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Advances in Production Management Systems
- 2007
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Proceedings (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- The IFIP series publishes state-of-the-art results in the sciences and technologies of information and communication. The scope of the series includes: foundations of computer science; software theory and practice; education; computer applications in technology; communication systems; systems modeling and optimization; information systems; computers and society; computer systems technology; security and protection in information processing systems; artificial intelligence; and human-computer interaction. Proceedings and post-proceedings of referred international conferences in computer science and interdisciplinary fields are featured. These results often precede journal publication and represent the most current research. The principal aim of the IFIP series is to encourage education and the dissemination and exchange of information about all aspects of computing.
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| 2. |
- Feldmann, Andreas, 1981-, et al.
(författare)
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Designing Manufacturing Networks - An Empirical Study
- 2007
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Ingår i: Advances in Production Management Systems. - New York : Springer. - 9780387741567 ; , s. 95-102
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Konferensbidrag (refereegranskat)abstract
- The design of the manufacturing network for a firm is an important factor for its competitive position. By manufacturing network we mean the plant or plants of the manufacturing firm and the relationships with external suppliers. The way that these operate together is central to the entire supply system supports the competition of the products in the marketplace. The decisions are typically categorised as related to facilities and vertical integration, two decision categories in an operations strategy. This paper presents the results of a survey of 84 Swedish manufacturing plants. The results show that competitive priorities such as quality and price play different roles in the networks, and that there is a significant difference in terms of how internal and external suppliers are selected
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| 3. |
- Feldmann, Andreas, 1981-, et al.
(författare)
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Utformning av produktionsnätverk - En empirisk studie
- 2007
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Ingår i: PLANs Forsknings- och tillämpningskonferens 2007: Kundfokuserade varor och tjänster. - Stockholm : PLAN - Logistikföreningen ;Jönköping :Tekniska högskolan, Högskolan i Jönköping. - 9789197644419 - 9197644412 ; , s. 67-82
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 4. |
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| 5. |
- Kleijnen, Jack, et al.
(författare)
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Screening for the important factors in large discrete-event simulation models : Sequential bifurcation and its applications
- 2006
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Ingår i: Screening. - New York : Springer. - 9780387280134 ; , s. 287-307
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The process of discovery in science and technology may require investigation of a large number of features, such as factors, genes or molecules. In Screening, statistically designed experiments and analyses of the resulting data sets are used to identify efficiently the few features that determine key properties of the system under study.This book brings together accounts by leading international experts that are essential reading for those working in fields such as industrial quality improvement, engineering research and development, genetic and medical screening, drug discovery, and computer simulation of manufacturing systems or economic models. Our aim is to promote cross-fertilization of ideas and methods through detailed explanations, a variety of examples and extensive references.Topics cover both physical and computer simulated experiments. They include screening methods for detecting factors that affect the value of a response or its variability, and for choosing between various different response models. Screening for disease in blood samples, for genes linked to a disease and for new compounds in the search for effective drugs are also described. Statistical techniques include Bayesian and frequentist methods of data analysis, algorithmic methods for both the design and analysis of experiments, and the construction of fractional factorial designs and orthogonal arrays.The material is accessible to graduate and research statisticians, and to engineers and chemists with a working knowledge of statistical ideas and techniques. It will be of interest to practitioners and researchers who wish to learn about useful methodologies from within their own area as well as methodologies that can be translated from one area to another.
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| 6. |
- Lindström, Veronica, 1966-, et al.
(författare)
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Data quality issues in production planning and control – Linkages to smart PPC
- 2023
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Ingår i: Computers in industry (Print). - : ELSEVIER. - 0166-3615 .- 1872-6194. ; 147
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Tidskriftsartikel (refereegranskat)abstract
- In the era of Industry 4.0 and digitalization, planning solutions need to co-exist with each other and be able to manage higher complexity and with a higher performance. As the concept smart production planning and control is a part of industry 4.0, it is highly relevant to study and is in this paper explored on the four elements of smart PPC (real-time data management, dynamic production planning and re-planning, autonomous production control, and continuous learning). This paper provides a framework for linking the four elements of smart PPC with data quality issues in state-of-the-art production planning and control environments. Maintaining a high standard of data quality in the business processes aids the organization to stay competitive in its market. Hence, our assumption is that a high level of data quality is needed in production planning and control for a high-performance outcome. The empirical part of our study results in a bar-chart of seven data quality problems and their occurrences together with their causes in PPC. According to the empirical data results, inaccurate data entries is the most common data quality problem related to PPC. The causes of the inaccurate data entries can be linked to human resources and organizational control. Future research should strengthen the validity of the proposed linkages between data quality problems and elements of smart PPC and implications on strategic, tactical, and operational planning levels.
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| 7. |
- Olhager, Jan, 1955-, et al.
(författare)
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Supply chain impacts at Ericsson - From production units to demand-driven supply units
- 2002
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Ingår i: International Journal of Technology Management. - 0267-5730 .- 1741-5276. ; 23:1-3, s. 40-59
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the impact of supply chains on operations management at Ericsson Mobile Communications. It specifically deals with the transition of the Link÷ping plant from being a production unit to the role of a supply unit in a demand-driven supply chain. This change has had a great impact on many factors. We discuss and analyse the most important issues. These are related to supply chain structure and flexibility, reengineering the information flow, the management of the supply process, and performance measurement.
