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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
211

Kapacitet och kapacitesplanering i ett kundorderstyrt företag : En fallstudie vid Lindab AB i Götene / Capacity and capacity planning in a make to order company : A case study at Lindab AB in Götene

Gadzo, Adam, Gecaj, Ardian January 2018 (has links)
Syfte: Syftet med rapporten var att bättre förstå vilka faktorer som har en inverkan på kapacitetsplaneringen samt de metoder som finns att tillgå gällande kapacitetsplanering. Utefter detta formulerades det tre stycken frågeställningar som studien avser att besvara: Vilka metoder inom kapacitetsplaneringen kan tillämpas i ett kundorderstyrt företag? Vad utmärker kapacitetsplaneringen i ett kundorderstyrt företag? Hur kan kapacitetsplaneringen förbättras utifrån fallföretagets nuvarande situation? Metod: För att besvara frågeställningarna och uppfylla studiens syfte valdes det att genomföras en fallstudie på Lindab Götene AB i Götene. Den första frågeställningen besvaras genom att identifiera relevant teori kring kapacitetsplanering och analysera dessa med empirin. Den andra frågan besvaras med hjälp av empirin där en nulägesanalys har genomförts som ger en inblick i fallföretaget samt den informationen om hur kapacitetsplaneringen tillämpas i fallstudieobjektet. Även här analyseras empirin med teorin. Den tredje frågan besvaras utifrån den analys och insamling av empiriskt material i nulägesbeskrivningen för att identifiera vad som kan förbättras angående kapacitetsplaneringen i en kundorderstyrd verksamhet. Den empiriska datan utgjordes utav intervjuer, dokumentstudier och observationer. Slutsats: I dagsläget sker kapacitetsplaneringen för hela företaget, författarna föreslår att fallföretaget tillämpar metoden kapacitetsbehovsprofiler då den möjliggör att planera kapaciteten per avdelning. Vilket skulle kunna ge en bättre uppfattning om hur beläggningen i produktionen ser ut utifrån fallföretagets förutsättningar. Ytterligare rekommendationer är att utföra tidsstudier för att säkerställa att korrekta operationstider finns tillgängliga som kapacitetsplaneringen baseras på för att inte över- eller underskatta graden av kapacitetsbehov. Uppföljning och återkoppling bör även göras för att se hur produktionen ligger till gentemot planeringen för att även skapa ett underlag för eventuella förbättringar som kan utföras, samt att skapa rutiner och se till att dessa följs. / Purpose: The purpose of the report was to achieve a greater understanding over which factors have an impact on capacity planning as well as the methods available regarding capacity planning. Along this, three questions were formulated that the study intends to answer: Which methods within capacity planning can be applied in a customer-managed company? What distinguishes a capacity planning in a customer-managed company? How can capacity planning be improved in the business case based on the current situation? Method: In order to answer the questions and fulfil the purpose of the study, it was decided to conduct a case study at Lindab Götene AB in Götene. The first question is answered by identifying relevant theory about capacity planning and comparing them with empiric materials. The second question is answered with the help of the empirics where a current situation analysis has been conducted that gives an insight into the case company and the information on how capacity planning is applied in the case study. The theoretical and empirical material are analysed as well. The third question is answered on the basis from the analysis and collection of empirical material in the current situation description to identify what can be improved regarding capacity planning in a customer-ordered business. The empirical data consisted of interviews, documentary studies and observations. Conclusion: Today the capacity plan is created for the whole company as one unit, the authors are suggesting that the business case applies the method capacity bills which makes it possible to plan capacity for each division. Thus, creating a better chance of understanding the current situation in the production. Further recommendations are such as conducting time studies to ensure that correct operational times are available which capacity planning is based on, this for not under- or overestimate the need of capacity. Follow-up and feedback should be done to see how the current situation of the production is against the production plan, also to create a ground for potential improvements that can occur. Creating routines and making sure that they are followed.
212

Additiv tillverkning för högre teknisk tillgänglighet i internationella insatsområden

