| 1. |
- Repo, Jari
(författare)
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Condition monitoring of machine tools and machining processes using internal sensor signals
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Condition monitoring of critical machine tool components and machining processes is a key factor to increase the availability of the machine tool and achieving a more robust machining process. Failures in the machining process and machine tool components may also have negative effects on the final produced part. Instabilities in machining processes also shortens the life time of the cutting edges and machine tool. The condition monitoring system may utilise information from several sources to facilitate the detection of instabilities in the machining process. To avoid additional complexity to the machining system the use of internal sensors is considered. The focus in this thesis has been to investigate if information related to the machining process can be extracted directly from the internal sensors of the machine tool. The main contibutions of this work is a further understanding of the direct response from both linear and angular position encoders due the variations in the machining process. The analysis of the response from unbalance testing of turn tables and two types of milling processes, i.e. disc-milling and slot-milling, is presented. It is shown that operational frequencies, such as cutter frequency and tooth-passing frequency, can be extracted from both active and inactive machine axes, but the response from an active machine axis involves a more complex analysis. Various methods for the analysis of the responses in time domain, frequency domain and phase space are presented.
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| 2. |
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| 3. |
- Eriksson, Stefan
(författare)
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Visual replenishment methods in the manufacturing industry and suggestion for a decision tool
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In almost all supply chains, materials need to be stored or buffered, implying that manufacturing companies need effective replenishment methods. However, this is challenging, since companies must balance inventory costs and customer service in complex and different situations. Therefore, it is important to choose replenishment methods carefully. One well-known and widespread method is Material Requirements Planning (MRP). But the method has problems, such as regarding volume flexibility. There are other methods, but the literature lacks case studies and detailed descriptions and analysis of them, especially for visually oriented methods. Therefore, it is important to explore different methods for materials supply.The purpose of this study is to analyze the application of visually oriented replenishment methods in manufacturing industry and further to design a tentative decision tool for selecting methods. The research aims to provide some answers to three key questions.The first research question concerns general factors that are important for evaluating how effective replenishment methods are. From the literature review, different factors emerged such as product characteristics (fit in the Kraljic matrix, volume issues, size, etc.); information, trust, and geographical proximity between supplier and customer; and different logistics goals (delivery service elements, tied-up capital, use of resources, inventory accuracy). It is also import to include the basic principles methods are related to. The factors were summarized in an analysis model, which is structured with three main areas (planning environment/conditions, basic principles, and effects). The model is used to analyze four case studies.The second research question focuses on the characteristics for visually orientedreplenishment methods. Examples of characteristics are: easy to understand and operate, offers uncomplicated flows, substantially applicable for noncritical and leverage parts with high yearly requirement and fairly even consumption, provides potential for reduced errors in stores/flows, potential for providing high delivery service and low levels of tied-up capital and resource utilization.The third research question focuses on what a tentative decision tool for selecting replenishment methods might look like, based on the factors that emerged from the other research questions and studies by others. In order to achieve an efficient materials supply, companies need to consider these factors when selecting replenishment methods. The decision tool consists of different steps, considering aspects of the planning environment/conditions in relation to the product and the supplier. The importance of the companies’ goals/motives for materials supply must also be assessed. The output from the decision tool is appropriate replenishment methods.
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| 4. |
- Gerth, Robert, 1978-
(författare)
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The Role of Production Topology in Information Based Structuring of Organizations : The design of craft-based and industrialized construction firms
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Industrialization of construction is a business strategy to significantly improve competitiveness. However, the organization structure of the construction firms needs to support the new production system. The knowledge on why and how this business development can be accomplished is scarce, both within academia and in business practice. This research seeks to fill this knowledge gap.The purpose of organization structure and the production system have is to coordinate the firm’s processes and control the work performing resources. Information is one of the most fundamental dimensions for steering and controlling the work. The different information types are determined by the firm’s product customization strategy and the production system flexibility. Further, diverse information types are managed in different extent by the organizational steering mechanisms. Consequently, firms with dissimilar customization strategy or production flexibility should organizationally be designed differently in order to be efficient.The developed model identifies four generic production topologies: “engineer-to-order” (ETO), “manufacture-to-order” (MTO), “assembly-to-order” (ATO), and “make-standard-products” (MSP). The differences between the topologies can be related to the location of the “customer-order-decoupling-point” (CODP) in the product realization process; and to what extent the upstream and downstream processes continuously use stored information or process information to accomplish the work of each product order. The model predicts which organization structure mechanisms that should be used for which processes for each production topology. It is the specific configuration of the mechanisms that gives each production topology their organizational capability. The model has been validated by case studies in four organizations, each representing one of the four generic production topologies. Three cases considered housing and one studied truck manufacturing.It has been shown that the conventional housing firms have an ETO-production topology, while industrialized housing firms belonging to one of the others, i.e. MTO, ATO or MSP. The reason is that ETO-firms rely on crafts-based production to manage the work, while the other topologies base their steering mechanisms on industrial principles. These two types of production are fundamentally different, which also explain the need for different organization structures. The research complements previous knowledge and significantly increases the ability to predict, analyze and explain an organization’s design and behavior. The model can be used in practice to guide business development work and performance improvement programs.
