High strength aluminum alloys have for a long time been a popular material utilized in the automotive and aerospace sector due to coveted mechanical properties in terms of weight, strength, fatigue, and corrosion. However, tribological mechanisms such as tribo-film formation and material transfer during the metal cutting manufacturing process of aluminum impose significant reduction of machining and tool-life performance. Additionally, environmental aspects associated with metal cutting manufacturing has got more interest and pushed cutting tool development in new directions to meet increased customer demands. One possible way of achieving this, is the implementation and utilization of diamond based cutting tools which has been shown to perform well in machining of high strength aluminum. However, in depth knowledge regarding the tribological properties of diamond based cutting tools is currently lacking. Thus, the aim of this master thesis has been to investigate the refined tribological characteristics and properties of WC-Co cemented carbide cutting tools coated with synthetically grown CVD diamond. Tribological testing methods, such as frictional scratch/sliding, pin-turning, contact-zone temperature measuring, and longitudinal turning have been conducted to acquire extensive amount of research material in the form of test samples and data information. Furthermore, pin-turning tests were performed using a newly developed Tribojan pin-turning equipment and the performance of this was evaluated as a subgoal task. Specimen sample analysis have primarily been performed through LOM and SEM/EDS microscopy techniques. The results acquired from testing, microscopy analysis and data set evaluation have showed promising results in terms of frictional characteristic and material transfer properties regarding CVD diamond coated surfaces. The average CoF of CVD diamond sliding against an Alumec 89 aluminum alloy surface were somewhat lower as compared with similar sliding of a conventional uncoated WC-Co cemented carbide material. Furthermore, the frictional behavior and characteristic of CVD diamond appears to be more consistent and regular over longer sliding distances. The contact interaction between the CVD diamond coated surface and Alumec 89 appears to have a more abrasive nature due to the rough surface structure and material properties of the coating. The corresponding tribo-pair contact interaction with WC-Co cemented carbide shows more adhesive tendencies. Additionally, the contact-zone temperature development during pin-turning is shown to be somewhat lower during CVD diamond/Alumec 89 surface interactions. Regarding material transfer properties, CVD diamond are shown to perform well when interacting with high-strength aluminum. The amount of material adherence is significantly reduced on CVD diamond coated surfaces. During longitudinal turning using CVD diamond coated cutting tools, no significant wear was observed. On the other hand, evidence of both adhesive and abrasive wear was observed during turning using conventional uncoated WC-Co cemented carbide tools. Finally, tribological mechanisms acting during Tribojan pin-turning tests was shown to be relatively comparable with an actual machining operation, which indicate that the testing method perform well as compliment to standard frictional sliding and machining testing. / Höghållfasta aluminiumlegeringar har länge varit ett populärt material inom bil- och flygindustrin på grund av deras eftertraktade mekaniska egenskaper när det gäller vikt, styrka, utmattning och korrosion. Däremot medför tribologiska fenomen, så som tribofilmbildning och materialöverföring under metallskärande tillverkningsprocesser för aluminium, en betydande minskning av prestanda hos utrustning och skärverktygens livslängd. Dessutom har miljöaspekterna i samband med metallskärande tillverkning fått ökat intresse och därmed drivit utvecklingen av skärverktyg i nya riktningar för att uppfylla kundernas ökade krav. Ett möjligt sätt att uppnå detta är att införa och använda diamantbelagda skärverktyg, vilka har visat sig fungera bra vid bearbetning av höghållfast aluminium. Dock saknas det för närvarande djupgående kunskaper om de tribologiska egenskaperna hos dessa diamantbaserade skärverktyg. Syftet med detta examensarbete har därför varit att undersöka de förfinade tribologiska egenskaperna hos WC-Co skärverktyg av hårdmetall belagda med syntetiskt odlad CVD-diamant. Tribologiska testmetoder, så som friktionsskrapning/glidning, pinnsvarvning, temperaturmätning i kontaktzonen samt longitudinell svarvning, har genomförts för att samla in analysmaterial i form av prover och datainformation. Dessutom utfördes pinnsvarvningstesterna med hjälp av en nyutvecklad så kallad Tribojan-utrustning, vars prestanda har utvärderats som ett delmål i projektet. Analyser av provexemplar har huvudsakligen utförts med hjälp av mikroskopitekniker så som LOM och SEM/EDS. Resultaten från provning, mikroskopianalys och utvärdering av data har visat lovande resultat när det gäller friktions och materialöverföringsegenskaper för CVD-diamantbelagda ytor. Den genomsnittliga CoF för CVD-diamant som glider mot en yta av aluminiumlegeringen Alumec 89 var något lägre jämfört med motsvarande glidning av konventionellt WC-Co hårdmetallmaterial. Dessutom verkar friktionsbeteendet hos CVD-diamant vara mer konsekvent och regelbunden över längre glidsträckor. Kontaktinteraktionen mellan ytor av CVD-diamant och Alumec 89 verkar också ha en mer abrasiv karaktär på grund av diamantbeläggningens grova ytstruktur och materialegenskaper. Motsvarande kontaktinteraktion mellan Alumec 89 och obelagd WC-Co hårdmetall visar däremot mer adhesiva tendenser. Dessutom tenderar temperaturutvecklingen i kontaktzonen under pinnsvarvning vara något lägre vid ytinteraktioner mellan CVD-diamant och Alumec 89. När det gäller materialöverföringsegenskaperna visar sig CVD-diamant fungera bra vid interaktion med höghållfast aluminium. Materialets vidhäftning minskar betydligt på diamantbelagda ytor. Vid kontinuerlig longitudinell svarvning med diamantbelagda skärverktyg observerades inget betydande slitage. Å andra sidan hittades tecken på både adhesivt och abrasivt slitage under svarvning med konventionella obelagda WC-Co hårdmetallverktyg. Slutligen visade det sig att de tribologiska mekanismerna som verkade under Tribojan-pinnsvarvning vara relativt jämförbara med faktisk bearbetning, vilket tyder på att testmetoden fungerar bra som komplement till friktions och svarvtester.

