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System dynamics as a decision support system for machine tool selection

Adane T. F., Nicolescu M.

Journal of Machine Engineering

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2016

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Vol. 16, No. 3

102--125

EN

The worldwide competitive economy, the increase in sustainable issue and investment of new production line is demanding companies to choose the right machine from the available ones. An improper selection can negatively affect the overall performance of the manufacturing system like productivity, quality, cost and companys responsive manufacturing capabilities. Thus, selecting the right machine is desirable and substantial for the company to sustain competitive in the market. The ultimate objective of this paper is to formulate a framework for machining strategy and also provide methodology for selecting machine tool from two special purpose machine tools in consideration of interaction of attributes. A decision support system for the selection of machine tool is developed. It evaluates the performance of the machining process and enhances the manufacturer (decision maker) to select the machine with respect to the performance and the pre-chosen criteria. Case study was conducted in a manufacturing company. A system dynamics modelling and simulation techniques is demonstrated towards efficient selection of machine tool that satisfy the future requirement of engine-block production.

2

Performance Evaluation of Machining Strategy for Engine-Block Manufacturing

Tigist A. F., Bianchi M. F., Archenti A., Nicolescu M.

Journal of Machine Engineering

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2015

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Vol. 15, No. 4

81--102

EN

This paper will introduce a novel methodology for the performance evaluation of machining strategies of engine-block manufacturing. The manufacturing of engine components is vital to the automotive and vehicle manufacturing industries. Machining are a critical processes in the production of these parts. To survive and excel in the competitive manufacturing environment, companies need to improve as well as update their machining processes and evaluate the performance of their machining lines. Moreover, the lines and processes have to be robust in handling different sources of variation over time that include such examples as demand fluctuations, work-piece materials or even any changes in design specifications. A system dynamics modelling and simulation approach has been deployed to develop a methodology that captures how machining system parameters from the machining process are interacted with each other, how these connections drive performance and how new targets affect process and machine tool parameters through time. The developed model could provide an insight of how to select the crucial machining system parameters and to identify the effect of those parameters on the output of the system. In response to such an analysis, this paper provides (offers) a framework to examine machining strategies and has presented model that is useful as a decision support system for the evaluation and selection of machining strategies. Here a system dynamics methodology for modelling is applied to the milling operation and the model is based on an actual case study from the engine-block manufacturing industry.

3

New Paradigm in Control of Machining Systems Dynamics

Nicolescu M., Frangoudis C., Semere D., Archenti A., Rashid A.

Journal of Machine Engineering

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2015

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Vol. 15, No. 3

117--137

EN

The increasing demands for precision and efficiency in machining call for effective control strategies based on the identification of static and dynamic characteristics under operational conditions. The capability of a machining system is significantly determined by its static and dynamic stiffness. The aim of this paper is to introduce novel concepts and methods regarding identification and control of a machining system’s dynamics. After discussing the limitations in current methods and technologies of machining systems’ identification and control, the paper introduces a new paradigm for controlling the machining system dynamics based on design of controllable structural Joint Interface Modules, JIMs, whose interface characteristics can be tuned using embedded actuators. Results from the laboratory and industrial implementation demonstrate the effectiveness of the control strategy with a high degree of repeatability.

4

Issues in machining of hollow core honeycomb sandwich structures by abrasive waterjet machining

Devadula S., Nicolescu M.

Journal of Machine Engineering

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2013

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Vol. 13, No. 1

117--124

EN

Machining of hollow core honeycomb sandwich materials is a challenging job as the mechanical properties of various layers (skin, core) are quite dissimilar, and the conventional solid cutting tool experiences a sudden change of conditions while machining that might lead to damage on the tool/part. Although, abrasive waterjets (AWJs) is highly efficient in the machining of advanced composite materials due to their unique characteristics, efficient machining of sandwich structures by AWJs needs many challenges to be addressed. This work presents various issues observed in AWJ machining of carbon- and glass- fiber skin based, aluminum sandwich structure composite materials, and the limitations of AWJs in processing these exotic materials. Finally, possible strategies for efficient machining of honeycomb structures were proposed for future investigation.

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Dynamic parameter identification in nonlinear machining systems

Nicolescu M., Archenti A.

Journal of Machine Engineering

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2013

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Vol. 13, No. 3

91--116

EN

The demand for enhanced performance of production systems in terms of quality, cost and reliability is ever increasing while, at the same time, there is a demand for shorter design cycles, longer operating life, minimisation of inspection and maintenance needs. Experimental testing and system identification in operational conditions still represent an important technique for monitoring, control and optimization. The term identification refers in the present paper to the extraction of information from experimental data and is used to estimate operational dynamic parameters for machining systems. Such an approach opens up the possibility of monitoring the dynamics of machining systems during operational conditions, and can also be used for control and/or predictive purposes The machining system is considered nonlinear and excited by random loads. Parametric and nonparametric techniques are developed for the identification of the nonlinear machining system and their application is demonstrated both by numerical simulations and in actual machining operations. Discrimination between forced and self-excited vibrations is also presented. The ability of the developed methods to estimate operational dynamic parameters ODPs is presented in practical machining operations.