bluuebunny/crossref_metadata_2025 huggingface dataset:
Fifth octave mode chatter in rolling
Authors: Hu P-H , Ehmann K F
Published: October 2002

An analytical model making it possible to determine rolling mill stability against fifth octave mode chatter is introduced. The constituents of this model, i.e. a linearized dynamic process model and a structural dynamics model, are defined and combined to obtain a complete expression of mill behaviour under dynamic conditions. Subsequently, mill stability is investigated, using established linear system analysis methods, as a function of a number of mill operational parameters. Finally, illustrative simulation examples are used to highlight typical mill responses in the presence of impending fifth and third octave mode instabilities.
Characteristics of rotary forging as an advanced manufacturing tool
Authors: Standring P M
Published: October 2002

Modern manufacturing requirements demand short lead times and cost effective flexible production. This paper describes how the incremental deformation process known as rotary forging is able to meet these needs. Fundamentally important process developments are presented and discussed. The nature of incremental deformation is introduced and the types of rotary forging systems explained. Tooling factors, state-of-the-art machine design and processing actions are included. Examples of some applications and processing characteristics are provided to assist process understanding and possible take-up.
Fluid drag, ball interaction and gyroscopic effects in magnetic fluid grinding
Authors: Chang F Y , Childs T H C
Published: October 2002

Experimental studies of the magnetic fluid grinding process have previously established that it is an abrasive grinding process. Sliding between the material being ground (for example, a ceramic ball being finished) and the grinding surface occurs because of viscous drag forces and torques acting on the ground material as it is driven through a magnetic liquid. Mechanical models of the process have qualitatively predicted trends in grinding rates resulting from changes in operating conditions, but have not been quantitatively accurate. This paper establishes that the reason is inaccurate modelling, in the previous work, of the fluid drag forces and torques. Improved modelling now gives accurate prediction of the motions in a grinding cell. Interactions between balls travelling in a train and gyroscopic effects are also reported on; they are of secondary importance in influencing slip magnitude at the grinding surface but do provide mechanisms for randomizing ball motions.
A computer aided process planning system for concurrent engineering
Authors: Pham D T , Gologlu C
Published: October 2002

This paper present ProPlanner, a hybrid computer aided process planning (CAPP) system designed to facilitate concurrent product development. ProPlanner automates information acquisition, product design interpretation, manufacturing operation planning, cutting tool selection, set-up planning and operation sequencing. The system employs a hybrid approach utilizing a combination of rule-based reasoning and object-oriented programming. It enables the early detection of design errors during the design stage before manufacturing and incorporates a feedback mechanism for correcting errors and giving suggestions to modify the product design.
A three-dimensional transient numerical model of milling
Authors: Bacaria J-L , Dalverny O , Caperaa S
Published: October 2002

This paper presents a transient numerical model of metal cutting using a milling operation. This finite element model takes into account dynamic effects, thermomechanical coupling with a damage criterion and contact with friction. The yield stress takes into account the strain, the strain rate and the temperature in order to reflect realistic behaviour in metal cutting. The simulation of an unsteady process needs a separation criterion (chip criterion), and thus many of the models in the literature use an arbitrary criterion based on either the effective plastic strain, the strain energy density or the distance between nodes of parts and the tool edge. The damage criterion adopted in the model presented here allows the definition of advanced simulations of tool penetration into the workpiece and of chip formation. The originality of such a criterion is that it is applied on all the workpiece and enables complex tool trajectories. This damage criterion has been defined from tensile tests for 4140 steel (corresponding to 42CD4 in the French standard), and it has been used for the machining process. Stress distributions, chip formation and tool forces are shown at different stages of the cutting process.
Layer manufacture of jewel ring by volume efficient methodology
Authors: Young Y Y , Yu K M , Kwong C K
Published: October 2002

Rapid prototyping (RP) technology has been widely used in making prototypes for quite a long time. However, an in-depth study of methods used to fabricate jewellery products with RP is not available. In this paper, a new direct and adaptive slicing methodology is applied to three-dimensional solid jewel ring models to produce maximum inscribed three-dimensional stacked slab models. Jewel rings that are symmetrical in one or more principal planes XY, YZ and ZX are considered. The maximum inscribed slab model will minimize material wastage in post-treatment processes and preserve the symmetric property of the original jewel ring model. A solid torus is used as a simplified representation of the jewel ring in the description of the methodology. A case study based on the methodology is presented.
Injection moulding simulation of filling and post-filling stages based on a three-dimensional surface model
Authors: Zhou H , Zhang Y , Li D
Published: October 2002

