murch (1) involve the use of empirical factors. Considering the complex formulae and computations required, the authors have decided to employ the centroid solid angle concept to predict the natural resting behaviour of a part. The method presented here is the centroid angle concept, which assumes that the probability of any surface of the part coming to rest is directly proportional to the difference between the centroid solid angle of that aspect and the average of the critical solid angles of the neighbouring aspects and is inversely proportional to the height of the centre of gravity of that aspect. The results showed that the predicted data agreed well with the experimental data obtained by the authors. This is the first successful attempt to analyse the natural behaviour of complex shaped parts on a hard surface without resorting to empirical factors.
Graphical approach to assembly tolerance stack analysis—the ‘Quickie’ GDT method
Authors: Ngoi B K A , Tan C S , Goh L C
Published: October 2002

More industries are now aware of the importance of geometric dimensioning and tolerancing (GDT) to their product design. Conventional methods of tolerance stack analysis for GDT is tedious and time consuming. This paper presents an elegant approach by using the ‘Quickie’ technique towards tolerance stack analysis for GDT. The proposed approach has the potential to significantly reduce the amount of work required and computerization is proving to be promising. Two examples are used to illustrate the effectiveness of the method. The ‘Quickie’ GDT method is applicable to all geometric characteristics. However, due to different treatments in various families of geometric characteristics, this paper describes the ‘Quickie’ GDT approach towards analysing runout and concentricity tolerances.
Ductile regime grinding of ferrite with variation of grain size by a piezoelectric-driven micropositioning grinding table
Authors: Kim J-D , Nam S-R
Published: October 2002

A mirror-like grinding of brittle materials is required in many precision engineering regions. Ductile regime grinding, a new grinding technology for brittle materials, is considered as a solution of this difficult-to-cut materials grinding. It is known that a fracture mechanism of brittle materials is transient to plastic deformation in the region of extremely small depth of grinding or removal rates. In this paper, the ductile regime grinding experiment of ferrite with variation of grain size has been performed using a micropositioning grinding table.
An approach to automating modular fixture design and assembly
Authors: Dai J R , Nee A Y C , Fuh J Y H , Kumar A Senthil
Published: October 2002

In the development of a modular fixture design system, it is essential to have a modular fixture element database that can be integrated with a CAD system, in addition to the other considerations such as fixture configuration, interference checking, etc., which are also important to fixture designers. This paper describes a new method to create the fixture element database and model the fixturing towers (i.e. subassemblies). By using this method, the database can be effectively created and is easy for use in fixture assembly. The modular fixture tower database is used to represent the subassembly of fixtures. This will simplify the fixture design and assembly process. A built-in interference checking methodology is embedded in the planning stage that will ensure a collision-free fixture design. The system is developed using the knowledge- based system, ICAD, and interfacing with UG-II for modelling the workpiece. Examples of fixture design generated by the system are also provided to illustrate the development.
A CAD-based approach to the design of fixtures for prismatic parts
Authors: Jeng Y C , Gill K F
Published: October 2002

The design scheme presented utilizes the knowledge representation and inference techniques from artificial intelligence and the geometric modelling technique for modular fixture design on a CAD (computer aided design) system. The fixture design problem is formulated in a hierarchical design structure. A systematic approach for selecting the locating and clamping positions on an automatically generated fixture configuration is outlined for the building of modular fixtures. Modular fixture elements are selected by considering the required function and geometric limitation. The generated fixture layout is then represented in the CAD system. To demonstrate the proposed approach, a prototype AutoCAFD (automatic computer aided fixture design) system is introduced and a practical example is presented.
Cold rolling of flat metal products: Contribution of mathematical modelling
Authors: Domanti S A , McElwain D L S
Published: October 2002

The significant contribution of mathematical modelling both to the understanding and improvement of the cold rolling of flat metal products is indisputable. This survey documents this contribution and claims that mathematical modelling will continue to provide a cost effective quality improvement tool with the finite element approach on fast large-memory computers and the use of the asymptotic approximation offering the best prospects for further major advances.
Automatic cut planning in an operative process planning system
Authors: Jain P K , Mehta N K , Pandey P C
Published: October 2002

