bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of pre-straining and grain size on the limit strains in sheet metal forming
Authors: Shakeri M , Sadough A , Dariani B M
Published: October 2002

Forming processes of metal sheets are generally limited by plastic instability phenomena and flow localization. The occurrence of these phenomena is dependent on the material properties such as strain-hardening exponent, strain rate sensitivity, anisotropy parameters and grain size and is also dependent on the strain path. The formability of the sheet metals can be assessed by the forming limit diagram (FLD). In this study, a theoretical model using the ‘many slices’ approach is introduced to simulate the neck growth. The effects of changing strain path and grain sizes on the limit strains are then investigated both theoretically and experimentally. The low carbon steel ST12 and austenitic stainless steel 321 are used in the experimental approach. The theoretical and experimental FLDs of these sheets are obtained for different grain sizes and after pre-straining in uniaxial and biaxial tension parallel to the prior rolling direction. It is shown that the limit strains are quite sensitive to the grain size and strain path. Thus, by selecting the proper strain path and grain size, better formability properties can be achieved. Also, good agreement is obtained between theoretical and experimental results.
Dimensional control as an integral part of next-generation aircraft development
Authors: Jeffreys D , Leaney P G
Published: October 2002

The next generation of both military and civil aircraft are now being designed and developed. Research undertaken by the authors has highlighted particular product and process characteristics that are becoming more critical in the design and manufacturing processes of modern and future aircraft structures. A particular requirement is for reduced assembly variation. This requirement emerges, for example, from design strategies seeking to maximize the structural use of carbon fibre composite materials, from the increasing requirements for low observability in military aircraft and from the need for flight cruise efficiency in civil aircraft. Large companies such as Boeing, McDonnell Douglas and BAE Systems and Industrie have all performed studies in dimensional control. One theme, that emerges is that dimensional control must be exercised with design and manufacturing departments working in close partnership. This is particularly true when considering the introduction of advanced material technologies such as carbon fibre composites and in the application of automation to major aircraft subassemblies. Such challenges are found to occur across both military and civil sectors. This communication highlights some such challenges and identifies a seven-point response for the basic technological infrastructure to support the deployment of an effective dimensional control methodology as an integrated part of the next-generation aircraft product development process. Further work is in progress on detailing and demonstrating such a methodology.
New product introduction practices in the British manufacturing industry
Authors: Williams M A , Kochhar A K
Published: October 2002

The pressures of the modern global market are placing an ever-increasing emphasis on the efficient development and introduction of new products. As a consequence the implementation of an effective business process for managing and controlling product innovation has become vital. Despite this situation, research carried out in this area has identified that the vital pre-detailed development stages of the so-called product introduction process are often the weakest. This paper presents the findings obtained from a set of detailed field studies carried out to analyse the process implemented within seven different manufacturing companies and discusses the implications of the results.
Performance tests characteristic of a pneumatic proximity tactile array sensing device
Authors: Benhadj R , Marrir F , Roome L
Published: October 2002

This paper details the design principles of operation and performance characteristic of a pneumatic proximity-to-tactile sensing device which can be used in part handling, slip detection-monitoring and recognition within flexible manufacturing environments. This sensing device utilizes a densely packed line array of piezoresistive pressure sensors, providing continuous, variable output. The sensing plane of the device incorporates a corresponding line array of air jets which form an air cushion when striking a target of interest. The back pressure data obtained from the proposed tactile sensing device are used to reconstruct a two-dimensional image profile of a target of interest to form the basis for the task of target detection and recognition. In this paper various parameters that can affect the response behaviour of the tactile sensing device are also described and experimental results are presented. Results of the experiments show that the sensitivity measurement of the tactile sensing device decreases with the increase of the number of sensing elements (back pressure air jet) which also reduces the sensing range (distance between the sensing plane and the target). The tactile device presented is a research prototype and has been evaluated on a simple test rig: in this form it is not at a stage where it can be applied to slip detection and part identification of flat surfaces on the shop floor.
Working the boundaries in the motor industry
Authors: Smart P K , Brookes N J , Lettice F E , Backhouse C J , Burns N D
Published: October 2002

Improving product development performance, through changes in organizational structure, has been an important goal for many researchers, organizational development consultants and industrialists in the 1990s. The challenges of the twenty-first century business environment will require a radical re-think of old ideas about formal organizational structures and their impact on company achievements. Perhaps it is time to question whether the choice of any one organizational structure over another is really conducive to improvements in product development performance. The ‘Working the Boundaries’ Project will undertake an investigation into the feasibility of a boundary-based view to product development in the automotive industry. This paper sets the research context and presents some preliminary research findings in the form of a ‘tentative theory’ that suggests the importance of the informal organization based on the network of interrelationships between product developers.
Three-dimensional finite element modelling of laser surface modification
Authors: Labudovic M , Hu D , Kovacevic R
Published: October 2002