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| 5. |
- João, Dias Ferreira, 1986-
(författare)
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Bio-Inspired Self-Organisation in Evolvable Production Systems
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The increasing market fluctuations and customized products demand have dramatically changed the focus of industry towards organizational sustainability and supply chain agility. Such critical changes in the strategic vision of the companies inevitably have a direct impact on the shop-floor operational requirements. In this sense, traditional shop-floor approaches are becoming increasingly inadequate leading to the adoption of more pluggable and reusable solutions.The emergence o modern manufacturing paradigms translates the effort undertaken by the academia in order to provide the required background to support the implementation of such distributed mechatronic systems. Biological systems, due to their similar distributed network-like structure, represent naturally a common analogy and source of inspiration for such distributed modular approaches. Hence, modern manufacturing paradigms usually rely on complexity science biologically inspired concepts to attain distributed control, adaptability, evolution, flexibility and robustness as core concepts. This originated the implementation of a number of different multi-agent based architectures. Nevertheless, with time the majority of the these implementation efforts left behind most of the bio-inspired concepts resulting in simple distributed approaches with considerable limitations regarding scalability, reconfigurability and distributed problem resolution. Particularly under the scope of Evolvable Production System (EPS) the implementation of self-organising mechanisms based on negotiation interaction protocols and dynamic coalition-based hierarchical complexity, have considerable hindered the system performance and limited the full exploitation of the paradigm potential.In this context, this licentiate thesis is focused on the development of a self-organising manufacturing systems that holistically mimics the main structural and regulatory principles followed by natural systems.For this purpose, the present approach was designed as opposed to the current tendency followed by modern productions approaches, in which the product holds the production knowledge and is responsible for the management of its own production. Instead, the production knowledge was reduced to the minimum and distributed over the manufacturing components. Self-organising principles heavily inspired on the regulatory mechanisms of biological systems, were then devised to regulate the critical control mechanisms of the manufacturing system. Hence, similarly to the natural world the characteristics and the system overall production emerge as consequence of the micro-dynamics of the systems. In this way, it becomes therefore possible to attain a system that is not only highly reconfigurable and scalable but also able to distributively tackle the manufacturing processes.Although the present work has been developed under the Evolvable Production System context, the introduced approach can be easily adapted to a wider range of modular networked-based systems.
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| 6. |
- Nilsson, Per
(författare)
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Conceptual ProductDevelopment in SmallCorporations
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of the thesis “Conceptual Product Development inSmall Corporations” is by the use of a case study test the MFD™-method(Erixon G. , 1998) combined with PMM in a product development project.(Henceforth called MFD™/PMM-method). The MFD™/PMM-methodused for documenting and controlling a product development project hassince it was introduced been used in several industries and projects. Themethod has been proved to be a good way of working with the early stagesof product development, however, there are almost only projects carriedout on large industries which means that there are very few references tohow the MFD™/PMM-method works in a small corporation. Therefore,was the case study in the thesis “Conceptual Product Development inSmall Corporations” carried out in a small corporation to find out whetherthe MFD™/PMM-method also can be applied and used in such acorporation.The PMM was proposed in a paper presented at Delft University ofTechnology in Holland 1998 by the author and Gunnar Erixon. (Seeappended paper C: The chart of modular function deployment.) The title “Thechart of modular function deployment” was later renamed as PMM,Product Management Map. (Sweden PreCAD AB, 2000). The PMMconsists of a QFD-matrix linked to MIM (Module Indication Matrix) via acoupling matrix which makes it possible to make an unbroken chain fromthe customer domain to the designed product/modules. (See Figure 3-2).The PMM makes it easy to correct omissions made in creating newproducts and modules.In the thesis “Conceptual Product Development in Small Corporations”the universal MFD™/PMM-method has been adapted by the author tothree models of product development; original-, evolutionary- andincremental development.The evolutionary adapted MFD™/PMM-method was tested as a casestudy at Atlings AB in the community Ockelbo. Atlings AB is a smallcorporation with a total number of 50 employees and an annual turnoverof 9 million €. The product studied at the corporation was a steady rest for supporting long shafts in turning. The project team consisted ofmanagement director, a sales promoter, a production engineer, a designengineer and a workshop technician, the author as team leader and acolleague from Dalarna University as discussion partner. The project teamhas had six meetings.The project team managed to use MFD™ and to make a complete PMMof the studied product. There were no real problems occurring in theproject work, on the contrary the team members worked very well in thegroup, having ideas how to improve the product. Instead, the challenge fora small company is how to work with the MFD™/PMM-method in thelong run! If the MFD™/PMM-method is to be a useful tool for thecompany it needs to be used continuously and that requires financial andpersonnel resources. One way for the company to overcome the probablelack of recourses regarding capital and personnel is to establish a goodcooperation with a regional university or a development centre.
