Next Issue
Volume 5, June
Previous Issue
Volume 4, December
 
 

Lubricants, Volume 5, Issue 1 (March 2017) – 8 articles

Cover Story (view full-size image): In sheet metal forming, problems with lubricant film breakdown and galling are significant issues. The present study elucidates the influence of trapped lubricant on a textured tool surface, which enables the substitution of hazardous lubricants by less harmful lubricants, thus preventing galling. The shallow, oblong pockets, perpendicular to the sliding direction with varying plateau width between them, were manufactured by milling of the hardened tools. The pockets were tested in a tribologically severe strip reduction test emulating the ironing of a deep drawn cup. By comparing measured drawing loads, an optimum tool texture was identified. Higher speeds and oil viscosity further enhanced the lubricant supply from the pockets. View the paper here.
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Select all
Export citation of selected articles as:
8544 KiB  
Article
Influence of Organo-Sulfur Compounds with Overbased Calcium Compounds on Lubrication in Cold Forming
by Tomohiro Takaki, Kazuhiro Yagishita, Teppei Tsujimoto and Toshiaki Wakabayashi
Lubricants 2017, 5(1), 8; https://doi.org/10.3390/lubricants5010008 - 16 Mar 2017
Cited by 2 | Viewed by 4739
Abstract
The authors analyzed the structures of sulfurized olefins using NMR spectroscopy and studied the effects of sulfur chain length and alkyl structure on the ironing performance. They found that branched chain olefins, which contain branched alkyl groups, show superior ironing performance to straight [...] Read more.
The authors analyzed the structures of sulfurized olefins using NMR spectroscopy and studied the effects of sulfur chain length and alkyl structure on the ironing performance. They found that branched chain olefins, which contain branched alkyl groups, show superior ironing performance to straight chain olefins, provided that their carbon numbers are relatively low. When the sulfurized olefins were used in combination with overbased detergents (calcium sulfonate or salicylate), they showed a higher performance in ironing than with sulfurized olefins alone. It was also found that lubricating films consisting of both iron sulfide and calcium carbonate seem to improve ironing performance. Full article
(This article belongs to the Special Issue Tribology in Manufacturing Process)
Show Figures

Figure 1

2020 KiB  
Article
Rotordynamic and Friction Loss Measurements on a High Speed Laval Rotor Supported by Floating Ring Bearings
by Rob Eling, Mathys Te Wierik, Ron Van Ostayen and Daniel Rixen
Lubricants 2017, 5(1), 7; https://doi.org/10.3390/lubricants5010007 - 15 Mar 2017
Cited by 5 | Viewed by 4966
Abstract
Floating ring bearings are the commonly used type of bearing for automotive turbochargers. The automotive industry continuously investigates how to reduce the bearing friction losses and how to create silent turbochargers. Many of these studies involve creating a numerical model of the rotor-bearing [...] Read more.
Floating ring bearings are the commonly used type of bearing for automotive turbochargers. The automotive industry continuously investigates how to reduce the bearing friction losses and how to create silent turbochargers. Many of these studies involve creating a numerical model of the rotor-bearing system and performing validation on a test bench on which a turbocharger is driven by hot gases. This approach, however, involves many uncertainties which diminish the validity of the measurement results. In this study, we present a test setup in which these uncertainties are minimized. The measurement results show the behavior of the floating ring bearing as a function of oil feed pressure, oil feed temperature, rotor unbalance and bearing clearances. Next to an increased validity, the test setup provides measurement data with good repeatability and can therefore represent a case study which can be used for validation of rotor-bearing models. Full article
(This article belongs to the Special Issue Bearings in Turbomachinery)
Show Figures

