A simple and inexpensive corrosion sensor has been manufactured to study the corrosion rate of new and water contaminated lubricating grease using a galvanic cell. The galvanic charge is developed between ENIG (electroless nickel immersion gold) and zinc, manufactured by selectively plating on a custom manufactured interdigitated PCB (printed circuit board). This paper shows the methodology in using this concept for any application which may require quantifying the corrosivity of a liquid or semisolid which could be applied to the surface of the sensor. Water contamination is a problem in many grease lubricated machine components, so a sensor concept was developed and a correlation between water content and the corrosion rate is shown. This method could be used to precisely study the corrosion rate of aged or contaminated lubricants and could potentially be used as a cheap and simple way to estimate water contamination of grease. To the knowledge of the authors, this sensor concept has not been used in industry or literature.
The purpose of this paper is to convey a simple and effective method to mix water with grease and verify the homogeneity of the mixture using Karl-Fischer (KF) titration as the analysis tool. This is required to better develop a future water in grease sensor for on-line condition monitoring. This paper will also attempt to investigate how well KF titration functions as a tool for measuring water content in grease. Additional investigations include how the water content varies with time in grease samples open to atmosphere at different temperature. This research verifies a simple grease mixing method and investigates the water transport in water contaminated grease samples.
The temperature dependence on the dielectric properties of water-contaminated grease is investigated in this article. The purpose of this investigation was to identify the dielectric properties that could be measured to differentiate varying levels of water contamination in calcium sulfonate complex (CaS-X) grease with three different test cells with the purpose of eventually developing a grease condition sensor. Measuring the change in dielectric constant over a small temperature change yielded useful estimations of water content and amount of grease where the added water content ranged from 0.22% to about 5.5%. Additionally, other parameters such as incomplete fill/coverage of the sensors were investigated as a prestudy. The results from this set of experiments show that the measurement has potential to be developed into a condition monitoring sensor in the future.
Water-contaminated grease samples are investigated with attenuation spectra in the visible and near-infrared (NIR) regions in this article. The purpose of this investigation was to identify a model with optical attenuation spectra such that the water content of grease samples could be characterized with a simple measurement setup using common methodology from the field of instrumental chemistry. The ratio between two chosen wavelengths of light appears to approximate the water content of grease samples with an acceptable coefficient of determination using a methodology to show what can potentially be done to develop condition monitoring tools. To illustrate the outlined method, a prestudy of grease aging and oxidation levels is also investigated to show that other variables do not significantly change the measurement.
Machine maintenance is important for improving machine uptime, reliability, and reducing costs. Grease is used in most rolling element bearings, and one common failure criterion is water contamination, so developing a sensor which can detect water content automatically without human input could be a useful endeavor. The temperature dependence on the dielectric properties of water-contaminated grease is investigated in this paper with computer logged instrumentation. This method has been termed Dielectric Thermoscopy (DT). Several off the shelf (two lithium, one lithium complex, and two calcium sulphonate complex) and one unadditivized lithium grease are tested with varying amounts of water contamination from 0% to approximately 5%. Another grease is tested with small increments of added water from 0% to 0.97% to test the resolution of the measurement. The purpose is to use the capacitance temperature slope (termed dielectric thermoscopy) to show correlations to the water content of the grease sample and investigate if any grease types will pose problems in the measurement. A small, custom made fringe field capacitance sensor with an integrated temperature sensor has been used for this characterization and data is logged automatically with laboratory equipment and a PC. A useable and positive correlation to water content and the DT measurement of roughly 0.5 pF per 10 °C and percentage of water is found, although it was found that some greases have different behavior than others.
In Europe it is approximated that around six million people are active in sport shooting. Currently, most bullets are manufactured out of lead which in many cases is combined with a copper jacket. There are several reasons for using lead; lead is relatively cheap, soft, and has a high density, and is therefore often the ideal material for bullets. Currently, the EU is seeking a restriction or ban on the use of lead in firearm bullets, with the main motivation that hunting with lead bullets might result in lead poisoning of both animals and people. The proposed lead ban will also have a major impact on sport shooting, as it is likely to be subjected to the same regulations. One caliber that has been shown to be very difficult to produce as a lead-free alternative is 22lr (long rifle), which today is the most common caliber for sport shooting in many disciplines. Today, there are not many scientific investigations available which show the performance of lead versus lead-free ammunition in caliber 22lr, even though it would make sense to investigate the possibilities of designing lead-free ammunition before a possible lead ban is further discussed. In this work the performance of two common lead-free 22lr-cartridges is evaluated and shown in comparison with existing lead-based ammunition, with a primary focus on sport shooting. Performance has been evaluated under both summer and winter conditions to cover different sports shooting disciplines. The results of this study clearly show the difficulty of finding lead-free 22lr cartridges with acceptable performance on the market today. In fact, the performance of the tested lead-free ammunition is so poor that the EU’s proposed lead ban could completely ruin shooting as a sport due to a lack of functioning ammunition.
