bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of the macromodel and neural network approaches for the prediction of microstructural evolution during hot forging
Authors: Brooks J W , Sabin T J
Published: October 2002

Data on the microstructural evolution of a titanium aluminide, derived from axisymmetric compression tests, have been used to define different models for the prediction of microstructure during hot deformation. Isothermally forged turbine blades have been manufactured and sectioned to provide the necessary metallographic validation data. Numerically based computer models, using finite element techniques, Gaussian methods and recurrent neural networks, have been used to obtain representative thermomechanical histories and microstructural predictions for the blades. It has been shown that, for the limited training data available, the macromodels provide more satisfactory predictions than the purely empirical neural network approaches.
Precision and ejection issues in the cold forging of a fuel injector nozzle
Authors: Kini S D , Shivpuri R
Published: October 2002

In this research, a fuel injector nozzle for a diesel engine currently made by machining was identified as a candidate part for cold forging. This part was selected to study for manufacturability by forming because of the potential of major savings in machining if the part could be made by net shape forming and possible improvements in material properties owing to cold work. This paper presents the methodology used, the approach to precision and ejection issues and a possible forging/machining sequence for the fuel injector nozzle. This methodology is applicable to cold forging of other small precision parts.
Process layout and forming results from deep drawing using pressurized membranes
Authors: Vollertsen F , Breede R , Beckman M
Published: October 2002

This paper gives an overview of sheet metal forming by liquid pressurized media separated from the sheet by membranes. The advantages and drawbacks in comparison with other sheet metal forming methods are shown. The boundary conditions for the choice of the membranes are discussed. The process window is determined by different failure modes of wrinkles and fractures. It can be determined by finite element method (FEM) calculations, which is nowadays a precondition for the use of the process in production. The forming results show high limiting drawing ratios of more than 3 and a sound working accuracy. The integration of different processes such as drawing and cutting into one step or the use of structured blanks makes shorter process chains possible.
On the selective removal of steel by laser-assisted vortex machining
Authors: O'Neill W , Voglsanger M , Elboughey A , Steen W M
Published: October 2002

Of all laser-based processes, laser machining has received little attention compared with others such as cutting, welding, heat treatment and cleaning. The reasons for this are unclear, although much can be gained from the development of an efficient laser machining process capable of processing difficult materials such as high-performance steels and aerospace alloys. Existing laser machining processes selectively remove material by melt shearing and evaporation. Removing material by melting and evaporation leads to very low wall plug efficiencies, and the process has difficulty competing with conventional mechanical removal methods. Adopting a laser machining solution for some materials offers the best prospects of efficient manufacturing operations. This paper presents a new laser machining process that relies on melt shear removal provided by a vertical high-speed gas vortex. Experimental and theoretical studies of a simple machining geometry have identified a stable vortex regime that can be used to remove laser-generated melt effectively. The resultant combination of laser and vortex is employed in machining trials on 43A carbon steel. Results have shown that laser slot machining can be performed in a stable regime at speeds up to 150mm/min with slot depths of 4mm at an incident CO2 laser power level of 600W. Slot forming mechanisms and process variables are discussed for the case of steel. Methods of bulk machining through multislot machining strategies are also presented.
A study of an arc sensor model for gas metal arc welding with rotating arc Part 2: Simulation of an arc sensor in mechanically rotating gas metal arc welding
Authors: Kim G-H , Na S-J
Published: October 2002

The high-speed rotating arc process forms a flat bead surface and decreased penetration depth. It can be effectively applied to automatic seam tracking, because the sensitivity of this type of arc sensor is greater than that of the conventional torch weaving method. In this study, a new rotation mechanism was developed by using a hollow shaft motor designed to be installed in the electrode nozzle. By rotating the welding arc, the amplitude of the current waveform increases remarkably since self-regulation of the arc is not fully performed. This paper presents a mathematical model for the dynamic behaviour of the electrode melting rate and arc length to simulate the welding signals in rotating arc welding. A simplified weld pool shape is considered with the dynamic wire melting model, because the welding arc rotates above the preformed weld pool.
Calculation of product architecture metrics within a solid modeller
Authors: Line J K , Steiner M W
Published: October 2002

