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.

The automated industry is in a growing phase and the human tasks is increasingly replaced by robots and other automation solutions. The increasing industry entails that the automations must be reliable and condition monitoring plays an important role in achieving that ambition. By utilizing condition monitoring of a machine it is possible to detect a wear before it turns into a critical damage that could result in complete failure. A useful tool when monitoring the condition of a machine is by sampling and analyzing vibrations. Vibrations are generated by the moving parts of the machinery and high amplitude vibrations can often be seen as an indication of the developed faults. The frequency of these vibrations can be calculated and then detected in the sampled data. Today there is no condition monitoring system that monitor industrial robots by analyzing vibrations. The problem with analyzing robots, is that they operate with a varying speed. Since the running conditions are changing rapidly all the time, this means that the vibration frequencies also changes constantly. This is due to the fact that the vibration frequencies are dependent and affected of the operation speed. This research is a sequel and continuation of a research from previous year. The purpose of the research is to investigate the possibility to monitor the condition of a gearbox in a industrial robot, by utilizing vibration analysis. The robot that has been tested under tuff conditions in order to reach a failure, is an ABB IRB 6600. To sample data in a stationary way even tough the speed is changing during the sample time, the method order tracking has been utilized. This makes it possible to sample data with numbers of measurement per rotation instead of sampling according to time. This is processed by SKF:s condition monitoring system multilog IMx and the signal is then presented as a time waveform in the software @ptitude Observer. In Observer, it is also possible to show the signal in a spectrum by using Fast Fourier Transform. By utilizing MATLAB, the research has also resulted in a new analyzing method. This method is called Spectral Auto-Correlation. The methodology of this practice is to correlated the time waveform with itself in order to see which frequencies that are reappearing. The correlated result is then calculated with a Fast Fourier Transform to illustrate the signal in a spectrum for further analysis. During the analysis of the parts in the gearbox, critical defects were found on both the cycloidal disks. The fault frequency for the defects were calculated and analyzed from the data. This resulted in trends where the amplitude from the fault frequency had more than doubled over the time the robot has been operating in the project. This report also include a production simulation where a robot cell from SKF is simulated. The robot cell is simulated with and without a condition monitoring system. A comparison was then made to see what advantages there were with utilizing a condition monitoring system. The result of the simulation was an increased productivity with two to three percent.

With industries aiming at higher efficiencies, lightweight parts, and easier manufacturability there has been a recent trend of replacing the metallic materials with polymeric materials and its composites. Particularly in the automotive industry, there is a demand of replacing metallic material of bushes and bearings with polymer based materials (PBM). For these heavy performance requirements (as in automobiles), the commonly used industrial polymers like Acetal and Nylon fail to provide good mechanical and tribological performance. High-performance polymer like Polyphenylene Sulfide (PPS) is a relatively newer material and shows a potential of being a PBM alternative for metallic bearings in automobiles if their tribological performance can be improved.  One of the ways of improving the tribological performance of the polymer is by the addition of filler material, hence making a polymer composite. In this study, we used Short Carbon Fibre as micro-reinforcement material and Nano-diamonds and Graphene Oxide as nano-reinforcement material to make PPS composites. The varying mechanical and tribological behaviour of PPS composites with different weight percentage of reinforcement materials was investigated. The optimum composition of the reinforcement materials was identified, which resulted in significant improvement in mechanical and tribological properties of the base material.

I detta projekt har vi fördjupat oss i en glidlagerkonstruktion som befinner sig i en skruvpress. Skruvpressen kompakterar en okänd massa som är sekretessbelagd. Robustus har ett förslag på överdimensionering av det nuvarande glidlagret. Målet med projektet var att analysera och optimera några glidlager i förhållande till det befintliga glidlagret samt att ta hänsyn till materialval och den miljö som lagret kommer att befinner sig i. Det som analyserna och optimeringen visade var att det befintliga glidlagret hade den bästa geometrin bland alla lösningar men inte det optimala materialet. Projektet befinner sig i ett tidigt stadium och det behövs en del geometriska förändringar. Det viktigaste av allt är att problemet har identifierats med hjälp av det havererade glidlagret och med en excelmodell. / We have in this project become engrossed in a plain bearing design that is located in a screw press. The screw press compact an unknown mass that is confidential. Robustus have a suggestion to over dimensioning the present plain bearing. The aim of this project was to analyze and to do an optimization on some plain bearings and compare them to the present bearing and to take the choice of material and the environment where the bearing is located into account. The analysis and the optimizations showed that the current plain bearing had the best geometry but not the optimal material selection. The project is in an early state and it needs some geometrical changes. The most important of everything is that the problem has been identified with the help of the wrecked plain bearing and with an excel model.