There are two main goals of this thesis. Firstly, to improve and develop an existing hot weartester at Karlstad University so that it may test more samples of different sizes. Secondly, totest previously impossible samples and investigate their tribological properties and measurethe coefficient of friction with high reproducibility. The development work on the tribometer wasdone by a prestudy including; Investigating the hot wear tester, idea generation in CAD andcollecting information from the creator and prior users of it. After a few rounds of conceptgeneration and discussion with the supervisor and workshop staff, a new sample holder withdifferent sample adapters was created. Five tests of four different materials were conductedand their friction was measured. The new sample holder was able to solve the mainconcerns with the old design and showed great promise in producing reproducible results,better than any previous versions. The friction of the different TiAlN samples, at roomtemperature, seemed to indicate that there is a certain amount of Al% that maximizes frictionand that there is no simple linear relationship between Al% and coefficient of friction. Finallyit can be concluded that the initial goals of the thesis have been met, and that a newscientific instrument has been created to aid in the further understanding of tribology. / Det finns två huvudsakliga mål med detta examensarbete. För det första, att förbättra ochutveckla en existerande varmnötare på Karlstad Universitet så att den kan testa fler proverav olika storlekar. För det andra, att testa tidigare omöjliga prov och undersöka derastribologiska egenskaper och mäta friktionskoefficienten med hög reproducerbarhet.Utvecklingsarbetet av tribometern skedde via en förstudie som innehöll följande:Undersökning av varmnötaren, idégenerering i CAD och samling av information frånvarmnötarens skapare, samt tidigare användare. Efter några iterationer avkonceptgenerering och diskussioner med handledare och verkstadspersonal så skapadesen ny provhållare med flera olika adaptrar. Fem tester med fyra olika material utfördes ochderas friktion mättes. Den nya provhållaren löste de huvudsakliga problemen med dengamla designen och påvisade goda förhoppningar angående att producera tester med högreproducerbarhet. Markant bättre än tidigare versioner. Friktionsmätningarna från de olikaTiAlN-proverna, vid rumstemperatur, indikerade att det finns en viss mängd Al% sommaximerar friktionen och att det inte finns något linjärt samband mellan Al% ochfriktionskoefficient. Slutligen kan det konstateras att de initiala målen för examensarbetet harblivit uppnådda, och att ett nytt vetenskapligt instrument har blivit skapat för att hjälpa utökaförståelse inom tribologi.