Pettersson, Alexander January 2018 (has links)
In this paper the military utility of additive manufacturing of spare parts during international deployment is explored. We also analyze the effect that additive manufacturing has on technical availability. International deployment can be tough for logistical reasons and this leads to a difficulty in supplying ground troops with spare parts. If the spare parts cannot be acquired in the deployment area these have to be shipped from central distribution centers or be ordered directly from the industries. Some spare parts are uncommon and not stored in distribution centers but only get manufactured on order. This type of production can lead to delivery times of up to 40-50 weeks. With additive manufacturing this process could be shortened to 4-10 weeks. Conclusions that can be drawn is that additive manufacturing has military utility and can give a higher technical availability, given that a few technical difficulties are resolved. At this point there is a shortcoming in the number of qualified materials for printing spare parts for regular vehicles and this makes it difficult for the industry to approve of spare parts constructed with additive manufacturing. The winning in technical availability is directly linked to how difficult the deployment area is to reach for logistical units. Additive manufacturing has a higher positive effect in areas that are hard to reach. / I denna uppsats undersöks den millitära nyttan med additiv tillverkning av reservdelar för markförband under internationell insats och hur detta kan påverka den tekniska tillgängligheten på systemen. Internationella insatser kan kräva långa logistikkedjor vilket innebär att reservdelar som inte kan införskaffas i närområdet måste fraktas från en bakre underhållsnivå eller beställas direkt från leverantör. Vid vissa tillfällen med skador på system som kräver nyproduktion av reservdelar från tillverkare, kan det i dagsläget ta upp till 40-50 veckor. Med additiv tillverkning kan förloppet kortas ner betydligt och tillverkningstiden blir istället 4-10 veckor. Slutsatser som kan dras är att additiv tillverkning har en militär nytta och kan ge en högre teknisk tillgänglighet, förutsatt att en del tekniska svårigheter klaras ut. I dagsläget finns det brister i mängden kvalificerade material för utskrifter till vanliga fordon vilket gör det svårt för industrin att godkänna reservdelarna som en ordinarie reparationsmetod i sina produkter. Vinsten i teknisk tillgänglighet är också kopplad till hur svårtillgängligt insatsområdet är. Desto svårtillgängligare området är desto större vinst medför additiv tillverkning.
213

Testing and evaluation of component made using electron beam melting and Alloy 718 powder

Nilsson, Erik, Johansson, Daniel January 2017 (has links)
The aerospace industry is constantly striving to becoming more economical and environmentally friendly. One of many efforts to achieve this is the Lightcam project which in this case is evaluating the use of additive manufacturing in the form of electron beam melting in conjunction with the nickel-based superalloy, Alloy 718. This combination is not fully explored and examined. For this purpose, a demonstrator vane was produced and it was subsequently evaluated in this thesis. The evaluation was performed in as-built condition and was divided in non-destructive testing, evaluation of these methods and metallographic review to confirm the results, and potentially revealing more properties. The non-destructive testing was performed using conventional radiography and computed tomography. Both methods struggled to deliver complete and reliable results, for varying reasons. Radiography could deliver results of the whole vane, but these were impossible to evaluate due to the rough surface created by the electron beam melting process. The computed tomography on the other hand was not affected by the rough surface and produced usable, though not complete, results of the vane. The reason for the computed tomography’s inability to deliver complete results was the material, varying thickness and complex geometry of the vane. As a complement and to verify the results from the non-destructive testing, a metallographic examination was conducted. These tests were conducted with the aim of answering the following three questions:  What non-destructive testing methods are suitable to evaluate Alloy 718 components manufactured with electron beam melting? - Neither radiography nor computed tomography are suitable as a sole evaluation method, for various reasons. All surface dependent methods were deemed unsuitable without testing due to the rough surface. What types of defects and in what quantity can they be found in the produced vane? - Defects found are: Porosity and lack of fusion, both found as internal and partially external and in varying sizes. Where are the defects located? - Pores are mainly found in the center of sections modeled to a 3mm thickness. Lack of fusion was found between build layers in all thicknesses. Apart from these results, hardness was found to vary depending on build height, increasing from the bottom towards the top. Microstructure was also found to vary with the build height, but always consisting of either equiaxed or columnar grains. / Lightcam
214