A three-dimensional finite element modelling of laser surface modification is presented. The design capabilities of the ANSYS parametric design language (APDL) were employed for this purpose. The model calculates transient temperature profiles and the dimensions of fusion and the heat-affected zone (HAZ). Model simulations are compared with experimental results, acquired on-line using an ultra-high shutter speed camera which is able to acquire well-contrasted images of the molten pool, and off-line, using metallographical analysis, that show very good agreement. The results are further discussed to provide directions for feedback and process control.
User-responsive interface generation for manufacturing systems: A theoretical basis
Authors: West A A , Bowen B A , Monfared R P , Hodgson A
Published: October 2002

Computer integrated manufacturing (CIM) systems with a significant level of human-computer interaction are often inefficient. This is particularly problematical for those users who have to interact with multiple subsystem interfaces. These difficulties can be traced back to the fact that representation of the user in existing manufacturing models and systems is inadequate. An approach that increases user representation to improve CIM interface design is proposed, in which stereotype-based user and task models are used to specify a common user interface for each individual system user. An overview of the architecture is followed by discussion of an application domain (statistical process control) in which a demonstrator based on the architecture has been tested.
Stability of keyhole in plasma arc welding
Authors: Zhang S B , Zhang Y M
Published: October 2002

Stability of the keyhole plays a fundamental role in producing quality welds in keyhole plasma arc welding. Some studies have assumed that keyhole diameter is a stability measurement. However, recent experimental observation by the authors revealed that width is not correlated with stability. To measure stability, this study uses the keyhole width as the lower limit of the weld pool width required to prevent keyhole collapse. Because the maximal width of the weld pool before burn-through is approximately fixed for particular applications, it can be used as the upper limit of the weld pool width for preventing burn-through. Hence, the margins of the keyhole process from collapse and burn-through can be measured based on how close the pool width is to its upper and lower limits. The stability distance and stability factor are then defined based on the margins to quantity the state of the stability of the keyhole process.
A flexible data acquisition system to support process identification and characterization
Authors: van Voorthuysen E J , Platfoot R A
Published: October 2002

A system has been developed to identify relationships between critical process variables for the purpose of process improvement and upgrading. It incorporates process monitoring, large data-set management, data visualization and fine-precision diagnostics. Implementing the process combines a meticulous and rigorous instrumentation selection with a data acquisition strategy. The identification of key process variables follows an Ishikawa process and is incorporated into a process model that supports the diagnostic function. A case study testing this methodology for a commercial gravure printing process was successfully completed. Understanding the mechanical behaviour of critical variables required data acquisition at sampling times up to 20 ms. Data analysis was carried out in time, amplitude and frequency domains. The result of this work was a series of practical recommendations to reduce waste within the printing process.
An automated inspection planning system for coordinate measuring machines
Authors: Zhang S G , Ajmal A , Wootton J , Chisholm A
Published: October 2002

This paper outlines a prototype automated inspection planning system for coordinate measuring machines (CMMs). This system consists of five functional modules: tolerance information input, accessibility analysis, clustering, inspection path generation and inspection process simulation. The theoretical and practical methodologies that are applied in the corresponding five functional modules are also outlined. An example demonstrates the general process for the application of the automated inspection planning system. The test result shows that the proposed theory and methods can be used for automatic generation of an inspection process plan for a CMM.
Product range models supporting design knowledge reuse
Authors: Costa C A , Young R I M
Published: October 2002

Redesign, where previous information is recovered in order to be adapted to a new situation, is an area of design where information technology can potentially provide substantial benefits. Information support to product design and manufacturing has been pursued through the use of product and manufacturing models. This paper introduces a new concept of a complementary information model, called a product range model, that aims to support variant and adaptive design activities. The general concept and structure of such an information model is defined in terms of product functions and their respective design solutions. The interactions taking place between particular design solution options are discussed, and methods are proposed for their evaluation against product specifications and design constraints. The concept of knowledge links is introduced to maintain the relationships between solutions within the product range model and the particular model of the product being developed. The work has been explored using injection mould tooling as an appropriate product range and evaluated through the design and implementation of a design support system utilizing an object-oriented database.
A software environment for flexible manufacturing system control software testing
Authors: Bi Z M , Zhang W J , Li Q
Published: October 2002

