Proceedings of the Institution of Mechanical Engineers,Part B: Journal of Engineering Manufacture

The results of an experimental study on friction stir spot welding (FSSW) of AA6082-T6 are reported. In particular, process mechanics is highlighted and joint strength is considered in relation to varying the most relevant process parameters. Furthermore, the results obtained are compared with those derived from the application of traditional mechanical fastening techniques such as clinching and riveting. In this way the effectiveness of FSSW is highlighted.

A model of the interfacial frictional conditions at the secondary shear zone in oblique cutting is under development. It has been suggested that the tool-chip interface consists of sticking and sliding microcontacts, each of which exhibit dynamic variations throughout the cut. The bond strength at the interface is difficult to determine because of the unpredictable characteristic of precipitation variability and the complex behaviour of the work material under severe cutting conditions. In this research the frictional interface is investigated on a microscopic scale to shed some light on these issues. Time-dependent cutting experiments illustrate the dynamic variations in sticking and sliding. It is also proved that the sticking and sliding areas exhibit fractal characteristics. Actual contact areas for sticking and sliding were calculated by using image analysis techniques. A relationship between the fractal dimension and the area of contact is noted. A mathematical model is proposed on the basis of the measured forces and calculated contact areas.

The belt-finishing process is a recent manufacturing technique in industry, the mechanisms and characteristics of which have not yet been fully explained. This paper attempts to make a contribution to the understanding of the consequences of the process on the surface roughness of surfaces prepared by hard turning. Abrasive film wear and contact parameters between grains and surfaces are analysed. The effects and significant interactions of the most influential belt-finishing parameters on the surface roughness are then investigated. It was shown that the applied force and the hardness of the roller have a great influence on the surface roughness. Furthermore, the film feed rate influences considerably the wear of grains and, as a consequence, this parameter has an important impact on the material removal mode and on the surface roughness.

This study conducts a finite element analysis of the plastic deformation and bonding behaviour of complex aluminium-copper sheets containing internal defective voids in the asymmetrical cold rolling process. The influences of the roll diameter, the thickness ratio of the upper/lower sheet layers, the total sheet thickness at the entrance, and the sheet thickness reduction ratio on the dimensions of the internal void at the exit and the effective stress/strain distributions in the complex sheet are examined. Additionally, the evolution of closing of the correlation between the upper/lower voids under different rolling process parameters is explored. The present numerical results provide a valuable insight into the deformation mechanisms involved in the cold rolling of complex sheets with internal defects.

Based on a non-linear model of a computer numerical control (CNC) system, a general adaptive robust controller (ARC) is presented in this paper. The ARC was used to treat problems including the compensation of friction non-linearity, parameter variation, and unmodelled dynamics in the design of a CNC system. It can enhance stability robustness and performance robustness. The simulation results show the effectiveness of the method.

The conventional approach to establish optimal processing conditions in ultraprecision diamond turning is empirical in nature. The achievement of a super mirror finish and submicrometre form accuracy in many current industrial applications still depends much on the experience and skills of the machine operators through trial cutting tests when new materials or new machine tools are used. In this paper, a virtual machining and inspection system (VMIS) is presented for ultra-precision diamond turning. The development of the VMIS aims at creating a virtual manufacturing environment for the optimization of process parameters and evaluating the quality of machined surface through various modelbased simulation modules. The VMIS is validated through a series of practical cutting tests conducted on a two-axis computer numerical control ultra-precision turning machine. The experimental results agree well with the simulated data.

Deformation of the spot-welded sub-assemblies in assembly operations and the gap between the matching sub-assemblies have been quality concerns specifically in the automotive industry. Overall quality of the car body and its sub-assemblies, apart from quality of each stamped part, depends markedly on the welding process. This paper considers optimization of three important process parameters in the spot welding of the body components, namely welding current, welding time, and gun force. In this research, first the effects of these parameters on deformation of the sub-assemblies are experimentally investigated. Then neural networks and multi-objective genetic algorithms are utilized to select the optimum values of welding parameters that yield the least values of dimensional deviations in the sub-assemblies. Welding sub-assemblies with the optimized set of parameters brought all of them into the tolerance range. The proposed approach can be utilized in manufacturing sub-assemblies that can fit and match better with adjacent parts in the automotive body. It enhances quality of the joint and will result in improving overall quality of the body in white.

The selection of machining parameters in any machining process significantly affects the production rate, quality, and cost of a component. The present work involves the application of a recently developed global optimization technique called differential evolution to optimize the machining parameters of a surface grinding process. The wheel speed, workpiece speed, depth of dressing, lead of dressing, cross-feed rate, wheel diameter, wheel width, grinding ratio, wheel bond percentage, and grain size are considered as the process variables. The production cost, production rate, and surface finish are evaluated for the optimal grinding conditions, subject to the constraints of thermal damage, wheel wear parameter, and machine tool stiffness. An example is taken from the literature to compare the results obtained by the proposed approach with other approaches.

