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  • 101.
    Ssemakula, Hamzah
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Manufacturihng of heavy rings and large copper canisters by plastic deformation2003Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Plastic deformation processes transform material fromas-received state to products meeting certain requirements inproperties, microstructure and shape. To achieve thistransformation, the relationship between material response andprocess conditions should be understood. This is usuallycomplicated by the complex conditions describing the actualprocess. Numerous techniques including empirical, physical,analytical and numerical can be employed.

    In this thesis, numerical technique supported by lab- andfull-scale experiments has been employed to analyse the formingparameters. The first part of the thesis is focused on the useof such parameters to predict occurrence of material poresduring manufacturing of bearing rings. The second part dealswith the influence of forming parameters on the grain sizeduring fabrication of large copper canisters for encapsulationof nuclear waste. The primary task has been to study with thehelp of commercial FE-codes the magnitude and distribution offorming parameters such as accumulated effective strain,temperature, instantaneous hydrostatic pressure and materialflow at different stages of the forming process. In the firstpart, two types of ring manufacturing routes, which result inpore free and pore loaded rings are studied and compared.Material elements located in different areas of the workpiecehave been traced throughout the process. Results of theaccumulated strain and instant hydrostatic pressure have beenanalysed and presented in pressure-strain space. It’sassumed that high hydrostatic pressures together with higheffective strains are favourable for pore closure. Area of theworkpiece with unfavourable parameters have been identified andcompared with ultrasonic test results. Good agreement has beenobtained. Based on the results of this analysis, a new conceptfor avoiding pores in manufacturing of yet heavier rings hasbeen presented. The concept proposes a lighter upsetting in theinitial stage of the process and a more efficient piercingwhich results in higher hydrostatic pressure and bigger andbetter distributed effective strain.

    In the second part of the thesis, the influence of formingparameters such as effective strain and temperature on thefinal grain size of the product has been studied in laboratoryscale. As-cast billets of cylindrical shape were extruded atdifferent temperatures and reductions. It has been shown thatthe grain size in the final product should be small in order toenable ultrasonic tests and to guarantee resistance towardscreep and corrosion. Simulations for different materialelements located at different distances from the axis ofsymmetry of the initial cylindrical workpiece have been carriedout. In this way, the parameters describing the deformationhistory of the elements have been determined as functions oftime. Experimentally obtained pre- and post deformation grainsize in the corresponding locations of the material weredetermined. It’s concluded that low temperature coupledwith high effective strain are conducive for obtaining a smallgrain size. Based on the beneficial conditions for extrusion ofcopper, a more detailed FE-analysis of a full-scale industrialprocess is carried out. A coarse-grained cast ingot of purecopper is heated and by upset forging formed into a cylinder,which is then punched into a hollow blank for subsequentextrusion. The blank is extruded over a mandrel through a45-degree semi-angle die. Accumulated effective strain andtemperatureas functions of the tubular wall thickness havebeen studied at five different locations along the tubularaxis. Forming load requirement as function of tool displacementfor each stage of the process has been determined. Strain andtemperature levels obtained have been related to the grain sizeinterval obtained in the earlier work. It has been concludedthat the levels reached are within the interval that ensures asmall grain size. A similar analysis has been carried out forforging of large copper lids and bottoms. Die designmodifications to improve the grain size in the lid and tooptimise the forging process with respect to forging load andmaterial yield have been proposed. A method requiring a smallforging load for fabrication of the lids has been analysed

    Keywords:Pores; grain size; low forging load; effective strain;temperature; hydrostatic pressure; extrusion; forging;canister; lid; rings

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  • 102.
    Ssemakula, Hamzah
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Manufacturing of heavy rings and large copper canisters by plastic deformation2001Licentiate thesis, comprehensive summary (Other scientific)
  • 103.
    Stake, Roger
    KTH, Superseded Departments (pre-2005), Production Engineering.
    On conceptual development of modular products - Development of supporting tools for the modularisation process2000Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    The research work detailed in this dissertation relates tothe development of modular products and product families.Historically, product variants have been developed more or lessindependently; but in order to stay competitive in today’sbusiness environment where globalisation and explosion ofvariety are some of the buzzwords, products should be developedas a product family. Developing product families instead ofsingle product variants increases the ability to offercustomised products produced cost efficient.