Automationsresan : Små och medelstora företags utmaningar och beslutsparametrar för automatisering / The Automation Journey : Small and meduim-sized companies' challenges and decision-making parameters for automation

Warsäter, Anton, Johansson, Jesper January 2020 (has links)
Generellt ser automationsgraden bra ut för tillverkande företag i Sverige, men vid en djupare granskning syns det att utvecklingen i små och medelstora företag (SMF), går långsamt framåt. För att Sverige ska behålla sina framträdande roll som industrination krävs ökad automation och robotisering i SMF. Därför syftar studien till att skapa ökad förståelse kring SMF:s utmaningar och påverkansfaktorer för automationsbeslut. I studien utförs kvalitativa intervjuer med fem små och medelstora företag. Forskningen grundar sig i ett ramverk som består av insamlat teoretiskt material och utgår från tre identifierade huvudområden; Produktiontekniska utmaningar, Interna utmaningar och Extern påverkan. Undersökningen visar på att SMF tenderar att stå inför en rad olika utmaningar som automation kan vara en lösning på, men också att viss problematik kan uppstå vid automatisering. Studien visar också på att samband existerar mellan företags utmaningar och att det även kan skilja sig beroende på om företag verkar som underleverantörer eller levererar produkter direkt till slutkund. / In general, the degree of automation for manufacturing companies in Sweden seems to be fine, but upon a deeper examination it appears that the development in small and medium-sized enterprises (SMEs) is slowly progressing. In order for Sweden to retain its prominent role as an industrial nation, increased automation and robotization in SMEs are required. Therefore, the study aims to create an increased understanding of SME challenges and influencing factors for automation decisions. In the study, qualitative interviews are conducted with five small and medium-sized companies. The study is based on a framework consisting of collected theoretical material and is based on three identified main areas; Production engineering challenges, internal challenges, and external impact. The study shows that SMEs tend to face a variety of challenges that automation can be a solution to, but also that some problems can exist within the implementation of automation. It also indicates that relationships exist between companies' challenges, but that they may also differ depending on whether companies act as subcontractors or deliver products directly to end customers.
215

Examining the performance of AR technologies to provide instructions for operators : a study at Siemens

Zellaya, Ibrahim, Brushwood, William January 2020 (has links)
Siemens Industrial Turbomachinery AB är intresserade av att digitalisera deras arbetsprocesser. Således är syftet med denna studie att undersöka om AR presterar bättre än papper som en instruktionsmetod för operatorer på Siemens i Trollhättan. För att kunna svara på frågan "Hur väl presterar Augmented Reality (AR) teknik som instruktionsmetod till skillnad från papper för operatorer i en produktionsmiljö?", har två kvalitativa metoder tillämpats. Datainsamling skedde med hjälp av observationer och semi-strukturerade intervjuer för analys tillstudien. Vårt val av teoretiskt ramverk tillämpades inte endast för att undersöka prestanda, det användes även för undersökning av operatörernas vilja att införa AR som en instruktionsmetod. Resultaten från denna studie visar att AR presterade bättre som en instruktionsmetod och att operatörerna hade en positiv inställning vid användning av AR. Däremot, är det fortfarande oklart hur väl denna teknologi kommer att accepteras. Detta beror huvudsakligen på faktum att framtida förbättringar behöver utföras när det kommer till hårdvara och avsaknaden av skräddarsydda applikationer för operatörernas behov. / Siemens Industrial Turbomachinery AB is interested in digitizing their current work processes. Therefore, the reason for this study is to examine if AR performs better than paper as an instruction method for operators at Siemens in Trollhättan. In order to answer the question "How well does Augmented Reality (AR) technology perform compared to physical papers as an instruction method for operators in a production environment?", two qualitative methods have been applied. Data was collected by using observations and semi-structured interviews for the analysis of this study. Our choice of theoretical framework was not only applied for evaluating the performance, but also the operators' willingness to adopt AR as a form of instruction method. The findings from the results show that AR performs better as an instruction method and that the operators had a positive attitude when using AR. However, it is still unclear how well this technology will be accepted. This is mainly due to the fact that future improvements still need to be made to the hardware and the lack of customized applications for the operators' needs.
216