The development of flexible manufacturing system (FMS) control software is a complex task in terms of both the hardware and the software. It is therefore an important task to provide testing facilities for FMS control software in the course of its development. This paper reports on the development of an FMS control software testing environment. The architecture of this testing environment is built to make the system open and intelligent. The openness is achieved to allow for the change in requirements, and the intelligence is meant to reduce manual work in software testing. A generic Petri net (GPN) model representing the behaviour of an FMS is introduced. A set of algorithms for detecting faults in the operation of an FMS control software program is proposed on the basis of the GPN model.
Design of a tool management system for a flexible machining facility
Authors: özbayrak M , De Souza R B R , Bell R
Published: October 2002

This paper addresses the design of an integrated tool management system for flexible machining facilities (FMFs). Modules with functions ranging from issuing tools according to a tooling strategy to diagnosing system operation have been developed and integrated around a centralized manufacturing database to guarantee streamlined manufacture. A review of the state-of-the-art tools to model an automated tool management system (TMS) within flexible machining facilities is presented first, in order to establish the merits of different design approaches. The approaches used in modelling, the structures and the functions of the modules are presented. Finally, a walkthrough example utilizing the design facility presented is given with an illustration of typical results.
The design process and a methodology for system integrity
Authors: Raine J K , Pons D , Whybrew K
Published: October 2002

Commonly used models of the design process do not reflect concurrent engineering, the influence of computer-assisted design on the design process, or the recursive divergent-convergent thinking processes at different levels of detail from whole system to subsystem to component design. Also, these models do not illustrate the process of establishing functional integrity in the design of multicomponent systems where multiple interdependencies are present. This paper outlines design model developments by the authors and introduces a methodology for designing for system integrity and minimizing risk from early in the conceptual phase, where uncertainty is high. The process involves probabilistic reasoning in propagating both qualitative and quantitative effects of changes or uncertainty in component or subsystem specifications through system models and determining the integrity of the design from multiple viewpoints.
Development of safer recreational trampolines
Authors: Alexander K
Published: October 2002

Recent research in New Zealand showed that trampoline injuries had risen 300 per cent in the preceding 10 years and that 2800 people (almost 0.1 per cent of the population) had been seen each year in hospitals as a result. These injuries arose from unsupervised recreational use of trampolines in backyards and playgrounds. Researchers and trampoline enthusiasts offered preventative measures which, while effective, were in many cases incompatible with how recreational trampolines were inevitably used. The present author believed that many of the injuries would be prevented if trampolines could be redesigned to remove the steel frame, springs and the holes between the springs from around the jumping area. As a result several soft-edged trampolines were built and tested. Tests were developed to compare performance with conventional trampolines. Edge stiffness was compared with standards for safety pads on trampoline frames. Market and production requirements were also significant since the new units need to compete with mature competitors. One solution that appears to meet most requirements is close to market release. This is described and compared with conventional recreational trampolines.
Numerical design of a new forging press drive incorporating non-circular gears
Authors: Doege E , Meinen J , Neumaier T , Schaprian M
Published: October 2002

Manufacturing processes as well as products have to be improved continually to meet all the requirements of international competition. Along with economic demands, changing consumer and environmental legislation lead to increased pressure for new and advanced products and processes. Consequently, the forging industry continually tries to improve hot forging processes. Precision hot forging technology, used for the production of connecting rods, bevel gears, straight planet gears, helical gears, clutch gearing or constant velocity joints, has been improved constantly [1–3]. Precision forging is carried out with closed dies in order to guarantee the continuous quality of the workpiece and to avoid possible damage to the forged parts by clipping or piercing operations. Many variables influence the quality of the final product and the economics of the process, especially the workpiece temperature, the die temperature and the pressure dwell time. High workpiece temperatures lead to high temperatures on the surface of the dies. Therefore, the temperature load depends directly on the pressure dwell time. Excessive temperature loads inevitably lead to damage of the dies [4]. This article presents a numerical study of a new press concept using non-circular gears in the drive mechanism. The new press kinematics result in a reduced pressure dwell time in comparison with a conventional press kinematic.
Experimental study of workpiece-level variability in blind-via electroplating
Authors: Poon G K K , Chan J S F , Williams D J
Published: October 2002