    The objective of this research has been to developsupporting tools for conceptual development of modular productsand to increase the understanding of the concept of moduledrivers. The results can be divided into two categories,descriptive and prescriptive results.

    The descriptive results concern the concept of moduledrivers. These module drivers have been analysed and the resultis a strategic module map where the module drivers are relatedto generic strategies. Furthermore, empirical data regardingthe usage of the module drivers is used to relate the moduledrivers to each other. The result is a grouping of the moduledrivers where similar module drivers are grouped together toform aggregated module drivers. By putting the module driversin a strategic context and by providing an in-depth analysis ofthe consequences of each module driver, as well as developing ahierarchical classification, the understanding of the conceptof module drivers is enhanced.

    The prescriptive result relates to the usage of clusteranalysis for the generation of modular concepts. Clusteranalysis provides an objectivetool that could be used to grouptechnical solutions into modules based on their module driverassessment. In addition to the module drivers, other factorsmay also be included in the cluster analysis. A softwareprototype has been developed in order to illustrate how clusteranalysis could be used to support concept generation of modularproducts.

  • 104.
    Stjernstoft, Tero
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Machining of Some Difficult-to-Cut Materials with Rotary Cutting Tools2004Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Automobile and aero industries have an increasing interestin materials with improved mechanical properties. However, manyof these new materials are classified as difficult-to-cut withconventional tools. It is obvious that tools, cutting processesand cutting models has to be devel-oped parallel to materialsscience. In this thesis rotary cutting tools are tested as analternative toexpensive diamond or cubic bore nitridetools.

    Metal matrix composites mostly consist of a light metalalloy (such as aluminium or titanium) reinforced with hard andabrasive ceramic parti-cles or fibres. On machining, thereinforcement results in a high rate of tool wear. This is themain problem for the machining of MMCs. Many factors affect thelife length of a tool, i.e. matrix alloy, type, size andfraction of the reinforcement, heat treatment, cuttingconditions and tool properties.

    In tests, the Al-SiC MMC formed a deformation layer duringmilling, probably affected by lack of cooling. The dominatingfactor for tool life was the cutting speed. Water jet or CO2cooling of turning did not provide dramatic increase in toollife. With PCD, cutting speeds up to 2000 m/min were usedwithout machining problems and BUE formation. Tool flank wearwas abrasive and crater wear created an "orange-peel type" wearsurface. PCD inserts did not show the typical increase in flankwear rate at the end of its lifetime.

    The use of self-propelled rotary tools seems to be apromising way to increase tool life. No BUE was formed on therotary tool at high cutting data. The measurements indicatethat the rotary tool creates twice as good surface as PCDtools. The longest tool life was gained with an inclinationangle of 10 degrees. Tool costs per component will beapproximately the same, but rotary cutting tool allows higherfeeds and therefore a higher production rate and thus a lowerproduction cost.

    The rotary cutting operation might have a potential toincrease productiv-ity in bar peeling. The lack of BUE withrotary cutting gives hope on higher tool life. The test resultsshow that tool wear was 27% lower with rotary cutting tools.Increase of cutting speed from 22 to 44 m/min did not affectcutting forces. This indicates that the cutting speed canincrease without significant change in tool wear rate.

    Issues related to rotary cutting like cutting models,cutting processes, standards, tools and models have beendiscussed. A tool wear model with kinetic energy has beendiscussed.

    KEYWORDS:Difficult-to-Cut material, Metal MatrixComposite (MMC), Machining, Machinability, Rotary Cutting Tool,Acoustic Emission

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  • 105.
    Tahir, Mohammed
    KTH, Superseded Departments (pre-2005), Production Engineering.
    A study on the possibilities of improving the environment by the use of less detrimental lubricants in cold rolling2001Licentiate thesis, comprehensive summary (Other scientific)
  • 106.
    Tahir, Mohammed
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Some aspects on lubrication and roll wear in rolling mills2003Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The thesis is focused on lubricants and roll wear in striprolling.