Filling and post-filling simulation packages of injection moulding have had success in predicting the behaviour of a polymer melt in extremely complicated geometries. Most of the current numerical solutions are based on a hybrid finite element-finite difference scheme and the middle-plane model. This middle-plane model leads to substantial defects during applications of the simulation tools. Instead of using the middle plane as the datum plane, the surfaces of the cavity are used as datum planes in this paper. Additional boundary conditions in the gapwise direction are employed to keep the flows in the surfaces at the same section coordinated. Also, comparisons with the experimental results obtained with instrumented test mould and C-Mold results show that this presented simulation is correct and reliable.
Prediction of processing parameters for injection moulding by using a hybrid neural network
Authors: Yarlagadda P K D V
Published: October 2002

In the present work attempts have been made to determine the process parameters that could affect an injection moulding process based on governing equations of the mould-filling process. Focus is then directed to parameters that require the use of trial and error methods or other complex software to determine the process parameters. The two parameters that are predicted from the developed network are injection time and injection pressure. In this work, the training data are generated by simulation using C-MOLD flow simulation software. A total of 114 data points under different process conditions were collected out of which 94 data points were used to train the network using MATLAB and the remaining information was used for testing the network. Two algorithms are used during the training phase, namely the error back-propagation algorithm and the Levenberg-Marquardt approximation algorithm. Results showed that the latter algorithm is more suitable for this application since the Levenberg algorithm converged rapidly with fewer training cycles when compared with the error back-propagation algorithm. The accuracy of the developed network has been tested by predicting the injection pressure and injection time for few engineering components.
Characterizing failures in design activity
Authors: Busby J S
Published: October 2002

A study was conducted of errors made during the design process in an organization that designed complex, hazardous installations. About 90 errors were investigated, and all were represented individually by a causal tree. Each case was categorized according to the particular activity that was implicated in the error in order to find out how error was distributed over the design process. The more fundamental causes of these errors—those without more basic causes in the causal trees—were compared, and an attempt was made to identify their instrumental elements. These instrumental elements included properties of the design task (such as idiosyncrasy, uncertainty and redundancy), properties of the inferences designers drew from their experience, properties of the organizational environment and properties of the models used by designers.
Analytical modelling of the effects of manufacturing errors on the accuracy for a TRR-XY hybrid parallel link machine tool
Authors: Chen S-L , Chang T-H , Hsei M-H
Published: October 2002

Using a parallel link mechanism as the basic structure of the parallel link machine tool is a new design concept and has become one of the most important research fields and attracts many previous researchers. However, the application of these machines as a machine tool has not proven itself in terms of accuracy enhancement over traditional machine tools. In general, the geometry of the machine tool (moving platform size relative to base size) has significant effects on the level of accuracy achievable. Therefore, an error model analysis for the parallel link machine tool to take advantage of the geometry to minimize the error and to increase the accuracy is very important and interesting and is focused on in this research. A TRR-XY hybrid five-degree-of-freedom parallel link machine tool is built for this research to investigate the error model theory. The errors from the component machining and assembly are defined and considered in the inverse kinematic solution. The effects of the manufacturing errors on the accuracy of the machine tool are shown in this research.
Selective laser sintering of a crystalline and a glass-filled crystalline polymer: Experiments and simulations
Authors: Childs T H C , Tontowi A E
Published: October 2002

A previously developed two-dimensional, thermal finite element simulation of the selective laser sintering (SLS) of amorphous polymers has been extended to the study of crystalline and composite crystalline polymers. Three developments were needed: the inclusion of the latent heat of melting; modification of the amorphous viscous sintering law to allow for the crystalline fraction of material during melting; and allowance for the CO2 laser radiation to be absorbed over a finite depth of the powder bed. The simulation is based on a continuum view of heat conduction in the powder bed. When it is applied to the SLS of nylon-12 parts, its predictions of how density and size accuracy depend on the laser energy absorbed by the powder bed can be brought into agreement with experiments by appropriate choices of sintering and absorption law parameters. However, when the simulation is applied to SLS of glass-filled nylon-11 parts, its in-plane size accuracy predictions are incorrect. It is speculated (based on experimental observations of sintered microstructure) that the continuum view of heat conduction is inadequate and that consideration must be given to differential absorption of laser radiation in the glass and polymer fractions of the powder. A final application of the simulation suggests that the ambient temperature of the powder bed must be held to within 4°C of its set value to maintain process accuracy.
Study on acoustic emission in machining hardened steels Part 2: Acoustic emission during continuous chip formation with a non-overlapping cutting arrangement
Authors: Barry J , Byrne G
Published: October 2002

