High heat in mechanical seals is a long-recognized main failure cause, disrupting the seal's vital lubricating film and heating temperature-sensitive process media. A way to accommodate the seal's heat generation is by choosing materials with high thermal conductivity, such as silicon carbide (SiC). In single-use and short operating time applications, the usage of SiC may be greatly over-dimensioned, unnecessarily environmentally intense, and expensive. There is a desire to apply other materials for these cases, but the heat generation of the mechanical seal poses great limitations in material selections.  The purpose of this study is to reduce the operating temperature of mechanical seals to enable the application of cheaper and more sustainable materials. The seals used for testing are presently used in Alfa Laval’s single-use separators, CultureOne, and accompanying this work is the designing of a temperature measuring rig for the specific mechanical seal to be tested in its applied environment. The following research questions have been formulated to concretize the presented problematization:     RQ1: Which parameters have the highest significance for generated heat in the single-use mechanical seal?   RQ2: How can the heat of the mechanical seal’s wear face be measured while operating in the CultureOne machine?    This study is deductive, intending to gather quantitative data through thermal measuring. The temperature measuring rig was designed with inspiration from previous similar studies and was then validated through repeated testing and comparisons with FEM-simulations of the tested case. This resulted in a detected temperature loss of 1°C, which has been accounted for in the conclusions. During validation tests, a standard original seal temperature to use as a comparison was found to be 41°C.    Heat-affecting parameters have been gathered and tested through the method of Design of Experiments (DoE), where a Placket-Burman design was chosen to enable testing 9 parameters with 12 tests. The results of the study indicate that surface roughness and sealing liquid temperature have significant effects on the seal temperature. Roughening the surface of the mechanical seal’s polished, static carbon face, as achieved with a 1000-grit abrasive paper, provided a heat mitigating effect of -9.3 °C, which is a 23% heat reduction. Similarly, introducing more cooling power to the system by cooling the sealing liquid with external methods such as an ice bath provided a heat-reducing effect of -5.4 °C at the end of a one-hour test, reducing the temperature with 13%. Combining the parameters provided a 36% reduction in heat for a one-hour run with the mechanical seal in the CultureOne Primo machine. Thus, the temperature-reducing strategies discovered in this study can be applied to enable more sustainable and cheaper material selections for mechanical face seals. / Hög temperatur i plantätningar är sedan länge uppmärksammat som en huvudsaklig haveriorsak eftersom det i många fall leder till att den smörjande vätskefilmen störs. En åtgärd för att avlägsna tätningens värme är att välja material med hög värmeledningsförmåga, som exempelvis kiselkarbid. Vid engångsapplikationer och andra tillämpningsområden med kort tid i användning har kiselkarbidtätningar ofta en överdimensionerad livslängd samtidigt som materialet är både miljöpåfrestande och dyrt i jämförelse med andra material. Således finns behovet att byta material hos tätningar i dessa applikationer, men värmegenereringen utgör hinder och begränsar alternativen i materialvalet.    Målet med denna studie är att sänka temperaturen hos mekaniska plantätningar för att möjliggöra val av billigare och miljövänligare material. Tätningarna som används för studiens experiment sitter i Alfa Lavals engångsseparator, CultureOne. Till denna studie hör framtagandet av en metod och testuppställning för att mäta temperaturen hos dessa tätningar under drift i sin tillämpade miljö. Utifrån problematiken har följande forskningsfrågor formulerats:    FF1: Vilka parametrar har störst signifikans för värmegenerering i engångstätningarna?    FF2: Hur kan temperaturen av plantätningarnas nötningsyta mätas under drift i CultureOne-maskinen?   Studien är av deduktiv natur, med insamling av primärt kvantitativa data genom temperaturmätningar. Metoden för temperaturmätning togs fram med stöd i mätmetoder från andra studier på tätningar, och mätvärdenas riktighet validerades genom kalibreringssteg, tester och jämförelser med FEM-simuleringar av tätningen. Under kalibreringen detekterades en värmeförlust på 1°C mellan uppmätt temperatur och sann temperatur av tätningens nötningsyta, vilket kompenseras för i slutsatserna. Under normala körförhållanden mättes tätningens temperatur till 41°C vilket användes som utgångspunkt att jämföra med senare experiment.    