The development of lightweight design for automotive applications has lasted for many years and is still increasing. Vehicles with light structures use less fuel, emit less CO2, and are better for the environment. The next generation of lightweight vehicle structures will be realized using materials with a high strength-to-weight ratio, corrosion resistance, and high bending stiffness such as high-strength aluminium alloys. Increased formability, lower spring-back, and the ability to incorporate age-hardening heat treatments into the process are all advantages of the hot forming of aluminium alloys. However, because aluminium is prone to adhesion even at low temperatures, it can be difficult to avoid its transfer onto the tool. When forming aluminium, lubrication is always required to lower the interfacial shear strength and avoid direct contact between the interacting surfaces, to promote low friction and wear. However, lubricants can fail and significant issues with material transfer arise. Because of this, interruptions are needed for tool refurbishing, this issue affects process efficiency. Developing new or improved lubrication technologies to prevent adhesion and high friction, surface engineering solutions, as well as effective testing platforms related to aluminium forming, are vital. A significant challenge when studying the interaction between lubricant, aluminium, and tools often result in poor reproducibility of tests and uncertainties regarding the effect of lubricant thickness/weight on the friction behavior. Problems associated with reproducibility also affect modelling and simulations of the forming operation, as there are many uncertainties in the experimental campaigns, thus affecting the validation stages. The current study aim is to optimize the tribology test methodology used in the hot strip drawing method, with emphasis on the lubricant application methodology, to improve the reproducibility of tribological tests. Lubricant application methodology was developed by using air-brush equipment, and a consistent amount of lubricant. Different lubricant weights were characterized using two different types of lubricants (graphite-based and polymer-based lubricants), and then the tribological response was evaluated after the tribological tests. Lubricants were applied on cast iron and tool steel (CrN coated) to take into consideration the effect of the surface material and topography on the reproducibility, and consistency of the lubricant application methodology. The hot strip drawing method was used to perform tests at 350°C temperature, 10MPa pressure and 100mm sliding distance. To simulate the forming conditions encountered in hot stamping of aluminium, solubilization of a 6XXX aluminium alloy at 540°C was done before testing. An optical microscope, 3D optical profilometry, and SEM were used for the characterization of specimens after the tribological tests. With the lubricant application method, good reproducibility was obtained and it was determined that, in the case of cast iron, as the amount of both lubricants (polymer-based, graphite-based) increases the effective sliding also increases, but tool steel (CrN coated) shows slightly good results only when lubricant amounts are highest.

Environmentally adaptable grease (EAG) lubricants are essential in applications with loss lubrication due to their biodegradable nature. This is because the lubricants could be expelled into the environment during usage in some applications e.g., marine and mining applications. However, although this type of grease is sustainable to use, it also needs to bridge the performance gap it has with the mineral-based grease counterpart.  In this thesis project, a tribological evaluation comparison between the performance of EAGs and traditional mineral-based greases in large open gears is carried out. A twin disc tribometer is used to mimic the contact mechanisms of the test gears while being lubricated automatically by the grease samples through a syringe pump. For the experiments, the material surface of all the discs in the tribometer setup is steel while the different grease samples are tested for each setup. Two of the grease samples; UPL 04123 (NLGI 1.5) and UPL 04124 (NLGI 0.5) are fully formulated EAGs, while the third is a popular commercial mineral-based grease currently used in large open gears in the mining industry. An investigation of the wear of the discs used in each grease test is carried out using optical interferometry and a Scanning electron microscope (SEM). The wear volumes and wear rates are then analysed and compared to evaluate the performance of the grease samples. The wear results from the tribological characterisation using the twin disc are validated with the ISO 14635-3 standard on the FZG back-to-back test rig. Also, chemical characterisation of the unused and used grease is carried out using the advanced ATR-FTIR method to evaluate additive depletion and lastly an SEM-EDS analysis to confirm the presence of tribofilm on the surfaces of the disc samples. In conclusion, it is found that there is a correlation between the consistency of the grease sample and wear prevention; where the commercial grease with the least consistency performs best, followed by the 0.5G and lastly the 1.5G. Also, there are clear indications in the wear rates of the actions of extreme pressure additives activation at high contact pressures between the discs. The inadequacies of the ATR-FTIR and SEM-EDS methods to evaluate additives and tribofilm respectively are also discussed.

Environmentally friendly lubricants are in demand in response to the rising concerns and restrictive legislation that surround the use of mineral oil lubricants. One area of importance is understanding the service life of the environmentally friendly base oils of these non-toxic, biodegradable and renewable alternatives. The service life of a lubricant is directly influenced by its degradation behavior, especially oxidation.  In this research, selected environmentally friendly base oils; Glycerol, Rapeseed oil, Polypropylene glycol, Polyethylene glycol, Bis(di-2-ethyl hexyl) sebacate, Squalene and reference mineral oil; paraffin,  were subjected to thermo-oxidative ageing at 150oC. The changes in the chemical structures of the samples were followed using Spectroscopic, chromatographic, rheological and corrosivity studies. Tribological tests were also carried out to quantify the changes in these lubricants. The results obtained showed that the thermal oxidation affected the physicochemical properties and the lubricating ability of the base oils. However, each base oil degraded distinctly to the accelerated ageing conditions.

