Tråddragning är en kallbearbetningsprocess där tråd dras genom en dragsten, som plastiskt deformerar materialet och reducerar tvärsnittsarean. En viktig parameter i tråddragningsprocessen är draghastigheten - en ökad draghastighet kan förbättra produktiviteten, vilket är önskvärt för företaget Suzuki Garphyttan AB då efterfrågan på produkter har ökat. Dessutom är ökad produktivitet positivt i avseende med ekonomisk hållbarhet, men får inte ske på bekostnad av trådkvaliteten. En försämrad kvalitet kan leda till en större mängd skrot vilket är negativt utifrån ett miljömässigt hållbarhetsperspektiv. I detta examensarbete har åtta olika experiment utförts med syfte att undersöka hur ökad draghastighet och ett ökat vattentryck påverkar ytkvaliteten på kolstålet Oteva 75. Data i form av temperaturmätningar, ytjämnhet och djup av defekter har samlats in för att göra jämförelser och dra slutsatser mellan ökad draghastighet och ytkvalitet. Resultatet indikerar att det uppstår mindre variationer gällande ytjämnheten vid lägre hastigheter samt att djupet på repor inte har försämrats eller förbättrats i ett specifikt mönster vid ökade hastigheter. Med ett ökat vattentryck var djupet på repor minst vid mellersta hastigheten och ytjämnheten hade marginellt större variationer vid högre hastigheter jämfört med den lägsta. För att kunna dra generella slutsatser måste fler liknande experiment göras i framtiden. Variablerna måste observeras mer noggrant genom att till exempel använda samma maskin, samma smörjmedelsförhållanden och samma leverantör. Detta kan göras genom att testa samma trådring, i samma maskin. / Wire drawing is a cold-working process in which a wire is pulled through a drawing die, resulting in plastic deformation of the material and wire diameter reduction. One important parameter in the wire drawing process is the drawing speed. An increased drawing speed can improve productivity, which is desired for the company Suzuki Garphyttan AB due to the increased demand for products. Furthermore, improved productivity is positive in terms of economic sustainability, but cannot be at the expense of wire quality. Worsen quality may lead to increased amount of scrap which is negative from a perspective of environmental sustainability. In this master thesis, eight different experiments have been performed with the aim to examine how increased drawing speed-, and pressure of cooling water, affects the surface quality of the carbon steel Oteva 75. Data in terms of temperature measurements, surface roughness and depth of defects have been collected to make comparisons and conclusions between increased drawing speed and surface quality. The result indicates that there are less variations regarding the surface roughness at lower speeds than higher speeds. The depth of defects has not deteriorated or improved in a specific pattern at increased speeds. With increased water pressure, the depth of defects was smallest at the first speed increase and the surface roughness had marginally larger variations at the highest speed. To be able to draw general conclusions, more similar experiments must be done in the future. The variables involved need to be observed more carefully by, for example, using the same shaving equipment, the same lubrication conditions, and the same supplier. This can be done by testing on the same wire ring, in the same machine.

Over one million hip prostheses are implanted in patients worldwide each year and the need is increasing as the patient group of younger and more active patients is increasing. Many parameters affect the longevity of the implant, where aseptic loosening caused by wear debris is the most common reason for revision. To be able to monitor wear in vivo and also to predict the longevity of new materials for hip prostheses are therefore important issues in this interdisciplinary research area. This thesis comprise a true non-invasive 3D method for determination of acetabular cup wear using Computed Tomography (CT) intended for clinical routine use in order to plan for a revision. It also comprises investigations of the influence of surface roughness and sterilization method in wear testing of materials for hip prostheses. Mainly wear of ultra high molecular weight polyethylene (UHMWPE) was investigated since it is the most common soft bearing in hip prostheses. The 3D-CT method was found to be easy to use and showed an accuracy and repeatability at a clinical relevant level for acetabular cup wear. It should lend itself well to semi-automation. The influence of surface roughness was investigated with both a multidirectional pin-on-disk machine and with a hip simulator. A new low friction coating, Micronite, was also evaluated with the pin-on-disk machine. This coating showed potential for use in artificial joints, but further investigations are needed. In the hip simulator test, it was found that not only a rougher counter surface increased wear, but also sterilization by γ-irradiation increased wear of UHMWPE cups. / QC 20101117