Värmegenererande parametrar för tätningar har sammanställts och testats genom en statistisk försöksplanering, där en Placket-Burman-design implementerades. Resultaten visar att ytfinhet och temperatur av tätningsvätska har signifikanta effekter för tätningens temperatur. Genom att skapa en grövre yta för plantätningens statiska halvas nötningsyta, som uppnått med ett sandpapper av finhet K1000, har en värmesänkning på -9.3 °C, motsvarande en 23% sänkning av utgångstemperaturen, uppnåtts för tätningen efter en timmes drift. På liknande sätt resulterade kylning av tätningsvätskan i en värmesänkning på -5.4 °C, vilket är 13% svalare än utgångstemperaturen. Tillsammans bidrar parametrarna till en 36% lägre temperatur hos plantätningen efter en timmes drift i CultureOne Primo-maskinen. Således skulle de testade strategierna för att sänka plantätningars temperatur kunna användas för att möjliggöra valet av miljövänligare och billigare material.

Volvo Cars in Skövde manufacture and assemble Volvo engines. When attaching the ignition coil to all 4-cylinder engines, a special mounting tool is required. This mounting tool is currently manufactured from injection-molded polyoxymethylene (POM), a thermoplastic. It has been noted that the life span of the tool is shortened as a result of abrasive wear that occurs during the attachment process of the ignition coil. An investigation of the possibility of manufacturing the mounting tool with a 3D-printer is undertaken in cooperation with ÅF, a consultant to Volvo Cars. A literature study is first presented to introduce broader knowledge on the subject. The abrasive wear and other material characteristics such as tensile strength, compressive strength and elongation of  POM and an alternative material for 3D-printing,  Ultem™, an amorphous thermoplastic polyetherimide are discussed.  These material characteristics are studied further and considered in tandem with both a theoretical analysis and a wear experiment, based on the pin-on-disc method. It is shown in the theoretical analysis that the wear is approximately six times larger for Ultem™ when compared to POM. The wear resistance of Ultem™ is highest when wear occurs parallel to the direction of the printed layers. In contrast, the experiment shows that the wear is about three times larger in Ultem™ than in POM.  The highest tensile strength of Ultem™ is also found in the direction of the printed layers. Some issues with the small elongation of the 3D-printed material are presented. It is recommended that ÅF apply the 3D-printing technique with Ultem™ only for construction details with complex geometries and where the material elongation will not exceed 5%. It is also recommended that ÅF both support and contribute to this innovative technique in order to develop leading edge competence in the subject. / Volvo Cars i Skövde tillverkar och monterar Volvomotorer. Vid monteringen av tändspolen till alla 4-cylindriga motorer behövs ett monteringsverktyg. Detta monteringsverktyg tillverkas för närvarande från formsprutad termoplast polyoximetylen (POM). Det har noterats att livslängden av verktyget förkortas på grund av abrasiv nötning som uppkommer under monteringsprocessen av tändspolen. Möjligheterna att tillverka monteringsverktyget med en 3D-skrivare utvärderas i samverkan med ÅF, en konsult till Volvo Cars. En litteraturstudie presenteras för att introducera en bredare kunskap i ämnet. Den abrasiva nötningen och materialegenskaper såsom draghållfasthet, tryckhållfasthet samt töjning hos POM och ett alternativt material för 3D-skrivning, Ultem™, en amorf termoplast polyeterimid, behandlas. Dessa materialegenskaper studeras vidare och tas i beaktning med både en teoretisk analys och ett nötningsexperiment, baserat på pin-on-disc metoden. Enligt den teoretiska analysen är nötningen hos Ultem™ approximativt 6 gånger större vid jämförelsen med POM. Nötningsbeständigheten hos Ultem™ är högst då nötning sker parallellt med 3D-skrivningsriktningen av lagren. Nötningsexperimenten visar att nötningen hos Ultem™ är ungefär 3 gånger större vid jämförelsen med POM. Den högsta draghållfastheten hos Ultem™ uppkommer också parallellt med 3D-skrivningsriktningen av lagren. Problem med den låga töjningen hos det 3D-skrivna materialet behandlas. ÅF rekommenderas att tillämpa 3D-skrivning med materialet Ultem™ främst för detaljer med komplexa geometrier med en töjning som inte överskrider 5 %. ÅF rekommenderas även att både stödja och bidra till denna innovativa teknik för att kunna skapa en ledande expertis i ämnet.