Gears are machine elements essential for mechanical transmission. Wear of gear teeth can causechanges in their profile geometry, causing vibration, noise, and subsequent gear failure. In this thesisproject, a twin disc tribometer has been used to mimic the actual Alfa Laval separator screw gearsystems. An investigation of the wear of different material pairs has been done using a twin disctribometer machine. In the twin disc tribometer, the material surface for one disc was bronze and thematerial for the counter disc surface was varied with steel of different types. Each bronze-steel pair wastested against different loading, lubricating and surface roughness conditions. For the wear tests, twodifferent loads, 75 N and 150 N and two different types of lubricants, Polyalphaolefin (PAO) andPolyalkylene Glycol (PAG) were taken. Wear tests were also done with the Applied Nano Surfaces(ANS) triboconditioning (TCG) steel disc samples which are surface treated to obtain a lower surfaceroughness. To obtain the wear volume and wear rate values the disc pairs were further analysed usinglaboratory equipment and computer software such as the digital microscope, optical interferometer andMountainsLab premium 9. Analytical calculations for minimum film thickness and thermally correctedminimum film thickness between the disc surfaces were obtained using the Dowson-Hamrock equationand Gupta formula, respectively. It has been found that the wear on the bronze disc is minimum if thecounter steel discs are Applied Nano Surfaces (ANS) of TCG 1 type followed by counter disc as casehardened steel, all of it at 75 N and with Polyalphaolefin (PAO) lubricant oil.

Electric machines are widely used in for instance the automotive industry in electric vehicles and in wind turbines. The electrical machines have mechanical bearings as an integral part used to transmit power and load. In addition, the main function includes reducing friction between interacting surfaces. However, it is one of the most failing machine elements in these machines. To improve operational sustainability and reduce maintenance costs, understanding bearing failure mechanisms under electrical influence is important. One of the main reasons of bearing failure is linked to high frequency power switches typically used to enhance electric machines’ efficiency. The increase in switching rate induces more frequent common mode voltage fluctuations making the system vulnerable to bearing currents. A small voltage difference of a few ten volts can induce significant electric stress on the bearing depending on the lubricant film thickness and related tribological parameters. The electric charge build-up leads to electric current conduction (arc discharge which happens when the voltage exceeds the breakdown voltage) ultimately damaging the bearing. There are different mitigation strategies which are used to restrict bearing currents through grounding or using completely insulative bearings such as ceramic ones. However, at the moment, there are no satisfactory solutions and there is a need for efficient and economical solutions to the problem. On the other hand, various filters are used to reduce the amplitude and its frequency of bearing currents, but they only partly solve the problem. Similarly, the insulative surface coatings provides high electrical resistance but start acting as capacitors. At a sufficiently high voltage difference, the current passes through the system. Therefore, mitigation strategies are still being explored to improve system performance and service-life. To understand the bearing discharge activity and electrical breakdowns, an electrified ball bearing rig is developed with the ability of testing different electrical properties of lubricants and running conditions. To be able to characterize the electrical properties of a bearing, two electrical circuits are designed. Experimental tests are carried out with PAO-15 and an electrical conductivity-enhanced PAO-15/P-SiSO lubricant with addition of ionic liquids. The influence of different tribological parameters such as rotational speed and viscosity are compared with respect to discharge activity. In addition, two fully formulated experimental oils are compared and evaluated in terms of their electrical performance. The bearing is found to be in different states showing electric-field dependent insulation breakdown ranging from resistive to resistive-capacitive to capacitive states. The electric characterization shows a difference between the boundary, mixed and full film lubrication regimes. Conclusively, the electrical behavior of a mechanical bearing is characterized experimentally to understand discharge problem and roadmap solution opportunities.

Obtaining an enhanced lifespan for mechanical transmissions has become a challenge in diverse application sectors. Micropitting as a contact fatigue mechanism has seriously jeopardized the well-being of rolling-sliding elements present for instance in gearboxes. Additivation through copper nanoadditives has demonstrated promising results in preventing contact fatigue. There is a need to assess the influence of copper nanoadditives on micropitting and mild wear before contemplating employing them in real transmission gearboxes. Consequently, this research work aims to acquire knowledge of the tribological behavior of rolling-sliding contacts additivated with a copper nanoadditive, emphasizing the influence of two different copper nanoadditive concentrations (0.3% and 3%) on wear and micropitting as failure mechanisms. Tests were performed using a micropitting test rig. Micropitting and wear were analyzed at different slide-to-roll ratios (1%, 5%, and 30%), different load conditions (1.5 GPa and 2.5 GPa), and different temperatures (60 °C and 100 °C), for all versions of the studied lubricant. There was no change in friction behavior between the versions of the oil additivated with the copper nanoadditive and its original version. Furthermore, it was found a reduction of micropitting for the 3% version of the studied oil in some operating conditions, and a reduction of the average wear volume for this same concentration in all studied operating conditions. On the other hand, it was found that the 0.3% version of the studied oil promoted wear with an increasing slide-to-roll ratio when compared with the original version of the studied oil. A higher reduction in wear was obtained for the 0.3% version of the studied oil with an increasing temperature when compared with the 3% version. These results indicate that copper nanoadditives exhibit the potential to reduce micropitting in non-conformal rolling-sliding contacts typically found in gears and rolling-element bearings.

The objective of this thesis work was to develop a method to detect early damage on small planetary gear sets that are installed in Atlas Copco nutrunners. The project has gone through several stages of product development, from idea to working product and signal analysis. Currently, Atlas Copco have a test rig for testing these planetary gears, this rig has been proven to be insufficient at detecting faults during an ongoing test. A new tailored test rig was therefore designed and manufactured. Low noise and low amount of vibration was of interest when designing the rig. Four concepts was thought of and evaluated through simulations using Matlab and Simulink. Most of the components of the rig were manufactured in the workshop at Atlas Copco in Nacka. Methods fo rmeasuring torsional, transverse and acoustic vibration was implemented and analyzed. There are many different parameters considering fault of fixed shaft gears. However, these are not easily applicable on a planetary gear because of the nature of its design. Therefore, special techniques are required. Two “new” parameters were tested (NSDS,FRMS [Lei. et al.]) with positive results. Pitting of individual gear members could befound.

No description available.

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.

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.