Different transmission fluids, with a focus on ATF, were presented together with some of their respective advantages and disadvantages. Fluid performance in several different areas, such as shear stability, frictional performance and gear protection were described. Industry trends in the ATF market regarding standards and product diversification were discussed from a global OEM point of view, including information on Volvo’s approach to transmission oil specifications. This is an abstract of a paper presented at the 16th International Colloquium Tribology Lubricants, Materials and Lubrication Engineering (Stuttgart/Ostfildern, Germany 1/15-17/2008).
The lubricants of the future have to be more environmentally adapted, show a higher level of performance, and give a lower total life cycle cost (LCC) than the lubricants that are used today. One way to be able to produce, choose and formulate these lubricants is to have good knowledge about the properties of the base fluids and their additive response. The base fluid properties can be divided into four different groups, i.e. physical, chemical, film formation properties and additive response. This thesis is based on the results from the Swedish HiMeC research project "Environmentally adapted lubricants for high performance components". A number of different environmentally adapted ester fluids, suitable for formulation of environmentally adapted lubricants were investigated according to properties, molecular structure and film formation capability. I t was found that both thermal conductivity and specific heat capacity are high for the esters compared to mineral fluids. There is a strong correlation between the number of carboxylate groups and the thermal conductivity. The film formation capability was investigated by the use of optical interferometry in a ball and disc apparatus. A new model for measuring the running in performance of mechanical components was developed. The tests are run un-accelerated, with the same contact pressure and speed as the real applications they represent. The method is based on a tribotest and exact measurement of the surface topography at the exact same spot before and after the test. The most interesting parameters to monitor were found to be Rdq and Rpk. It was found that even very small changes at the uppermost parts of the topography can be measured and monitored whit this method. The additive response for both traditional anti wear additives and specially designed more polar additives where studied. The test where performed at Iwate University in Japan. A modified Falex pin and vee block tribotest machine where used. It was found that the new type of additives is efficient but further research is needed to be able to formulate fluid based on this chemistry. When putting all together, it could be seen that it will be possible to tailor make base fluids with suitable properties and additivate them with the correct additives for the task they should perform. That will make it possible to achieve better results than the fluids used to day in both environmental and performance aspects.
Future lubricants have to be more environmentally adapted, have a higher level of performance, and lower total life cycle cost (LCC) than presently used lubricants. To be able to formulate those lubricants, the properties of the base fluids have to be well known. Base fluid properties that influence the formulated lubricant performance could be divided into three different groups. These groups are: physical, chemical, and film formation properties. In this study, properties from all of these groups are investigated to improve the understanding on thier influence on base fluid overall performance. There are more or less environmentally adapted base fluids available for formulation of lubricants. They could be divided into different groups, mineral, semi-synthetic, and synthetic fluids. Synthetic fluids could be of different types: polyalpha olefins (PAO), synthetic ester, polyglycols, and others. The most interesting group for formulation of environmentally adapted lubricants are the synthetic esters. In this study, the properties for a large number of environmentally adapted ester base fluids are studied in detail. The tested properties relate to the macroscopic/molecular behavior and include: viscosity-temperature-pressure effects, η(p,T) , thermal conductivity, λ(p,T), and heat capacity per unit volume, pcp(p,T) . The film formation capability in elasto-hydrodynamic contacts is also studied. Different connections between the molecular structure and the performance of the fluids are discussed. As an example, it is found that a large number of carboxylate groups in the ester molecule improve the thermal properties, and thereby a thicker lubricating film could be maintained in highly loaded, high-slip contacts.
The lubricants of the future have to be more environmentally adapted, have a higher level of performance, and lower total life cycle cost (LCC) than commonly used lubricants today. Since we live on a planet with finite resources, we have to think about coming generations and work for a sustainable development in the field of tribology. To be able to formulate those lubricants, the properties of the base fluids have to be well known. Base fluid properties that influence the formulated lubricant performance could be divided in to three different groups. These groups are; physical, chemical and film formation properties. In this study are properties from all of these groups investigated to improve the understanding on there influence on base fluid overall performance. There are more or less environmentally adapted base fluids available for formulation of lubricants. They could be divided in to different groups, mineral, semi synthetic and synthetic fluids. Synthetic fluids could be of different type: PAO (poly alpha olefins), Synthetic ester, Poly glycols and others. The most interesting group for formulation of environmentally adapted lubricants are the synthetic esters. In this thesis the properties for a large number of environmentally adapted ester base fluids are studied in detail. The tested properties relate to the macroscopic / molecular behaviour and include: viscosity-temperature-pressure-effects, thermal conductivity, and heat capacity per unit volume. The film formation capability in EHD contacts is also studied. Different connections between the molecular structure and the performance for the fluids are discussed. As an example, it is found that a large number of carboxylate groups in the ester molecule are improving the thermal properties, and thereby a thicker lubricating film could be maintained in highly loaded, high slip contacts.