Hard chrome exhibit hardness of about 70 HRC and lubricity that prevents seizing and galling and is therefore the common first choice for engineers to reduce friction and minimize wear. These properties enable engineering applications such as cutting and drilling, especially in manufacturing, production and consumer good industries. Hard chrome has a wide set of functions as being decorative, corrosion resistant and ease cleaning procedures. Hence, electroplating is a common process to synthesize hard chrome butthis process is banned by EU due to the rise of hazardous components. However, the need for alternative material is at rise but, fundamental issues for hard chrome are yet to be solved. The purpose of the work is to develop atomic structures for two systems using different programs such as OpenMX, VESTA and Ovito. The goal is to identify atomic wear mechanisms of hard chrome in an ideal system (Al2O3- Cr) and a real system (Al2O3 - Cr2O3) using density functional theory (DFT). These two systems are analyzed since every surface oxidises in air (real system) and under increased mechanical loads the pristine surface of hard chrome (ideal system) can be exposed to the counter body (Al2O3). DFT based molecular dynamics simulations are carried out at a temperature of 300 K and a sliding speed of 10 ms−1. The simulation interval is 0-15000 fs and radial distribution function (RDF) is employed to analyse the atomic wear mechanisms. Both systems start to show adhesive wear due to amorphization, mixed with signs of abrasive wear on the atomic scale. The systems are further analyzed using electron density distribution (EDD), that plots electronic structures enhancing the analyse of different type of bondstaking place. The bulk structures mainly show covalent bonds with ionic and metallic bonds less represented. Furthermore, same observations have been made for the interfaces of the ideal and real system. / Hårdkrom uppvisar hårdhet på ungefär 70 HRC och en smörjförmåga som förhindrar nötning och är därför det vanliga första valet för ingenjörer att minska friktionen och minimera slitaget. Dessa egenskaper möjliggör tekniska tillämpningar, såsom skärning och borrning, särskilt inom tillverknings, produktions och konsumentvaruindustrin. Hårdkrom har ett brett användningsområde och flera egenskaper såsom att vara dekorativ, korrosionsbeständig och underlätta rengöringsprocedurer. Därav är galvanisering en vanlig process för att syntetisera hårdkrom, men denna process är förbjuden av EU på grund av utsläpp av farliga komponenter. Behovet av alternativt material är vid uppgång men, de grundläggande problemen för hård krom är ännu inte lösta. Syftet med arbetet är att ta fram atom strukturer för två system med hjälp av olika program, såsom OpenMX, VESTA och Ovito. Målet är att identifiera vilken typ av nötning som sker på hårdkrom i ett idealt system (Al2O3- Cr) och i ett verkligt system (Al2O3- Cr2O3) genom att använda täthetsfunktionalteorin (DFT). Dessa två system analyseras eftersom varje yta oxiderar i luften (verkligt system) och under ökade mekaniska belastningar kan den orörda ytan av hårtkrom (idealiskt system) exponeras för motkroppen (Al2O3). DFT simuleringar är skapade med en temperatur på 300 K och en glidningshastighet på 10 ms−1. Simulerings intervallet är från 0-15000 fs och med hjälp av radiell fördelningsfunktion (RDF) analyseras de atomiska nötnings mekanismerna. Båda systemen börjar visa adhesiv nötning på grund av amorfisering, samt ett tecken på abrasiv nötning på en atomisk skala. Systemen analyseras vidare med användning av elektrondensitetsfördelning (EDD) som plottar elektroniska strukturer vilket förbättrar analysen av olika typer av bindningar som äger rum. Bulkstrukturerna visar huvudsaklig en kovalent bindning med joniska och metalliska bindningar mindre representerade. Samma observationer har gjorts för gränssnitten mellan det ideala och verkliga systemet.