The architecture of a product is defined as the scheme in which functions are mapped to physical components. Architecture affects how a product satisfies design objectives. There are several ways to measure architecture, and one is implemented into a solid modelling program that will do the quantification automatically. The software used is the I-DEAS solid modelling package, for which an internal program file was created to perform the calculations automatically. This program works by counting the parts that the user has created and then uses an internal I-DEAS function to find all of the joined parts. The program counts the joints and then prompts the user for the strength of each joint. With this information, an adjusted parts connectivity and average joint strength are calculated and can be used to evaluate the degree to which the architecture of a product is either integral or modular. Several case studies are presented that were used to evaluate the effectiveness of the program.
Comparative study of interference caused by different position settings of a conical milling cutter on a ruled surface
Authors: Monies F , Rubio W , Redonnet J-M , Lagarrigue P
Published: October 2002

This article covers the side milling of ruled surfaces using a conical milling cutter. This problem, encountered in real-life industrial situations, concerns parts such as turbine blades that entail problems of accessibility. To deal with this, industrialists use conical milling cutters that can mill the base of the blades while the larger main body of the milling cutter can be applied to the end of the blade. In the present article, five types of positioning on ruled surfaces are introduced, including two developed within the Toulouse Mechanical Engineering Laboratory. These position settings, studied for cylindrical milling cutters, were able to be adapted to the conical milling cutter. A comparative study was then made of these five position settings from the point of view of interference between the milling cutter and the theoretical surface. Working from two ruled surfaces (one hyperbolic paraboloid and one ruled surface of any nature), different tests were performed, with variation in the milling cutter geometry (end of milling cutter radius and half-angle at the apex). The results obtained made it possible to validate improved positioning, and this led to an industrial contract with the SAPEX-PROFOR Company. A final example based on a turbine blade is given.
Geometric shape errors in forging: Developing a metric and an inverse model
Authors: Rolfe B F , Cardew-Hall M J , Abdallah S M , West G A W
Published: October 2002

The complexity of the forging process ensures that there is inherent variability in the geometric shape of a forged part. While knowledge of shape error, comparing the desired versus the measured shape, is significant in measuring part quality the question of more interest is what can this error suggest about the forging process set-up? The first contribution of this paper is to develop a shape error metric which identifies geometric shape differences that occur from a desired forged part. This metric is based on the point distribution deformable model developed in pattern recognition research. The second contribution of this paper is to propose an inverse model that identifies changes in process set-up parameter values by analysing the proposed shape error metric. The metric and inverse models are developed using two sets of simulated hot-forged parts created using two different die pairs (simple and ‘M’-shaped die pairs). A neural network is used to classify the shape data into three arbitrarily chosen levels for each parameter and it is accurate to at least 77 per cent in the worst case for the simple die pair data and has an average accuracy of approximately 80 per cent when classifying the more complex ‘M’-shaped die pair data.
Using a data fusion neural network in the tool wear monitoring of a computer numerical control turning machine
Authors: Chen S-L , Chang T-H
Published: October 2002

The cutting force and the vibration signal of a computer numerical control (CNC) turning machine centre are detected for on-line tool wear monitoring. The feature elements are first extracted from the detected signals. The feature indices are obtained from the feature elements through data preprocessing. Six data fusion methods are used for integrating the feature indices to obtain the fusion indices. The obtained fusion indices are used as the input data of a neural network for online tool wear monitoring. The feasibility of coupling a neural network algorithm with different data fusion methods is investigated, based on the monitored data. The research results show that using a data fusion neural network in tool wear monitoring is feasible.
Hierarchical stochastic production planning with delay interaction and demand constraints
Authors: Yan H S
Published: October 2002

This paper explores the hierarchical stochastic production planning (HSPP) problem of flexible automated workshops, each with a number of flexible manufacturing systems (FMSs), the part transfer between which is delayed by a time period (i.e. delay interaction). The problem not only includes uncertainties in the demand, capacities, material supply, processing times, necessity for rework and scrap but also considers multiple products and multiple time periods. The objective is to devise a production plan which tells each FMS how many parts to produce and when to produce them so as to obtain the lowest cost under the condition of demands being just met. Herein, the HSPP problem is formulated by a stochastic non-linear programming model whose constraints (including demand constraints) are linear but whose objective function is piecewise linear. For the convenience of solving the stochastic non-linear programming model above, it is approximately transformed into a deterministic non-linear programming model and further into a linear programming model. Then, Karmarkar's algorithm and an interaction/prediction algorithm are used to solve the model, the former for the medium- or small-scale problems and the latter for the large-scale problems. With the help of the implementations of the above-mentioned algorithms and through many HSPP examples, Karmarkar's algorithm, the interaction/prediction algorithm and the linear programming method in Matlab 5.0 are compared, the result of which shows that the proposed approaches are very effective and suitable for not only ‘push’ production but also ‘pull’ production.
Modelling of a steel ball's grade based on image texture features
Authors: Pan H , Dong S , Liang Y , Zhu L , Xie S
Published: October 2002