The sources of acoustic emission (AE) in the machining of hardened steels have been investigated using a novel ‘non-overlapping’ cutting technique, in which the depth of cut increases with tool path. The relationship between AERMS and depth of cut was found to vary considerably; depending on work material hardness and cutting speed, AERMS may increase, remain constant or decrease with increases in depth of cut. The lack of proportionality between AERMS and the combined work rate of plastic deformation and sliding friction contrasts with the current models of AE in metal cutting, for which plastic deformation and sliding friction are assumed to be the dominant sources of AE. In considering the nature of AE in metal cutting, particular attention is given to the transition from rubbing to chip formation (due to increasing depth of cut), the structure of continuous type chips and the propagation of AE through the shear zones.
A boundary-based view of product development—a feasibility study
Authors: Smart P K , Brookes N J , Lettice F E , Backhouse C J , Burns N D
Published: October 2002

The ‘Working the Boundaries’ research project investigates the organization structural changes in the Rover Group arm of the BMW AG corporation. An important aim of this research is to determine the feasibility of a ‘boundary-based’ view to organizing human resources during product development. This viewpoint stresses the need for firms to consider not only the strategic placement of formal organizational boundaries but also the concurrent development of innovative options for overcoming them. This paper presents some important grounded theoretical developments. They focus on the identification of an important mechanism—the informal organization used to overcome formal organization boundaries. The informal organization is based on a network of self-generated, self-organized and self-managed interrelationships between product developers. They form the foundations of effective and efficient flows of information, experience, knowledge and ideas during product development task activity. Consequently product development performance relies significantly on a formal recognition of the informal organization.
Workpiece temperature measurement in machining
Authors: O'Sullivan D , Cotterell M
Published: October 2002

Temperature plays a vital role in the machining industry today. With increasing cutting speeds being used in machining operations, the thermal aspects of cutting have become more important. The temperature not only directly influences the rate of tool wear but also will affect the thermal expansion and final surface finish of a workpiece material. The surface temperatures of newly machined workpieces are investigated in this paper. An experimental study was performed using both thermocouples and infrared thermography to monitor the newly machined surface temperatures of an aluminium alloy tube for various cutting conditions. Cutting temperatures have been measured for a range of cutting speeds and feed rates at a constant depth of cut. The effects of tool wear were also investigated. The results showed that machined surface temperatures decrease with corresponding increases in feed rates. Cutting forces were measured by a dynamometer and were shown to decrease with increasing cutting speed, but they increased with greater tool flank wear land. The progression of tool wear is also accompanied by a consistent increase in workpiece temperature. An infrared thermal imaging camera was used to monitor the cutting process and these results were correlated with thermocouple readings.
Fracture criteria evaluation and finite element modelling of plate shearing
Authors: Domblesky J P , Zhao L
Published: October 2002

This paper summarizes the results of a study conducted to evaluate a finite element model of the plate shearing process. A plane strain model, employing the element destruction method, was developed and tested using the tensile strain and Cockroft-Latham fracture criteria. To test the model, simulated edge geometry and microhardness for each criterion were compared with results from an AISI 1020 steel plate. Results showed that the model provides a reasonable approximation of the process although it is dependent on the fracture criteria used. The normalized Cockroft-Latham criterion was found to provide the best representation of shearing behaviour and yielded good agreement with results for edge geometry and microhardness.
Curved helical drill points for microhole drilling
Authors: Chyan H C , Ehmann K C
Published: October 2002

The ubiquitous microdrills with planar point geometry used by industry suffer from a number of undesirable characteristics and limitations that influence their drilling performance with respect to hole quality and tool life. In this paper, a new family of drill points, the ‘curved helical drill points’, and the related grinding methods for their manufacture are introduced to alleviate the undesired characteristics and limitations of planar drills. The mathematical foundation and an analytical and graphical comparative drill point geometry analysis between curved helical drill points, linear helical drill points and planar drill points are presented.
Studies on the combination of the forward and reverse postprocessor for multiaxis machine tools
Authors: Cheng H-Y , She C-H
Published: October 2002