This thesis aims to investigate the coefficient of friction between steel on steel contacts with the addition of solid lubricants such as h-BN, WS2, MoS2 in powder form, in dry conditions and wet conditions. More specifically, the purpose is to enhance the sliding between the piston rings and cylinder block in a modern high temperature steam engine developed by RANOTOR. The friction test was carried out as a linear sliding test with determined loads and sliding speed. Hertzian contact theory was deployed to calculate contact pressure and shear stresses to make sure the contact was elastic, alternatively plastic. It was found that WS2 and  MoS2 lowered the coefficient of friction quite heavily in dry conditions, acting as a thin protective-lubricating film. h-BN performed rather poorly, increasing the coefficient of friction. In a water slurry, none of the powders managed to decrease the COF due to the particles not interacting with the surfaces.The solid lubricants tested should be further tested as coatings since they acted like it in dry conditions. / Denna rapport syftar till att undersöka friktionskoefficienten i stålkontakter med tillsats av fasta smörjmedel som  h-BN, WS2, MoS2 i pulverform, under torra och våta förhållanden. Mer specifikt är syftet att förbättra glidningen mellan kolvringarna och insidan av cylindern i en modern högtemperatur-ångmotor utvecklad av RANOTOR. Friktionstestet genomfördes som ett linjärt glidtest med bestämda belastningar och glidhastighet. Hertzian-kontaktteorin användes för att beräkna kontakttryck och skjuvspänningar för att säkerställa att kontakten var elastisk alternativt plastisk. Det visade sig att WS2och MoS2 kraftigt sänkte friktionskoefficienten under torra förhållanden genom att agera som en tunn skyddande-smörjfilm. h-BN presterade dåligt och ökade friktionskoefficienten. I vattenblandning lyckades inget av pulverna minska friktionskoefficienten eftersom partiklarna inte interagerade med ytorna. De testade fasta smörjmedlen bör vidare testas som beläggningar eftersom de fungerade som dessa under torra förhållanden.

In this thesis, the aim is to study possible tribo-materials for a rotating inlet valve and to find a suitable material combination for the contact. The valve is part of a modern oil-free and high temperature steam engine. Systematic material selection together with tribological tests and wear analyses are performed. The metals Nitronic 60 and Stellite 6B are tested as self-mated metals, and run against graphite. None of these combinations are found suitable. However, the tests show carbon-based materials to be promising. After further study another carbon-based material, antimony impregnated mechanical carbon is selected as valve seat. For the mating part valve distributor, the material ZrO2-MgO is selected. This tribo-pair has shown friction and wear in the same interval as oil-lubrication. The friction and wear are 50% respectively 10% of the second best tribo-pair found in this thesis. The valve seat material is realizable if supported by a valve block of a Ni-resist cast iron with thermal expansion similar to the valve seat. Lastly a redesign of the valve distributor is suggested to comply with ceramic design guidelines. / Målet med denna rapport är att studera möjliga tribo-material för en roterande inloppsventil och att hitta en lämplig materialkombination för kontakten. Ventilen är en del av en modern oljefri och högtempererad ångmotor. Ett systematiskt materialval tillsammans med tribologiska tester och nötningsanalyser utförs. Metallerna Nitronic 60 och Stellite 6B testas dels mot sig själva, och dels mot grafit. Ingen av dessa kombinationer finns lämplig. Testerna visar dock att kolbaserade material är lovande och eftervidare studier är ett annat kolbaserat material, antimonimpregnerat mekaniskt kol, väljs till ventilsätet. Till motytan till ventilsätet, ventilfördelaren, väljs materialet ZrO2-MgO. Detta tribo-par har visat friktion och nötning i samma intervall som oljesmörjning. Friktionen och nötningen är 50 % respektive 10 % av det näst bästa tribo-paret som hittats i denna avhandling. Ventilsätets material är realiserbart om det stöttas i ett ventilblock av ett ”Ni-resist” gjutjärn med en värmeexpansion som liknar ventilsätets. Slutligen föreslås en omkonstruktion av ventilfördelaren för att uppfylla riktlinjerna för keramisk konstruktion.

