The effect of ester-based turbine oil on the performance characteristics of a tilting pad journal bearing was studied. Mineral oils with viscosity grade of 32 and 46 and synthetic oil with viscosity similar to that of the mineral oil VG32 were used. Both mineral and synthetic oils provided similar temperatures. Pad temperature was strongly affected by rotational speed. A slower increase in temperature at higher speeds was caused by the shift in the maximum temperature zone due to the pad thermal crowning. Synthetic oil ran slightly hotter than VG32 mineral oil at lower speeds. At higher speed these oils had almost the same temperatures. This is an abstract of a paper presented at the World Tribology Congress (Kyoto, Japan 9/6-11/2009).

The aging behavior of synthetic lubricants, in particular environmentally adapted lubricants esters, in comparison to mineral base oils, is studied. V Three fully commercially formulated lubricants were subjected to an oxidation process using a modified dry-Waterless Turbine Oil Oxidation Stability Test. The oils were: Oil A (hydraulic unsaturated ester with antioxidants and corrosion inhibitors), Oil B (turbine mineral oil with antioxidants and corrosion inhibitors), and Oil C (turbine saturated ester oil with antioxidants and corrosion inhibitors). This is an abstract of a paper presented at the 15th International Colloquium Tribology - Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).

Experiments are conducted to compare the performance of fresh and aged samples of three oils in a boundary lubricated contact. These oils are Oil A (a commercially available unsaturated synthetic ester based hydraulic fluid (ISOVG32)), Oil B (a mineral based turbine oil (ISOVG68), and Oil C (a saturated synthetic ester based lubricating fluid (ISOVG46)). Tests are performed using a tin-bronze on steel contact in a pin-on-disc apparatus. Results from these tests provide data relating to friction and wear and their coupling to the aging of the fluids. No evidence of any significant deterioration of lubricant performance is observed for any of the fluids tested. This is an abstract of a paper presented at the 15th International Colloquium Tribology - Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).

Research regarding environmentally adapted lubricants results of the research performed at Luleå University of Technology were positive. Thus, the formulation work of an environmentally adapted lubricant for hydropower applications started. A change to a synthetic ester based lubricant would give technical advantages as well as environmental benefits. The initial tests were conducted on the base fluid. Two turbine oils were developed, Turb Way SE and TurbWay SE LV, for hydropower applications. Oxidation tests were performed in both the RPVOT (ASTM D 2272) and in TOST (ASTM D 943). The stability of the turbine oil was > 20 times better than tested environmentally adapted hydraulic fluids. Field tests were conducted in a full scale turbine at Porjus hydropower plant to confirm the promising results obtained from the research in the tilting thrust bearing rig. This is an abstract of a paper presented at the 15th International Colloquium Tribology - Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).

Headchecks are a common type of damage in heavily loaded curved freight tracks. This paper deals with synthetic ester formulations' ability to prevent damage caused by headchecks through mild tribochemical wear. An experimental study pertaining to wear and friction of two rail steels lubricated by two synthetic ester base fluids, TMP-oleate and TMP-C8-C10, has been carried out. Six different free fatty acids were used in this study to act as performance additives. Three of the fatty acids were mono-acids with different, straight, carbon chain lengths (stearic acid C18, decanoic acid C10 and octanoic acid C8), one was a mono-unsaturated straight-chain fatty acid (oleic acid C18:1) while two were dibasic acids with intermediate carbon chain length (C9 and C10). Each fatty acid was blended with either ester, one at a time. The tests were carried out by using a high frequency reciprocating friction and wear test machine. In these tests, the gage face/wheel flange contact was simulated, and all tests were conducted in the boundary lubrication regime. An initial contact pressure of 316 MPa and a maximum sliding speed of 0.11 m/s were employed during the tests. The tests showed a wide range of wear rates, as well as different surface features depending on the interactions between synthetic esters, fatty acids and steel. The use of stearic and azaleic acid in lubricating rail steels results in very smooth surfaces with significant differences in their wear rates.

Lubricated transient elastohydrodynamic (EHD) conjunctions are extremely difficult to simulate numerically since lubricant properties such as temperature and viscosity vary significantly during the loading-unloading event. Nevertheless, industry has invested considerable time and effort in trying to create such models in order to improve performance and to reduce emissions and friction. One of the essential requirements for a successful model is accuracy in the implementation of frictional properties. The experimental method presented in this paper used an impact on the end surface of a beam to generate propagating waves that were subjected to fast Fourier transform analysis. The method yielded detailed information about the build-up and decay of normal and frictional forces as a function of time for various lubricants at three different initial temperatures (20, 40 and 80 °C) and at relevant EHD pressures. A variety of lubricants were studied to a peak Hertzian pressure of 2.5 GPa for loading-unloading times of 200-400 µs (typical for elastohydrodynamically lubricated conjunctions in ball bearings and gears). A qualitative study of the thermal properties of the lubricants and their influence on viscosity and friction coefficient was also undertaken and, finally, a plausible explanation of the observed behaviour is presented and parallels to dynamic simulations of polyatomic gases are drawn.

Environmentally adapted lubricants (EALs) have been a slowly growing segment of the lubricants business since the early 1970s. The evolution of environmental thinking has led to the change of focus, from biodegradability to renewability. In the future, the focus will be more on fuel economy and lower emissions. Technical development drivers include the availability of suitable base fluids and additives for lubricants formulation and the adaptation of technical standards, OEM specifications and eco-labels. Important non-technical development drivers include environmental management tools and eco auditing. Environmental policy, and procurement guidelines for cities and government organizations, clearly has a large impact. EALs have been repeatedly heralded as one of the few future growth segments of the lubricants business, hence the relatively large increase in R&D activity over the last decade. In sales terms, growth has been slow, limited by high cost and several other factors. For a good future development, both technical and political hurdles must be overcome.

A comparative life cycle assessment (LCA) study of three types of base oils used in the manufacture of hydraulic fluids has been carried out, and is reported here. The fluid types investigated are a mineral oil, a synthetic ester, and a rape seed triglyceride oil. The applications chosen for the finished lubricants are in mobile hydraulic systems in forestry operations, some of which are almost 100% total loss applications. The scope and limitations of the LCA model are discussed, and conclusions drawn concerning the application of LCA models as evaluation tools for the development of environmentally adapted lubricants. The methodology used is compatible with the ISO 14000-type industrial standard.