Participatory design of a 3D-printed furniture concept for learning spaces : A study of large-scale additive manufacturing opportunities and limitations

Lundgren, Herman January 2021 (has links)
Today, learning spaces are stuck in the industrial age with rows of desks and chairs. Differentiated teaching and personalised learning are not effective in traditional learning spaces and should focus on creating future classrooms (Kariippanon, 2017). This thesis is covering how furnishing for learning environments can be improved and designed through a participatory design process with Katedralskolan in Växjö by using recycled materials and additive manufacturing technology. The thesis is also exploring the opportunities of involving stakeholders to create new learning through the additive manufacturing process in interior and furniture design. Together with Katedralskolan and Sculptur, this project is exploring a concept for schools to have integrated education in interior design through semiotics that will contribute to students’ learning and explore large-scale additive manufacturing. The objective is to design a collection of interior products that will inform and communicate at an educational level and how a circular manufacturing technique is possible through 3D-printing using communicating design and semiotics. The aim is also to understand Sculptur’s product development- and manufacturing process through large-scale 3D-printing. The mission statement whereas follows: Develop a furniture concept based on an understanding of the needs of, and participation with, the user group in a co-design process as a case to study the large-scale additive manufacturing techniques together with the given conditions provided by Sculptur. The thesis process has been following an iterative design process called the design thinking process (The Interaction Design Foundation, 2021) and a co-designing process (Sanders, 2018). The design thinking process is a design methodology that provides a solution-based approach to solving problems. The five stages of Design Thinking are as follows: Empathise, Define, Ideate, Prototype, Test. Through studies, surveys, and observations a list of stakeholder needs was created and was used when developing ideas through workshops, drawings, and prototyping. The ideas were then developed into concepts that were tested through both desktop 3D-printing and large-scale additive manufacturing. The concepts were also evaluated by stakeholders as well as through a concept evaluating matrix (Wikberg N., et.al., 2015). The result of this master thesis is the conclusion of the furniture concept as well as the study of large-scale additive manufacturing as an industrial designer. The furniture concept “Unfold lounge chair” is based on stakeholder needs and manufacturing restrictions. It is also an attempt to use theory to make the next generation of pedagogical furnishings using sustainable and circular manufacturing techniques. Through design thinking, the master thesis result was created with a human-centred approach to integrate the needs of people, the possibilities of technology and the requirements for business success (IDEO, n.d.). / Idag sitter läromiljöer fast i den industriella epoken med rader av skrivbord och stolar. Differentierad undervisning och personlig inlärning är inte effektiv i traditionella läromiljöer och bör vara i fokus för att skapa framtidens klassrum (Kariippanon, 2017). Detta examensarbete tar upp hur inredning för inlärningsmiljöer kan förbättras och utformas genom en deltagande designprocess med Katedralskolan i Växjö med hjälp av återvunna material och additiv tillverkningsteknik. Arbetet har också undersökt möjligheterna att involvera intressenter för att skapa nytt lärande genom tillämpning av additiv tillverkning inom inredning och möbeldesign. Tillsammans med Katedralskolan och Sculptur har detta projekt undersökt ett koncept för skolor att ha integrerad utbildning i möbler genom semiotik och pedagogisk design som kommer att bidra till elevernas lärande samt utforska storskalig additiv tillverkning. Målet är att utforma en samling möbelkoncept som informerar och kommunicerar på utbildningsnivå och hur en cirkulär tillverkningsteknik är möjlig genom 3D-printnig med hjälp av kommuniationsdesign och semiotik. Målet är också att förstå Sculpturs produktutvecklings- och tillverkningsprocess genom storskalig additiv tillverkning. Projektets Mission statement var följande: Utveckla ett möbelkoncept baserat på en förståelse av behoven hos användargruppen i en samdesignprocess som ett fall för att studera storskalig additiv tillverkning tillsammans med de givna förutsättningarna från Sculptur. Examensarbetet har följt en iterativ designprocess som kallas design thinking process (The Interaction Design Foundation, 2021) tillsammans med en co-designprocess (Sanders, 2018). Design thinking är en designmetodik som ger en lösningsbaserad metod för att lösa problem. De fem faserna i design thinking är följande: Empathise, Define, Ideate, Prototype, Test. Genom studier, undersökningar och observationer skapades en lista över intressenters behov och användes när idéer utvecklades genom workshops, skisser och prototyper. Idéerna utvecklades sedan till koncept som sedan testades genom både mindre 3D-utskrift och storskalig additiv tillverkning. Koncepten utvärderades också av intressenter samt genom en konceptviktningsmatris (Wikberg N., et.al., 2015). Resultatet av detta examensarbete är sammanfattningen av möbelkonceptet samt studien av storskalig additiv tillverkning som industridesigner. Möbelkonceptet ”Unfold lounge chair” bygger på intressenternas behov samt tillverkningsrestriktioner. Det är också ett försök att använda teori för att skapa nästa generation av pedagogiska möbler med hållbara och cirkulära tillverkningstekniker. Genom design thinking skapades resultatet med ett mänskligt centrerat tillvägagångssätt för att integrera människors behov, teknikens möjligheter och kraven för produktens framgång (IDEO, n.d.).
217

