In the agricultural industry, cultivator tines are used for stubble cultivation and seedbed preparation. They are exposed to rapidly developing abrasive wear, which becomes a major economic problem. The occurring wear in the tines is heavily dependent on the characteristics of the soil which it passes through. In this master thesis the goal is to produce a method which, in a laboratory environment, can reproduce the circumstances which real cultivator tines are exposed to in the field. The method will enable analysis and evaluation of the initial wear mechanisms causing the wear. In order to simulate the tillage, a pendulum setup was constructed. With this, a series of repeated impact tests were performed into a soil sample. Throughout the tests, the “cultivator tine” samples were made of aluminium. This material choice would enable an accelerated wear rate, following its low hardness. All tests were performed in the same soil, with moisture content being the only varying parameter;~0% and 18% respectively. The samples which had passed through soil with higher moisture showed reduced wear compared to those which had passed through dry soil. The pendulum setup contributed to the tests being executed in a controlled and reliable manner. Hence, it is determined to be suitable for further use in any future project work related to the subject.

<p>Vid konstruktion och tillverkning av motorer idag finns flera krav att tillgodose i form av lång livslängd, låga utsläpp samt liten bränsleförbrukning. Dieselmotorn har högre verkningsgrad än bensinmotorn men problemet med dieselmotorn är i form av utsläpp där lagstiftningen blir allt strängare. En del av utsläppen från dieselmotorn kan bero på smörjoljan och olika motorer och ytor uppvisar olika mängd oljeförbrukning. Denna kan även variera mellan samma modell av motor. Ett sätt att få ner oljeförbrukningen och variationen av denna är att mäta ytan och säkerställa att denna är optimal för dess funktion. Målet med arbetet är att ta fram en metod för att med hjälp av den befintliga mätutrustningen beskriva ytans funktion och säkerhetställa att ytkvalitén är optimal. Arbetet har utförts på en motor som drog mer smörjolja och en motor som drog mindre. Arbetet har utförts inom forskningsgruppen funktionella ytor på Högskolan i Halmstad där mätningar utförts på Toponova och mätningar har skett på dieselmotorer från Volvo Cars. Arbetet har bestått av litteraturstudier samt mätningar av cylinderytor. Resultat från mätningar av kolvringarna och oljeförbrukningen har använts för att göra en jämförelse vad som skiljde en högre oljeförbrukande motor från en lägre. Arbetet har resulterat i ett förslag för hur motorn skall mätas och vilka parametrar som skall användas. En finare yta visade sig ge lägre oljeförbrukning och ett mindre och jämnare slitage</p>

Vid konstruktion och tillverkning av motorer idag finns flera krav att tillgodose i form av lång livslängd, låga utsläpp samt liten bränsleförbrukning. Dieselmotorn har högre verkningsgrad än bensinmotorn men problemet med dieselmotorn är i form av utsläpp där lagstiftningen blir allt strängare. En del av utsläppen från dieselmotorn kan bero på smörjoljan och olika motorer och ytor uppvisar olika mängd oljeförbrukning. Denna kan även variera mellan samma modell av motor. Ett sätt att få ner oljeförbrukningen och variationen av denna är att mäta ytan och säkerställa att denna är optimal för dess funktion. Målet med arbetet är att ta fram en metod för att med hjälp av den befintliga mätutrustningen beskriva ytans funktion och säkerhetställa att ytkvalitén är optimal. Arbetet har utförts på en motor som drog mer smörjolja och en motor som drog mindre. Arbetet har utförts inom forskningsgruppen funktionella ytor på Högskolan i Halmstad där mätningar utförts på Toponova och mätningar har skett på dieselmotorer från Volvo Cars. Arbetet har bestått av litteraturstudier samt mätningar av cylinderytor. Resultat från mätningar av kolvringarna och oljeförbrukningen har använts för att göra en jämförelse vad som skiljde en högre oljeförbrukande motor från en lägre. Arbetet har resulterat i ett förslag för hur motorn skall mätas och vilka parametrar som skall användas. En finare yta visade sig ge lägre oljeförbrukning och ett mindre och jämnare slitage