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| 7. |
- Pervaiz, Salman, 1984-
(författare)
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Investigation Cooling and Lubrication Strategies for Sustainable Machining of Titanium Alloys
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The manufacturing sector is one of the most rapidly growing sectors in the industrialized world today. Manufacturing industry is concerned with being more competitive and profitable. Profit margins are directly related to the productivity of the company, and productivity improvements can be achieved by making manufacturing processes more efficient and sustainable. Knowledge of cutting conditions and their impact on machined surface and tool life enable productivity improvement. These days the main emphasis is not only to increase productivity, but also to make processes cleaner and more environmental friendly. This research aims to study machinability of difficult to cut, titanium alloys, in close reference to the application of different cooling/ lubrication strategies and their environmental impact. Total energy consumed (kWh) and carbon dioxide (CO2) emissions produced in machining are common environmental indicators. In this research project environmental implications of the cutting process were calculated in terms of carbon dioxide (CO2) emissions and energy consumption analysis. The experimental work consisted of controlled machining tests with cutting force, surface roughness, power, and flank wear measurements under dry, mist, combination of vegetable oil mist and cooled air (MQL+CA) and flood cutting environments. The current study provides better understanding of the cutting performance of TiAlN coated and uncoated carbide tools. The study also investigated tool failure modes, tool wear mechanisms, surface roughness and energy consumption to improve machinability of Titanium alloys. The study revealed the promising behaviour of minimum quantity lubrication (MQL) under specific ranges of cutting speed for both coated and uncoated tools. Variation in the cutting force showed close link with built up edge (BUE) formation. MQL based systems have huge potential to improve machinability of Titanium alloys and should be investigated further.
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| 8. |
- Repo, Jari, 1976-
(författare)
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Condition Monitoring in Machining Using Internal Sensor Signals
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Condition monitoring of critical machine tool components and machining processes is a key factor to increase the availability of the machine tool and to achieve a more robust machining process. Any failure in the machining process and machine tool components may have negative effects on the final produced part. Instabilities in machining processes also shortens the life time of the cutting edges and the machine tool. The condition monitoring system may utilise information from several sources to facilitate the detection of disturbances in the machining process. To minimise additional complexity to the machining system, internal sensor signals for condition monitoring are used.The main contribution from this work is a further understanding of the measured responses from linear and angular position encoders during excitation of the machine tool structure. It is shown that the measured encoder responses contain the operational frequencies and this applies to both active and passive machine axes. The response from an active machine axis however, involves a more complex analysis. The fundamental principles on the extraction of the generated micro-vibrations (translational and torsional vibrations) from the linear and rotary encoders are presented. Various methods for their analysis in time domain, frequency domain and phase space domain are also presented. New extentions to the nonlinear numerical methods in order to facilitate the extraction of features from Poincaré sections are introduced.The experimental work shows that encoders are sensitive to small disturbances in the machining process. The possibility to use the proposed measurement method and numerical methods for tool wear detection in a milling operation has therefore been investigated. It is shown that tool wear can be detected and quantified by utilising the signals already available in machine tools.
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| 9. |
- Rosén, Jonas, 1971-
(författare)
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Development of Industrial Information Systems based on Standards
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis has studied how ISO STEP application protocols can be used as a base for development of enterprise information systems that provides information sharing capabilities in a collaborative environment. In this thesis, five papers have been selected and are presented in the context of four themes that characterize the whole research body. The four themes are: - Standard models as a base for development of IT systems - Applications operating on integrated (standard) models - Sharing of information - Sharing of collaborative processes The research have been performed in both an academic and industrial context, where the researcher have taken an active role in how to shape the solutions that became the result of the research project. Initially the projects were limited to virtual manufacturing with a focus on the management of manufacturing information. However, gradually the scope grew to include management of product information across the lifecycle. Also the organizational context was widened to include management of information that is shared between companies across their company borders. The growing scope made the research to take on new aspects for each new area of issues that surfaced. One overall issue that surfaced was how to be able to exchange product data between companies over a long time and at the same time be able to impose configuration control of the shared information. One of the major conclusions is that sharing of information over time and across the lifecycle in a virtual enterprise is a task that involves more efforts than the task of exchanging product data of the same type (e.g. design data, CAD files) between two companies. The results of the research show that the ISO 10303 application protocols are qualified for use in an enterprise product data management environment. However, the result also shows that there are a number of issues to deal with when developing a product data sharing environment based on standards. For example, how to efficiently transform and use the data structures of ISO 10303 application protocols in the different layers of a software system, the data layer, the business object and services layer and the user interfaces. Other issues are on how to deal with the neutral representation such that companies can integrate their contextual information with the neutral product data representation. Future research is recommended to look more close into how the new evolving software architectures that becomes more mainstream today, such as Enterprise Service Bus technology (ESB) and Cloud Computing, amongst others, can utilize the ISO 10303 application protocols as their canonical format. Another important area is to further elaborate, and integrate ISO 10303 with existing technologies for Reference Data and unstructured data that today get more and more traction
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