This thesis has been conducted at Ovako Bar for a period of 10 weeks and is the final part of the bachelor's programme in mechanical engineering. Ovako Bar is a business unit of the European steel concern Ovako which specializes in the manufacturing of engineering steel for applications in various fields of mechanical engineering. The company wants to improve profitability of their sawing centre by reducing the consumption of saw blades and increase productivity at one of their sawing machines. In the current situation the company uses disposable blades which are discarded either when a tool break occurs or when the quality requirements are no longer met for the outgoing material. A literature review was conducted in which various factors affecting the life span of the saw blades were analyzed after their impact on the outcome in which two factors was selected to be used for a design of experiments. The factors selected were feed per tooth and cutting speed in which a total of four experiments were conducted and finally the results showed that the interaction effect was the decisive factor for the outcome. To investigate the tool wear that had arisen a scanning electron microscope was used where a few teeth on each blade were studied for any damages. The conclusions that could be drawn from the experiment is that a high feed rate must be combined with a high cutting speed for best result which has to do with the fact that a higher feed requires a greater heat generation for the best chip formation. The same applies for the lower feed rate which must be combined with a lower cutting speed because a higher cutting speed causes a dominating wear on the clearance face.

In the present work further modifications are implemented to an existing test setup for the evaluation of the wear of cemented carbide drill buttons in rock drilling applications. The test setup has been evaluated in previous diploma works, which has shown that the test successfully mimics the wear seen in rock drilling applications. The new modifications include friction and normal force measurements together with the collection of rock debris. This has been made possible by redesigning the sample holder and by manufacturing equipment making rock debris collection possible. The new modifications to the test setup were evaluated by comparing the wear of three different cemented carbide grades tested against sandstone and granite with two different loads. The data collected from the new modifications were found to be robust with lower than expected spread of data. The coefficient of friction when testing against sandstone was higher than when testing against granite. More adhered material was observed on the wear surface when testing against granite than against sandstone. Load dependence on the wear of the cemented carbide buttons is only seen for the softer cemented carbide grades when testing against sandstone. The wear of the buttons indicates a high dependence on the hardness of the different grades as shouldbe expected. This diploma work has been performed for Sandvik Mining, Rock Tools,a world leading supplier of rock drill equipment.

There has been much discussion about the beneficial uses of lamellar graphite iron in piston rings–cylinder liner systems, where a good combinations of both thermal and tribological properties are essential. The excellent tribological performance of lamellar iron under such sliding conditions is principally associated with lubrication behaviour of the graphite particles which are distributed as lamellas throughout the matrix. During sliding, graphite particles are extruded and smeared onto the counterfaces, act as solid lubricating agents and form a thin graphite film between the sliding surfaces. Although this process especially, during the running-in period significantly changes the sliding wear response of the components, the exact mechanism behind of this phenomenon has rarely been discussed in previous studies. It is tribologically beneficial to keep the graphite open, particularly in applications where the scuffing issues do matter. In this thesis, the main causes involved in closing the graphite lamellas are discussed, with a focus on matrix plastic deformation that occurs during sliding. In first step, the relationship between graphite lamellae orientation and plastic deformation was investigated. To do so, two piston rings, belonging to the same two-stroke marine engine operated for different periods of time, were selected and compared to the unworn sample. The worn piston rings displayed a substantial decrease in both frequency and area fraction of the graphite lamellas. Most of the lamellas were closed as a result of plastic deformation of matrix. This happening was caused mainly by the interaction between abrasive particles and metallic matrix. Additionally, it was found that graphite lamellas parallel or near-parallel to the sliding direction exhibited maximum closing tendency under sliding condition. In next step, to have a better understanding of the graphite film formation mechanism and matrix deformation role in closing the graphite lamellas, microindentation and microscratch testing were performed on typical lamellar iron. The qualitative results showed a similar mechanism involving in graphite contribution to lubricate the sliding surfaces. Moreover, microindentations made nearby the graphite lamellas demonstrated that the deformation of the matrix causes the formation of cracks in the centre of the graphite lamellas, compressing and then extruding the graphite from its natural position, irrespective of the lamellas′ size. Furthermore, it was found that subsurface graphite orientation had a large influence on the extrusion behaviour, in that, for graphite lamellas oriented towards the indenter, the effect was observed more pronounced. Furthermore, an improved fully ferritic solution strengthened compacted graphite iron was produced for future wear studies. The effects of different Si levels and section thicknesses on tensile properties and hardness were investigated as well. The influence of Si content and section thickness on mechanical properties was revealed by improving the materials strength and slightly enhancing the hardness through increasing Si content. Besides, Si addition up to 4.5 wt% significantly affected the strength and elongation to failure of cast samples. / Helios / FFI