Process Mapping for Laser Metal Deposition of Wire using Thermal Simulations : A prediction of material transfer stability / Processkartläggning för lasermetalldeponering av tråd baserat på termiska simuleringar : En prediktering av materialöverföringsstabilitet

Lindell, David January 2021 (has links)
Additive manufacturing (AM) is a quickly rising method of manufacturing due to its ability to increase design freedom. This allows the manufacturing of components not possible by traditional subtractive manufacturing. AM can greatly reduce lead time and material waste, therefore decreasing the cost and environmental impact. The adoption of AM in the aerospace industry requires strict control and predictability of the material deposition to ensure safe flights.  The method of AM for this thesis is Laser Metal Deposition with wire (LMD-w). Using wire as a feedstock introduces a potential problem, the material transfer from the wire to the substrate. This requires all process parameters to be in balance to produce a stable deposition. The first sign of unbalanced process parameters are the material transfer stabilities; stubbing and dripping. Stubbing occurs when the energy to melt the wire is too low and the wire melts slower than required. Dripping occurs when too much energy is applied and the wire melts earlier than required.  These two reduce the predictability and stability that is required for robust manufacturing.  Therefore, the use of thermal simulations to predict the material transfer stability for LMD-w using Waspaloy as the deposition material has been studied.  It has been shown that it is possible to predict the material transfer stability using thermal simulations and criterions based on preexisting experimental data. The criterion for stubbing checks if the completed simulation result produces a wire that ends below the melt pool. For dripping two criterions shows good results, the dilution ratio is a good predictor if the tool elevation remains constant. If there is a change in tool elevation the dimensionless slenderness number is a better predictor.  Using these predictive criterions it is possible to qualitatively map the process window and better understand the influence of tool elevation and the cross-section of the deposited material. / Additiv tillverkning (AT) är en kraftigt växande tillverkningsmetod på grund av sin flexibilitet kring design och möjligheten att skapa komponenter som inte är tillverkningsbara med traditionell avverkande bearbetning.  AT kan kraftigt minska tid- och materialåtgång och på så sett minskas kostnader och miljöpåverkan. Införandet av AT i flyg- och rymdindustrin kräver strikt kontroll och förutsägbarhet av processen för att försäkra sig om säkra flygningar.  Lasermetalldeponering av tråd är den AT metod som hanteras i denna uppsats. Användandet av tråd som tillsatsmaterial skapar ett potentiellt problem, materialöverföringen från tråden till substratet. Detta kräver att alla processparametrar är i balans för att få en jämn materialöverföring. Är processen inte balanserad syns detta genom materialöverföringsstabiliteterna stubbning och droppning. Stubbning uppkommer då energin som tillförs på tråden är för låg och droppning uppkommer då energin som tillförs är för hög jämfört med vad som krävs för en stabil process. Dessa två fenomen minskar möjligheterna för en kontrollerbar och stabil tillverkning.  På grund av detta har användandet utav termiska simuleringar för att prediktera materialöverföringsstabiliteten för lasermetalldeponering av tråd med Waspaloy som deponeringsmaterial undersökts. Det har visat sig vara möjligt att prediktera materialöverföringsstabiliteten med användning av termiska simuleringar och kriterier baserat på tidigare experimentell data. Kriteriet för stubbning kontrolleras om en slutförd simulering resulterar i en tråd som når under smältan.  För droppning finns två fungerande kriterier, förhållandet mellan svetshöjd och penetrationsdjup om verktygshöjden är konstant, sker förändringar i verktygshöjden är det dimensionslös ”slenderness” talet ett bättre kriterium.  Genom att använda dessa kriterier är det möjligt att kvalitativt kartlägga processfönstret och skapa en bättre förståelse för förhållandet mellan verktygshöjden och den deponerade tvärsnittsarean.
218