Det här examensarbetet är en fortsättning på ett tidigare kandidatexamensarbete vars syfte var att bestämma form och funktion för ett elektriskt stearinljus som skulle se så verklighetstroget ut som möjligt. En prototyp av ljuset byggdes för att testa den nya tekniska lösningen. Syftet med föreliggande examensarbetet var att undersöka hur ljuset skulle kunna tillverkas industriellt. Vad som var optimal tillverkningsteknik och bästa material för varje komponent undersöktes. Svårigheten var att fatta välgrundade beslut för hur vissa komponenter skulle tillverkas, varför det krävdes fysiska experiment för detta. Ett exempel på en sådan komponent var ljusets låga vars uppgift är att sprida ljus, jämt i alla riktningar. Lågan behöver därför ha en skrovlig yta som kan sprida ljus. För att kunna tillverka lågan krävdes en teknik som gör det möjligt att producera dess komplicerade form tidseffektivt. Först bestämdes därför att lågan skulle formsprutas då det är är en teknik som möjliggör gjutning av avancerade former som går på kort tid. Det bestämdes även att lågan skulle göras i akrylplast då det är en plast med hög transparens. För att bestämma hur den skrovliga ytan skulle åstadkommas utfördes sedan ett experiment där olika gjutformar tillverkades. Dessa gjutformar ytbearbetades på olika sätt med bl.a. blästring, gnistbehandling, etsning och gravering. Genomskinlig plast användes för att formspruta i gjutformarna. Det resulterade i formsprutade plastbrickor med olika ytstrukturer. Dessa ytor belystes och dess ljusspridande förmåga mättes med två olika mättekniker. Det visade sig att den etsade ytan spred ljus bäst. Jämfört med ytan som fanns på prototypens låga så visade mätningar att den etsade ytan var något bättre på att sprida ljus. Även andra experiment gjordes för val av en fjäderkomponent och val av limmetod.Ytjämnhetsmätning av den etsade ytan visade att ytjämnheten var Ra 18 µm och på grund av skrovligheten i ytan kunde lågan inte gjutas i ett stycke utan fick delas upp i två halvor. En CAD-modell av ett formverktyg som gjuter en halv låga konstruerades med tillräckliga släppvinklar.  Tack vare den etsade ytans goda ljusspridande förmåga behövde ljusets ljuskälla inte lysa starkare än 30 lumen vilket innebär att LED-lampans effekt inte behöver vara större än 0,5 W. De två AA batterier som strömförsörjer ljuset skulle då räcka i minst 15 timmar. / This master thesis is a continuation of an earlier bachelor projectwhere the purpos was to develop form and function for an electric candle that would look as realistic as possible. A prototype of the light was made to test the technical solution. The purpose of this master thesis was to find out how this candle should be manufactured in industry. Optimal manufacturing process and material were assigned to all the components. For some components it was harder to make well grounded decitions about the manufacturing process which is why physical experiments were needed. One of such components is the flame who’s function is to spread light even in all directions. Therefor the flame needs a rough surface that can scatter light. In order to manufacture the flame it required a manufacturing process that could make the complex form on short time. Acrylic plastic was choosen as the material for the flame due to its high light transmittance. To determine how the surface on the flame would be created an experiment was conducted were a couple of mold forms were made. The surface of the forms was processed with blasting, electrical discharge machining, etching and scraping. Transparent plastic was injection molded in these forms. That resulted in pieces of plastic with different surfaces. These pieces were lit and the light scattering properties were measured in two different ways. It showed that the etched surface scattered most light. Other experiments concerning spring testing and glue testing were made. The surface roughness were measured. The etched surface had a surface roughness of Ra 18 µm and because of the high roughness the flame could not be molded in one piece but was split in two. A CAD-model of a mould that makes a half flame was constructed with required draft angles. Thanks to the good light scattering of the etched surface, the lightsource did not need to be stronger than 30 lumen which meen the power of LED-light only had to be around 0,5 W. That meant that two AA batteries could power the light for 15 hours.