With ever shorter development times and market demands on overall system performance such as efficiency, reliability and low maintenance, accurate predictive tools are necessary and gear drives prove to be no exception. All these characteristics have an impact on a process which has remained a riddle: running-in. Even though no consensus on a definition of this phenomena is readily available, this thesis examines efficiency, surface roughness and simulation through the optics of running-in. Geared transmissions are known for their formidable efficiency and their extreme reliability. However, with an ever increasing power density, the ability to accurately predict mesh losses becomes of utmost importance. The accurate quantification of bearing losses as well as efficiency of ground and superfinished gears under dip lubrication are examined with respect to running-in. Results show a considerable influence on the calculation of gear mesh losses originating from which bearing loss model is chosen. Furthermore, when a larger running-in load is used on ground gears, an increase in efficiency can be observed during working operation, while for superfinished no significant changes are found. These efficiency/frictional changes are also shown to occur in the initial cycles of the running-in phase. From a surface transformation point of view running-in is shown to be a reduction of asperity tips in case hardened ground gears, while in superfinished gears no changes were seen. These gear surface changes were measured with a novel method with a surface profilometer in-situ before, after running-in and after efficiency testing. Results also show that such changes in ground gear roughness profile occur during the very initial cycles. In order to predict running-in, a simulation method was developed. Such method utilizes a 2D surface integral method to simulate contact between rough surfaces, but requires the use of surface hardness and an accurate lower cutoff wavelength. This cutoff wavelength proved to play a pivotal role in determining an accurate contact pressure at the proper level of granularity, hence a well defined real contact area. The predicted and measured run-in surfaces are compared and are found to be in accordance with each other. / <p>QC 20170928</p>

In this master thesis two simplified and small-scale methods for two-body and three-body abrasive wear were examined. It was examined how representative the methods were compared to field-tested points in a cultivator for agriculture. A total of six points with different compositions were tested and ranked based on the test results. For the two-body test, a lathe and aluminium oxide abrasive paper with 125 μm grain size were used. For the three-body test, a lathe, paper cloth and sand with 200-700 μm grain size were used. The weight difference before and after the tests were measured and the samples were also analysed before and after the tests with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). A ranking of the points could be established and the points with the highest wear resistance for the two tests were Marathon and Ferobide. Marathon consisted of cemented carbides in a cobalt matrix and Ferobide consisted of cemented carbides-regions in a matrix of iron, cobalt and chromium. Marathon had the highest wear resistance for the two-body test and Ferobide had the highest wear resistance for the three-body test. The tests were not a perfect representation of the field-test but there were similarities between them which shows that some parts of the tests were representative. The test that was the most representative compared to the field-test was the three-body test.

During the production of metal zippers, cemented carbide (CC) tools are used to cut preformed brass wire into small elements. Even though the cemented carbide is much harder than the copper alloy, it gets worn and eventually the tool must be replaced. This wear mechanism, which allows soft copper alloys to gradually wear hard CC, must be better understood in order to extend tool life. The mechanism is believed to be tribochemical, as oxides have been found on the surface of the wear mark. Given that most metals oxidize in the presence of oxygen, it is relevant to examine if oxidation of tungsten carbide and cobalt contribute to the wear. The purpose of this work has been to study the influence of oxygen availability on the slow wear of cemented carbides during copper alloy processing. A simplified sliding test rig, developed in a previous study, was used. A small CC cylinder slid against a large rotating copper or brass cylinder in a “crossed cylinders” configuration. The point of contact was encapsulated by a 3D-printed cover. Some tests were done in an oxygen deficient atmosphere, where the cover was continuously filled with flowing nitrogen gas. One test was performed with compressed air flowing through the cover, and one was performed without flowing gas. The wear marks on the CC cylinders were analyzed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and optical profilometry. The wear volume of these marks was also calculated. SEM pictures showed that both brass and copper transferred to the cemented carbide. When the test was performed with brass, zinc oxide was found in the wear mark. When it was performed with copper, no oxide was found.