Due to the fact that many combinations can be synthesized to generate various multiaxis machine tool configurations and that multiaxis numerically controlled (NC) data can only be applied to the specific configuration, the portability of the NC data is inevitably reduced. The purpose of this paper is to present the development of the combined forward and reverse postprocessor for multiaxis machine tools. The NC data for a specific machine tool can be explicitly transformed to other machine tool configurations using the homogeneous coordinate transformation matrix together with forward and inverse kinematics. Moreover, the proposed methodology is verified by solid cutting simulation and a trial cut on a typical five-axis machine tool. The algorithm presented can enhance the facility of machine tools and thus make production schedules more flexible.
Selection of mould design variables in direct stereolithography injection mould tooling
Authors: Harris R A , Newlyn H A , Dickens P M
Published: October 2002

Stereolithography (SL) can be used rapidly to produce injection moulding tools. The disadvantage of the technique is that it is capable of producing only a small number of parts before failure. Stereolithography tools may break under the force exerted by part ejection when the friction between a moulding and a feature of the tool is greater than the tensile strength of the tool, resulting in tensile failure.

Very few justified recommendations exist concerning the choice of mould design variables that can lower the part ejection force experienced and reduce the risk of SL tool failure. This research investigates the ejection forces resulting from the injection moulding of polypropylene (PP), acrylonitrile-butadiene-styrene (ABS) and polyamide 66 (PA66) parts from SL tools that are identical in all respects except for their build layer thickness (a process variable when generating the SL tooling cavities) and incorporated draft angles (a tooling design variable). This work attempts to identify appropriate evidence for recommendations with respect to these variables and SL injection moulding.

The results show that linear adjustment of draft angle results in a fairly minor linear change in part ejection force according to the moulding material. A linear adjustment of the build layer thickness results in a greater change in part ejection force as a more non-linear relationship. In both cases the greatest ejection forces were experienced by PA66, then ABS and then the PP parts. The results also show that the surface roughness of all tools remains unchanged after moulding a number of parts in all polymers.

A mathematical model was used in an attempt to predict ejection forces according to the moulding material used. This model did reflect the experimental results in terms of relative values but not in absolute values, which may be due to the limitations imposed by the development of the expressions and uncertainty about some specific values.
Friction characteristics for surface finish and the stoning direction of stamping dies
Authors: Kim D H , Kim B M , Lee Y , Min B H
Published: October 2002

This paper investigates the combined effects of parameters such as die surface finish, die stoning direction, contact pressure and draw speed on the resulting friction coefficient. The study shows the correlation between the artificial neural network (ANN) and the design of experiments (DOE). The ANN and the DOE have been implemented for minimizing the friction coefficient and for investigating the effect of the parameters in the straight pulling friction test effectively. The experiments were run in random order with at least three replications. It was found that directional stoning orthogonal to the pulling direction lowers the friction more than directional stoning parallel to the pulling direction using die material FCD55 and sheet material SPCEN.
Linear motor drive ultrahigh-speed injection moulding machine
Authors: Bang Y-B , Ito S
Published: October 2002

This paper presents a report on the development of a linear motor drive injection moulding machine for the attainment of ultrahigh-speed injection moulding. Until now it has been impossible to produce such a high speed with all-electric injection moulding machines, although the need for such ultrahigh-speed, electrically driven injection moulding machines has clearly existed. However, direct drive by linear motors may cause brief nozzle separation from the sprue bushing because of an inertia force as large as the total output thrust of the linear motors, and this momentary separation can cause molten plastic leakage. In this paper, two solutions are proposed for this inertia force problem. One is mechanical cancellation of the inertia force, the other is an increase in the nozzle contact force. Furthermore, a new nozzle contact mechanism is proposed that prevents the stationary platen bending caused by the nozzle contact force. Some experimental results on a manufactured all-electric, ultrahigh-speed injection moulding machine are presented.
Incorporating the voice of multiple customers into product design
Authors: Bamforth S , Brookes N J
Published: October 2002

Listening to the voice of the customer is made complicated when the roles of the customer are carried out by more than one individual or stakeholder (a stakeholder performs one or more of the decision-making roles normally enacted by a single customer). The issues surrounding multiple stakeholder requirements are examined with particular reference to small to medium enterprises (SMEs) and the rehabilitation industry; this industry is concerned with products that enable the elderly and disabled to live more independently. A series of case studies has been conducted to identify the current practices of rehabilitation companies and the suitability of accepted design methods for incorporating the voice of the customer into the design process. The results of the study indicate that smaller companies within the rehabilitation industry do not use formal methods of design or market research; this is partly attributable to their limited resources and experience. An outline is given of a method developed by the CACTUS Project to enable resource-limited companies in the rehabilitation industry to incorporate the voice of the customer into their design. The method is currently being tested. It is hoped that the CACTUS approach will be applicable to other industries with similar characteristics and multiple stakeholders.
A neural network approach to the design of a vehicle's non-linear hybrid suspension system
Authors: Spentzas K N , Kanarachos S A
Published: October 2002