    Regarding lubricants, the possibility of introducing newones, which are less detrimental towards environment, isstudied in laboratory scale. This is done for cold rolling,both of an Al- alloy and a low carbon steel. The lubricationperformance of such newly developed–water-based–synthetic lubricants is compared with currently used mineraloils and emulsions. By using the experimental method of"forward slip" measurements combined with slab methodcalculations and FE- simulations, friction coefficients areevaluated for different single pass reductions. Lubricantsbearing capacity and the product surface roughness are alsoevaluated. The results are encouraging.

    A synthetic water-based lubricant, used in the cold rollingof an Al- alloy, showed good lubrication capability, betterthan the mineral oil but worse than the emulsion. The rolledAl- strip finish was found to be finest for the syntheticlubricant followed by the mineral oil and the emulsion. Similarresults were obtained from the steel rolling. Here foursynthetic lubricants were compared with two mineral oils andone emulsion. The best lubricant was found to be one of thewater-based synthetics, showing the lowest value of thefriction coefficient and a smooth product surface.

    The aim of the wear study is to develop an accurateroll-wear prediction for hot strip finishing mills, which takesmore influential parameters into account. A new model of higheraccuracy is presented. This model is based on a large amount ofproduction campaigns. The strategy of the work is describedbelow.

    After a comprehensive literature study a promising modelstructure was found. The corresponding equation is tested ontwo hot strip mills. Predicted wear is found to be inqualitative agreement with industrial experience and measuredwear. Thus the structure–taking the influence of back-uprolls into account–was chosen for further development.This was done on behalf of results obtained from one mill builtup by six stands and three different work-roll materials.Campaigns of "mixed" and "similar" strip grades were used. Theobtained model is tested successfully in two other hot stripmills.

    Contradictory to the currently used on-line model, the newmodel takes the work roll flattening and back-up rolls contactarea into consideration. Also the influence of strip- and workroll grades is included. The model enables increased rolledstrip length and prolonged lifetime of the rolls, because ofimproved process control. Further more, grinding cost and timefor roll changing can be minimized. Of course thesepossibilities should result in considerable energy saving.

    Keywords:Strip rolling, lubricants, environment, rollwear modeling, production campaigns, regression analysis

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  • 107.
    Tangen, Stefan
    KTH, Superseded Departments (pre-2005), Production Engineering.
    A theoretical foundation for productivity measurement and improvement of automatic assembly systems2002Licentiate thesis, monograph (Other scientific)
  • 108.
    Tangen, Stefan
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Evaluation and revision of performance measurement systems2004Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Performance measurement is a topic that has received considerable attention during the last decades. There are many motives for using performance measures in a company but perhaps the most crucial one is that they will help to improve productivity when used properly. Productivity is of vital importance to a company’s ability to compete and make profits over time. A company that is not able to efficiently utilise its resources in creating value for its customers will not survive in the competitive business environment of today.

    However, the development of fully functional and suitable performance measurement systems (i.e. set of measures) has proven to be a very challenging task. This research has focused on the last phase of the development of performance measurement system, namely the continuous updating of the performance measures, which still have not been explored in a satisfactory manner. The objective is to investigate and clarify how to evaluate and revise performance measurement systems. In order to reach this objective, several obstacles that contribute to the complexity of the research area are treated.

    In the beginning, the thesis thoroughly investigates the confusing terminology within the field and frequently used terms like productivity, profitability, performance, efficiency and effectiveness are explained. Then, a categorisation of ways to measure performance is presented along with advantages and shortcomings of different productivity and other performance measures. Several key-factors found to affect the productivity of a manufacturing company are also discussed, such as: design of processes and equipment, disturbances and losses, management and control, product design, and job design and work organisation. Much attention is given to the different requirements that performance measurement systems must fulfil, both on the system level and the measure level. Finally a method called the performance measurement progression map is finally proposed, which has been developed in order to give measurement practitioners a comprehensive guide of how to evaluate and revise performance measurement systems.

    The thesis is concluded with the results from several empirical investigations in which the usefulness of the developed method is validated.

