"De-lubrication is the first stage in a sintering operation, where the lubricants (higher weight hydrocarbons) are removed from the parts by controlled heating. Improper de-lubrication leads to defects such as blistering, sooting, micro-porosity etc in a sintered part. Most of these problems arise, as there exists a gap in the present understanding of de-lubrication. The primary motive of this work is to direct research towards the development of sensors and controls and thus, mitigate the various problems due to improper de-lubrication. Currently, there exists a myriad of lubricants being used during the process of compaction. They include metallic based lubricants, polymers and non-metallic lubricants. In this work, research was limited in understanding the de-lubrication of EBS (Ethylene Bisstearimide), as, it the most commonly used lubricant in the industry. It has replaced commonly used lubricant due to cleaner burnouts, absence of metallic residue and, cost effectiveness. The entire work is divided into three phases: • Phase 1: Ascertained the most important parameters that affect the kinetics of de-lubrication. • Phase 2: Investigated the type of gases released during the decomposition of EBS. • Phase 3: Recommended a control strategy. TGA (Thermo-gravimetric analysis) was used in the phase I, the results clearly show that the rate of heating is the most important parameter during de-lubrication. Identification of gases was performed using the FTIR (Fourier transform infrared spectroscopy) and DUV (Deep ultraviolet spectroscopy). This constituted the second phase of our experiments. The primary gases identified in Phase II were carbon dioxide and a hydrocarbon (hepta-decane). Finally, an empirical model for de-lubrication has been proposed in Phase III. The model was verified in an industrial furnace. It has been observed that there exists a very good correlation between the proposed empirical model and the experiments performed in Phase II of this study. This study lays down the following guidelines for the development of future sensors and controls: • The development of future sensors should focus in the detection of CO2 and hepta-decane. • Rate of heating determines how fast or slow the lubricant decomposes and finally escapes form the compacted part. • The empirical model may be used, as a means to determine the time a part should reside in a furnace for complete lubricant burnout at a given heating rate."

In electromagnetic launcher (EML) systems, the behavior of the materials and forces at the armature-rail interface involves fluid mechanics, electromagnetics, thermal effects, contact mechanics and deformation mechanics. These factors must interact successfully in order for a launch to be successful. A lubricant film either deposited on the rails prior to launch or injected from the armature during launch has been suggested as a means of improving the electrical conductivity of the rail-armature interface and of avoiding the occurrence of arcing. The fluid pressure generated by such film, together with the magnetic force, the contact force and the uneven temperature field in the armature, deforms the armature and changes the interface gap shape. An analytical model to study the interfacial behavior under these influences is necessary in order to predict the performance of a potential EML design and to provide optimization information. Studies of this interfacial behavior have been done by a number of researchers. However, many critical factors were not included, such as surface roughness, cavitation, injection, magnetic lateral force, interface deformation and thermal effects. The three models presented in this study investigate the influence of those factors on the EML interface problem. The magneto-hydrodynamic (MHD) model establishes a description of the lubrication process under electromagnetic stress but neglects interface deformation. The magneto-elastohydrodynamic (MEHD) model extends the MHD model by considering the lateral magnetic force, interface contact force and elastic deformation. Finally, the magneto-elastothermohydrodynamic (METHD) model adds the thermal effects to the deformation analysis. A coupled analysis of the interface behavior with the METHD model is developed and the history of a typical launch is studied. Detailed injection, lubrication and launch processes are revealed and the performance is predicted. A failed launch is simulated and the cause of failure is identified to be debris left on the rails. Several operation and design parameters, such as rail surface profile, electric current pattern, reservoir load, lubrication length, pocket size and geometry, injection conduit diameter, are analyzed and a recommended injection design procedure is developed. A scaling study is performed by doubling the dimensions to predict the scaling effects. In the end, the base case configuration and scaled configuration are optimized using the technique developed in this study.

This diploma thesis is concerned with simulation of elastohydrodynamic lubrication of point contacts using the finite element method. The first part of the thesis focuses on the study of the issue and introduces equations for model creation and numerical methods which can be used for EHD calculation. The most suitable solution approach has been chosen from the overview, namely the Full system approach. The software we chose for applying the method was COMSOL Multyphysics. The following part of the thesis deals with model’s creation and gives its elaborate description. We introduce models for calculation of line and point EHD lubrication for newtonian lubricants and, last but not least, we also present a model for calculation of point contact EHD lubrication for non-newtonian lubricants. The next part of the thesis then verifies all the models. That is achieved by comparing the calculated results to results from different papers. The conclusive part of the thesis then examines the matches of acquired results to different prediction relationships and experiments.

The purpose of this thesis is to reveal production mechanisms of lubrication films between non-conformal surfaces in situations, when is not possible to designate lubrication regime as fully flooded elastohydrodynamic contact. Under certain conditions of lubrication volume, rolling speeds, temperatures, lubrication properties or loads could lubrication film decrease under values determined by fully flooded formulas. This regime is designated as starvation at it includes risk of increased wear. In this thesis the methodology and the new simulator of starving contact are described. Obtained film thickness results are compared with existing numerical models.

This master’s thesis is aimed at the lubrication of machina tools. There are described the basic type sof lubrication systems, design of maintenance-free lubricated vertical lathe and technical-economic evaluation. The last section is devoted to the design proces.