Ultra high molecular weight polyethylene (UHMWPE) is a polymer commonly used in various applications, particularly in hip joint replacements. Despite its good performance, it is susceptible to oxidation degradation, which can be mitigated with the addition of vitamin E, and to excessive wear against metal countersurfaces, which can potentially be improved with the addition of nanoparticles. In this work, sixteen newly developed UHMWPE nanocomposites with different nanofillers (multi-walled carbon nanotubes, graphene oxide and nanodiamonds), blended with and without vitamin E, and both irradiation crosslinked and non-crosslinked were studied. Thermomechanical characterisation (dynamic mechanical analysis and thermogravimetric analysis) and tribological pin-on-disc testing showed that both nanofillers and the addition of vitamin E ensured improved the performance of the nanocomposites compared to the virgin UHMWPE. Vitamin E improved the oxidative and thermal stability of UHMWPE, decreased the wear and increased the coefficient of friction. The nanoparticle reinforcements contributed to improved thermal stability to some degree and decreased the wear. Crosslinking was also shown to result in improved thermomechanical performance, although it appears that the addition of vitamin E inhibits the crosslinking process.

No description available.

In this thesis, the development of a new type of seal is presented along with the steps taken to attain the conclusive design. The results are presented in this paper as a cross-sectioned CAD-model along with the selection of materials and suggestions for future work. The project was commissioned by the multi-discipline engineering consultancy company Projektengagemang AB in Karlstad, Sweden, and carried out as a master’s thesis at Karlstad University. The commission was due to a demand for a new type of sealing solution, as friction is a problem within the field of micro-pneumatics. The work done consists of a study of different low-friction materials where a 30/70 PTFE/PEEK compound was selected as it displayed promising friction and wear properties. The material was then implemented into a design concluded by employing a product development process. The result rendered a prototype for a new kind of low-friction seal which uses the fluid pressure to achieve a sealing contact load between a piston/rod and the seal, which also was the goal set to achieve at the start of the project. Additionally, a design of experiments study was conducted to settle what design parameters were significant with respect to the contact load. For proceeding, making the concept a product ready for production, additional work is needed in the form of experimental material testing, development of a leakage model to optimize the contact load, determination of temperature and creep behaviour, as well as sufficient field testing. Lastly, a die tool must be designed for manufacturing with injection moulding as well as determining if any further processing is required. / Detta arbete behandlar utvecklingen av en ny sorts tätning samt arbetet som utförts för att nå en slutlig design. Resultaten presenteras i form av en CAD-modell tillsammans med materialval och förslag till fortsatta studier. Projektet utfördes efter förfrågan av konsultconcernen Projektengagemang AB i Karlstad, Sverige och utfördes som ett examensarbete för civilingenjörsexamen i maskinteknik vid Karlstads universitet. Detta gjordes eftersom det finns en efterfrågan på lågfriktionstätningar inom mikropneumatik där friktion är ett rådande problem. Arbetet består av en studie över att antal lågfriktionsmaterial där en komposit med 30/70 PTFE/PEEK valdes på grund av dess lovande nötnings- och friktionsegenskaper. Materialet implementerades sedan i design som togs fram genom en produktutvecklingsprocess. Resultatet är en prototyp för en ny sorts lågfriktionstätning som utnyttjar fluidtryck för att uppnå en tätande effekt mellan tätning och kolv vilket även var målsättningen för projektet. Flerfaktorförsök har under processen utnyttjats för att hitta vilka geometriska parametrar som påverkar kontaktkraften mellan tätning och motliggande yta. För att ta konceptet till en färdig produkt krävs fortsatt arbete innehållande experimentella materialtester, framtagning av en läckagemodell att optimera kontaktkraften mot, studier kring temperatur- och krypberoende samt fälttester för att verifiera funktionen över tid. Slutligen behöver ett verktyg för formsprutning tas fram tillsammans med eventuell ytterligare bearbetning för slutlig tillverkning av produkten.