In the following, a design method is presented for non-linear hybrid suspension systems of vehicles based on neural networks. A hybrid suspension system is one that behaves as an active suspension system only when the road excitation amplitude is above a prescribed value. Discontinuous operation of the controller helps to minimize the energy consumed by the actuator. The design targets of our method are the minimization of the vertical acceleration imposed on the passengers as well as the respect of all the design and construction constraints. The neural network used is obtained by a Taylor approximation of the unknown non-linear control function. Because of the existence of numerous local minima of the neural network, an evolutionary algorithm is used to solve the resulting neural network problem.
An empirical study of compatibility on rotary control and horizontal display
Authors: Chan A H S , Shum V W Y , Poon K K
Published: October 2002

The precise effect of scale side, indicator type and control knob position on stereotype strength, index of reversibility and response time for a horizontal display/rotary control arrangement was studied with a factorial experiment. All the main effects and two-factor interactions were found to be highly significant on response time, while both control position and direction of instruction influenced the stereotype strength. Because of the decline in the counterclockwise-for-left stereotype found from the left- to the right-hand side of the display, the stereotype reversibility decreased across the control positions in the same direction. Other than the clockwise-for-right principle and Warrick's principle, the results were also explained with a clockwise-for-push principle, which gave a particularly good account of the extreme values of stereotype strength and reversibility for control positions located at the right- and left-hand ends of the display. With analysis performed separately for top and bottom controls, on which different conditions of compatibility between clockwise-for-right and Warrick's principle exist, two different significant relationships were established between response time and stereotype strength. A further precise analysis of counterclockwise-for-left and clockwise-for-right stereotypes on response time showed that response time decreases not only with clockwise-for-right stereotype strength but also with counterclockwise-for-left ( SCC-L) stereotype strength at bottom positions on which the SCC-L stereotype agrees with Warrick's principle. Finally, based on the consideration of response time, stereotype strength and stereotype reversibility, some practical implications for the design of horizontal linear display and rotary control configuration were established. The results of this study provide recommendations for interface design on control consoles used in a manufacturing environment.
Re-examining the machining frictional boundary conditions using fractals
Authors: Raman S , Chellaperumal J
Published: October 2002

This paper presents experimental evidence for the existence of non-Euclidean contact geometry at the tool-chip interface in the machining of aluminium alloy, which challenges conventional assumptions. The geometry of contact at the tool rake face is modelled using fractals and a dimension is computed for its description. The variation in the fractal dimension with the cutting speed is explored.
An intelligent fuzzy decision system for a flexible manufacturing system with multidecision points
Authors: Chan F T S , Chan H K , Kazerooni A
Published: October 2002

This paper describes an intelligent fuzzy decision support system for real-time scheduling and dispatching of parts in a flexible manufacturing system (FMS), with alternative routing possibilities for all parts. A fuzzy logic approach is developed to improve the system performance by considering multiple performance measures and at multiple decision points. The characteristics of the system status, instead of parts, are fed back to assign priority to the parts waiting to be processed. A simulation model is developed and it is shown that the proposed intelligent fuzzy decision support system keeps all performance measures at a good level. The proposed intelligent system is a promising tool for dealing with scheduling FMSs, in contrast to traditional rules.
Evaluation of combined dispatching and routeing strategies for a flexible manufacturing system
Authors: Chan F T S
Published: October 2002

This paper is concerned with the evaluation of combined dispatching and routeing strategies on the performance of a flexible manufacturing system. Three routeing policies: no alternative routeings, alternative routeings dynamic and alternative routeings planned are considered with four dispatching rules with finite buffer capacity. In addition, the effect of changing part mix ratios is also discussed. The performance measures considered are makespan, average machine utilization, average flow time and average delay at local input buffers. Simulation results indicate that the alternative routeings dynamic policy gives the best results in three performance measures except for average delay at local input buffers. Further, the effect of changing part mix ratios is not significant.
A study of the strength and shape of surface mount technology leadless chip solder joints
Authors: Hui I. K. , Ralph B
Published: October 2002