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| 8. |
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| 9. |
- Persson, Fredrik, 1971-
(författare)
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A Study of Factors Affecting the Particle Size for Water Atomised Metal Powders
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The production of metal powders by water atomisation is a well established process, which can be used to produce a wide range of particle sizes. A careful control of the particle size distribution is necessary, to atomise powders with a high quality and at a low production cost. Therefore, it is necessary to have a substantial knowledge of the relation between operational parameters and the particle size, to be able to produce water atomised metal powders with consistent and high yields. The main purpose with this thesis was to increase the knowledge about factors which affect the mass median particle size (d50) for water atomised metal powders. The specific objectives with the study were to develop a theoretical d50 model and to investigate the relation between the particle size and the physical properties of the liquid metal. Pilot scale experiments for liquid iron showed that alloy additions of carbon and sulphur decreased the d50 value, at a maintained liquid steel temperature before atomisation. Moreover, it was indicated that the reduced particle size at increased %C and %S contents may be related to a decreased viscosity and surface tension of the liquid metal, respectively. An alternative explanation could be that raised superheats at increased carbon contents increased the total available time for atomisation, which may have contributed to a reduction of the d50 value. The theoretical d50 model developed in this work showed a very good correlation to the current experimental data. The model considers the influence of surface tension, viscosity, melt stream diameter, water pressure, water jet angle and water to metal ratio. This model was further used to analyse how the d50 value was influenced by the viscosity and the surface tension. A reduced viscosity from 4∙9 to 2∙1 mPa s decreased the d50 value with 33%. In addition, the particle size was estimated to decrease with 21% by decreasing the surface tension from 1840 to 900 mN m-1.
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| 10. |
- Persson, Fredrik, 1971-
(författare)
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A Study of Parameters and Properties Influencing the Size, Morphology and Oxygen Content of Water Atomized Metal Powders
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The production of metal powders by water atomization is a well-established process, which can be used to produce a wide range of particle sizes for different applications. In general, there is a lack of detailed knowledge about what process parameters that affect the powder properties for water atomized metal powders. More specifically, this thesis focuses on the particle size, morphology and oxygen content of water atomized iron powders. A careful control of the particle size distribution is necessary to atomize powders with a high quality and at a low production cost. Demands on the particle morphologies vary depending on the application for the final product. It is important to control both the melt properties and atomizing parameters, to produce powders with an even particle shape and sintered steel components with tight tolerances. The oxidation of the liquid metal should also be as low as possible during the water atomization, to avoid a large amount of harmful oxide forming in the final powder. Pores are generally considered as defects in metal powders. Therefore, the powder porosity should be as low as possible.The main objective of this thesis is to obtain a more in-depth knowledge of water atomization of metal powders, by investigating some fundamental parts of the process. The study investigates how the median particle size (d50 value) for iron powders is influenced by the water pressure, the melt stream diameter, the jet angle, the water level in the atomizing tank, changed configurations of the water jets, superheat of the melt, and the carbon and sulfur content in the liquid steel. Similarly, the thesis also investigates factors that influence the particle shape, porosity and oxidation of water atomized iron powders.Laboratory and pilot experiments show that the effect on the d50 value was large for the water pressure, medium for the viscosity, surface tension and water to metal ratio, and small for the melt stream diameter. Calculations indicate that the water jet angle has a large effect on the d50 value. In practice, this effect cannot be exploited beyond certain limits caused by instabilities in the atomizing system, which occur if the jet angle is too large.The particle size decreases when the carbon and sulfur contents in the liquid iron are increased. This is attributed to decreased viscosities and surface tensions, respectively. An alternative explanation could be that the superheats at increased carbon contents result in a longer time spent in the molten state before the atomization is completed. This may also lead to a decrease in the particle size. Calculations using a developed d50 model estimate that a decreased viscosity from 6.8 mPa s to 4.3 mPa s leads to a reduction in the d50 value by 33%. Similarly, a decreased surface tension from 1840 mN/m to 900 mN m-1 reduces the d50 value by 27%.The distribution of oxides in pilot water atomized Fe-Mn-C powders was determined by using optical and scanning electron microscopy, combined with energy dispersive X-ray microanalysis. The oxygen in the atomized powders was mainly present as thin surface oxide layers, which increase in thickness from 10 nm to 50 nm as the particle sizes increase from 10 microns to 750 microns. Manganese oxides were observed to be unevenly distributed at the surface of several particles, when the alloy contained 0.3 wt.% manganese. Experimental data indicate that between 10 - 20% of the manganese was present as oxides in the powders. However, equilibrium calculations at 1550 °C estimate that only 4% of the initial manganese content remained in the steel after a completed atomization.The sphericity of the atomized powders decreases as the particle size increases. One feasible explanation is that some larger particles are irregular, since they are formed by collisions of smaller particles. Conversely, smaller particles are formed directly from breakups of the melt and are not the product of collisions between droplets. The sphericity of the size fraction 20-45 microns increases as the carbon content in the iron increases from 0.2 wt.% to 4.2 wt.%. The atomized droplets with larger carbon contents spend a longer time in the molten state, which allows them more time to form a spherical shape during the atomization process. The porosity of iron-carbon powders increases with increasing carbon contents in the melt. Dissociation of steam to hydrogen at the melt surface and precipitation of hydrogen pores in the melt were the most likely mechanisms to cause a pore formation in the powders.Keywords: water atomization; metal powder: particle size; oxygen content; particle shape; porosity; steelmaking
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