The purpose of this study was to determine which type of bevel in a class IV dental composite restoration is the most esthetic and has the best blend to natural tooth structure via clinical and spectrophotometric evaluations. The null hypotheses were as follows: (1) there is no difference in visual evaluation rank scores among five groups of evaluators for each type of bevel; (2) there is no agreement in the visual evaluation rank scores of the seven groups of bevels among all evaluators or within each group of evaluators; (3) there is no difference in the lightness values among seven types of bevels at each of eight measurement points or for the whole tooth as measured by a spectrophotometer; and (4) there is no correlation between the visual evaluation and the spectrophotometric evaluation. The class IV samples were made via CAD/CAM milling for standardization. There were seven groups: negative control (no bevel); short (1mm) and straight bevel; short (1mm) and scalloped bevel; long (2mm) and straight bevel; long (2mm) and scalloped bevel; infinite (3+mm) and straight bevel; and infinite (3+mm) and scalloped bevel. The fractures were restored with the same type of dental composite via a digitally designed mold fabricated with a 3D printer. Once completed, the samples were randomized and evaluated visually by 91 people in five groups (faculty, graduate residents, pre-doctoral dental students, assistants/hygienists, and auxiliary staff). Evaluators placed the samples in the order they deemed least to most esthetic within a lightbox set to CIE Standard Illumination D65. After the visual evaluation, the lightness (L*) values were measured optically with a reflectance spectrophotometer at eight points on each of the seven bevel groups, as well as on an un-prepared typodont tooth used for reference. One-way ANOVA on ranked data with the post-hoc Bonferroni test was conducted to detect a significant difference in median rating score among five groups of evaluators, and Kendall’s W was used to evaluate an agreement among multiple raters. One-way ANOVA with the post-hoc Tukey’s HSD was used to find a significant difference in mean lightness values among seven types of bevels. Dunnett’s test was used to compare the reference group with each of the seven bevel groups when evaluating the lightness values. Pearson Correlation test along with the simple linear regression analysis were used to determine whether a significant relationship existed between visual evaluation scores and lightness values. The groups were ranked from least to most esthetic as follows: no bevel, short and straight bevel, short and scalloped bevel, long and straight bevel, long and scalloped bevel, infinite and straight bevel, and infinite and scalloped bevel by the 91 evaluators and Kendall’s W was 0.80 (strong agreement). Moreover, no significant difference in rating scores was found among the five groups of evaluators regarding each type of bevel (p>0.05). The overall mean lightness values observed in groups 1-3 were significantly higher than those in groups 6 and 7 (P< 0.05), but no significant difference was noted among groups 1-5 or among groups 4-7. As the lightness values measured by the spectrophotometer decreased, the overall visual evaluation score increased. The Pearson Correlation Coefficient of -0.89 indicated there was a strong negative correlation between the two variables (p=0.0066). Linear regression analysis revealed that the predictor of lightness was significant (strong negative correlation, R-square 0.99, p< 0.0001). The first null hypothesis was accepted and the second, third, and fourth were rejected. There was no difference in median visual evaluation rank scores among five groups of evaluators for each type of bevel, however, there was agreement in the ranked order as the findings of this study indicated that infinite and scalloped bevel was the most preferred and no bevel was the least preferred via a strong agreement the evaluators. There was a significant difference in lightness values among the seven bevel groups; the shorter bevels had higher L* values that were closer to the L* values of the reference tooth while the longer bevels had lower L* values. The correlation data showed that placing a longer bevel (3+mm) allowed for a more gradual transition and better blending capabilities between the tooth structure and dental composite. The overall conclusion from this study was the longer the bevel, the more gradual the change in Lightness (L*), which correlated to the more esthetic restoration, as determined by the evaluators.

Companies have put much focus on production systems to generate and maintain competitiveness which has contributed in less focus to logistics. The material flow is the process after the main processes and has therefore been regarded as “unimportant”. If the material flow fails, there can be consequences such as inventory-build ups or undersupply of material. Lean thinking is one strategy that may be applied to analyze and identify wastes, but the identification of problems has been harder to detect, while the ability to solve them has not improved at the same rate. Following two research questions has been asked to identify how companies should proceed to improve their inventory management but also what factors contribute to the inventory build-ups.  ·        What may cause excess inventory in manufacturing companies? <ul type="disc">How can a manufacturing company reduce WIP´s? The research method is based on a qualitative approach with an interpretivist research methodology to help answer the questions. A case study was done at a manufacturing company to help answer the research questions. The data has been collected by observations trough section B1 and unstructured interviews with both management and operators. The collected data was later compared to the literature according to the inductive reasoning to be able to make suggestions for improvements. The DMAIC tool has been a central point of this research regarding the mapping of the current state and suggestion of a future state. The case study was conducted at Company X AB in the middle of Sweden which is a company that manufactures components and complete solutions. The focus on production has resulted in less focus on the internal logistics. With the low focus on the internal logistics, inventory build-ups have occurred. The results point to the OEE being a contributing factor to the inventory build-up. The availability of both machines was low and therefore caused the OEE to be low. The low availability was caused by long changeovers, staff shortages, and emergency reparations. The conclusions are that Company X must make improvements so that the factors of the low availability decrease in frequency and severity to reduce the work-in-process (WIP). The improvements should be approached with different lean-tools such as SMED, KANBAN, FIFO and 5S.