Figure 1

8543 KiB  
Article
The Effect of Non-Circular Bearing Shapes in Hydrodynamic Journal Bearings on the Vibration Behavior of Turbocharger Structures
by Lukas Bernhauser, Martin Heinisch, Markus Schörgenhumer and Manfred Nader
Lubricants 2017, 5(1), 6; https://doi.org/10.3390/lubricants5010006 - 03 Mar 2017
Cited by 14 | Viewed by 7016
Abstract
Increasing quality demands of combustion engines require, amongst others, improvements of the engine’s acoustics and all (sub)components mounted to the latter. A significant impact to the audible tonal noise spectrum results from the vibratory motions of fast-rotating turbocharger rotor systems in multiple hydrodynamic [...] Read more.
Increasing quality demands of combustion engines require, amongst others, improvements of the engine’s acoustics and all (sub)components mounted to the latter. A significant impact to the audible tonal noise spectrum results from the vibratory motions of fast-rotating turbocharger rotor systems in multiple hydrodynamic bearings such as floating bearing rings. Particularly, the study of self-excited non-linear vibrations of the rotor-bearing systems is crucial for the understanding, prevention or reduction of the noise and, consequently, for a sustainable engine acoustics development. This work presents an efficient modeling approach for the investigation, optimization, and design improvement of complex turbocharger rotors in hydrodynamic journal bearings, including floating bearing rings with circular and non-circular bearing geometries. The capability of tonal non-synchronous vibration prevention using non-circular bearing shapes is demonstrated with dynamic run-up simulations of the presented model. These findings and the performance of our model are compared and validated with results of a classical Laval/Jeffcott rotor-bearing model and a specific turbocharger model found in the literature. It is shown that the presented simulation method yields fast and accurate results and furthermore, that non-circular bearing shapes are an effective measure to reduce or even prevent self-excited tonal noise. Full article
(This article belongs to the Special Issue Bearings in Turbomachinery)
Show Figures

Figure 1

1592 KiB  
Review
Progress in Tribological Properties of Nano-Composite Hard Coatings under Water Lubrication
by Qianzhi Wang and Fei Zhou
Lubricants 2017, 5(1), 5; https://doi.org/10.3390/lubricants5010005 - 17 Feb 2017
Cited by 18 | Viewed by 6495
Abstract
The tribological properties, under water-lubricated conditions, of three major nano-composite coatings, i.e., diamond-like carbon (DLC or a-C), amorphous carbon nitride (a-CNx) and transition metallic nitride-based (TiN-based, CrN-based), coatings are reviewed. The influences of microstructure (composition and architecture) and test conditions (counterparts and friction [...] Read more.
The tribological properties, under water-lubricated conditions, of three major nano-composite coatings, i.e., diamond-like carbon (DLC or a-C), amorphous carbon nitride (a-CNx) and transition metallic nitride-based (TiN-based, CrN-based), coatings are reviewed. The influences of microstructure (composition and architecture) and test conditions (counterparts and friction parameters) on their friction and wear behavior under water lubrication are systematically elucidated. In general, DLC and a-CNx coatings exhibit superior tribological performance under water lubrication due to the formation of the hydrophilic group and the lubricating layer with low shear strength, respectively. In contrast, TiN-based and CrN-based coatings present relatively poor tribological performance in pure water, but are expected to present promising applications in sea water because of their good corrosion resistance. No matter what kind of coatings, an appropriate selection of counterpart materials would make their water-lubricated tribological properties more prominent. Currently, Si-based materials are deemed as beneficial counterparts under water lubrication due to the formation of silica gel originating from the hydration of Si. In the meantime, the tribological properties of nano-composite coatings in water could be enhanced at appropriate normal load and sliding velocity due to mixed or hydrodynamic lubrication. At the end of this article, the main research that is now being developed concerning the development of nano-composite coatings under water lubrication is described synthetically. Full article
(This article belongs to the Special Issue Green Tribology)
Show Figures

