| 1. |
- Björling, Marcus, et al.
(author)
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EHL friction mapping : the influence of lubricant, roughness, speed and slide to roll ratio
- 2010
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In: 14th Nordic Symposium on Tribology. - Luleå : Luleå tekniska universitet. - 9789174391244
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Conference paper (peer-reviewed)abstract
- A friction test is conducted in a WAM ball on disc test rig. The output from the test is friction coefficient versus entrainment speed and slide-to-roll ratio presented as a 3D friction map. A number of parameters are varied while studying the friction coefficient; surface roughness, base oil viscosity and EP additive package. Entrainment speed, slide to roll ratio and oil temperature are also varied. The results show that the mapping is efficient in showing the different types of friction that may occur in an EHL contact. The results also show that the friction behaviour can be strongly influenced by changing surface roughness as well as base oil viscosity, EP additive content and operating temperature.
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| 2. |
- Björling, Marcus, et al.
(author)
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Elastohydrodynamic lubrication friction mapping : The influence of lubricant, roughness, speed, and slide-to-roll ratio
- 2011
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In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - : SAGE Publications. - 1350-6501 .- 2041-305X. ; 225:7, s. 671-681
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Journal article (peer-reviewed)abstract
- A friction test is conducted in a Wedeven Associates Machine ball-on-disc test rig. The output from the test, friction coefficient versus entrainment speed and slide-to-roll ratio (SRR), is presented as a three-dimensional friction map. A number of parameters are varied while studying the friction coefficient; surface roughness, base oil viscosity, base oil type, and extreme pressure (EP) additive package. Entrainment speed, SRR, and oil temperature are also varied. The results show that the mapping is efficient in showing the different types of friction that may occur in an elasto-hydrodynamic lubrication contact. The results also show that the friction behaviour can be strongly influenced by changing surface roughness as well as base oil viscosity, base oil type, EP additive content, and operating temperature.
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| 3. |
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| 4. |
- Del Din, Massimo, et al.
(author)
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Wear characteristics with mixed lubrication conditions in a full scale journal bearing
- 1999
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In: Wear. - 0043-1648 .- 1873-2577. ; 232:2, s. 192-198
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Journal article (peer-reviewed)abstract
- Increased awareness of environmental problems has stressed the importance of switching from traditional lubricants to more environmentally friendly alternatives. Different investigations with standard test methods indicate that such a switch is possible without loss of lubricating power. The question arises if the statement above is true for industrial lubricating conditions, without laboratory cleanliness. This paper presents a study of friction and wear in a two grooved journal bearing at different shaft speeds, oil temperatures and contamination levels. A number of tests have been conducted combined with a theoretical analysis of film thickness and lubricating regime. The aim was to investigate whether an environmentally adapted rape seed-synthetic ester oil could replace a traditional mineral oil in a full scale application. The results show that the rape seed-synthetic ester oil gives significantly lower values of wear regardless of the operating conditions and there is also a tendency of lower values of frictional torque compared with the mineral oil. Mainly operating in the mixed lubrication regime, no signs of impending bearing failure have been registered, even though a large amount of silica particles added to the oil gave higher wear values than with uncontaminated oil.
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| 5. |
- Gren, Per, et al.
(author)
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Feasibility of using digital speckle correlation in the study of seal contacts
- 2009
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In: Lubrication Science. - : Wiley. - 0954-0075 .- 1557-6833. ; 21:4, s. 123-134
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Journal article (peer-reviewed)abstract
- This paper presents studies of the contact between a soft rubber specimen and glass counterface using the Digital Speckle Correlation method, which provides information of displacements and structural similarities between recorded images. The setup is designed with a real contact and changes in the contact can be varied. Microscopic images using laser light illumination for different displacements are recorded and correlated. The results show that the contact area can be identified both for dry and lubricated contacts. The method can be applied on different geometries, surface roughness and lubricants. Influences of scars and contaminations, e.g. wear particles, may also be analysed.
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| 6. |
- Hardell, Jens, et al.
(author)
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Friction and wear behaviour of high strength boron steel at elevated temperatures of up to 800 °C
- 2008
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In: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 264:9/10, s. 788-799
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Journal article (peer-reviewed)abstract
- There has been a growing usage of high strength steels, particularly in automobile applications mainly as structural parts in view of their light weight and high strength properties. These materials are also being considered for dynamic applications. However, the understanding of their tribological behaviour vis-a-vis their hot forming and also as tribological materials is highly inadequate. The present work thus aims at creating new knowledge about the tribological characteristics of high strength steels and bridging this existing gap. High temperature tribological studies on different tool steels (with and without surface treatment) sliding against high strength boron steel (with and without coating) and studies on self-mated hardened high strength boron steel under dry reciprocating sliding conditions have been conducted. High temperature tribological studies keeping in view the hot metal forming aspects were conducted by using an SRV machine whereas a two-disc machine was employed for investigating their fundamental friction and wear behaviour. The results from the high temperature studies indicate that the friction is dependent on temperature since a reduced friction level was observed with increasing temperature. The wear of the tool steels increased with increasing temperature and nitriding of the tool steels provided better protection against severe wear. The results from the study on self-mated hardened high strength boron steel showed that sliding speed has a marginal effect on friction whereas the effect of contact pressure is more pronounced (decreasing friction with increased contact pressure). The specific wear rate decreased with increased sliding speed.
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