This exam report includes a survey of surface treatment materials and their associated surface treatment methods for application in a tissue machine commissioned by Valmet AB. The tissue machine produces 24 hours a day in a demanding environment consisting of water, heat, oils, glue, dust and various chemicals. The demanding environment makes it difficult to maintain the machine clean due to the limited access at various machine parts when the machine is operating, which can lead to both personal risks and risks for production stoppages. These factors form the basis for the build-ups that takes place at various machine parts. Mostly, it’s about paper fibres that either are loose and dry or clustered into lumps. They also appear as lumps of fibres held together by oil, glues or other chemicals. Over time, they can loosen and, in the worst case, are due to breakages and production failures. The build-ups can also destroy the function of moving machine parts or lead to corrosion. The commission was assigned by Bengt O Andersson and Mickey Lindevall at Valmet AB. The project was conducted as the examining part in the course Degree Project for the Bachelor of Science in Mechanical Engineering, MSGC17, at the faculty of health, science and technology at Karlstad university. The project was carried out individually by a student at the Bachelor of Science program in Mechanical Engineering at Karlstad university. This degree project has taken precedence where the previous degree project at Valmet AB completed its work. The previous degree project has served as a reference document in this report to work out a requirement specification and identifying machine parts that are desired to undergo some form of surface treatment. The acting environments that exist at the various machine parts that are desired to be surface treated have also been examined from the previous degree project. This report has taken a different approach compared to the previous thesis work and is instead directed towards finding suitable surface treatment materials and associated application methods using the material database, CES EduPack. The purpose of the degree project has been to present suitable surface treatment materials and associated surface treatment methods. These are to solve the existing problems, thus facilitating cleaning and maintenance of the tissue machine. To achieve this, a list of suitable materials and associated surface treatment methods has been presented. From this list, conclusions are drawn to find as good surface treatment materials and its associated application methods as possible. With these, the problem should be eliminated or reduced drastically for the number of build-ups regarding the treated machine parts. The objective for this project thesis has been to analyse and proposing suitable methods and materials for surface treatments. With the chosen method and material for the surface treatment, the surfaces upon application are to achieve such properties that build-ups do not adhere to them. The project also contains a requirement specification that has been translated into restriction terms that all investigated material candidates have had to fulfil to be classified as suitable material candidates. The report has also taken a stand to the literature and theory available in the subject area to further investigate what materials are currently used in similar industrial applications. The information that has been processed has, in a final phase, been used as a basis for the list of suitable surface treatment materials and their associated surface treatment methods presented in the report. / Denna examensrapport innefattar en undersökning av ytbehandlingsmaterial samt tillhörande ytbehandlingsmetoder för applicering i en mjukpappersmaskin på uppdrag av Valmet AB. Mjukpappersmaskinen producerar 24 timmar om dygnet i en krävande miljö bl.a. bestående av vatten, värme, oljor, lim, damm samt diverse kemikalier. Den krävande miljön gör att det är svårt att hålla maskinen ren eftersom att det är svårt att komma åt överallt under drift, vilket kan medföra både personrisker och risker för produktionsstopp. Dessa faktorer ligger till grund för att uppbyggningar uppstår vid diverse maskindelar. Mestadels handlar det om pappersfibrer som endera är lösa torra eller fasttorkade i klumpar men de förekommer även som klumpar av fibrer som hålls ihop av olja, lim eller andra kemikalier. Med tiden så kan dessa lossna och ligger i värsta fall till grund för banbrott och produktionsbortfall. Uppbyggningarna kan även förstöra funktionen på rörliga maskindelar eller leda till korrosion. Uppdraget är utgivet av Bengt O Andersson och Mickey Lindevall på Valmet AB. Projektet utförs som den examinerande delen i kursen Examensarbete för högskoleingenjörsexamen i Maskinteknik, MSGC17 vid fakulteten för hälsa, natur- och teknikvetenskap vid Karlstads universitet. Projektet har utförts enskilt av studerande vid Högskoleingenjörsprogrammet i Maskinteknik vid Karlstads universitet. Detta examensarbete har tagit vid där föregående examensarbetare vid Valmet AB avslutade sitt arbete. Dennes examensrapport har fungerat som ett referensdokument i denna rapport för att kunna arbeta fram en kravspecifikation samt identifiera maskindelar som önskas genomgå någon form av ytbehandling. De verkande miljöerna som existerar vid de maskindelar som önskas ytbehandlas har även undersökts från det tidigare examensarbetet. Denna rapport har tagit ett nytt tillvägagångssätt gentemot föregående examensarbetare och riktas istället mot att identifiera lämpliga ytbehandlingsmaterial samt tillhörande applikationsmetoder med hjälp av materialdatabasen, CES EduPack. Syftet med detta examensarbete har varit att presentera lämpliga ytbehandlingsmaterial samt tillhörande ytbehandlingsmetoder som löser de befintliga problemen och därmed underlättar rengöring och underhåll av mjukpappersmaskinen. För att kunna göra detta har en lista av lämpliga material samt tillhörande ytbehandlingsmetoder tagits fram. Ur denna lista med material och ytbehandlingsmetoder dras slutsatser för att hitta ett så bra ytbehandlingsmaterial och tillhörande ytbehandlingsmetod som möjligt. Med dessa skall problemet elimineras eller minskas drastiskt gällande antal uppbyggningar vid behandlade maskindelar. Examensarbetet har som mål att analysera och ge förslag på lämpliga metoder och material för ytbehandlingar. Med vald metod och material för ytbehandling skall ytorna vid applicering få en sådan egenskap att uppbyggningar inte vidhäftar vid dessa. Projektet innehåller även en kravspecifikation som översatts till restriktionsvillkor som samtliga undersökta materialkandidater varit tvungna att passera för att klassas som lämpliga materialkandidater. Rapporten har även tagit ställning till den litteratur och teori som funnits tillgänglig inom ämnesområdet för att vidare undersöka vilka material som används i dagsläget inom liknande industriella tillämpningar. Informationen som tagits fram har i ett slutskede legat som grund för den lista av lämpliga ytbehandlingsmaterial samt dess tillhörande ytbehandlingsmetoder som presenteras i rapporten.