I pappersmaskiner används kräppblad för att kräppa av pappret från en stor roterande cylinder, en så kallad yankee-cylinder. Dessa blad utstår stora nötningar och beläggs därför med antingen en kromoxidbeläggning eller en hårdmetallsbeläggning för att öka bladets nötningsbeständighet. Bladen beläggs med termisk sprutning, kromoxiden via plasmasprutning och hårdmetallen via "High-Velocity-Oxy-Fuel"-sprutning (HVOF). I detta arbete har slitagetester utförts på belagda kräppblad genom att använda en "slider-on-flat-surface" (SOFS) tribometer för att ta reda på vilken av dessa beläggningar som är bäst lämpad för att användas på kräppblad. Vid användning av SOFS belastas kräppbladen med en normalkraft och glider mot en platta till önskad total glidsträcka är uppnådd. För att kunna genomföra slitagetesterna i SOFSen behövdes en fixtur konstrueras och tillverkas och kräppblad behövde kapas till önskad geometri. Det skapades tre koncept för fixturen och med en beslutsmatris gjordes valet vilken av dem som skulle tillverkas. Den tillverkade fixturen håller kräppbladen stabila i både sidled och i glidriktningen och håller kräppbladen i en vinkel likt i verkligheten. Slitagetesterna utfördes vid tre olika glidsträckor med konstant normallast. Efter slitagetesterna analyserades bladen i stereomikroskop och svepelektronmikroskop för att identifiera nötningsmekanismer. De dominerande nötningsmekanismerna var abrasiv och adhesiv nötning. På grund av porositet i beläggningarna ökades antalet sprickor och mer och mer fragment lossnade vid ökande glidsträcka under slitagetesterna. Det visade sig efter mätningar av bortnött bredd på bladet att det hårdmetallbelagda kräppbladet hade bäst nötningsbeständighet. Detta på grund av dess hårda tungstenkarbider som minskade den abrasiva nötningen och spricktillväxten i beläggningen och dess högre duktilitet jämfört med kromoxiden. / Creping blades are used in paper machines for creping tissue paper from a rotating cylinder called a yankee cylinder. These blades experience severe wear and are therefore coated by either chromium oxide or a hard metal coating to make the blades more wear resistant. The coatings are sprayed on to the blade by thermal spraying processes, the chromium oxide coating with plasma spraying and the hard metal coating with "High-Velocity-Oxy-Fuel" (HVOF) spraying. In this thesis wear testing of the coated creping blade using a "slider-on-flat-surface" (SOFS) tribometer has been done to find out which of these coatings that is best suited for coating on the creping blade. When using the SOFS, the creping blade is subjected to a chosen normal force and is scraped against a counterface for a set total distance. In order to execute the wear tests in SOFS, construction and manufacturing of a holder for the creping blades was needed and the creping blades had to be cut to correct geometry. Three concepts were created for the holder and the decicion about which one to manufacture was made with a decision matrix. The new holder holds the creping blades stable in side movements and in the sliding direction. It also keeps the blade at a set angle to the counterface as in the real application. The wear tests consisted of three sliding distances with constant normal load. The blades were analyzed in a stereo microscope and in a scanning electron microscope to identify the wear mechanisms when the wear tests were completed. The major wear mechanisms were abrasive and adhesive wear. Because of porosity in the coatings, the number of cracks increased and fragments from the blades came loose when increasing the sliding distance during the wear tests. It showed that by measuring the eroded width on the blades that the hard metal coated blade had the best wear resistance because of the hard tungsten carbides that lowered the abrasive wear and the crack growth in the coating and because of its higher ductility in comparison to chromium oxide.

