July 2011


MM (Modern Machinery) Science Journal, July 2011
Jana Horejsi1, Petr Horejsi1, Muhammad Latif2
1Department of Industrial Engineering
University of West Bohemia, Czech Republic
2School of Engineering, Manchester Metropolitan University, UK

To provide for an efficient elevator system, a variety of diverse and sometimes conflicting constraints have to be solved. This paper focuses on using discrete event simulation as a means to model and explore elevator dispatching strategies. Arena simulation software has been used as a test-bed for model building, simulation and some experimentation. Model building using Arena building blocks are described in detail followed by four different elevator call strategies. The mains steps in the methodology are described with reference to a single elevator servicing a four floor office building. The elevator call strategies are simulated and results compared. It has been found that the data set significantly skews the results and overshadows any efficiency gains that might be possible from the different dispatching strategies. The paper concludes with the need to carefully selecting the data set as the basis for simulation comparisons and outlines future work required.

Keywords: Elevator, Elevator Dispatcher System, Discrete Event Simulation, Simulation, Arena
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MM (Modern Machinery) Science Journal, July 2011
Pavel Kopecek
Department of Industrial Engineering University of West Bohemia, Czech republic

Common ERP systems do not solve the support for workshop management. This paper shows why and under what conditions computer support for workshop schedules is necessary. Demands on the quality of operation plans, factors having an influence on the scheduling process and criteria for selection of appropriate operations are discussed. A verification program was developed for testing the proposed hypotheses. This program proved that a repeated random selection and simulation of the production process could be a good tool for a small number of machines and production tasks. There is no need for sophisticated scheduling for a great number of machines and tasks, operational plans are enough for this purpose.

Keywords: Scheduling, Production Process, ERP, Direct Control of Production in Mechanical Engineering, Discrete Optimization
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MM (Modern Machinery) Science Journal, July 2011
L. Kolarik, K. Kovanda, M. Valova, P. Vondrous, J. Dunovsky
Czech Technical University in Prague, Faculty of Mechanical Engineering, Department of Manufaturing Technology Prague, Czech Republic

The article presents results of weldability test of precipitation hardenable aluminium alloys used often for rolling stock production. The research was conducted at Department of Manufacturing Technology, Faculty of Mechanical Engineering, Czech Technical University in Prague. The used material was EN AW 6082 T6. The weldability by GTAW and GMAW welding methods was assessed by Houldcroft`s weldability test (Fishbone test). Using this weldability test susceptibility of the base metal and influence of filler wire selection to solidification cracking was evaluated. As filler wire AlSi5, AlMg4.5MnZr and AlMg5Cr were selected, because they are recommended for selected base metal. During the tests, it was found that to evaluate the susceptibility to solidification cracking GTAW method is much more sensitive than GMAW welding. The results of base metal test had shown that it is very susceptible to solidification cracking. As the filler metal the AlMg5Cr gave the best results, it suppressed solidification cracking the most.

Keywords: Aluminium Alloys, Houldcroft Test, Fishbone Test, Weldability, GTAW, GMAW
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MM (Modern Machinery) Science Journal, July 2011
P. Drasnar1, J. Kudlacek1, V. Kreibich , Vojtech Kracmar1, Miroslav Vales2
1Czech Technical University in Prague, Faculty of Mechanical Engineering
2Aeronautical Research and Test Institute, Testing laboratories Prague, Czech Republic

The requirements for the properties of the surface of highly stressed components are getting increasingly higher so the pure metal coatings are not sufficient any more. The research and development makes it possible to use new alloy or composite coatings which extend the possibilities of surface treatment applications. This study looks at the composite, electrolytically deposited Zn-PTFE coatings (polytetrafluoroethylene) focusing on the manufacturing technology and composition analysis. An optimised technological process results in obtaining a coating of the required properties, i.e. a coating with uniformly distributed content of PTFE particles. It describes the relations between the technological parameters of metal plating and the contents of PTFE in the coating. The analysis of the Zn-PTFE coating composition, i.e. the presence of PTFE has been proved using the method of infrared micro-spectroscopy in the Molecular Spectroscopy Laboratory in the Institute of Chemical Technology (ICT) in Prague. The metallographic tests for the assessment of coating structures were carried out at the Institute of Manufacturing Technology of the Faculty of Mechanical Engineering at Czech Technical University in Prague. The research into the electrochemical composite coatings contributes to the possibilities of producing composite coatings with a wide range of applications.

Keywords: galvanization, zinc, PTFE, composite coating, electroplating, technological process
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