The acid copper electroplating process for the manufacture of printed wire boards was studied by statistical techniques. The objectives of this study were to investigate the effects of process and product parameters on the workpiece-level uniformity during the acid copper plating of blind vias and to explore the minimization of the deposit thickness variation. The parameters studied were the concentrations of copper sulphate, sulphuric acid and additive, average current density (ACD), electrode separation (ES), the aspect ratio and the depth ratio of the via holes. Multifactor two-level factorial and the central composite rotatable five-level experiments were designed and conducted sequentially to generate statistical process models. Only the average current density and the electrode separation were found to be significant. A second-order model was then developed for the process in the proximity of the optimum region and verified experimentally to locate the optimum combinations of ACD and ES with respect to minimum thickness variability across the whole workpiece. Post-optimal analysis showed that the optimum solution was more sensitive to the electrode separation than the average current density.
An initial investigation into active disassembly using shape memory polymers
Authors: Chiodo J D , Harrison D J , Billett E H
Published: October 2002

The aim of the work was to demonstrate an alternative to conventional end-of-life (EOL) disassembly strategies such as robotic or hand dismantling. This initial investigation reports the disassembly of consumer electronic products using smart materials in the design of embedded releasable fasteners. A series of products was tested in a variety of different ways using shape memory polymers (SMPs). Tests were run on macroassemblies and subassemblies of telecommunications goods. The devices designed with SMP used two distinct properties of the material suited to active disassembly:

the mechanical property loss (MPL), in this case a loss of rigidity in the thread of the SMP screws; the shape memory effect (SME), a change in form, resulting in this case in the loss of moulded thread from SMP shape memory effect screws.

Once SMP components were developed and embedded into the candidate products, timed disassembly experiments were conducted. These tests used infrared, air jet and water bath methods for applying heat to trigger the SMP devices. Once the trigger temperature was reached, shape change and property loss occurred in the screws and brackets, allowing assembly release.
An Internet-enabled technology to support evolutionary design
Authors: Kryssanov V V , Tamaki H , Ueda K
Published: October 2002

This paper discusses the systematic use of product feedback information to support life cycle design approaches and provides guidelines for developing a design at both the product and the system levels. Design activities are surveyed in the light of the product life cycle, and the design information flow is interpreted from a semiotic perspective. The natural evolution of a design is considered, the notion of design expectations is introduced and the importance of evaluation of these expectations in dynamic environments is argued. Possible strategies for reconciliation of the expectations and environmental factors are described. An Internet-enabled technology is proposed to monitor product functionality, use and operational environment and to supply the designer with relevant information. A pilot study of assessing design expectations of a refrigerator is outlined, and conclusions are drawn.
Designing and life cycle engineering—a systematic approach to designing
Authors: Eder W E
Published: October 2002

Engineering a system for its whole life cycle involves the phase of designing the system, when all requirements for function, capabilities, life cycle and societal (economic, ergonomic, aesthetic, law conformance, etc.) properties should be established, and as far as possible fulfilled. Designing need not be just an intuitive and idiosyncratic procedure—it can be made more rational.

Design Science has set itself the goal of providing a comprehensive theory. Theories cannot be directly applied. Methods and models derived from the theory can be applied if the relevant parts of the theory are understood (at least at an awareness level) by the applying designer, and the actions and documentation are demanded by design management. The resulting improvement in the process will also render the design process more transparent, and open to review and audit, as demanded by the ISO 9000 series of quality standards. Some contacts with the disciplines of systems engineering and life cycle engineering are indicated. Most formal models of design processes are formulated for novel design problems. They can help to clarify the problem in a more formalized way. Design Science can effectively be applied to novel or redesign problems.
Indirect selective laser sintering of metal parts with overhung features
Authors: Volpato N , Childs T H C , Stewart T D , Watson P
Published: October 2002

The manufacture of metal parts by indirect selective laser sintering (SLS) involves initially joining metal powders with a binder to form a fragile green part. The green part is then placed in a furnace where the binder is removed and the metal powder is sintered. An infiltrant such as copper or bronze can then be used to fill the pores in the structure to result in a fully dense part. For sections of the part which are supported from underneath the basic shape is usually retained to a reasonable accuracy during the furnace stage. However, unsupported features tend to fracture or warp. This paper describes a way of manufacturing metal parts with overhanging or unsupported features, by combining new SLS technology with traditional foundry technology.
Recognition of machine cells in a group technology layout using self-organizing neural networks
Authors: Rao M Ananda , Rao M Sreenivasa , Srinivas J , Krishna P V Gopal
Published: October 2002