Cone crushers are widely used in the mining, mineral processing and quarrying segments of the industry to crush ores and large rocks. In such machinery, the load to be carried is rather heavy and the motion is gyratory which creates a need for a bearing set that can withstand such severe conditions. Sandvik AB is a high-technology Swedish engineering group specialized in tools and tooling systems for metal cutting, equipment, as well as tools and services for the mining and construction industries. One of their products relevant to the mining industry is the cone crusher which utilizes a 3-piece bearing set to carry thrust load. This bearing can be classified as a Spiral Groove Bearing \footnote{The abbreviation S.G.B will be used interchangeably throughout the thesis.}, and it has been incurred that it wears out rather quickly and is believed to be running under mixed-lubrication conditions where the interfaces in the bearing-set are not fully lubricated. The aim behind this thesis is to create a multiphysics model of this bearing in order to understand deeply how it works and the reasons why it does not perform as expected as well as to predict design improvements which can improve the performance of the bearing-set, thus increasing its operating life. It has been concluded that the bearing operates under severe mixed-lubrication conditions and that the generation of a squeeze film is the only method by which lubrication takes place due to the excessive depth of the grooves which is needed to allow for an adequate amount of cold oil to flow into the grooves and cool the interface as well as to accommodate for a considerable amount of wear particles. In light of the results and insight gathered from the simulations, possible design variations of the bearing which can be advantageous in terms of mitigating asperity friction in the interfaces of the bearing are discussed and tested.

This project has been executed at the forestry machine track manufacturer Olofsfors AB and has been aimed at development of a rig for simulation of the wear that occurs in the linkage of Olofsfors AB forestry machine tracks. The problem is that link hooks in the tracks wears out first, often several times faster than other components. Olofsfors AB want to be able to test this wear in a controlled environment. The purpose of the wear rig is to distinguish what type of wear that is in effect as well as be able to optimize materials for Olofsfors AB: s products.   The project began with an pilot study of different types of relevant wear and different types of complete methods of wear measurement and simulation to better understand the problem. After this a market screening of existing machines and rigs that could be of interest was done. The project continued with creation of concepts of wear rigs and methods of wear. After a selection process the project proceeded with one concept to a 3D prototype.   From the market screening it could be found that the market is very thin with few suppliers. Their products are relatively expensive and need specially made test samples. The recommendation to Olofsfors AB will therefore be to construct a rig themselves. The market screening could be used by Olofsfors AB as a basis if they decide to expand their test activity in the future.    The project reached the overall goals and delivered a prototype that passes the set demands. This means that the project is basically ready to move on to construction of a physical wear rig. There are still some problems to overcome but these will be easiest to solve during the construction phase. / Projektet har utförts hos skogmaskinbandstillverkaren Olofsfors AB och har gått ut på att ta fram en rigg för att simulera den nötning som uppstår i länksystemet på Olofsfors AB:s skogsmaskinband. Problemet är att länkkrokar i banden nöts ut först, ofta flera gånger snabbare än andra komponenter. Nu vill Olofsfors AB kunna testa denna nötning i kontrollerade miljöer. Syftet med nötningsriggen är att kunna avgöra vilken typ av nötning som verkar samt kunna göra materialoptimering för Olofsfors AB:s produkter.   Projektet inleddes med en förstudie av olika typer av relevant nötning samt olika typer av färdiga metoder för att mäta och simulera nötning för att förstå problemet bättre. Efter detta gjordes en marknadsundersökning av befintliga maskiner och riggar som kan vara av intresse. Projektet fortsatte med konceptgenerering av nötningsriggar och nötningsmetoder. Efter utsållning gick projektet vidare med ett koncept till en 3D-prototyp.   Från marknadsundersökningen konstaterades det att marknaden är väldigt smal med få leverantörer. Deras produkter är relativt dyra och kräver speciella provbitar. Rekommendationen till Olofsfors AB blir därför att konstruera en egen rigg. Marknadsundersökningen kan användas som underlag av Olofsfors AB om de vill expandera sin testverksamhet i framtiden.   Projektet nådde de övergripande målen och levererade en prototyp som klarar av uppsatta krav. Detta innebär att projektet är i stort sett redo att gå vidare till konstruktion av en fysisk nötningsrigg. Vissa problem kvarstår, men dessa löses enklast under konstruktionsfasen.

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