It was found that the measurements captured by confocal microscopy and scanning electron microscopy had a statistically significant difference for bovine tissue. There was not a statistically significant for porcine and poultry tissue. The intent of the study is to perform a comparative study to examine efficacy of two distinct technologies for a singular purpose: tissue surface roughness characterization. The two technologies compared are a confocal reflectance microscope and a scanning electron microscope. The comparison was made by comparing two surface roughness parameters [Ra and Rq] within ImageJ. The study examined three different animal species [porcine, bovine, and poultry] to highlight if different tissues presented alternative conclusions for the efficiency of either technology. Additional analysis was produced comparing two cutting methods [Kleen Kut versus conventional], as well as six different poultry processing technique combinations.

This thesis investigates the cooling behaviour of polymers during the microinjection moulding process. The work included bespoke experimental mould design and manufacturing, material characterisation, infra-red temperature measurements, cooling analysis and cooling prediction using commercial simulation software. To measure surface temperature of the polymers, compounding of polypropylene and polystyrene with carbon black masterbatch was performed to make materials opaque for the IR camera. The effects of addition of carbon black masterbatch were analysed using differential scanning calorimetry and Fourier transform infrared spectroscopy. Sapphire windows formed part of the mould wall and allowed thermal measurements using an IR camera. They were laser machined on their inside surfaces to generate a range of finishes and structures. Their topographies were analysed using laser confocal microscope. The surface energy of sapphire windows was measured and compared to typical mould steel, employing a contact angle measurement technique and calculated using Owens-Wendt theory. A heating chamber was designed and manufactured to study spreading of polymer melts on sapphire and steel substrates. A design of experiments approach was taken to investigate the influence of surface finish and the main processing parameters on polymer cooling during microinjection moulding. Cooling curves were obtained over an area of 1.92 by 1.92 mm of the sapphire window. These experiments were conducted on the Battenfeld Microsystem 50 microinjection moulding machine. A simulation study of polymer cooling during the microinjection moulding process was performed using Moldflow software. Particular interest was paid to the effect of the values of the interfacial heat transfer coefficient (HTC) on the simulated cooling predictions. Predicted temperature curves were compared to experimentally obtained temperature distributions, to obtain HTC values valid for the material and processing parameters.

The use of nanofluids as heat transfer fluids has received a lot of attention from the heat transfer research community. Due to the increased thermal conductivity of nanofluids over their base fluids, the number of nanofluids scientific publications increased significantly in the past decade. The effects of the heated surface roughness, nanoparticles and surfactant concentrations on pool boiling of nanofluids have been thoroughly investigated. However, contradicting findings have been observed under what appeared to similar test conditions. In this experimental investigation, two boiling surfaces have been prepared with an average surface roughness of 6 and 60 nm using high precision machining. Alumina Oxide-Water based nanofluids have been used in this investigation. The initial nanoparticle size reported by the manufacturer is 10 nm. The nanoparticles concentration has been kept at 0.05 wt. %. A Sodium Dodecylbenzenesulfonate (SDBS) surfactant has been added to the nanofluids in order to improve its stability. Results showed that the nanofluids boiling performance depended on the boiling surface roughness. The heat transfer coefficient (HTC) obtained in the case of the smooth, mirror finished surface showed an enhancement of 205% with respect to pure water. This trend was reversed in the case of the rough surface which is believed to be due to significant nanoparticles deposition. The HTC obtained with the rough surface was 12% lower than that of pure water. The effect of the surfactant concentration on nanoparticles deposition has been investigated by changing the surfactant concentration from 0.1 to 1.0 wt. %. In the case of the rough surface, the increase of surfactant concentration was found to reduce the formation of the nanoparticles deposition layer. The HTC obtained with the higher surfactant concentration was increased by 46 %. The effect of nanoparticles concentration on the smooth surface shows an unexpected trend of 20 % reduction of the transfer rate of the nanofluids coupled with the increase of the nanoparticle concentration from 0.05 to 0.1 wt. %. However all concentrations showed heat transfer enhancement with respect to pure water. The minimum heat transfer coefficient ratio enhancement was 11 % using 0.1 wt. % nanofluids with respect to pure water. Since nanoparticles deposition has been observed and attributed to micro-layer evaporation, an investigation has been carried out to examine the nucleation process during the pure water and nanofluids pool boiling. The bubble growth rate in both cases was analyzed at different wall degrees of superheat ranging from 104.3 to 105.9 ºC. In addition, the bubble departure diameter and frequency have been measured and compared for both cases. The nanofluid bubble size was about 80 % smaller than that of pure water. The nanofluid bubble departure had almost constant frequency of 500 Hz over the range of wall superheats whereas the maximum bubble frequency in the case of pure water was 22.72 Hz. / Thesis / Master of Applied Science (MASc)