A method that directly pulled the components off printed circuit boards was used as a means for testing the bond quality of surface mount technology leadless chip solder joints. Components D7243, CC1206, RC1206, RC1210 and CC1812 were selected for the study. It was found that the ultimate tensile force that breaks a component off the printed circuit board has the potential to be used as a parameter for measuring the quality of the solder joint. The failure modes of the joints were recorded and are discussed. The effect of solder thickness on the strength of a joint has also been investigated. The shape of joints soldered by two methods, wave soldering and infra-red reflow, were compared. Joints at the two ends of a component produced by infra-red reflow were found to be more uniform than the ones produced by wave soldering. A recommendation is made here for the wave soldering approach in achieving uniform solder joints. The effects of solder shape on the joint strength were further investigated by finite element analysis. A convex joint was found to be marginally more robust than a concave joint.
Finding the best possible solutions to simple assembly line balancing problems
Authors: Ma X
Published: October 2002

Assembly line balancing (ALB) is an important aspect in the design of many flow line type manufacturing systems which may or may not be assembly oriented. It involves essentially assigning individual tasks into stations such that certain constraints are satisfied and some specified objectives achieved. Although this problem has attracted a great deal of research effort over the past forty years, it still remains unsolved. This paper presents a computer-based method for the simple assembly line balancing problem (SALBP). For a given problem, the method makes use of some efficient and systematic search and identification techniques to establish task trees for individual stations and to develop a station tree for multiple solutions. Different from all known existing assembly line balancing methods, this method aims at finding the best possible solutions that lead to the maximum production rate and the minimum station workload variation. The essential and distinct concepts adopted by the method are described in this paper, along with its step-by-step execution procedure and an illustrative example. Since the method does not involve difficult mathematics, many industrial practitioners can easily understand it and appreciate its effectiveness.
Plant layout improvements to a medium volume manufacturing system using systematic techniques to form just-in-time manufacturing cells
Authors: Khan M K , Gwee S H
Published: October 2002

This paper describes the application of systematic techniques for factory layout improvements undertaken at Renold Gears Limited (Bradford) who manufacture hydraulic and mechanical variable-speed drives. The company needed to redesign its layout to form JIT (just-in-time) manufacturing cells so that improvements in material flow and reduced lead times could be achieved. In this case study, an overview of the plant layout problem is covered for the particular company. A detailed study of the plant layout is then carried out using production flow analysis (PFA) techniques of group technology, ‘from-to’ (cross charts) and relationship (REL) charts. The PFA matrix, with the constraints included, is solved using King's rank order clustering (ROC) technique, through the use of a spreadsheet. Eight manufacturing cells are identified and manual input is carried out to determine the best machine positions within the particular cells. Results of the new cells are presented and compared with the original layout. The case study has shown that the new layout significantly improves the process flow through the plant, helping to reduce waste in terms of scheduling, lead time inventories and space.
Force control in turning based on robust PI controller design
Authors: Harder L , Isaksson A J
Published: October 2002

Real-time cutting force control is a very straightforward way to improve safety, performance and quality in rough turning operations. The main problem in controller design for force control is to achieve robustness. Several time-variable process parameters, such as the depth of cut, the spindle rotational speed and the specific cutting force, directly affect the closed-loop system gain and time constant. In this paper, two approaches to robust PI (proportional integral) controller design based on the internal model control (IMC) method are presented. The first approach treats the cutting process as a first-order system with a time- variable gain. By designing for highest process gain, the controller becomes robust, but perhaps a bit sluggish for the lower range of process gain. In the second approach, the cutting process is linearized by introducing non-linear transformations. In this way, the design may be based on a constant-gain system and the time-variable parameters may be considered as additive disturbances. This controller is somewhat faster than the first approach and shows almost identical behaviour over the entire operating range. Both controllers incorporate, in addition, simple parameter adaptation by gain scheduling with respect to spindle speed variations, in order to handle variations in the process time constant. The work presented in this paper shows that it is possible to achieve robust force control in turning using the common PI controller.
Real-time automatic statistical control for the grinding process
Authors: Mo J P T , Squires M R , Brien G C
Published: October 2002

The highly consistent axes control of current computer numerically controlled (CNC) grinding machines has ensured a high-quality output provided that the process parameters can be kept constant. However, there are many variations in the process that give rise to differences between workpieces. Typical process variations such as tool wear, materials and temperature changes are inevitable and cannot be compensated by advancements in axis servo-control. This paper addresses this problem by applying a high-level control methodology which makes use of real-time statistical process control (SPC) information to determine whether the process has deteriorated due to process variations. Adjustments to machine parameters to offset these changes can then be made. The methodology has been successfully incorporated in a control loop within the controller of the CNC grinders to achieve truly unattended grinding operations.
An algorithm for incremental inductive learning
Authors: Pham D T , Dimov S S
Published: October 2002