The question for this work was: How to design and control the guidance of sheet metal molding tool in order to achieve precision over time.The work has been based on the method of product development where the product development is methodically done, individual opinions are eliminated to the greatest possible extent.Several different concepts have been developed, which have since been evaluated in a selection process that has been done by using elimination matrice and criterion weight matrice.A knee joint mechanism has emerged from this selection process. The main advantage of the knee joint mechanism is that it is least affected by the dynamic forces that excite in the molding tools. When the magnitude of the dynamic forces could not be determined, a mechanism emerged that largely eliminates this problem. / Frågeställning för detta arbete var: Hur skall en styrning av ett formverktyg för tunnplåt utformas för att kunna uppnå precision över tid.Arbetet har utgått från metoden om produktframtagning där produktutvecklingen sker metodiskt och individuella åsikter elimineras till största möjliga utsträckning.Flera olika koncept har tagits fram, dessa har sedan har sedan utvärderats i en urvalsprocess som har använts sig av elimineringsmatris samt kriterieviktsmatris. Ur denna urvalsprocess har en knäledsmekanism framkommit. Knäledsmekanismens främsta fördel är att den är minst påverkad av de dynamiska krafterna som exciterar i formverktygen. Då storleken på de dynamiska krafterna inte har kunnat fastställas framkom en mekanism som till stor del eliminerar detta problem.

The use of computational methods in tribology can be a valuable approach to deal with engineering problems, ultimately saving time and resources. In this work, amodel problem and methodology is developed to deal with a common situation found in experiments in tribology, namely a linearly reciprocating block-on-flat drysliding contact. The modelling and simulation of such case would allow a better understanding of the contact pressure distribution, wear and geometry evolutionof the block as it wears out during a test. Initially, the introduction and motivation for this work is presented, followed by a presentation of relevant scientific topics related to this work. Wear modelling of published studies are reviewed next, along with studies available in the literature and the goals for this thesis.The fourth section refers to the methodology used and the built-up of the model problem. In this work the Finite Element Method and Archard’s wear model through COMSOL Multiphysics® and MATLAB® are used to study the proposed contact problem. The construction of the model problem is detailed and the procedure for wear, geometry update and long term predictions, is presented inspired by the literature reviewed. Finally, the results are presented and discussed; wear increment and new geometries evolution are presented in the figures, followed by pressure profile evolution at selected times. The final geometry is also compared for different time steps. At last, conclusions and recommendations for future work are stated.