In this master thesis, performed at Sandvik Coromant Västberga (Stockholm), a comprehensive study has been made to investigate the wear on textured alumina (Inveio™) coated cutting tools when turning low-alloy steels. Specifically, wear studies have been made on tools’ rake faces when turning two separate batches of SS2541, after an initial turning time of 4 min. A particular focus has been given to elucidate what particular role the inclusions might have for the wear of the alumina coating onthe tools. Evaluation of tool wear has been made by employing several different analytical techniques, such as LOM, SEM, Wyko, Auger-spectrometry (AES), EPMA and XRD. The results shows that the arisen wear marks on both tested tool types may be divided into three separate and highly distinguishable wear zones, denoted here in thiswork as “wear bands”. Largest amount of wear tended to occur initially at the topmost part of the 3rd wear band. This was true for both tested tool types. This area demonstrated a characteristic 'lamellar' wear pattern, composed of narrow andstructured ridges. All the tools tested demonstrated the adhesion of workpiece materials of various composition that formed into smeared layers in these formed ridges. Depth-profiling Auger-spectrometry revealed that a significant amount of calcium was present in the machined alumina coating layers. This suggests that a reaction between the calcium-containing inclusions found in the steel and the aluminacoating layer had occurred during the performed turning tests.These results arecontradictory to the general belief that alumina is chemical inert during machiningand has previously, to the authors knowledge, not yet been published. Based on the results from this thesis and from a literature review concerning thebehavior of α-alumina during deformation, a new theoretical wear model has been developed. In this model, it is emphasised that the sliding of hard inclusions from the steel may activate pyramidal slip systems in the textured alumina coating. This causes a nano-crystallisation and/or amorphisation in the topmost part of the coating, which facilitates the further wear of these coated tools. / I detta examensarbete, som har utförts vid Sandvik Coromant i Västberga (Stockholm), har en omfattande studie gjorts i syfte att undersöka slitaget på texturerad aluminiumoxid-belagda skärverktyg (Inveio™) vid svarvningen av låglegerade stålsorter. Förslitningsstudier har framförallt gjorts på verktygens spånsidor vid svarvningen av två separata batcher av stålsorten SS2541 efter en inledande ingreppstid på 4 min. Ett särskilt fokus har även ägnats åt att belysa vilken roll stålets inneslutningar kan ha för slitaget av aluminiumoxidbeläggningen. Utvärderingen av verktygsslitaget har gjorts med hjälp av flera olika analytiska tekniker, däribland LOM, SEM, Wyko, Auger-spektrometri (AES), EPMA samt XRD. Resultaten från detta examensarbete visar på att det uppkomna slitaget på de verktyg som har testats kan uppdelas till tre separata och mycket distinkta ”slitagezoner”. Dessa zoner har för detta arbete benämnts som ”nötningsband”. Störst förslitning framträdde initialt i den översta delen av det 3:e nötningsbandet på de testade skärverktygen. Detta område uppvisade ett karaktäristiskt ”lamell”-liknande utseende, bestående av smala och strukturerade åsar och skåror. Vidare uppvisade samtliga undersökta verktyg på förekomsten av påsmetat arbetsmaterial av varierande sammansättning i dessa bildade åsar. När de slitna verktygen undersöktes med djuprofilerande Auger-spektrometri påvisades det att en signifikant mängd kalcium fanns inuti aluminiumoxidbeläggningen. Detta tyder på att en reaktion mellan de kalciuminnehållande inneslutningarna (som finns inuti stålet) och aluminiumoxidbeläggningen har reagerat med varandra under bearbetningsförloppet. Dessa resultat är motsägande till den allmänna uppfattningen om att aluminiumoxid är kemiskt inert vid bearbetningen av stål. Därutöver har dessa resultat även, till författarens kännedom, aldrig tidigare publicerats. Baserat på de resultat som har erhållits från detta examensarbete, och från en omfattande litteraturstudie gällande deformationen av α-aluminiumoxid, har en ny teoretisk förslitningsmodell utarbetats. I denna modell betonas det särskilt att glidningen av hårda inneslutningar från stålet kan aktivera s.k. pyramidala glidsystem i den texturerade aluminiumoxidbeläggningen. Detta orsaker en nano-kristallisering och/eller amorfisering av den översta delen av aluminiumoxidbeläggningen.  Denna omvandling tros kunna underlätta den fortsatta förslitningen av dessa belagda skärverktyg.