Today, many organizations are following traditional manufacturing layouts. These are easy to form, but involve very high overall manufacturing cost. An alternative is to introduce a cellular manufacturing system in modern production shops, which recognizes the existence of machining groups and their dedicated component families in discrete lot manufacturing. The essential problem in implementing cellular manufacturing is in the identification and formation of the machine cells. This paper proposes a new methodology for cell formation utilizing a syntactic pattern recognition approach. The selection of an appropriate cell for a new part is based on the operational information of the part. With the use of self-organizing neural networks, the machine cells are identified. Results are presented with a numerical example.
Machining of martensitic stainless steel (JETHETE) with coated carbides
Authors: Jawaid A , Olajire K A , Ezugwu E O
Published: October 2002

Tool life and wear models were fitted for machining a martensitic stainless steel (JETHETE) with three ceramic-coated carbides [CVD-Ti(C,N)/Al2O3 (T1), CVD-Ti(C,N)/TiC/Al2O3 (T2) and PVD-TiN (T3)] using statistical regression analysis. The statistical analysis revealed the contribution of the cutting speed and feed rate to tool performance to be in excess of 80 per cent, with the cutting speed showing the greater degree of influence. Significant nose wear was the common failure mode observed at higher speed conditions. Plastic deformation and chipping/fracture at the cutting edge were additional failure modes observed when machining with the T2 and T3 tool grades respectively. The coarse grain size and high cobalt content contributed to the very poor performance of the multicoated T2 grade insert, while the improved microhardness of the PVD-TiN coating gave the single layer coated T3 grade a comparable performance with the multicoated T1 grade. Attrition wear was the principal wear mechanism at lower speed conditions, while dissolution/diffusion and abrasion were additional wear mechanisms when machining at higher speed conditions. A higher degree of diffusion wear occurred on the T3 grade insert owing to the relatively lower level of cubic carbides in the tool composition.
A computer numerically controlled dieless incremental forming of a sheet metal
Authors: Matsubara S
Published: October 2002

In a previous paper a new incremental tube-forming method was proposed in which forming is carried out by a series of movements of a hemispherical head tool without using any die or mandrel that corresponds to the product shape. This paper aims to develop a similiar method that can form flat metal sheets into three-dimensional shapes without using dedicated dies. For this purpose, very simple and compact tooling is devised and put on the bed of a numerically controlled (NC) machine tool. It can be controlled with an NC program, which is made by commercial CAD/CAM (computer aided design/manufacture) systems. The method is broadly applicable to any product where the outer surface is convex, and is examined for the forming of an aluminium sheet into cones and pyramids having an arbitrary number of sides with a half-apex angle with a minimum of 10°. Sharp edges between adjacent sides of the pyramid are easily formed. The ratio of the wall thickness of the product to that of the original sheet corresponds with the sine of the half-apex angle of the pyramid, and the sine law in shear spinning holds. The outer surfaces of the products have a glossy appearance due to ironing by the tool.
Process strategies for sheet metal hydroforming of lightweight components
Authors: Geiger M , Vahl M , Novotny S , Bobbert S
Published: October 2002

Lightweight construction is based on parts with high strength and low weight. This has triggered the development of innovative forming technologies such as hydroforming, which is already in industrial use for the manufacturing of parts that can be formed out of tubular semifinished goods. New research is now being carried out on sheet metal hydroforming. Hollow parts with large differences in diameter and high strength can be produced in one tool by hydroforming unwelded sheet metal pairs. There is great potential for this technology, but various challenges lie in process limits such as leaking and bursting, in wrinkling with or without induction by the flange geometry and in the process-specific material behaviour. Using state-of-the-art tools for process design, solutions to these issues are proposed and possibilities of processing lightweight materials such as aluminium or magnesium alloys at elevated temperatures are outlined.
Metallurgical aspects relating to the production of ferritically hot-rolled interstitial-free steel
Authors: Barrett C J , Wilshire B
Published: October 2002

Although ferritic hot rolling was introduced to avoid the temperature control problems that can be encountered during traditional hot rolling of thin strip in the austenite condition, numerous advantages are offered by finishing the hot rolling operations with a fully ferritic microstructure. Laboratory hot rolling facilities and procedures were therefore developed to establish the influence of variations in the reheating, finishing and coiling temperatures on the microstructure and mechanical properties of interstitial-free (IF) steels. Processing schedules suitable for both recrystallized and strained ferritically hot-rolled IF steels are identified and discussed in relation to the feasibility of manufacturing these products using conventional hot mills.
A composite tool for ball endmilling
Authors: Koshy P , Aspinwall D K , Dewes R C
Published: October 2002