Fundamental properties of six synthetic ester base fluids, suitable for the formulation of environmentally adapted lubricants, have been investigated. High pressure viscosity data for the test fluids were obtained through experimental measurements with a high pressure Couette rheometer. The temperature, pressure and viscosity data η(p, T) were parameterized against the Roelands pressure-viscosity equation. Thermal conductivity and specific heat capacity data were obtained using a transient hotwire method, and the EHD friction coefficient, γ, was obtained experimentally as well. The results from these measurements are reported, and the correlation between thermal properties, molecular structure, and the fluid rheology parameters, of the test fluids are discussed.
The running-in properties of a hydraulic rotator of vane type for angular positioning of crane tools has been studied. The sliding contact between the vane nose and the stator ring was studied in detail. A pin-on-disc configuration tribometer was used for the tribotests. The pin was made out of a slice from a real vane and the disc was manufactured of the same material and with the same machining process as the real stator ring. Collected data included friction, wear and electric contact resistance. A new method was used to enable measurements of changes in surface topography at a specific location during the test. The results show that the relocation method is useful for monitoring small changes in surface topography under running-in, but the most significant parameter for detection of running-in for this application is electric contact resistance. Significant changes in friction and contact resistance were observed during the running-in period. The main reason for the changes is the build-up of a non-conducting tribofilm. The change in surface topography alone is too small to change the lubricating regime. The tribofilm is formed after a short distance but can not grow until the steepest asperities have been worn off. The results show that the plane milled surface has better running-in properties than the turned surface
Five different anti-wear additives, suitable to formulate environmentally adapted hydraulic fluids, were tested. The used base fluid was a saturated, environmentally adapted synthetic complex ester. The tested materials were steel-steel and bronze-steel. A modified Falex pin and a vee-block tester were used for the tribotests. XPS was used to characterize the surfaces. It was found that the new types of more polar additives work better than the traditional ones, though they can give selective transfer of cupper to the steel pin. To use this type of additives in fully formulated products more investigations have to be performed.
Five different anti-wear additives, suitable for the formulation of environmentally adapted hydraulic fluids were tested, both commercially available and newly developed. The used base fluid was a high performance saturated complex ester. The formulated fluids' performance was evaluated through the use of an assembled pin & vee block in a modified Falex wear tester according to wear and frictional behaviour. The combinations of tested materials were steel-steel and bronze-steel tribopairs. The friction, wear scar volume and visual appearance both inside and outside the wear scar were studied. Some of the tested combinations gave unwanted performance, such as high friction, large wear and etching damages, whereas others gave good performance. It was found that the new additives showed promising results for formulation of environmentally adapted lubricants based on saturated complex esters. Further investigations will look closer at the chemical composition of the formed tribofilms with the use of surface sensitive analysis technology.
The film formation capabilities of six environmentally adapted ester based fluids have been investigated using optical interferometry in a Ball and Disc apparatus. A mineral oil was used as a reference. The properties and molecular structure for the tested base fluids are well known from earlier investigations. The fluids were tested at three different slide/roll ratios of 0, 0.6, and 1.2. The film formation capability was compared to the molecular structure and other properties. It was found that some of the fluids maintain a superior lubricating film at high slide/roll ratios than others, because of their molecular properties. A high level of carboxylate groups in the ester molecule gives high thermal conductivity and heat capacity, which promotes heat transportation out of the contact and this also maintain separation
In order to further improve the performance and efficiency of automatic power-shift transmissions for heavyduty applications such as trucks and construction equipment, transmission fluid development is an important activity. There are several different approaches on how to design and lubricate power-shift transmissions. With the correct selection of lubricant extended drain in combination with increased efficiency will result in a reduction of life-cycle cost, and at the same time reduce the environmental impact of the vehicles. In this paper different transmission fluids, with a focus on ATFs, are presented together with some of their respective advantages and disadvantages. Fluid performance in several different areas such as shear stability, frictional performance and gear protection are presented. Also, industry trends in the ATF market regarding standards and product diversification are discussed from a global OEMs point of view, including information on Volvo's approach to transmission oil specifications.
Wear of starved oil-lubricated heavily loaded, oscillating journal bearings, which operates at low sliding speed and under dynamic load, was studied. These bearings were normally intermittently lubricated by grease or oil. No distinct difference in wear rate could be discerned between the CuSn12 reference and CuSn8Ni15 sample bushings. Since the oil flow and pressure were low, most of the oil escaped from the contact, resulting in metal-to-metal contact between pin and bushing, and yielding initial adhesive wear that quickly evolved into abrasive wear. Due to the relative high surface roughness and hardness of the pin, the system did not perform well as bearing. This is an abstract of a paper presented at the World Tribology Congress (Kyoto, Japan 9/6-11/209).