The gears in a transmission are lubricated to prevent their premature failure as a result of pitting and wear on the tooth surfaces. Furthermore, the lubricant also limits the rise in surface temperature of the gears, which could otherwise lead to failure as a result of scuffing. The purpose of this thesis was to construct a fairly realistic theoretical lubrication model for spur and helical gears, the primary output parameters of this model being film thickness and flash temperatures, which would help in the identification of areas on the gear tooth surface prone to the aforementioned modes of failure. This thesis was carried out at the Gear Technology group in Scania CV AB in collaboration with the department of machine design at KTH. Gear lubrication is tricky as it entails the determination of parameters such as loads, curvatures, and velocities; which are different along the entire surface of the gear tooth. Primarily the loads are hard to obtain as they are dynamic in nature; the load is shared between different pairs of teeth during motion. The calculation of velocities and curvatures in an area of the gear surface called the tip relief can also not be done in a straightforward manner. These issues were simplified to a large extent with the assistance of a program called Helical 3D; owing to its powerful contact analysis algorithm, values of the film thickness and flash temperatures could be determined in almost every region where contact occurred between the gear teeth. The results of the lubrication model showed a reduction in film thickness in the tip relief area of the gear tooth surface; which meant that there were higher chances for the incidence of pitting and wear in this region. This was later confirmed when photographs from experimental tests illustrated a pitting line in the tip relief region of the helical gear. It was also inferred from the model that the occurrence of pitting could be greatly reduced if a quadratic tip relief modification were applied when compared to the existing linear modification used at Scania. Another important conclusion drawn was that thermal effects contributed to a significant decrease in the film thickness. Furthermore, the model showed higher flash temperatures close to the tip of the gear tooth surface, and photographs from experiments conducted showed the prescence of scuffing marks there.

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other / no / The effect of sulphuric acid on the chemical and physical behaviour of the piston ring lubricant in a marine engine cylinder was investigated. To reveal the basic influence of H2SO4 on the lubricant film, the saturated hydrocarbon Squalane (C30H62) was chosen as a simple model oil. The interfacial tension between aqueous H2SO4 (0-98% w/w) and C30H62 was measured between -3 and 165 degrees C to understand droplet formation in the lubricant. Interfacial tension decreases with increasing acid concentration and is temperature dependent. / The wettability of engine parts with corrosive sulphuric acid was characterised by the contact angle. The contact angle of H2SO4 (0-98% w/w) on a grey cast iron cylinder liner material (Wartsila, RT84) and a piston ring chrome-ceramic coating (Federal Mogul Goetze, CKS, empty set960 mm) immersed in C30H62 was measured over a temperature range from 20 to 165 degrees C. In general, larger contact angles were measured under higher temperature conditions and on chrome surfaces. / In addition to the physical measurements, chemical reaction between H2SO4 and C30H62 was observed which influenced the interfacial tension, visual appearance, phase separation and formation of solid matter. The reaction time was found to be faster than the neutralisation times of commercially formulated lubricants. The reaction products were analysed using FTIR spectroscopy and EDX to find oxidation and sulphonation.

Submitted in partial fulfillment of the academic requirements for the Masters degree in Technology, Chemistry department, Durban University of Technology, Durban, South Africa, 2015. / The focus of most lubricating grease testing has been based on performance and appearance rather than determining the concentration of chemical components. The primary reason being lubricating grease is a difficult matrix to work with from the perspective of the analytical laboratory. The purpose of this study was to develop a simple, reproducible method for elemental determination in lubricating grease and to apply the developed method to work out a flushing procedure for the filling lines in a grease manufacturing plant. The first part of the experimental work focused on developing a suitable and efficient sample preparation technique. Three techniques were explored: direct dilution, microwave assisted acid digestion and emulsification. Direct dilution involved shear mixing the lubricating grease with metal free base oil and diluting it with an organic solvent. Use of these solvents caused plasma destabilization or even plasma extinction and their use posed health risks for laboratory personnel. Microwave digestion involved mineralising the lubricating grease using an optimised microwave assisted acid digestion procedure. In the third sample preparation technique, microemulsions were formed by mixing the lubricating grease with a relatively small volume of a strong mineral acid mixture followed by the surfactant (triton X-100) at room temperature and pressure (RTP). This approach does not require the destruction of the organic matter or the use of large amounts of organic solvents. For all three techniques the sample was subsequently analysed for Al, B, Ba, Ca, Li, Na, S, Mo and Zn. All analysis was performed using an Optima ICP-OES with previously optimised parameters. The direct dilution method gave the most inconsistent results with relative standard deviation (RSD) as high as 56% for calcium, 79% for boron and 66% for lithium. Microwave digestion and emulsification gave comparable results, with the calibration curves of oil emulsions not differing significantly from aqueous ones. For microwave assisted acid digestion the limits of detection ranged from 0.028 mg/L for sodium to 0.255 mg/L for boron. Correlation coefficient values (r2) of all the elements were greater than 0.99. Likewise the limits of detection for emulsification ranged from 0.03 mg/L for aluminium to 0.37 mg/L for sulphur. The correlation coefficients for all the elements were greater than 0.99 and this indicates that the calibration curves were sufficient for analysing the digested grease samples. Five quality assurance samples were analysed using both methods and in addition a t-test performed at the 99.9% confidence level and 4 degrees of freedom showed that the two sample preparation techniques gave similar results. Emulsification has several advantages over microwave digestion technique and superior analytical performance over direct sample dilution using solvents, and hence was chosen as the method of choice for routine analysis of lubricating grease. The second part of the experimental work focused on developing a flushing procedure for filling lines in a lubricating grease plant. A flushing procedure is essential in order to minimise waste, which will in turn minimise production costs and avoids incurring disposal costs. In this series of experiments, the microwave digestion sample preparation technique was utilised for the subsequent determination of the flushing mass required in between product changes. The flushing procedure was implemented and monitored by the use of statistical quality control tools for a specified period of time, and as indicated by Shewart Control charts, the process was in statistical control.