The paper reports on the performance of a novel composite ball nose endmill that utilizes cermet and tungsten carbide indexable inserts on the same cutter body, with a view to optimizing both tool life and workpiece surface roughness. The technique exploits the asymmetric design of the cutter to position the cermet and tungsten carbide inserts appropriately, so that their characteristic tribological attributes are consistent with the functions of surface generation and wear resistance. Experimental work on ball endmilling of hardened AISI H13 tool steel is presented to illustrate the concept. The mechanism of performance enhancement of the composite tool is also detailed with reference to the flank wear pattern of the inserts and the morphology of the machined surface.
Development of an algorithm for tungsten inert gas welding of an austenitic stainless steel sheet
Authors: Tušek J , Markelj F
Published: October 2002

This paper examines the development of an algorithm for manual and robotic tungsten inert gas (TIG) welding of austenitic stainless steel sheet with a thickness of 0.9–2.0 mm. Generally, an algorithm is a means of describing an optimum course of a technological process and includes mathematical models for computation of individual quantities. In the present case the algorithm optimizes the course of TIG welding and welding parameters. It includes mathematical models for the computation of optimum welding current intensity, welding speed, energy input, arc length, gas flowrate and diameter of the non-consumable tungsten electrode as a function of sheet thickness. A general algorithm for manual and robotic welding of a butt-welded joint with a plain butt weld and a complete algorithm for four welded joints on a sheet with a thickness of 0.9–2.0 mm are stated. Conclusions are drawn and guidelines for future work are given.
A hybrid neural network-feature-based manufacturability analysis of mould reinforced plastic parts
Authors: Marquez M , White A , Gill R
Published: October 2002

The purpose of this research is to establish a method to perform manufacturability analysis of reinforced plastic components by using a hybrid system including automatic feature recognition and a feature-based assessment of manufacturability. Feature recognition plays a fundamental role and is usually the first step in downstream activities concerning the product development process, such as design for manufacturing, design for assembly and process planning.

Critical features to successful reinforced plastic moulding are identified, and the relationship between geometric information of the model, expert geometric reasoning and knowledge of related manufacturing processes is clarified and predetermined in a useful and efficient manufacturability analysis system. A prototype system using solid modelling, object-oriented programming and a rule-based system, which is intended to consider the fuzziness of the expert reasoning about reinforced plastic component design, is under construction to test the proposed concepts. The major contribution from this work is a consistent and systematic methodology for analysing the geometry of models, allowing assessment of manufacturability. This methodology considers available manufacturing process capabilities, materials and tooling required. Some virtual parts have been used to test the system, showing promising results.
Optimal process plans for manufacturing and tolerance charting
Authors: Thimm G , Britton G A , Whybrew K , Fok S C
Published: October 2002

A graph theoretical approach is presented that permits the calculation of optimal process plans from datum hierarchy trees, which are elegant representations of tolerance charts. The theory is developed for a cost function that minimizes machine and datum changes. Restrictions on the sequence of machining operations arising from technical constraints or the layout of a group cell are taken into account. The process plans are optimal with respect to a specified datum hierarchy tree, manufacturing constraints and cost function. It is shown that the number of possible plans for real industrial trees is very large, and therefore this kind of optimization is beyond the ability of a human process planner. Trial runs with industrial parts indicate that optimization can be performed by a computer within a time period that is acceptable for industrial use.
Manufacture of production injection mould tooling incorporating conformal cooling channels via indirect selective laser sintering
Authors: Dalgarno K W , Stewart T D
Published: October 2002

This paper reports the results of a study designed to assess the extent to which layer manufacture processes were able to produce production quality injection mould tools. The specific layer manufacture process considered was the DTM RapidTool process. Tools produced using this process were used in industrial trials to assess productivity benefits arising from the use of conformal cooling channels and to investigate tool wear. A cost model of the injection moulding process has been developed to investigate the economic case for the use of layer-manufactured tools. It is concluded that significant productivity benefits are available through the use of conformal cooling and that the RapidTool process is economically competitive with existing production tool manufacture methods for injection mould tools which do not require significant finishing. Future developments in layer manufacture technology are expected to offer further challenges to conventional tool manufacture methods.
Investigation of internal cracking and its prevention during induction heating of cold-forged parts
Authors: Shivpuri R , Pauskar P , Kini S
Published: October 2002