The quality of steel balls has a substantial influence on bearing performance. The conventional way of measuring steel balls is by examining randomly selected specimens owing to the lack of efficient test methods. However, this cannot guarantee that every individual ball meets a certain standard. The traditional measurement is not acceptable in those fields where stability and reliability are highly demanded. An automatic method to measure a steel ball's quality to make exhaustive examination feasible and efficient was investigated. This paper describes the prediction model of a steel ball's vibration level based on image texture features by regression analysis method. The model establishes the relationship between the surface microscopic image of a steel ball and its vibration level, which is the major criterion to judge the quality of a steel ball. Experimental results have demonstrated that the prediction model approximates the real vibration level very closely. Several fitting models have been tested and a non-linear quadratic prediction model gives rise to the highest fitting precision.
Rapid prototyping based on variable polarity gas tungsten arc welding for a 5356 aluminium alloy
Authors: Wang H , Kovacevic R
Published: October 2002

This paper presents a new deposition process for directly building cylindrical parts of the 5356 aluminium alloy with variable polarity gas tungsten arc welding (VPGTAW). The relationship between the geometric sizes of the deposited layer and the welding parameters is investigated. A machine vision sensor is used to monitor and control the arc length that is a key welding parameter in the achievement of a uniform deposition. By optimizing the depositing speed and the thickness of the depositing layer, there is no need for a cooling system to cool the part. Three-dimensional parts with different wall thicknesses and different shapes are successfully obtained. The surfaces of the deposited parts are smooth and uniform.
Influence of micromachining on strength degradation of silicon nitride
Authors: Wakuda M , Yamauchi Y , Kanzaki S
Published: October 2002

In recent years, much research has been devoted to the development of micromachining technologies for ceramic materials. This paper investigates two kinds of machining methods capable of dimpling a ceramic surface with highly controlled precision: abrasive jet machining (AJM) and laser beam machining (LBM). A comparative discussion of the geometrical and topographical characteristics of microdimples machined on to an Si3N4 surface is first presented, followed by the main topic, an examination of the effects of micromachining on the strength degradation of ceramics. Dimpling by LBM cannot be prevented from forming a sharp edge around the dimple bottom face, which may degrade the flexural strength of the ceramic considerably. In contrast, the AJM dimple has a smooth-faced rounded shape, and only negligible deterioration of the strength takes place.
Supporting fault diagnosis through a multi-agent architecture
Authors: Marzi R , John P
Published: October 2002

In the industrial environment a short down-time of computer numerical control (CNC) machine tools is increasingly important. One approach to counter the loss of production is to make the machines more reliable, thereby reducing their times of non-use. Another is to enable machine operators to locate and to remove machine faults and their causes themselves, in order to reduce delay until maintenance staff is sent from a location far away. Operators may be supported in the fault-finding process by a knowledge-based decision-support system. The questions as to how to avoid the negative consequences of using such systems and how to even increase competence on the job is addressed by ComPASS, a system based on a multi-agent architecture. A running, functioning prototype was developed and evaluated. Based on this experience the system is currently being extended and improved, first results of which are presented here.
Waves on wood
Authors: Jackson M R , Parkin R M , Brown N
Published: October 2002

The rotary machining process as applied to timber is introduced and compared with the milling and grinding of metals. The emphasis of this work is on the waviness surface quality of the machined timber and initially focuses on a review of the techniques applied to improve surface quality at higher workpiece feed velocities—typically 120 m/min. The main work concentrates on mathematical and computer-based modelling of surface waviness defects generated by two classical woodworking machine engineering science phenomena, caused primarily by forced structural vibration. Surface assessment of machined timber is discussed, with results from contact and non-contact methods highlighted. The causes of surface waviness defects are presented and possible solutions are outlined.
Laser milling
Authors: Pham D T , Dimov S S , Petkov P V , Petkov S P
Published: October 2002

Laser milling is a new manufacturing process that has attracted much attention from engineers and researchers for the last decade. The process allows complex parts and tooling inserts to be fabricated directly from three-dimensional computer aided design (CAD) data in a wide range of advanced engineering materials such as ceramics, hardened steel, titanium and nickel alloys. The paper starts with a description of the physical phenomena underlying the process and the factors influencing its performance. It then outlines the machining techniques that can be utilized in laser milling. The paper concludes with a discussion of the advantages and disadvantages of the process and a summary of its application areas.
Digital information—potentials for TeleX applications
Authors: Westkämper E , Niemann J , Stolz M
Published: October 2002