Additive Manufacturing (AM) for metals includes is a group of production methodst hat use a layer-by-layer approach to directly manufacture final parts. In recent years, the production rate and material quality of additive manufactured materials have improved rapidly which has gained increased interest from the industry to use AM not only for prototyping, but for serial production. AM offers a greater design freedom, compared to conventional production methods, which allows for parts with new innovative design. This is very attractive to the aerospace industry, in which parts could be designed to have reduced weight and improved performance contributing to reduced fuel consumption, increased payload and extended flight range. There are, however, challenges yet to solve before the potential of AM could be fully utilized in aerospace applications. One of the major challenges is how to deal with the poor fatigue behaviour of AM material with rough as-built surface. The aim of this thesis is to increase the knowledge of how AM can be used for high performance industrial parts by investigating the fatigue behaviour of the titanium alloy Ti6Al4V produced with different AM processes. Foremost, the intention is to improve the understanding of how rough as-built AM surfaces in combination with AM built geometrical notches affects the fatigue properties.This was done by performing constant amplitude fatigue testing to compare different combinations of AM material produced by Electron Beam Melting(EBM) and Laser Sintering (LS) with machined or rough as-built surfaces with or without geometrical notches and Hot Isostatic Pressing (HIP) treatment. Furthermore, the material response can be different between constant amplitude and variable amplitude fatigue loading due to effects of overloads and local plastic deformations. The results from constant amplitude testing were used to predict the fatigue life for variable amplitude loading by cumulative damage approach and these predictions were then verified by experimental variable amplitude testing. The constant amplitude fatigue strength of material with rough as-built surfaces was found to be 65-75 % lower, compared to conventional wrought bar, in which HIP treatments had neglectable influence on the fatigue strength. Furthermore, the fatigue life predictions with cumulative damage calculations showed good agreement with the experimental results which indicates that a cumulative damage approach can be used, at least for a tensile dominated load sequences, to predict the fatigue behaviour of additive manufactured Ti6Al4V.

This bachelor’s degree project aimed to improve the wheel profile of a rail mounted trolley and determine the cause of wheel failure. The proceedings of this project where modelled after an approach for solving wear problems with an emphasis on designing for sustainability. A case study and root cause analysis (RCA) was performed and the flanged wheels were deemed insufficient for the given heavy-haul system. Possible areas of wheel profile improvement were identified and further researched with multiple literature reviews. Throughout the projects duration several limitations were introduced that reduced the concept testing to exclusively theoretical prediction models. Archard’s model was implemented to predict wear and operating time for the proposed material and wheel tread profile concepts. The wheel flange dimensions were chosen based on recommendations from wheel and rail interference handbooks among other sources. The final wheel and rail profile suggestion improved operating time by approximately 300% and wear resistance by 50% compared to its predecessor. This result was achieved by applying the same theoretical prediction model to both current and suggested profiles. The findings of this project are meant to aid SCA among others in similar cases and additionally highlight the value of product improvement from a technological, sociological, and environmental perspective.