With the trend towards manufacturing large complex shaped parts by cold forging followed by hot forging, problems such as internal cracking during the induction heating of a cold-forged workpiece have become common. One way to solve this problem is to have an annealing step after cold forging. However, this solution adds to the manufacturing operation the additional cost of annealing and post-annealing lubrication. In this investigation, internal cracking was studied by developing numerical models of the cold forging and induction heating processes. These models were applied to several industrial cases of failed as well as successfully forged parts. It was found that the main causes of internal cracks include excessive deformation during cold forging which damaged the material matrix and high tensile thermal stresses during induction heating which led to crack propagation. On the basis of this analysis, recommendations for preventing internal cracks were developed for H8620 steel, which provided for the design of a successful cold forging deformation sequence and induction heating cycles.
Investigation of end cracking and its prevention by a double reduction die in the cold extrusion of automotive parts
Authors: Shivpuri R , Pabalkar A , Kini S
Published: October 2002

End cracking failures occur randomly during cold extrusion of automotive shafts or sometimes even during service. Finite element analysis of this failure shows that cracking is primarily due to a combination of damage during cold deformation and tensile unloading at the exit of the die land. This paper proposes a failure mechanism and a stress-based failure criterion for this cracking. It analyses the original single die design and investigates a double reduction die design, which was patented for the extrusion of brittle materials. It is seen that while the double reduction die reduces end cracking, it increases the probability of chevron cracks at the part centre. Finally, a design of experiments technique is used for determining the optimum die design parameters for the minimum tensile stress state both at the surface and at the billet centre. Production validation experiments confirm the efficacy of the optimal die design in suppressing the initiation of end cracks without the need for special billet shearing or annealing procedures.
Surface blending for machining purposes: A brief survey and application for machining compound surfaces
Authors: Hatna A , Grieve R J , Broomhead P
Published: October 2002

Rolling ball blending techniques are widely used for rounding edges and corners of mechanical parts in computer aided design. The techniques of computing trim curves for blending are used in this paper to delimit the domains of machinability of parametric surfaces. Whereas the principle of the rolling ball can be used for machining single or compound surfaces, the focus here is only on compound surfaces. A survey of existing methods is given followed by an application for a new approach for the generation of flow line tool paths.
A multisensor-based system for manufacturing process monitoring
Authors: Hu W , Starr A , Leung A
Published: October 2002

In order to improve the availability and productivity of manufacturing systems, process monitoring has become an important matter in modern automated plants. The traditional monitoring technologies are based on single sensors and are inadequate, especially for manufacturing processes of highly complicated and automated systems. Instead, multisensor-based technologies are developing rapidly and are widely used for such monitoring tasks. This paper introduces a multisensor-based process monitoring system for an existing machining centre. The system can monitor the major manufacturing process faults or abnormalities of the machining centre and provide maintenance planning through measuring and analysing multiple sensor parameters such as power, vibration, temperature and pressure of spindle, feed axes and hydraulic and pneumatic systems of the machining centre. The general structure of the monitoring system and the implementation of the main steps of the monitoring system development are presented in detail.
Common generic model of the holonic manufacturing systems project
Authors: Fletcher M , Deen S M
Published: October 2002

This report discusses the common generic model for developing the next generation of low-volume high-variety manufacturing systems geared towards the making of highly customized products. This model has been developed through phase I of the international consortium on holonic manufacturing systems.
An experimental study on thixoforging of semi-solid materials and solutions for avoiding defects
Authors: Cho W G , Kang C G
Published: October 2002

commercial semi-solid cast aluminium alloy A356 and extruded wrought alloy A12024 were used to fabricate an arbitrarily shaped part by thixoforging. Thixoforging was conducted with four different die temperatures ( Td = 400, 350, 300 and 250°C) and two levels of applied pressure ( P = 100 and 150 MPa). The influence of process parameters on the defects in the thixoforging process of cast and wrought aluminium alloys is discussed in terms of the microstructure of each alloy. The fabricated components were heat treated to T6, and the mechanical properties were also investigated as a function of the process parameters. Various defects were observed, particularly at the lower die temperatures. It was necessary to increase the punch speed and to optimize the gate design. The tensile properties improved with increasing applied pressure.
Cutting conditions and tool optimization in the high-speed milling of aluminium alloys
Authors: López de Lacalle L N , Lamikiz A , Sánchez J A , Cabanes I
Published: October 2002

The high-speed milling (HSM) of aluminium alloys was one of the first fields of application of this technology. It might be thought that this is the field where the technology has been most commonly used, with the largest number of users, and is therefore best known. However, the continuous improvements in modern machine tools on the one hand, together with the development of new tool materials and tool geometries on the other, have produced a constant increase in the cutting conditions (i.e. speed and feed rate). During the past 5 years the use of high-silicon (12–21 per cent) castings has grown considerably owing to the fact that a high silicon content results in excellent properties, mainly wear and high-temperature resistance. However, the machinability of the material becomes too poor on account of its abrasiveness.