The paper describes how the application of new information and communication technologies in manufacturing systems and technical consumer goods gives companies the possibility to create added value services in the usage phase, e.g. through remote operations or virtual facility management. In this regard, a communication platform for a digital factory has been developed to make diagnoses of the machine, program changes or process optimizations possible in less time by using an integrated control system, visualization and surveillance. The precise reproduction of the production system in a virtual world makes it possible to analyse and optimize all influences on the real production in that virtual world.
Static and dynamic models for predicting the effects of supports on machining flatness and roughness
Authors: Behzadi M R , Arezoo B
Published: October 2002

This paper presents analytical static and dynamic models of a rigid workpiece held in a machining fixture in contact with locators and clamps (in a 3-2-1 scheme) and three supports (in three locating planes) influenced by machining forces and moments. The model is used to predict the effects of support parameters including the support position, rigidity and preload on improving machining accuracies. Milling and creep feed grinding experiments are performed to verify the model. The model can be used to develop present computer aided fixture design systems that consider only locators and clamps in a force analysis module.
Evaluation of existing and new feature recognition algorithms: Part 2: Experimental results
Authors: Owodunni O , Hinduja S
Published: October 2002

This is the second of two papers investigating the performance of general-purpose feature detection techniques. The first paper describes the development of a methodology to synthesize possible general feature detection face sets. Six algorithms resulting from the synthesis have been designed and implemented on a SUN Workstation in C++ using ACIS as the geometric modelling system. In this paper, extensive tests and comparative analysis are conducted on the feature detection algorithms, using carefully selected components from the public domain, mostly from the National Design Repository. The results show that the new and enhanced algorithms identify face sets that previously published algorithms cannot detect. The tests also show that each algorithm can detect, among other types, a certain type of feature that is unique to it. Hence, most of the algorithms discussed in this paper would have to be combined to obtain complete coverage.
Evaluating alternative manufacturing control strategies using a benchmark system
Authors: Brennan R W , W O
Published: October 2002

This paper describes an investigation of the effects of dynamic job routing and job sequencing decisions on the performance of a distributed control system and its adaptability against disturbances. This experimental work was carried out to compare the performance of alternative control strategies in various manufacturing environments and to investigate the relationship between the ‘control’ and ‘controlled’ systems. The experimental test-bed presented in this paper consists of an agent-based control system (implemented in C++) and a discrete-event simulation model. Using this test-bed, various control strategies were tested on a benchmark manufacturing system by varying production volumes (to model the production system with looser/tighter schedules) and disturbance frequencies. It was found that hybrid strategies that combine reactive agent mechanisms (and allocation strategies such as the contract net) with appropriate job sequencing heuristics provide the best performance, particularly when job congestion increases on a shop-floor.
Development of a real-time monitoring system
Authors: Marzi H
Published: October 2002

This paper describes a pattern recognition (PR) technique, which uses learning vector quantization (LVQ). This method is adapted for practical application to solve problems in the area of condition monitoring and fault diagnosis where a number of fault signatures are involved. In these situations, the aim is health monitoring, including identification of deterioration of the healthy condition and identification of causes of the failure in real-time.

For this reason a fault database is developed which contains the collected information about various states of operation of the system in the form of pattern vectors. The task of the real-time monitoring system is to correlate patterns of unknown faults with the known fault signatures in the fault database. This will determine cause of failure and degree of deterioration of the system under test.

The problem of fault diagnosis may involve a large number of patterns and large sampling time, which affects the learning stage of neural networks. The study here also aims to find a fast learning model of neural networks for instances when a high number of patterns and numerous processing elements are involved. It begins searching for an appropriate solution. The study is extended to the enforcement learning models and considers LVQ as a network emerged from the competitive learning model through enforcement training. Finally, tests show an accuracy of 92.3 per cent in the fault diagnostic capability of the technique.
Efficient allocation of knowledge in distributed business structures
Authors: Spath D , Elsner J , Sternemann K-H
Published: October 2002

Accelerated business processes demand new concepts and realizations of information systems and knowledge databases. This paper presents the concept of the collaborative information space (CIS), which supplies the necessary tools to transform individual knowledge into collective useful information. The creation of ‘information objects’ in the CIS allows an efficient allocation of information in all business process steps at any time. Furthermore, the specific availability of heterogeneous, distributed data is realized by a web-based user interface, which enables an effective search by a multidimensionally hierarchical composition.
Forging force in resistance spot welding
Authors: Tang H , Hou W , Hu S J
Published: October 2002