Microstructure and mechanical properties of low-temperature hot isostatic pressed Ti-6Al-4V manufactured by electron beam melting

Thalavai Pandian, Karthikeyan January 2022 (has links)
Ti-6Al-4V manufactured by electron beam melting Keywords: Additive manufacturing, high-temperature tensile properties, low cycle fatigue, neutron diffraction, fatigue crack growth ISBN: 978-91-89325-27-2 (Printed) 978-91-89325-26-5 (Electronic) Ti-6Al-4V is the most widely used α+β titanium alloy in aerospace engine applications due to its high specific strength. Typically, the alloy is manufactured as castings or forgings and then machined to final geometry. These conventional manufacturing processes do however generate a lot of waste material, whereas additive manufacturing (AM) can potentially produce a near-net-shape geometry directly from the feedstock. In the past decade, electron beam melting (EBM), one of the powder bed fusion techniques, has been widely researched to build Ti[1]6Al-4V components. Still, the as-built material can contain defects such as gas pores that require post-processing, such as hot isostatic pressing (HIP) to produce nearly fully dense components. HIP treatment of conventionally cast Ti-6Al-4V is normally performed at 920 ˚C, 100 MPa for 2 hours. This same HIP treatment has then been adapted also for EBM-manufactured Ti-6Al-4V, which however results in coarsening of α laths and reduction of yield strength. Therefore, finding a more appropriate HIP treatment for this new type of Ti-6Al-4V material, i.e. EBM manufactured, would be of great benefit for the industry. Lowering the HIP treatment temperature to 800 ˚C and increasing the pressure to 200 MPa has recently been proven to close the porosity to a high degree while sustaining the high yield strength. In this thesis, the high-temperature tensile properties of EBM-manufactured Ti[1]6Al-4V subjected to a low-temperature (800 ˚C) HIP treatment were evaluated and compared with standard HIP-treated (920 ˚C) materials. Metallurgical characterization of the as-built, HIP-treated materials have been carried out to understand the effect of temperature on the microstructures. The standard HIP[1]treated material measured about 1.4x - 1.7x wider α laths than those in the low[1]temperature HIP treated and as-built samples, respectively. The standard HIP[1]treated material showed about 10 - 14% lower yield strength than other HIP treated materials. At 350 ˚C the yield strength decreases to about 65% compared to the room temperature strength for all tested materials. An increase in ductility vi programvaran NASGRO där livsförutsägelserna visade god överensstämmelse med experimentella livscykler i de flesta fall. vii Abstract Title: Microstructure and mechanical properties of low-temperature hot isostatic pressed Ti-6Al-4V manufactured by electron beam melting Keywords: Additive manufacturing, high-temperature tensile properties, low cycle fatigue, neutron diffraction, fatigue crack growth ISBN: 978-91-89325-27-2 (Printed) 978-91-89325-26-5 (Electronic) Ti-6Al-4V is the most widely used α+β titanium alloy in aerospace engine applications due to its high specific strength. Typically, the alloy is manufactured as castings or forgings and then machined to final geometry. These conventional manufacturing processes do however generate a lot of waste material, whereas additive manufacturing (AM) can potentially produce a near-net-shape geometry directly from the feedstock. In the past decade, electron beam melting (EBM), one of the powder bed fusion techniques, has been widely researched to build Ti[1]6Al-4V components. Still, the as-built material can contain defects such as gas pores that require post-processing, such as hot isostatic pressing (HIP) to produce nearly fully dense components. HIP treatment of conventionally cast Ti-6Al-4V is normally performed at 920 ˚C, 100 MPa for 2 hours. This same HIP treatment has then been adapted also for EBM-manufactured Ti-6Al-4V, which however results in coarsening of α laths and reduction of yield strength. Therefore, finding a more appropriate HIP treatment for this new type of Ti-6Al-4V material, i.e. EBM manufactured, would be of great benefit for the industry. Lowering the HIP treatment temperature to 800 ˚C and increasing the pressure to 200 MPa has recently been proven to close the porosity to a high degree while sustaining the high yield strength. In this thesis, the high-temperature tensile properties of EBM-manufactured Ti[1]6Al-4V subjected to a low-temperature (800 ˚C) HIP