The present paper discusses a knowledge-based interactive CAPP system for symmetrical turned parts. In this system, which is modular in structure, special emphasis has been laid on geometric reasoning and cut planning—two aspects which have received little attention in the CAPP systems reported in published literature. The present paper deals mainly with the description of the cut planning module of UOR_PLAN. The task of cut planning in UOR_PLAN is divided into two subtasks—macro cut planning and micro cut planning. Macro cut planning deals with the identification of pockets of unwanted metal. As a first step a mesh of nodal points is generated by taking into account the geometry of the part profile and the shape of the blank. Next, by rule-based successive elimination of nodal points from the mesh, pockets of unwanted metal for a given operation sequence are identified. This process is repeated for all possible sequences. The distinguishing feature of this technique is that it identifies the machinable volumes automatically without the preparation of an incidence/precedence matrix. A further breakup of machinable volumes is dealt with in micro cut planning. In phase one of micro cut planning, each machinable volume is divided into a number of rough cuts of equal depth by leaving a suitable finishing allowance. Optimum machining parameters (depth of cut, feed rate, cutting speed and number of passes) are selected by applying the sequential unconstrained minimization technique (SUMT). The best of the cut plans is selected on the basis of minimum production time. Phase two of the micro cut planning deals with the removal of the finishing allowance and has been discussed in an earlier paper.
Visual assessment of free-form surfaces in CAD/CAM
Authors: Cripps R J , Ball A A
Published: October 2002

This paper reviews the current graphical tools available for checking the quality of CAD/CAM (computer aided design/manufacture) surface models and highlights the difficulties of their use. A new range of geometrically based tools is proposed, especially designed for the task of enabling design engineers to visually assess the quality of free-form surfaces at a workstation screen to within an accuracy comparable with working to full-scale drawings. The tools should be easy to use without recourse to understanding the underlying mathematical theory of surface differential geometry on which the techniques are ultimately based.
Evaluation of a laser Doppler based non-contact in-process diameter measuring system
Authors: Yandayan T , Burdekin M
Published: October 2002

This paper investigates a laser Doppler based non-contact in-process diameter measuring system, which is used to measure the diameter of rotating workpieces while they are located in a CNC (computer numerical control) turning machine. A wide range of experiments were carried out to evaluate the system. Various workpiece diameters, surface finishes, surface velocities and focusing ranges were used to investigate the accuracy and repeatability of the technique, and possible effective parameters were studied. Error sources were found and solutions were proposed to improve the technique.
Integration infrastructure requirements for agile manufacturing systems
Authors: Weston R H
Published: October 2002

Current approaches to the design and construction of enterprise systems lead to fixed interdependences between valuable resources. This constrains resource reuse and the agility of systems, often preventing close alignment between system behaviour and business process requirements. This paper describes the important role that software-based integration infrastructures and integration structures can play respectively in supporting and organizing system behaviour in a way that facilitates system extension and change. Also described are different types of reusable software component and their infrastructural needs. These components are likely to become common building blocks of next-generation agile manufacturing systems. The paper illustrates the concepts described by reporting on research in the MSI Research Institute which is producing proof-of-concept agile manufacturing systems in collaboration with UK end user and vendor companies.
A role interaction approach to support manufacturing enterprise integration
Authors: Lim S H , Juster N , de Pennington A
Published: October 2002

Enterprise integration can be described as involving business process integration, business data integration, business software application integration and business computer system integration. In addition, these four must also be interlinked to achieve a truly integrated enterprise. This paper describes a ‘role interaction’ approach to meeting these integration needs of manufacturing enterprises. In short, ‘role interaction’ refers to the interaction that occurs between roles played by enterprise participants when performing their assigned tasks. An example showing this role interaction approach is discussed, using an enhanced form of the IDEF3 process description capture method.
Surface topography of machined fibre reinforced plastics obtained by stylus instruments and optical profilometers
Authors: Eriksen E , Hansen H N
Published: October 2002