This paper studies an intentional force increase during the process of resistance spot welding (RSW). Known for decades, the forging force as a way of influencing weld quality has rarely been applied in the automotive industry. There has been little research in this area. In this paper, the effects of varying forging force are investigated using both experimental and analytical approaches. Through the analysis of dynamic electrical resistance, the mechanism of the forging effects is explored. This study achieves a better understanding of forging force application and shows the benefits of the forging force on weld quality.
The role of grit blasting in the production of high-adhesion plasma sprayed alumina coatings
Authors: Griffiths B. J. , Gawne D. T. , Dong G
Published: October 2002

This paper describes the adhesion mechanism of sprayed alumina particles on to grit-blasted surfaces. Two types of impacted particles are identified, these being disc and splash types of splats. The impact of the splats on various surfaces is identified which indicates why grit-blasted surfaces are considered the best. A series of surfaces has been prepared in which the alumina is built up to full coverage. The proportion of splats in the valleys, on flats and on peaks is identified for high-and low-adhesion samples. This is related to the definition of grit-blasted topography for manufacturing quality assurance.
A simple approach for on-line tool wear monitoring using the analytic hierarchy process
Authors: Das S , Islam R , Chattopadhyay A. B.
Published: October 2002

A wide variety of on-line tool condition monitoring techniques have been developed to the present time. Timely decision making for cutting tool indexing needs a proper method for assessment of the state of the tool on-line.

The present work demonstrates a very simple system based on cutting force measurement for determination of the tool condition on-line using the analytic hierarchy process (AHP). The technique shows reasonably close estimation of the tool condition and enables successful on-line tool wear monitoring.
Study of powder sintering-compaction by a micromechanics model
Authors: Zhu J. S. , Liu S , Chandra A
Published: October 2002

The sintering-compaction process is one of the important methods of Ti-Al alloy component manufacturing. It is essential to obtain a thorough understanding of the mechanics involved in the process, such as the load-compaction relationship, void evolution, residual stress and plastic deformation. A unit cell micromechanics approach is used in this study to investigate the load-compaction relationship for various materials under different temperatures. The friction effect is evaluated and void evolution is observed. A formula based on the principle of soil mechanics is developed to describe the phenomenological pressure-compaction responses of materials during the sintering-compaction process.
Theoretical and computational investigation of the electrochemical machining process for characteristic cases of a stepped moving tool eroding a plane surface
Authors: Hardisty H , Mileham A R , Shirvani H
Published: October 2002

A theoretical and computational investigation into the electrochemical machining (ECM) process for the case of a moving stepped tool eroding an initially flat surface is presented. Five parametric variations of the basic geometry of the stepped tool machining process are possible, depending on the relative distance between the moving tool and eroded work. For each of the five cases, and based on one-dimensional theory, formulae have been developed to predict the minimum depth of working material that must initially be provided to enable a particular step size to be machined to a specified tolerance.

The computer simulation of the ECM process which has been developed is based on the finite element method (FEM). The geometry of tool, electrolyte and work is simulated by means of a two-dimensional mesh of square elements. A system of macros has been developed which interact internally with an FE package to move component boundaries systematically to simulate both tool movement and surface erosion. Such boundary movements are accomplished automatically and continuously without user intervention during a simulation run. The algorithms employed to achieve characteristically different erosion rates are described.

Results both from one-dimensional ECM theory and from the computer simulations of the characteristic cases are presented. Comparisons show that there is good agreement between computer predictions and theory.

The differential erosion process is fundamental to all ECM processes. Complex shapes evolve because of spatial differences in erosion rates. Thus the one-dimensional results presented here for the formation of a step should provide a basis for comparisons between spatially separated regions of one-dimensional differential erosion on bodies of arbitrary shape.
Acoustic emission monitoring of tool wear during the face milling of steels and aluminium alloys using a fibre optic sensor. Part 2: Frequency analysis
Authors: Carolan T A , Kidd S R , Hand D P , Wilcox S J , Wilkinson P , Barton J S , Jones J D C , Reuben R L
Published: October 2002

This paper describes the application of acoustic emission (AE) frequency analysis to cutting tool wear monitoring in finish milling operations. AE detection was achieved using a fibre optic interferometer which, unlike conventional piezoelectric transducers, allows absolute measurements of the frequency content of the signals, generated during face milling of various steels and aluminium alloys, to be made. A model detailing the expected variations in AE mean frequency with various forms of tool wear in the different processes is presented and is validated by the practical set of tool wear tests using the fibre optic interferometer.
In-process detection of grinding wheel truing and dressing conditions using a flapper nozzle arrangement
Authors: Maksoud T M A , Mokbel A A , Morgan J E
Published: October 2002