Figure 1

163 KiB  
Editorial
Editorial: Friction and Lubricants Related to Human Bodies
by Ille C. Gebeshuber and George Van Aken
Lubricants 2017, 5(1), 4; https://doi.org/10.3390/lubricants5010004 - 13 Feb 2017
Cited by 4 | Viewed by 4336
Abstract
Biolubrication plays a crucial role in assisting the sliding contacts in many organs in the human body.[...] Full article
(This article belongs to the Special Issue Friction and Lubricants Related to Human Bodies)
10449 KiB  
Article
The Influence of Tool Texture on Friction and Lubrication in Strip Reduction Testing
by Mohd Hafis Sulaiman, Peter Christiansen and Niels Bay
Lubricants 2017, 5(1), 3; https://doi.org/10.3390/lubricants5010003 - 17 Jan 2017
Cited by 19 | Viewed by 5722
Abstract
While texturing of workpiece surfaces to promote lubrication in metal forming has been applied for several decades, tool surface texturing is rather new. In the present paper, tool texturing is studied as a method to prevent galling. A strip reduction test was conducted [...] Read more.
While texturing of workpiece surfaces to promote lubrication in metal forming has been applied for several decades, tool surface texturing is rather new. In the present paper, tool texturing is studied as a method to prevent galling. A strip reduction test was conducted with tools provided with shallow, longitudinal pockets oriented perpendicular to the sliding direction. The pockets had small angles to the workpiece surface and the distance between them were varied. The experiments reveal that the distance between pockets should be larger than the pocket width, thereby creating a topography similar to flat table mountains to avoid mechanical interlocking in the valleys; otherwise, an increase in drawing load and pick-up on the tools are observed. The textured tool surface lowers friction and improves lubrication performance, provided that the distance between pockets is 2–4 times larger than the pocket width. Larger drawing speed facilitates escape of the entrapped lubricant in the pockets. Testing with low-to-medium viscosity oils leads to a low sheet roughness on the plateaus, but also local workpiece material pick-up on the tool plateaus. Large lubricant viscosity results in higher sheet plateau roughness, but also prevents pick-up and galling. Full article
(This article belongs to the Special Issue Tribology in Manufacturing Process)
Show Figures

Graphical abstract

281 KiB  
Editorial
Acknowledgement to Reviewers of Lubricants in 2016
by Lubricants Editorial Office
Lubricants 2017, 5(1), 2; https://doi.org/10.3390/lubricants5010002 - 10 Jan 2017
Cited by 23 | Viewed by 2590
Abstract
The editors of Lubricants would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...] Full article
4940 KiB  
Article
Surface Film Adsorption and Lubricity of Soybean Oil In-Water Emulsion and Triblock Copolymer Aqueous Solution: A Comparative Study
by Reza Taheri, Buyung Kosasih, Hongtao Zhu and Anh Kiet Tieu
Lubricants 2017, 5(1), 1; https://doi.org/10.3390/lubricants5010001 - 30 Dec 2016
Cited by 8 | Viewed by 5637
Abstract
This paper investigates the surface film adsorption and lubricity of two different types of potential environmentally friendly cold metal forming lubricants: soybean vegetable oil in water VO/W emulsions and triblock copolymer aqueous solutions. The lubricants have different visual appearance, surface film adsorption characteristic, [...] Read more.
This paper investigates the surface film adsorption and lubricity of two different types of potential environmentally friendly cold metal forming lubricants: soybean vegetable oil in water VO/W emulsions and triblock copolymer aqueous solutions. The lubricants have different visual appearance, surface film adsorption characteristic, lubricity and surface cleaning behaviour. The effects of concentration, temperature and emulsification ultrasonic energy (for VO/W emulsion) are studied. The result shows that the soybean VO/W emulsions have stronger adsorption, superior lubricity and anti-wear property compared to the copolymer solutions. The effect of temperature is investigated at 30 °C and 65 °C which are below and above cloud point of the aqueous copolymer solutions. Both lubricants show improved friction and anti-wear property at 65 °C. However, tenacious residual film remained on the discs surface after surface cleaning indicates lower cleanability of the soybean VO/W emulsions compared to the copolymer solutions, postulating the need for extra post-processing cleaning operations after cold forming process with VO/W emulsion lubricant. Full article
(This article belongs to the Special Issue Green Tribology)
Show Figures

Figure 1

Previous Issue
Next Issue
Back to TopTop