Most of the rolling element bearings are lubricated with Grease lubricant. Generally, the grease is expected to serve for life. The major causes of the bearing failure are due to the failure of the lubrication. The grease will experience creeping, oil permeation, oil separation etc. The separated oil will be lost permanently from the bearing. The widely used grease for general application is the lithium grease. The thickener of the grease consists covalent bond. When the grease is sheared, the breakage of the covalent bond will be permanent, resulting in the permanent loss of the rheological properties. The gels have unique properties such as thermal reversibility, viscoelasticity and thixotropy. They become mobile under shear stress and solidify again when the shear stress is removed. This property can be harnessed to avoid the base oil creeping, oil permeation, leakage in gears and bearings. Due to the presence of the polar group in the gels, they form a good tribo film and prevent the wear.  Under the shear stress, weak supramolecular interactions will be distorted, and this leads to the release of the oil and they re-form the structure after a certain period of rest. When the gel is in the solid-state, it will avoid creeping and evaporation. Many classes of gels are either derived from natural sources or from environmentally friendly materials. Thus, the lubricant formed out of gel would effectively solve both environmental as well as lubrication problems. In this work, supramolecular gel lubricants were prepared out of fully green, cellulose derivatives and starch hydrolysates. The non-ionic hydroxyethyl cellulose (HEC) and anionic sodium carboxymethyl cellulose (NaCMC) were chosen to understand the effect of ionic and non-ionic gelators on the rheological and the tribological parameters. Traditionally fat was used as a lubricant, now, in food industry various fat replacers are being used. To study whether the fat replacers can act as a thickener, Dextrin and maltodextrins were chosen.  Dextrin and maltodextrin with the different DE values were selected to understand the influence of molecular weight on gelation and tribological performance.  Inspired by the recent developments and advantages of aqueous lubrication, mixer of water and poly(ethylene glycol) 200 (PEG 200) is chosen as the base fluid. It was found that a very small amount of gelator can increase the viscosity of the PEG/water to several orders. The thermal stability of the gels was studied using thermogravimetric analysis (TGA) and found that gels can increase the thermal stability of the base fluid. FTIR results showed the formation of a non-covalent bond between the PEG molecules and water. It is shown that anionic gelator will result in producing low friction and wear in comparison to non-ionic gelator. The possible tribo-film formation due to the negative charge in the NaCMC molecules is attributed to these results. The very low friction and low wear was exhibited by the dextrin and maltodextrin gels. It is proposed that this could be due to the microspherical particles of gels which can act as nano bearings. It was found that choosing the optimum concentration of the gelator is important to reduce friction and wear. The higher gelator concentration will form the hard gel, which cannot flow and replenish the sliding contact, resulting in the starved lubrication. This will cause high wear and friction. These gel lubricants can be used in food, pharmaceutical and biomedical industries.

Generating gear grinding is a method used for hard machining of gearbox gears. It facilitates a productive gear manufacturing with tight tolerances regarding surface roughness and geometrical accuracy. However, if the grinding is done with incorrect parameters, so called grinding burns can arise with consequences such as changes in surface hardness, changes in residual stress levels, surface embrittlement and compromised fatigue strength. This thesis investigates the gear tooth quality resulting from grinding parameters contributing to an improved grinding time. A literature study will cover gear geometries and material, grinding wheel properties, influences by grinding parameters and several verification methods. An experimental test will then be used to put four different grinding parameters to the test. The results showed that an increased cutting speed indicated finer surface roughness andincreased Barkhausen noise but showed no influence on gear geometry. Increasing both rough and fine feed rates resulted in a minor increase in geometry deviation but no significant difference in surface roughness. Large variations within the different verification method results related to grinding burns madeit difficult to draw conclusions regarding the experimental factors chosen. However, several factors apart from the experimental ones varied in the testing were believed to have significant influence, such as the flow of the cooling fluidand the amount of retained austenite from the carburizing process. In fact, the trends which seemed to be connected to these factors could be seen in both Barkhausen noise analysis, hardness measurementsand microstructure.