This paper describes RULES-4, a new algorithm for incremental inductive learning from the ‘RULES’ family of automatic rule extraction systems. This algorithm is the first incremental learning system in the family. It has a number of advantages over well-known non-incremental schemes. It allows the stored knowledge to be updated and refined rapidly when new examples are available. The induction of rules for a process planning expert system is used to illustrate the operation of RULES-4 and a bench-mark pattern classification problem employed to test the algorithm. The results obtained have shown that the accuracy of the extracted rule sets is commensurate with the accuracy of the rule set obtained using a non-incremental algorithm.
Set-up reduction (SUR) beyond total productive maintenance (TPM)
Authors: Mileham A R , Culley S J , McIntosh R I , Gest G B , Owen G W
Published: October 2002

There is a growing awareness of the importance of set-up performance in multiproduct manufacturing environments. This paper contrasts the potential business contribution of conducting set-up reduction (SUR) as an initiative in its own right with the contribution SUR will make as a component part of a rigorously conducted total productive maintenance (TPM) initiative. It is argued that under TPM a business can easily fail to recognize the global impact of SUR and fail to take the opportunities afforded by improved setup times. It is demonstrated that in the nature of TPM, and in the manner in which it is implemented and measured, there is pressure to move away from responsive, small-batch manufacture that SUR promotes. While there is a growing awareness of SUR benefits, there are relatively few reported cases in which sustained long-term improvements have been seen. One reason for this is that although faster changeovers are perceived as a ‘good thing’, there is little in-depth analysis of their impact on overall business performance. A classification is proposed against which the potential SUR benefits may be assessed and the commercial opportunities that can arise through having a more responsive manufacturing system are also highlighted.
Design of a performance repetitive manufacturing system
Authors: Banaszak Z A , Honczarenko J
Published: October 2002

Max-plus algebra is applied to the modelling of flexible manufacturing systems with mutual exclusion interactions of processes. The method based on this algebra provides a framework for building an executable, performance-oriented model of sequential and repetitive processes where each set of activities is performed repetitively in a fixed sequence that specifies product routing through machines. A new concept of a virtual process as well as the conditions sufficient for a stability margin computation are introduced. An example illustrating the method is presented.
Investigation on arc light intensity in gas metal arc welding. Part 2: Application to weld seam tracking
Authors: Yoo C D , Sunwoo H-K , Koh K-I
Published: October 2002

The arc sensor has been widely used to detect the weld seam by monitoring welding current or voltage variation during weaving in gas metal arc welding (GMAW). In this work, the arc light intensity and welding resistance are utilized as the seam tracking sensor. Signal characteristics of the arc light intensity and welding resistance are compared when argon and CO2 gas are used for shielding. The performance of signal processing methods such as the least squares and integration methods is evaluated experimentally. It is found that the arc light intensity provides higher quality signals than welding resistance with CO2 gas. While both signal processing methods demonstrate almost equal seam tracking capabilities, the integration method appears to be more efficient because of the short computation time.
Representation and reasoning in computer aided process planning
Authors: McMahon C A , Cox D R , Williams J H Sims , Scott J A
Published: October 2002

This article is concerned with part representation and reasoning algorithms for automatic process planning in CADCAM (computer aided design and manufacture). Process planning involves the translation of a part description into instructions for a sequence of operations for the manufacture of the part. Part representations in CADCAM are reviewed, and a hierarchical representation is introduced which describes parts as the set-theoretic union of positive (protrusion) features, with the set-theoretic union of negative (depression) features subtracted. The model information hierarchy also incorporates topological relationships among features (adjacency, ownership and intersection), tolerances and links to a boundary representation (B-rep) geometric model. The hierarchical part representation is used as the basis for a reasoning scheme that uses topological relationships between features to restrict the search space of operation sequences. A recursive algorithm produces candidate operation sequences that are then ranked by applying manufacturing heuristics in a process called machining regularization. The representation approach is illustrated by an example, and possible extensions to the scheme are briefly discussed.
Three-dimensional filtering of engineering surfaces using a least squares non-parametric B-spline surface
Authors: Tholath J , Radhakrishnan V
Published: October 2002

With the advent of cheap and powerful computers, three-dimensional evaluation of surfaces is possible. The three-dimensional surface requires a filtering procedure for waviness separation. This paper deals with the waviness plane construction through a least squares non-parametric B-spline surface. Roughness values obtained by two-, two-and-a-half- and three-dimensional evaluations of typical surfaces are also given.
The importance of holistic model driven manufacturing systems
Authors: Weston R H
Published: October 2002