The energy produced by the flow of water is known as hydropower. It is an easily accessible and available source of energy in large quantity in the form of, rivers, lakes, streams and runoffs around the world. Hydropower is dependent upon hydrological cycle hence; this beneficial characteristic of hydropower makes it a renewable source of energy. Hydropower is free from poisonous emission; therefore, it is considered as a safer and pollution free source of energy. It is usually used to develop electricity from generators. These generators are connected to the hydro turbines by means of shaft. The electricity produced from hydropower is stable and steady because of its higher capacity, thus it can be a suitable source to work as base-load and used to balance the power fluctuations caused by varying loads. The hydropower can also be accommodated with different sources such as solar and wind system. This way of power sharing needs quick regulation as the deviation in the power grid changes rapidly. To fulfil this power demand with higher stability prompted to the development of modern turbines with more efficient, reliable and robust design.   To achieve the above target, it is of prime importance to improve efficiency of hydro turbine. Nevertheless, many methods are in practice for improvement for efficiency of the turbine; though one of the prime elements which influence the turbine efficiency is surface roughness. The effect of surface roughness differs for different turbine components like stay vanes, guide vanes, runner, draft tube and spiral casing.   The main purpose of this thesis is to examine the effect of surface roughness for hydro turbine step-up efficiency. It is based on reduced scale model to prototype conversion method. For this purpose, IEC_62097 has provided an excel sheet as an attachment for calculation. There has been always a need to perform model test, since performing test on the prototype itself is very accurate, and calculations too, do not yield reliable results. Therefore, the model to prototype conversion method is considered a better solution.   A sensitivity analysis is conducted on a Kaplan turbine situated at the Granfors power station located along the Skellefteå river about 30 km from the city of Skellefteå. The results obtained after applying the latest step-up expressions are described and presented. These outcomes have shown significant positive impact on the hydro turbine efficiency improvement, which are presented in graphs.   The most significant variations of step-up efficiency against surface roughness were observed in the runner part of the turbine. This specific characteristic makes it evident that more focus and test should be conducted on this part to improve efficiency.

Top hammer drilling uses a percussive force at the top combined with a rotational energy that transmits through a rod to a drill bit that crushes rock. It is a drilling method that is preliminary used in mining, construction and operations under ground. Fatigue strength plays an important role in the drill rods life span. A top hammer drill rod has a through hole in the center called a flush hole used to flush up the drilling cuttings. The flush hole is a weak spot in the rod. In this preliminary study the purpose was to investigate if, and how, the surface in the flush hole affects the fatigue strength in rock drill rods. Four test methods; Refined inner surface, lathed core, without lubricant and sealed hollow bar. With three samples of each method that affected the surface of the flush hole, were used in the manufacturing of the rods and compared to references. Different tests were applied to measure the quality of the flush hole and of the rods. The material used were fatigue tested under a pulsating pull-pull condition with flushing water. Finally, the fracture surfaces were studied. The fatigue test showed that refined inner surface had supreme fatigue strength, the other methods exhibit approximately 10% more cycles than the references. In conclusion the inner surface affects the fatigue strength. The parameter with the most distinct correlation to the fatigue test was surface roughness. Other parameters that seems to affect were oxidation, hardness and scratches. To obtain statistical certainty more samples are needed.

No description available.

No description available.