The term ‘world-class maintenance (WCMt)’ is being used frequently nowadays and refers to the collection of best practices in maintenance. Different researchers and consultants have proposed several frameworks of WCMt representing these best practices. If an organization or a maintenance manager wants to implement a framework, it may not be easy for him or her to identify a single framework from a variety of frameworks that are reported in the literature. Thus the task of choosing a particular framework has become a major issue for the managers. Hence in this paper, an attempt has been made to perform an analysis for comparing different WCMt frameworks based on their strengths, weaknesses, opportunities, and threats (SWOT). In addition to this, a comparative study of WCMt with other maintenance systems has been carried out to understand the similarities and differences. The SWOT analysis of frameworks revealed a list of best practices in maintenance to be considered by an organization, when it attempts to achieve a world-class status in maintenance apart from the weaknesses and threats associated with each framework. Such an analysis can prove valuable as a decision aid for the operations or maintenance manager while making a decision of choosing a suitable framework of WCMt.

This paper presents a swarm intelligence approach for optimal orientation of a part produced by the fused deposition modelling method, with a view to reduce the volumetric errors that are primarily responsible for poor surface finish. A part is oriented in such a way to assist the designer in reducing build time, while at the same time enhancing part quality and orientational efficiency. The conventional approach in optimization of part orientation considers only minimization of the staircase effect in order to enhance the part quality. In the approach used by the present authors, a part is oriented by transforming it about x and y axes and an orientation is selected that not only provides minimum volumetric error and building time but also enhances orientational efficiency of the fused deposition modelling method. Using the swarm intelligence technique, the hierarchical particle swarm optimization algorithm is employed to obtain optimal part orientation. The results obtained by using the hierarchical particle swarm optimization algorithm are further compared with the results obtained by using the genetic algorithm; the results reveal that the hierarchical particle swarm optimization algorithm provides a better outcome than the genetic algorithm. An example is given to illustrate the approach.

With the development and integration of the global supply chain, manufacturing industries are rapidly adjusting their modes of operation within and between enterprises. Existing manufacturing processes are being improved to meet the requirements of lean and agile manufacturing, and suppliers are given additional responsibilities to provide parts and services dynamically. An enterprise must strategically re-engineer its operations model to face the rapid changes of the global market place. This paper identifies prevailing challenges and highlights a future vision of the global logistics management framework for the automotive industry. An integrated business and logistics hub (IBLH) model integrating information flows (via the business hub) and material flows (via the logistics hub) is presented. This research uses the case of a Taiwan automobile parts and assembly manufacturer to analyse the processes of the IBLH. The goals of the case are to shorten supply chain processes, reduce inventory costs, and ensure information transparency during material flow and product distribution. Finally, this research provides suggestions to depict the case company's current limitations and deficiencies, and presents a future plan for e-logistics services.

This paper studies the effects of service-level constraint and failure-in-repair on an economic manufacturing quantity (EMQ) model with random defective rate. It starts with the proof that the long-run average cost of an EMQ model with backlogging permitted is less than or equal to that of the same model without backlogging. The relationship between the ‘imputed backorder cost’ and maximal permitted shortage level is dependent for decision making on whether or not the required service level is achievable. An equation that calculates the intangible backorder cost is proposed for dealing with situations when the required service level is not attainable. Finally, by utilizing this intangible backorder cost in the proposed mathematical analysis, an optimal lot-size policy that minimizes expected overall costs as well as satisfies the service-level constraint can be derived. A numerical example with a discussion that demonstrates the effects of service-level constraint and failure-in-repair on the EMQ model is provided.

This study classifies design parameters in mechatronic systems as structure parameters and time-domain parameters. Time-domain parameters influence (or decide) working states and performance specifications of a mechatronic system. Based on information content defined for design parameters, the control principle of time-domain parameters, the priority principle of greater information content, and the maximum-control-efficiency principle are presented as guidelines for mechatronic design, together with the definitions of the mechatronic ratio and control efficiency. The example of the solid slicing manufacturing (SSM) system shows that, in addition to applying more controllers to minimize the number of time-domain parameters, mechatronic design also needs to search for an optimal design scheme with maximum control efficiency. Such a scheme may be obtained through reducing the number of uncertainties, limiting the uncertainty information content, and/or integrating the components.

Managing engineering projects is a complex activity involving multiskilled engineers, who have varying levels of capability in these skills. This paper outlines a preliminary approach to modelling and planning the composition of engineering project teams, taking into consideration the skills and capabilities of engineers and the nature of the project work to be undertaken. The approach includes a simple means of identifying engineers' skills and then quantifying their level of capability in these skills. Subsequently, the approach uses a genetic algorithm along with a task-to-engineer allocation strategy to establish how best to utilize the mix of skills and capabilities of the team of engineers assigned to the project under consideration. The approach also provides a means of identifying imbalances or shortfalls in skill and capability within a team, and the formulation of an appropriate development strategy to redress/overcome them. An application of the approach to an industrial case study is presented, which led to significant potential reductions in expected project duration and labour cost. These potential reductions could be achieved by appropriately modelling engineers' skills and capabilities, and redressing the imbalance within the team through proposed changes to its composition.