The spatial distribution of sharp cutting edges around the active periphery of a grinding wheel has an important effect on the surface finish of ground components. In addition, random protrusion of sharp edges can result in a random distribution of grinding forces acting on the ground surface. A uniformly dressed and accurately trued wheel is essential for successful grinding. Since these conditions will alter during use, monitoring of them during grinding must be a requirement for critical grinding operations. This paper describes a new system for achieving on-line detection of the grinding wheel condition. The system uses a small air flapper nozzle-transducer arrangement which detects in-process changes of the grinding wheel surface topography, where external triggering of the data-acquisition system ensures a highly accurate identification of the wheel's surface topography irrespective of wheel speed. The benefits of this system are illustrated by experimental results that correlate the measurement of wheel topography by two means: flapper nozzle and stylus.
Engineering document management strategy: Analysis of requirements, choice of direction and system implementation
Authors: Harris S B , Owen J , Bloor M S , Hogg I
Published: October 2002

The business requirements for better document management in engineering environments are forever increasing and the underlying technologies for implementing system solutions are changing rapidly. In these contexts, it is vital that the strategic aspects of the document management decision-making processes and the user and functional requirements of document management are fully understood prior to consideration of shorter term implementation decisions. This paper goes some way to providing guidelines on addressing these issues through the development of a structured approach to engineering document management, coupled with the specification of generic process and data models which can form the basis for developing company-specific strategies, plans, models and requirements before committing to investments in technology to implement solutions. The paper is therefore specifically aimed at those engineering, production, project and quality managers within manufacturing companies who have the responsibility for implementing data and document management systems. Relationships with relevant standards and technology, and future issues are briefly discussed.
The re-engineering and reconfiguration of manufacturing cell control systems and reuse of their components
Authors: Monfared R P , Weston R H
Published: October 2002

Contemporary approaches to the design and construction of manufacturing systems often results in inflexible enterprises that cannot readily be sharply tuned to changing business goals. Manufacturing cells represent a typical domain in which the existence of hard, inflexible links between tasks and resources will result in suboptimal performance and an inability to cope with change. Hence this paper reports progress on the definition of a semi-generic meta model of manufacturing cell control systems which can be used in conjunction with (a) modelling tools and (b) computerized infrastructure technology to facilitate system re-engineering and reconfiguration and the reuse of cell components in different manufacturing cells. The meta model has been conceived, formalized and evaluated under laboratory conditions by utilizing systems modelling and integration tools, based on CIM-OSA, Petri nets, EXPRESS, STEP and CIM-BIOSYS infrastructural elements.
Automatic dwell control in computer numerical control plunge grinding
Authors: Allanson D R , Rowe W B , Chen X , Boyle A
Published: October 2002

Accuracy in precision grinding is strongly affected by variations in the normal grinding force. The force gives rise to deflections of the machine, grinding wheel and workpiece. To allow relaxation of the deflection a dwell period is included at the end of the grinding cycle. Estimation of the time constant during grinding allows the automatic selection of the correct dwell time for the individual workpiece and current force level. A new strategy has been developed for the estimation of the time constant based on power measurement during dwell. The strategy employs the weighted least mean squares technique together with weightings based on classification of the power level into bands. The power bands are designed so as to employ lower weightings to be applied to power samples in the regions of the power curve most prone to causing an inaccurate estimate of the time constant.

The complete system was implemented on an adaptive system comprising a PC and an Allen Bradley 8200 CNC (computer numerical controller). The time constant identification and dwell control algorithms were executed within the PC and synchronized to the grinding cycle executed under the control of the CNC. The system was successfully tested under laboratory and industrial conditions. It was shown to produce a reliable and accurate estimate of the time constant with workpieces exhibiting time constants in a range from 0.7 to 55 s. The system was shown to cope with this wide range of time constants without user intervention and to be tolerant of the high signal noise levels typically encountered in an industrial environment.
Acoustic emission sensing as a tool for understanding the mechanisms of abrasive water jet drilling of difficult-to-machine materials
Authors: Kovacevic R , Kwak H-S , Mohan R S
Published: October 2002

For drilling difficult-to-machine materials, abrasive water jet (AWJ) drilling provides several advantages not offered by other machining methods, such as the capability to achieve higher depth-diameter ratios, the absence of a heat-affected zone, and no thermal distortion. An acoustic emission (AE) sensing technique is used to study the material removal mechanisms involved in the AWJ drilling process. The feasibility of using r.m.s. acoustic emission (AERMS) to monitor the AWJ drilling depth on-line is also investigated. Stochastic modelling of the time domain AE signal provides more insight into the physics of the process.
Engineering surfaces—a philosophy of manufacture (a proposal for good manufacturing practice)
Authors: Stout K J
Published: October 2002