Att ha statistiskt säkerställda mått på slitstyrkan hos precisionsverktyg så som tryckeriraklar kan användas för att underlätta vidare utveckling samt marknadsföring av dessa produkter. I följande examensarbete har utveckling av en metod för att studera slitstyrkan hos tryckeriraklar genomförts. Studierna har genomförts i en testrigg som simulera en rotogravyrtryckeripress. Examensarbetets mål är att utveckla en metod för att testa slitstyrkan av olika rakelprodukter i testriggen samt att tillämpa denna metod för att få dokumenterade jämförande tester mellan fem olika produkttyper. Resultaten av testerna visar nötningen av rakelbladen med lamellängdförlust och viktförlust som mått på nötningen. Det resultat som definitivt kan konstateras är att Produkt C visar lägre slitage än Produkt A. Lamellängdförlust rekommenderas som mått på slitaget under fortsatta studier för att underlätta jämförelser mellan blad med och utan ytbeläggning. För att erhålla högre repeterbarhet rekommenderas fortsatta studier med avseende på färgens korrosivitet, temperatur och viskositet. Vidare studier rekommenderas även för olika färgtyper, då med mjukare pigment och längre testlängd för att se huruvida det ökar repeterbarheten. Vidare studier bör genomföras med avseende på de olika nötningsmekanismer som rakelbladen utsätts för under testerna. / Having statistically acquired measurements on the wear of precision tools like doctor blades can be used to assist further development and marketing of these products. In this thesis the development of a testing method for studying the wear on doctor blades has been conducted. The tests have been performed in a testing rig to simulate a rotogravure printing press. The goal of the thesis work is to develop a method for testing the wear resistance of five different doctor blade products in a testing rig and then applying this method to get a documented comparative study between the different doctor blade products. The results from the testing shows wear of the doctor blades using lamella length loss and weight loss and units of measurement.The results clearly show that Product C shows less wear than Product A. Lamella length loss is the recommended unit of measurement for measuring the wear on the doctor blades, this makes it possible to compare coated and uncoated blades. For a higher repeatability of the tests further studies are recommended with the paints corrosiveness, temperature and viscosity in mind. Further studies are also recommended into different kinds of paint, with softer pigments while increasing the test length. Further studies should also be performed to gain a greater understanding of the different wear mechanisms that contribute to the wear of the doctor blades during testing.

BorgWarner located in Landskrona are developing components for the four-wheeldrive drivetrain that are being massed produced in the automotive industry. Thanks to Borg- Warner’s unique product’s properties they have achieved a worldwide leading position as a provider of systems for advanced four-wheeldrive drivetrain (all-wheel drivetrain). The assignment from the BorgWarner is to create a better understanding about when vibrations occur and what properties of a friction disc affect vibrations in the wet clutch. The goals of this thesis are to: Map system parameters like Surface topografy. Measure pressure distribution between the friction discs. Measure the Youngs modulus, also known as stiffness. It is not sure that a bad pressure distribution could cause vibrations in the wet clutch. The results from the topography explain the appearance of the pressure distribution. Varying stiffness means that the density of the material is also varying because the stiffness depends on the material composition. When forces are applied on the friction disc, it leads to varying deformation on samples. When the samples all deforms different, the result of the different deformation could be slanting surface. When a disc with non- parallel friction surface rotates it could generate vibration in the wet clutch.

To ensure that manufactured cartridges is safe to use, a tensile test is performed. The frictional force between the bullet and the case is required according to Normas standard to be between 15 – 75 Kg. Variations of the frictional force, with values outside of the standard had been noted by Norma Precision without understanding the cause. The aim of this report was to investigate and evaluate possible causes of the variations measured by tensile tests, difference between extreme values and to find a solution to what can be done to prevent the variations. Two different cases and three different bullets were used by request from Norma in the scope of this report. Different combinations of the bullets and cases was tested by alternating process parameter, surfaces and loading procedures. The loaded cartridges went through tensile tests to investigate differences. Bullets and cases with extreme values from the measured frictional force were chosen for further investigation in SEM and profilometer. To be able to draw further conclusions four different simulation models was created in Abaqus and different parameters was calculated. The dimensions and shape of the bullet resulted as the cause of changes of the tensile test curves. The smallest frictional force was found to differ from the largest by a change in wear mechanism from mainly abrasive ploughing to cutting and adhesion that caused transfer of material from the bullet to the case. The change in wear mechanism was found to be caused by an increased bullet diameter. The loading procedure was found to cause variations in plastic deformation on the neck of the case and damage the bottom of the bullet. The loading procedure was assumed to have the largest impact on the variations in frictional force. To minimize the variations the central axis of the case was suggested to be in line with the central axis of the bullet.