Aluminium alloys for structural elements in the aeronautical industry are nowadays high-speed milled (HSMed) at very high removal rates, which makes possible the use of monolithic structures instead of sheet metal formed structures. Complete removal of coolant fluids has not been possible so far, but their use can be effectively minimized if techniques such as micropulverization are applied. In this paper, the problems in the machining of the previously mentioned alloys are analysed, along with the possibilities of the so-called minimum quantity of lubricant (MQL) technique.
Modelling and computer simulation of grinding of the ball end type rotating cutter with a constant helical angle
Authors: Wu C-T , Chen C-K , Tang Y-Y
Published: October 2002

This paper presents a systematic method for design and manufacturing of the circular arc type ball end rotating cutter. By using the principles of differential geometry, the correlative models and simulation results on the cutting edge are presented. On the basis of the engagement condition, approaches for solving inverse problems related to the manufacturing models are also presented. The section profile and relative feeding speeds of grinding wheels in machining processes are deduced. The effects of design and manufacture of the cutter are analysed according to the computer simulation result for the groove surface enveloped by the grinding wheel. In addition, the deviation of cutting edge, residual material and lack of land caused by the modified radial feeding speed are discussed. In order to finish the residual material and to rebuild the land of the cutter, a post-process method has been developed in this research.
On process modelling for selective laser sintering of stainless steel
Authors: Katz Z , Smith P E S
Published: October 2002

The principle of the laser sintering process as applied to stainless steel powder for rapid prototyping is discussed. The work attempts to present and explain the process modelling concept with respect to potential analytical/empirical relationships between the input and output parameters. It considers aspects related to process behaviour, material characteristics, laser parameters and product accuracy. A comprehensive experimental set-up with empirical results is presented.
Development of a quality estimation model using multivariate analysis during resistance spot welding
Authors: Cho Y , Kim Y , Rhee S
Published: October 2002

Several researchers have studied the quality assurance of resistance spot welding using various methods. Because of the characteristics of the spot welding process, many problems arise when the weld quality is examined non-destructively in the in-process system. In order to solve such problems in this study, the process variables were monitored from the welding machine timer, from which it is possible to estimate weld quality in a real-time in-process system. For quality estimation, the factors were extracted as indices from the primary circuit dynamic resistance patterns, which were measured in the welding machine timer. The relationship between the indices and strength of the welds was observed through the correlation analysis. Using the indices, regression models that could estimate weld strength were obtained by regression analysis and factor analysis. Among the models, the most effective model was a stepwise-type regression model. Also, it is shown that the results of the proposed estimation models were consistent with the weld strength obtained through the experimentation.
A theoretical and experimental investigation of thrust and torque in vibration microdrilling
Authors: Wang L-P , Wang J-S , Ye P-Q , Wang L-J
Published: October 2002

A method for predicting the thrust and torque in vibration microdrilling is proposed. The model is based on the mechanics of vibration cutting analysis, which involves the development of a dynamic uncut chip thickness analysis for each vibration cutting element at the lips and chisel edge. The proposed method has been tested for a range of vibration parameters and feeds. The predicted thrust and torque values have been compared with those obtained in vibration microdrilling experiments. These comparisons showed good agreement between the theoretical predictions and the experimental evidence.
An investigation of material removal in polishing with fixed abrasives
Authors: Zhang L , Tam H Y , Yuan C-M , Chen Y-P , Zhou Z-D
Published: October 2002

This paper investigates the removal of material from a surface during polishing with fixed abrasives. The material removal profile prescribes the amount of material removed from the surface along a direction orthogonal to the tool path as a polishing tool is moved along the surface. It depends on the geometry and mechanical properties of the tool and the surface as well as on the polishing condition. A wear index for polishing is introduced to relate the material removal to the polishing condition. On the basis of the wear index, an approach for calculating the material removal profile is developed. It assumes that the pressure distribution is Hertzian at the contact between the tool and the surface. Polishing experiments are conducted which consist of polishing convex surfaces with cylindrical tools and concave surfaces with spherical tools. The proposed approach has been confirmed by measurements of material removal profiles in these experiments.