    Keywords: Performance measurement, Performance measurement systems, Productivity, Evaluation

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  • 109.
    Tangen, Stefan
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Performance measurement: From philosophy to practice2004In: International Journal of Productivity and Performance Management, ISSN 1741-0401, E-ISSN 1758-6658, Vol. 53, no 8, p. 726-737Article in journal (Refereed)
    Abstract [en]

    Even though remarkable progress has been made over recent years in the design of performance measurement frameworks and systems, many companies are still primarily relying on traditional financial performance measures. This paper presents an overview of the more common, more modern approaches to performance measurement and attempts to identify whether they have in fact addressed the limitations of traditional ways of measuring performance. The paper suggests that the modern frameworks have indeed addressed the underlying conceptual issues, but have rarely addressed the practicalities of measurement in ways that render them meaningful to practitioners. What is needed is further work to explore how these conceptual frameworks can be translated and tailored to fulfil the unique measurement needs of a specific company, especially at the operational level.

  • 110.
    Tesfamariam, Daniel
    et al.
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Lindberg, Bengt
    Improving the Performance of a Manufacturing Cell by Reconfiguration2002In: Proceedings of CIRP International Seminar on Intelligent Computation in Manufacturing Engineering, Ischia Italy 14:18, 2002, 2002, p. 14-17Conference paper (Other academic)
  • 111.
    Tesfamariam Semere, Daniel
    et al.
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Lindberg, Bengt
    KTH, Superseded Departments (pre-2005), Production Engineering.
    An Integrated Approach To Evaluate Alternative System Configurations2004In: Proceedings of The EUROMA 2004: Operations Management as a Change Agent INSEAD, Fontainebleau, 27 : 29 June 2004, 2004, p. 589-598Conference paper (Other academic)
  • 112.
    Tesfamariam Semere, Daniel
    et al.
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Lindberg, Bengt
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Comparison of Manufacturing System Configurations Using Simulation Cycle2004In: Proceedings of the Fifteenth IASTED International Conference on Modelling and Simulation, 2004, p. 379-382Conference paper (Refereed)
    Abstract [en]

    Given the requirements and the design space, multiple alternative system configurations may be generated that have to be evaluated to select the best. Simulation based performance analysis is an indispensable method to accomplish such tasks particularly to complex systems as manufacturing systems which may not be analyzed appropriately by other methods. For systems with significant variability within or operating in a variable condition, their performance is non-linearly and adversely affected. Performance plots such as cycle time and throughput plots are convenient way of capturing and summarizing the system dynamic performance and hence is a suitable way to systematically compare. In this paper, a simulation-based experiment is presented to compare systems with variability using their steady state cycle time and throughput.

  • 113.
    Tesfamariam Semere, Daniel
    et al.
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Lindberg, Bengt
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Manufacturing Strategy and System Configuration: a Systematic Analysis of a Decision Making Process2004In: Proceedings of the International IMSForum 2004. May 17:19, 2004. Villa Erba, Como, Italy, 2004, p. 682-690Conference paper (Other academic)
  • 114. Tseng, M. M.
    et al.
    Kjellberg, Torsten
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Lu, S. C. Y.
    Design in the new e-commerce era2003In: Cirp Annals-Manufacturing Technology, ISSN 0007-8506, Vol. 52, no 2, p. 509-519Article in journal (Refereed)
    Abstract [en]

    The computing and communication have become indispensable in every aspect of design and manufacturing. Its impacts on production engineering community have been significant and long lasting. In this paper, we reviewed new e-Commerce models that directly link among production capabilities and with end consumers. We then identified three major forces that will affect the design community, namely, speed of decision, expansion of scope and degree of concurrency. Understanding the implication of these forces would be conducive to leading structural changes in design. The transformations include expanding the scope of design, linking customers and suppliers proactively throughout the entire value chain, and collaborating across boundaries.

  • 115. Van Gils, S.
    et al.
    Holten, S.
    Stijns, E.
    Vancaldenhoven, M.
    Terryn, H.
    Mattsson, Lars
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Electropolishing of aluminium: processing and assessment of visual appearance2003In: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 35, no 2, p. 121-127Article in journal (Refereed)
    Abstract [en]

    The process of electropolishing aluminium and its influence on the visual appearance are studied. Angle-resolved scattering (ARS) and total integrated scattering (TIS) are used to investigate the influence of electropolishing on surface roughness. The ARS apparatus is built similar to the ASTM E430-97A standard. This standard test method is used for measurement of distinctness of image and haze by goniophotometry. These visual appearance parameters, together with TIS, reflect the changes in surface roughness. Total reflectance is correlated to the composition of the aluminium as well as the composition and thickness of the layer formed on the aluminium.