This paper considers a new approach to controlling the finishing process of engineering surfaces to ensure that their final topography and surface mechanical properties make them suitable for the intended functional purpose. It is proposed that this ‘engineering’ of the final surface is achieved by controlling the final machining or surface working process to impart the required mechanical properties. It is shown in the paper that some surface engineering processes are already employed by industry but that many of these processes are implemented through an empirical understanding of them. The intention of the paper is to lay down a basis for a more rigorous approach to engineering surfaces for their final function.
Development of a methodology for using function analysis in flexible design strategies
Authors: King A M , Sivaloganathan S
Published: October 2002

This paper shows the development of a function analysis methodology for use in flexible design. This is a strategy to identify common areas of existing designs and then form a new ‘core design’ on which the new designs can be based. A full review of current function analysis techniques is given, from which the new systematic methodology is based. The method has three stages: function identification, function description and function systematization. An industrial case study is given with the function analysis of a powered wheelchair.
An experimental investigation of the filling of a thin section casting and simulation by the finite element method
Authors: Abdullah S , Gethin D T , Bell F
Published: October 2002

A thin section filling model is summarized which adopts a finite element solution to the governing equations. This is compared with three experimental case studies. Two experimental case studies were established in this work, one based on flow visualization and the second on an experiment that uses a short shot method to build an image of the metal flow pattern into a pressure die cast part. This shows how a jet forms at the gate early in the filling stage and that filling is completed in a zone opposite this gate section. When the numerical model was compared with experimental data gathered from a gravity sand casting and a simple semicylindrical section, very good agreement was displayed when a turbulent flow model was adopted. This model was also compared with results from the pressure die cast part, but with less success since at this stage of development it is not capable of capturing the hydraulic losses that are associated with sharp changes in section and flow direction.
Application of the Taguchi method and new hatch styles for quality improvement in stereolithography
Authors: Onuh S O , Hon K K B
Published: October 2002

In recent years, rapid prototyping (RP) technology has been implemented in many spheres of industry, particularly in the area of new product development. Rapid prototyping has the capability to produce a tangible solid part, directly from three-dimensional computer aided design (CAD) data, from a range of materials such as photocurable resin, ceramic and metallic powders and paper. However, in most cases, models built in acrylic-based resin in the stereolithography (SL) process have not yielded the desired quality, which has led to a shift in the use of this resin to more expensive ones that have longer build time. An experimental investigation has been carried out to determine statistically the optimum build parameters with the use of the Taguchi method in order to improve the SL product quality. Two new hatch styles have been developed in this study and a confirmation experiment has shown a significant improvement in part accuracy.
Effective thermal properties of grinding wheels and grains
Authors: Morgan M N , Rowe W B , Black S C E , Allanson D R
Published: October 2002

The thermal properties of the grinding wheel are required for energy partitioning in grinding. This paper describes an investigation of the effective thermal properties of alumina and cubic boron nitride (CBN) grinding wheels. Results are presented for a novel sensor that was designed to measure the bulk thermal properties of grinding wheel samples. The effective bulk thermal properties of the grinding wheel and the effective thermal properties of the abrasive grains were also investigated. It was found that the bulk thermal property is dominated by the properties of the bond and does not account for the improved thermal performance of CBN compared with alumina. Values of the effective thermal conductivities for alumina and CBN abrasive grains are therefore proposed. It is concluded that the effective thermal conductivity of the grains is best obtained inversely from grinding experiments.
Computer aided design of cutters for helicoidal surfaces
Authors: Karunakaran K P , Dhande S G
Published: October 2002

The design of cutters is an important consideration for the manufacture of helicoidal surfaces such as extruder screw surfaces. These surfaces are produced mostly by milling processes using form cutters of end mill type, side mill type or disc type, such as side-and-face mill or grinding wheel. The methodology proposed in the paper addresses the problem of the design of cutters for the machining of helicoidal surfaces. Using the proposed methodology, the characteristic profile(s) of the cutter can be determined from the given cross-sectional profile and lead of a helicoidal surface. By sweeping this characteristic profile along an appropriate path or around an axis, the geometry of the specific form cutter can be obtained. Such a geometry could be a turning tool, an end mill, a side mill, a side-and-face mill or a grinding wheel, depending on the process adopted for manufacture. The proposed methodology can also be used to determine the geometry of the helicoidal surface that will be obtained by using a given cutter. In the paper, the procedure to obtain the geometry of the cutters for machining extruder screws is explained with illustrations.
Assessment of waste streams in electric-discharge machining for environmental impact analysis
Authors: Yeo S H , Tan H C , New A K
Published: October 2002