Different lubricant additives such as dialkyldithiophosphates (DTPs) of different metals have been extensively used as multifunctional additives to control wear and friction in mechanical systems. These additives can produce protective films on steel rubbing surfaces and, therefore, control friction and reduce wear. On the other hand, these additives contain large amounts of metals, phosphorus and sulfur, which can adversely affect the environment by degrading catalytic converters in automobiles. Boron based additives are recognized as friction modifiers, corrosion inhibitors, antioxidants, and effective antiwear additives. These additives are emerging as attractive alternatives for the additives already used in lubricants. The aim of the project is to investigate the tribological performance of some novel alkylborate dithiocarbamates.This project was performed in the following steps:1- Chemical synthesis of three different borated dialkyl dithiocarbamate additives with alkyl chains of different lengths.2- Tribological tests of novel compounds using a four ball tribometer.3- Surface analysis using an optical profiler (Veeco WYkO NT 1100) and Scanning Electron Microscopy coupled with X-ray Energy Dispersive Spectroscopy (SEM/EDS).The effect of the alkyl chain length in both DTC and the borate molecular moities of three B-DTC compounds on the tribological performance was studied. An increase in the alkyl chain length at the borate side improves antiwear properties in steel-steel contact. It was found that cyclo-N,N-alkylenedithiocarbamato-S-alkyl-di-n-alkyl-borate previously synthesized and studied [1], has the best antiwear performance compared with the other compounds synthesized in this work. All the novel additives were able to stabilize friction coefficient over a wide concentration range of the additives in the base oil. B-DTC additives with long alkyl chains show greater reduction in friction compared to the one with short alkyl chains. A possible explanation of this phenomenon is that longer chains have improved deposition process of additives on surfaces leading to a thicker and more stable tribofilm. EDS spectra show the presence of sulfur atoms on the rubbing surfaces lubricated by the base oil with B-DTC additives. / <p>Validerat; 20111001 (anonymous)</p>

The increasing worldwide demand for more eco-friendly materials with improved tribo- logical properties has expanded the interest in research on polymer as an alternative for conventional metal/metal contacts under dry lubrication. Specifically, UHMWPE, a semi-crystalline polymer, has shown interesting tribological properties for low demanding applications, allied with excellent recyclability, manufacturability and low cost. Though, its limited working temperature range and wear resistance claims reinforcements to modulate these drawbacks. Metal sulfides, such as MoS2 and SnS2 are well-known 2D materials with outstanding thermal, mechanical and tribological properties which have the potential to increase the range of applicability of UHMWPE. Therefore, this work aims to investigate the influence of metal sulfide-based micro-particles on UHMWPE-based composites properties under reciprocating movement and to determine further acknowledgements about the mechanisms involved. The results showed that the incorporation of fillers im- proved in hardness and wettability, whereas thermal properties were conserved. Though, it is noted that chemical degradation processes (oxidation and un-saturation reactions) that occurred during the manufacturing negatively influenced the composite’s tribological response. Higher reinforcement weight percentages (10%) promoted metal-sulfides agglomeration, increased degradation and ultimately diminished wear resistance. Overall, optimizing the amount of filler in the matrix at 5 wt% provided its homogeneous dispersion and a good interface with the matrix, leading to enhancement in wear resistance up to 62%. Indeed, the incorporation of metal-sulfide based materials in the UHMWPE matrix revealed an excellent solution where wear resistance improvements are needed.

Plastics contribute 2 GTons to the global carbon footprint, today, several countries have set targets to achieve carbon neutrality. Plastics, being a major contributor to global carbon footprint, would need to be reduced significantly from our daily life to achieve that or a way needs to be devised to recycle them. A big bottleneck in this process is to reduce the consumption of thermosetting plastics or to reduce the emissions associated with plastic and move towards economical and environmentally safe plastics having a longer lifespan and efficient recyclability. Fused filament fabrication (FFF) is the most commonly used 3D printed technology available today. Its applications range from production of prototypes to hollow shafts, and fully functional commercial components. This technology is revolutionary in a sense that it offers advantages such as cheaper raw materials, high degree of customizability, production in smaller batches at lower costs, decrease in material wastage, rapid prototyping, and complex geometry. A number of thermoplastic polymers can be used with FFF technology to produce parts, in addition research is on going to print materials not commonly used for FFF process. Polyoxymethylene (POM) could be a viable option for utilization as FFF basestock for the production of tribologically functional components. POM is an engineering thermoplastic that offers high resistance to wear, low friction, excellent impact resistance, and good chemical resistance. These properties render it suitable for production of gear wheels and low load bearings. It is currently processed using traditional manufacturing methods such as injection and compression moulding, while its printability has received very little attention in the openly available literature. An attempt has been made in this thesis to fill up this research gap by providing insight into POM filament quality, and the thermal, mechanical, and tribological behaviour of POM printed parts. The influence of overfill and layer height on the bulk properties of the printed samples, its play with counterface surface roughness and applied load has also been investigated.