The findings of two UK government funded studies are reviewed which have highlighted requirements of next generation manufacturing systems. The studies have (a) generated a view of alternative futures for manufacturing enterprises and (b) identified barriers to their realization. This illustrates an important future role for holistic model driven manufacturing systems, which respond rapidly to competitive forces and sociopolitical economic change while maintaining good alignment between business goals and related processes and operations. The findings help to identify requirements of next generation enterprise integration methods, architectural frameworks, reference models, integration mechanisms and component elements. Based on this requirement definition the capabilities of emerging and proprietary enterprise integration methods and tools have been assessed and classified.
Development of a laser doppler system for in-process evaluation of diameters on computer numerical controlled turning machines
Authors: Yandayan T , Burdekin M
Published: October 2002

The diameter of the workpiece is measured, while the workpiece is located on the CNC (computer numerical controlled) turning machine, using a new laser instrument and technique. The optical instrument is based on the laser Doppler principle, using an He—Ne laser as a light source. It obtains data by detecting the scattered light from the surface of a rotating workpiece, processing this data with respect to the rotation of the spindle and providing a value representing the workpiece diameter. The basic resolution of the system depends on the wavelength of the laser and geometry of the optics. Higher resolution can be achieved by obtaining the data from the workpiece surface over more than one complete revolution of the spindle. The resolution for one revolution of the spindle is 0.5μm and for ten 0.05μm. The measurement system is also integrated with the CNC turning machine, particularly for autofocusing of the instrument. The instrument is mounted on the tool holder of the CNC turning machine, which is focused by means of a tool offset parameter for non-contact measurement of each different diameter. Autofocusing is carried out using the MI5 machine tool interface unit which is already established for the Renishaw probe system, according to CNC part programming. The performance of the proposed technique and instrument is verified through the experiments.
Finite element analysis for precision cold forging of helical gear using recurrent boundary conditions
Authors: Park Y B , Yang D Y
Published: October 2002

In metal forming, there are problems with recurrent geometric characteristics without explicitly prescribed boundary conditions. In such problems, so-called recurrent boundary conditions must be introduced. In this paper, as a practical application of the proposed method, the precision cold forging of a helical gear (which is industrially useful and geometrically complicated) has been simulated by a three-dimensional rigid-plastic finite element method and compared with the experiment. The application of recurrent boundary conditions to helical gear forging analysis is proved to be effective and valid. The three-dimensional deformed pattern by the finite element analysis is shown, and the forging load is compared with the experimental load. The profiles of the free surface of the workpiece show good agreement between the computation and the experiment.
Re-engineering the product development process with ‘design for X‘
Authors: Huang G Q , Mak K L
Published: October 2002

Shortcomings of sequential engineering and advantages of concurrent engineering in product development have become better understood. However, the transformation from a sequential engineering environment to a concurrent engineering environment remains challenging. A dynamic transformation approach by combining the focused application of ‘design for X’ (DFX) with the extensive use of business process re-engineering (BPR) is discussed in this paper. The main role of DFX is to provide the drive, focus, vision and concurrence necessary for BPR, while the main role of BPR is to institutionalize good practice and make improvement permanent and continuous.
Flat pattern generation of thin-walled objects based on a mechanism theory
Authors: Lin Y-L , Yang D C H
Published: October 2002

This paper presents an analytical study of automatic flat pattern generation of thin-walled objects. Formulae based on mechanism theory are derived to determine the required number of seams for developing thin-walled objects. Subsequently, the seam locations are determined via the identification of the minimum required seam number at each vertex. An algorithm based on the spanning tree technique has been developed to automatically generate all possible developments. A new unfolding technique based on individual surface transformation has been presented. This technique requires less computational time in the unfolding process than the traditional sequential transformation method.
A passive compliant wrist for chamferless peg-in-hole assembly operation from vertical and horizontal directions
Authors: Haskiya W , Maycock K , Knight J A G
Published: October 2002

This paper presents a chamferless vertical/horizontal remote centre compliance (CVHRCC) mechanism developed for robotic peg-in-hole assembly operations. The wrist adopts the passive accommodation approach and differs from other devices in its category in its ability to accommodate positional errors between the mating parts without a chamfer on either part. In addition, the wrist is designed to work from both the vertical and the horizontal directions. A series of experiments have been carried out for testing the new wrist. The main conclusion of the assembly experiments is that the CVHRCC can work effectively from the vertical direction in accommodating positional errors between chamferless mating parts with large clearance (over 0.2 mm) between the peg and hole.