Since the turn of the century, many manufacturing processes have been systematically and scientifically analysed, with new ones being developed at the same time. This was done with the aim of achieving, through a high measure of innovation, a maximum efficiency in association with current economic manufacturing conditions. There has recently been growing awareness of the need to recognize a balanced approach to market objectives with green requirements. This paper presents a methodology for analysing the environmental impact of electric-discharge machining (EDM). The analytical model of EDM integrates the wear characteristics of the tool and workpiece, and the dielectric fluid flows. The multiple waste streams generated are compared by examining factors such as toxicity and flammability. A case study has been included as an illustrative example. This model may serve as a framework for decision making in process planning and selection of operating parameters.
An intelligent system for selection of grinding wheels
Authors: Li Y , Mills B , Rowe W B
Published: October 2002

This paper describes the development of a neural network system for grinding wheel selection. The system employs a back-propagation network with one hidden layer and was trained using data from reference handbooks. It is shown that a neural network is capable of learning the relationship between the wheel and the grinding process without a requirement for rules or equations. It was further found that a relatively small number of training examples allows the system to produce reliable recommendations for a much greater number of combinations of grinding conditions. The system was developed on a PC using the C++ programming language.
A new criterion for quality monitoring of pulsed laser spot welding using an infrared sensor Part 1: The radiation feature as a criterion for quality monitoring
Authors: Lim D-C , Gweon D-G
Published: October 2002

Many manufactured goods use pulsed laser spot welding in joining and weld quality has to be controlled in particular. This paper suggests a criterion for quality monitoring of pulsed laser spot welding of thin metal sheets using a point infrared (IR) sensor. A new radiation feature is derived from a mathematical model and its properties are examined. Weld quality is closely related to temperature profile and there are many cases that can generate the expected weld quality. Change in weld quality should be detected from the variation in temperature profile. Simulation results show that the radiation feature can be used to detect the change in the initial temperature profile. In the experiments, radiation features and weld cross-sections were examined for various welding conditions. Results show that the radiation feature could detect the dimensional variation of the heat-affected zone (HAZ).
A new criterion for quality monitoring of pulsed laser spot welding using an infrared sensor Part 2: Quality estimation using an artificial neural network
Authors: Lim D-C , Gweon D-G
Published: October 2002

This paper suggests a method for estimating weld quality using a radiation feature. In one experiment the dimensions of the weld joint were examined using the radiation feature. Results show that the feature can be used to estimate weld dimensions. In another experiment, weld strength was estimated using the feature. Since it would be laborious to examine a large number of radiation features and find the explicit relationship, an artificial neural network (ANN) was employed. In experiments, the significant welding parameters were varied within a controllable range and 640 laser spot welds were used for ANN learning. The correlation coefficient between the estimated and the measured strength was as high as 0.98 for learned parts. The other 180 welds were used to appraise the learned ANN. The correlation coefficient between the estimated and the measured strength was as high as 0.95 for the unstudied parts and the mean square error of estimation was as low as 0.78 kgf.
Arc interference and a unique push-pull arc solution in alternating current plasma arc welding of aluminium alloys
Authors: Zheng B , Wang Q L , Kovacevic R
Published: October 2002

This paper analyses the arc interference in an a.c. combined (both the pilot arc and the plasma arc exist in the welding process) plasma arc welding of aluminium alloys. This phenomenon results in an unstable welding process and weld formation. To maintain the pilot arc during the period when the electrode is positive, a cathode region must be formed in front of the tungsten electrode tip. However, to guarantee plasma arc initiation during the same period, this region must be the anode region. Consequently, neutralization of the positive and negative charge in the region in front of the tungsten electrode tip will occur. This will result in the instantaneous disappearance of the conducting region in front of the tungsten electrode tip, which will cause the plasma arc or pilot arc or both to be instantaneously extinguished. Arc interference appears because the potential of the nozzle is unable to adapt to that of the conducting plasma arc column in the d.c. positive electrode mode. A unique push-pull arc solution for solving the trade-off between the arc interference and the reliable initiation of the a.c. plasma arc is proposed and implemented. In addition, high-quality weld formation in the keyhole mode, which is energy efficient and avoids a double arc, is achieved.