In the manufacturing industry it is important to be able to specify and control the surface quality of the components produced. This is often done with stylus profilometers, by which standardized roughness parameters are found. In recent years instruments based on laser autofocusing have been introduced. They use another working principle to obtain the same parameters, but the settings of most of the measuring variables are not standardized. The present study has investigated aspects that have to be taken into account when the roughness of short fibre reinforced thermoplastics is measured by stylus instruments and by optical profilometers. The measurements were performed on machined surfaces with three distinct different roughness levels. The materials were two thermoplastics, polyoxymethylene and polypropylene, reinforced with short glass fibres. The two stylus instruments gave almost identical values, whereas significantly higher roughnesses were measured with one of the two optical instruments. The optical instruments were identical but with different settings of the control parameters, which resulted in large deviations between the values measured. Some of the differences between the two types of instrument are supposed to relate to the different properties of the fibres and the matrix, whereas others seem to relate to the instruments.
Prediction and computer simulation of dynamic thrust and torque in vibration drilling
Authors: Wang L-P , Wang L-J , He Y-H , Yang Z-J
Published: October 2002

A predictive model for dynamic thrust and torque in vibration drilling is presented. The model is based on the mechanics of vibration cutting analysis, assuming that the deformation process at the lips and chisel edge is treated as a number of vibration cutting elements, each with different dynamic characteristics. The result of a simulation study conducted for a low frequency range has shown a very good agreement between the theoretical predictions and the experimental evidence.
Development of virtual coordinate measuring machines incorporating probe errors
Authors: Pahk H J , Burdekin M , Peggs G N
Published: October 2002

In this paper, a comprehensive computer model is described which can be used to predict the volu- metric errors from the parametric errors of the coordinate measuring machine (CMM) and its probing system, for most configurations of CMMs. Several sets of previously unpublished rules have been derived to transform the CMM parametric errors into a corresponding volumetric error map. Thus a virtual CMM has been developed, implementing the integrated volumetric error model. The developed system has been applied to two practical configurations of CMM, in order to demonstrate the performance and practical application of the system.
Strategy investigation of precise robotic assembly operations with symmetric regular polyhedral objects
Authors: Qiao H , Tso S K
Published: October 2002

In this paper, a general strategy for the precise robotic assembly of symmetrical regular polyhedral objects is presented, according to the character of the objects being assembled. The assembly operations with force sensors included are discussed. The general strategy of the operations with force sensors included is first developed. The assembly operations without relying on force sensors are next analysed. This method can be generally used in industry for the precise assembly operations for symmetric regular polyhedral objects.

This paper covers the following items:

An important problem demanding solution in the general robotic assembly operations with force sensors is presented. The general strategy investigation for the assembly operations with force sensors included is analysed. The mappings, firstly, between the directions of the contact forces and the location of the peg in the hole coordinate frame and, secondly, between the input forces and the actual movement of the peg in the hole coordinate frame are obtained. The general strategy investigation for the robotic assembly operations for symmetric regular polyhedral objects without using force sensors is designed on the basis of the mappings and the general principles in the strategy investigation. The experiments on the precise round and triangular peg—hole systems are presented to prove the validity of the general strategies designed. The strategy of assembly operations for other symmetric regular polyhedral objects without using force sensors is presented.
Enterprise modelling in support of business process visualization and improvement
Authors: Murgatroyd I S , Hodgson A , Weston R H
Published: October 2002

In order to remain competitive, manufacturing enterprises must be able to adapt their business processes, and the associated resources and information systems, to ongoing change. This paper highlights the shortcomings of current business process re-engineering practice and proposes that there is a requirement for a business process for ‘process visualization and improvement’. A framework and methodology for the above business process are described and a case study utilizing the framework is detailed. It is concluded that the process visualization and improvement framework enabled a wide range of company personnel to participate in the case study exercise, to contribute to improved processes and subsequently to hold the view that a significant improvement over previous best practice had been achieved.
Computer comparison of design knowledge
Authors: Li Q , Zhang W J
Published: October 2002

Automatic comparison of design knowledge generated and consumed during a design process is very useful. Basically, design knowledge can be classified into four categories: (a) artefact (product) structures, (b) artefact behaviours, (c) artefact functions and (d) causalities among structures, behaviours and functions. This paper proposes an intelligent hybrid graph approach to represent design knowledge associated with these categories. Comparison of design knowledge thus turns out to be the comparison of hybrid graphs. A general algorithm is developed for the graph comparison purpose. In this general algorithm, comparison of line graphs is an important task, which is realized by using the Hopfield—Tank neural network algorithm. An initial implementation of this algorithm proves to be promising.