treatment were evaluated and compared with standard HIP-treated (920 ˚C) materials. Metallurgical characterization of the as-built, HIP-treated materials have been carried out to understand the effect of temperature on the microstructures. The standard HIP[1]treated material measured about 1.4x - 1.7x wider α laths than those in the low[1]temperature HIP treated and as-built samples, respectively. The standard HIP[1]treated material showed about 10 - 14% lower yield strength than other HIP treated materials. At 350 ˚C the yield strength decreases to about 65% compared to the room temperature strength for all tested materials. An increase in ductility viii was observed at 150 ˚C compared to that at room temperature, but the ductility decreased between 150 - 350 ˚C because of activation of different slip systems. The low cycle fatigue (LCF) behavior of such a modified HIP (low-temperature HIP) material is assessed at two different strain levels and compared with the corresponding LCF properties for the standard HIP material. Even though the modified HIP material had lowest minimum life cycles to failure, the overall fatigue performance is comparable with that of the standard HIP material. Also, fatigue life predictions were made from the measured defect size at the crack initiation site using NASGRO. The calculated life predictions showed good agreement with the experimental values in most cases. In-situ neutron diffraction measurements on tensile test specimens were conducted, at both room temperature and at 350˚ C, for the standard and modified HIP-treated materials. The objective was to gain essential insights on how the crystal lattice strains relate to the macroscopic strengths in these specific microstructures. This investigation helped to understand the load partitioning between different slip planes and constituent phases in the microstructure at different temperatures. / Ti-6Al-4V är den mest använda α+β titanlegeringen i flygmotortillämpningar på grund av sin höga specifika hållfasthet. Vanligtvis tillverkas legeringen som gjutgods eller smide och bearbetas sedan till slutlig geometri. Dessa konventionella tillverkningsprocesser genererar dock en hel del avfallsmaterial, medan additiv tillverkning (AM) potentiellt kan producera en nästan slutgiltlig geometri direkt från råvaran. Under det senaste decenniet har elektronstrålesmältning (EBM), en av pulverbäddsfusionsteknikerna, undersökts mycket för att bygga Ti-6Al-4V-komponenter. Ändå kan det byggda materialet innehålla defekter såsom gasporer som kräver efterbearbetning, såsom varm isostatisk pressning (HIP) för att producera nästan helt täta komponenter. HIP[1]behandling av konventionellt gjutet Ti-6Al-4V utförs normalt vid 920 ˚C, 100 MPa under 2 timmar. Samma HIP-behandling har sedan anpassats även för EBM[1]tillverkat Ti-6Al-4V, vilket dock resulterar i förgrovning av α-lameller och minskning av sträckgränsen. Att hitta en mer lämplig HIP-behandling för denna nya typ av Ti-6Al-4V-material, dvs EBM-tillverkat, skulle därför vara till stor fördel för industrin. Att sänka HIP-behandlingstemperaturen till 800 ˚C och öka trycket till 200 MPa har nyligen visat sig stänga porositeten i hög grad samtidigt som den höga sträckgränsen bibehålls. Ti-6Al-4V används huvudsakligen i applikationer för flygmotorer upp till en maximal driftstemperatur på 300 ˚C. Därför studerades högtemperaturdragegenskaperna hos de olika HIP-behandlade EBM[1]byggmaterialen i detta forskningsarbete. Denna studie visade att duktiliteten påverkas av aktiveringen av olika glidsystem baserat på temperatur. Ytterligare neutrondiffraktionsexperiment utfördes tillsammans med in-situ dragprovning för att bestämma det aktiva glidsystemet vid en specifik temperatur. Utmattningsbeteendet hos det lågtemperaturbehandlade HIP-materialet utvärderas också genom lågcykelutmattningstestning och utmattningsspricktillväxttest. Utmattningsprestandan för det modifierade HIP[1]materialet utvärderades mot standard HIP- material och visade sig ha jämförbara utmattningsegenskaper. Förutsägelser om utmattningsliv utfördes med hjälp av vi programvaran NASGRO där livsförutsägelserna visade god överensstämmelse med experimentella livscykler i de flesta fall. / <p>Submitted papers or manuscripts have been excluded from the fulltext file.</p>
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Corrosion of additively manufactured magnesium alloy WE43 : An investigation in microstructure and corrosion properties of as built samples manufactured with Powder Bed Fusion-Laser Beam