  • 116. Vinet, Bernard
    et al.
    Berne, Cecile
    Pasturel, A
    Desré, Pierre Jean
    Fecht, H.J.
    Fredriksson, Hasse
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Gránásy, Laszlo
    Greer, A.L.
    Hermann, R.
    Löser, W.
    Magnusson, Lena
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Study and Modelling of Nucleation and Phase Selection Phenomena: Application to Refractory Metals and Alloys from Drop-Tube Processing2001In: Microgravity Research and Aplications in Physical Sciences and Biotechnology: Proceedings of the First International Symposium held 10-15 September, 2000 in Sorrento, Italy. Edited by O. Minster and B. Schürmann. European Space Agency, ESA SP-454., 2001, Vol. SP454, p. 1123-Conference paper (Refereed)
  • 117.
    Von Euler-Chelpin, Astrid
    et al.
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Holmström, Patrik
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Richardsson, J.
    A neutral representation of process and resource information of an assembly cell: supporting control code development, process planning and resource life cycle management2004In: Proceedings 2nd International Seminar on Digital Enterprise Technology, 2004Conference paper (Refereed)
  • 118.
    Wiktorsson, Magnus
    et al.
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Andersson, T.
    Volvo Car Corporation, Göteborg, Sweden .
    Broman, M.
    Swedish Institute of Prod. Eng. Res., Stockholm, Sweden .
    A note on the specification of assembly systems2000In: International Journal of Production Research, ISSN 0020-7543, E-ISSN 1366-588X, Vol. 38, no 16, p. 3997-4002Article in journal (Refereed)
    Abstract [en]

    Although the characteristics and cost of any technical system are highly influenced by the early design phases, little focus has been on the structure and use of the specification in manufacturing system design, in this paper exemplified by assembly systems for large, high-volume products. This paper proposes a framework for elaborating such specifications. The framework is based on a division in qualifying and winning criteria, and is structured into four classes: functional requirements; internal design constraints; external design constraints; and winning criteria. Defining the specification by these terms is justified and explained by comparing standard mathematical formulation for this kind of problem to the framework. Future research efforts are pointed out where the framework is used throughout the development project for goal-focus, as the specification is used and refined in an iterative manner.

  • 119. Zhang, Q.
    et al.
    Nicolescu, Mihai
    KTH, Superseded Departments (pre-2005), Production Engineering.
    Jiang, X.
    Zhang, Y.
    Yue, W.
    Xiao, W.
    Sensors' network and its application in the intelligent storage security2004In: UNMANNED/UNATTENDED SENSORS AND SENSOR NETWORKS, 2004, p. 255-264Conference paper (Refereed)
    Abstract [en]

    Intelligent storage systems run on different advanced technologies, such as linear layout, business intelligence and data mining. Security, the basic desire of the storage system, has been focused on with the indraught of multimedia communication technology and sensors' network. Along with the developing of science and the social demands, multifarious alarming system has been designed and improved to be intelligentized, modularized and have network connections. It is of great moment to make the storage, and further more, the logistics system more and more efficient and perfect with modern science and technology. Diversified information on the spot should be caught by different kinds of sensors. Those signals are treated and communicated to the control center to give the further actions. For fire-proofing, broad-spectrum gas sensors, fume sensors, flame sensors and temperature sensors are used to catch the information in their own ways. Once the fire is taken somewhere, the sensors work by the fume, temperature, and flame as well as gas immediately. Meanwhile the intelligent control system starts. It passes the tidings to the center unit. At the same time, it sets those movable walls on to work quickly to obstruct the fire's spreading. While for guarding the warehouse against theft, cut-off sensors, body sensors, photoelectric sensors, microwave sensors and closed-circuit television as well as electronic clocks are available to monitor the warehouse reasonably. All of those sensors work in a net way. The intelligent control system is made with a digital circuit instead of traditional switch one. This system can work in a better way in many cases. Its reliability is high and the cost is low.

  • 120.
    Åberg, Jonas
    KTH, Superseded Departments (pre-2005), Production Engineering.
    On the Experimental Determination of Material Damping in Metals2001Licentiate thesis, comprehensive summary (Other scientific)
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