Wahman, Clarence January 2021 (has links)
The work presented in this thesis was conducted at Uppsala University and at Swerim AB. The study aims to broaden the knowledge about the corrosion of additively manufactured bioresorbable alloy WE43 in humanlike conditions for future applications. Biodegradable metal implants are implants meant to stay in the body and support the wounded bone for a certain time period, and then degrade as new, healthy bone forms in its place. Magnesium alloys have properties that are desired for these kind of implants as it is biodegradable, non-toxic and matches the mechanical properties of bone. Furthermore, magnesium alloy WE43, containing yttrium, neodymium and zirconium, already exist on the market as a powder extruded screw that treats Hallux valgus, thus proves the alloys compatibility as a bioresorbable implant. However, in order to optimize implants for specific situations, additive manufacturing can be a powerful tool. By utilizing the advantages of additive manufacturing, patient specific, complex designs implant can be manufactured rapidly in order to be used in a patient. On the other hand, additive manufacturing is a complex method with many aspects affecting the outcome. Therefore it is important to study the influence that different parameters have on the material's properties, especially the corrosion properties. This thesis aims to study different power settings on the laser in the manufacturing process and what effect it has on the microstructure as well as the corrosion properties of as built WE43 samples. Samples of three different parameters settings were manufactured with a Powder Bed Fusion-Laser Beam 3Dprinter. These samples were analyzed regarding surface roughness and microstructure with Light Optical Microscope, Scanning Electron Microscope, Energy Dispersive Spectroscopy, Electron Backscatter Diffraction and Alicona InfiniteFocus. Furthermore, the corrosion properties of the samples were investigated by collecting and measuring hydrogen gas that is released during the corrosion process. In addition, the electrolyte were examined regarding the change in ion concentration and electrochemical tests were performed. It was found that the samples did not differ substantially in microstructure as all three parameter settings exhibited a matrix of magnesium and precipitates of alloying elements. However, the sample manufactured at the lowest energy density had pores incorporated in the bulk. Despite the porous bulk this sample performed best in the immersion tests and exhibited the lowest corrosion rate over 28 days. The reason for this behavior is not determined, however possible causes are discussed and further studies are recommended.
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How Beads come Together : Late Iron Age glass beads as past possessions and present sources

Råhlander, Moa January 2017 (has links)
This study aims to demonstrate the potential for understanding first millennium glass beads not as individual representatives of types, but as collections of objects brought together and curated by owners. It uses the author’s experience as a skilled bead maker to investigate processes of bead production and mechanics of bead collection current in Scandinavia and Anglo-Saxon England in the period of 6th to 9th century AD. In the study the bead collections of seven graves are examined from the perspective of their production techniques, materials, and damage from wear and cremation. The results point to beads being acquired in different numbers and often worn for long periods of time before being buried.

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