| 1. |
- Grguraš, Damir, et al.
(författare)
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A novel cryogenic machining concept based on a lubricated liquid carbon dioxide
- 2019
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Ingår i: International Journal of Machine Tools and Manufacture. - : Elsevier BV. - 0890-6955. ; 145
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Tidskriftsartikel (refereegranskat)abstract
- A novel single-channel supply of pre-mixed (a) liquid carbon dioxide (LCO2) and (b) oil – delivered via minimum quantity lubrication (MQL) – represents a significant advancement in cryogenic-machining technology. In this proof-of-concept study, an attempt is made to advance the understanding of the oil solubility in LCO2 and to analyze the oil-droplets and their impact on machining performance. The results indicate that the physical and chemical properties of oil distinctively affect its solubility in LCO2. The achieved solubility further influences the achievable oil-droplet size and distribution and tool life.
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| 2. |
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| 3. |
- Krajnik, Peter, et al.
(författare)
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Transitioning to sustainable production - part III : developments and possibilities for integration of nanotechnology into material processing technologies
- 2016
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Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 112, s. 1156-1164
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Tidskriftsartikel (refereegranskat)abstract
- A nanoparticle-based cooling-lubricating fluid (nCLF), designed and fabricated by suspending engineered nanoparticles (ENPs) in biodegradable vegetable-based fluids, has been developed for integration into material processing technologies. This new product exhibits tribological properties superior to those of conventional metalworking fluids. The major innovation is the ability to create a stable nCLF through the modification of ENP surfaces. Functionalized MoS2 nanotube ENPs were successful used as low friction additives. The experimental work, required for the proof-of-concept and technology validation, was carried out on three different levels to quantify the improved tribological behavior of nCLF. These experiments include standard tribological tests, mock-up tests to simulate machining, and actual machining tests. It is demonstrated that the specific properties of ENPs, fluid design and composition, as well as specific lubrication mechanisms, exhibit superior performance of nCLF in terms of friction and wear. The objective of this paper is to demonstrate how recent nanotechnology developments support innovation needed for transitioning to sustainable production via new product development and integrated industrial applications.
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| 4. |
- Martinovic, Milan, et al.
(författare)
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A lubrication and cooling device and a method for lubricating and cooling a work piece
- 2016
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The invention relates to a lubrication and cooling device(1), comprising;a cooling fluid device(3), which comprises a first channel (5), which is connected to a first inlet port (7), and a lubricant fluid device (9), which comprises a second channel (11), which is connected to a second inlet port (13). The lubrication and cooling device (1) further comprises a heat exchanger (15), which comprises a cooling circuit (17) and a lubricant delivery circuit (19). The heat exchanger (15) is arranged to cool the lubricant fluid (24) by means of the cooling fluid (22), wherein the cooling fluid is a cryogenic fluid. The invention further relates to a method for lubricating and cooling a workpiece or a process by using a lubrication and cooling device (1), wherein the method comprises the steps of: a) cooling the lubricant fluid (24 by means of the cooling fluid (22) using the heat exchanger (15), and b) providing the cooled lubricant fluid (24) to the workpiece or process being lubricated and cooled.
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| 5. |
- Martinovic, Milan, et al.
(författare)
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Lubrication and cooling device and a method for lubricating and cooling a workpiece
- 2018
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The disclosure relates to a lubrication and cooling device (1), comprising; a cooling fluid device (3), which comprises a first channel (5), which is connected to a first inlet port (7), and a lubricant fluid device (9), which comprises a second channel (11), which is connected to a second inlet port (13). The lubrication and cooling device (1) further comprises a heat exchanger (15), which comprises a cooling circuit (17) and a lubricant delivery circuit (19). The heat exchanger (15) is arranged to cool the lubricant fluid (24) by means of the cooling fluid (22), wherein the cooling fluid is a cryogenic fluid. The disclosure further relates to a method for lubricating and cooling a workpiece or a process by using a lubrication and cooling device (1), wherein the method comprises the steps of: a) cooling the lubricant fluid (24) by means of the cooling fluid (22) using the heat exchanger (15), and b) providing the cooled lubricant fluid (24) to the workpiece or process being lubricated and cooled.
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| 6. |
- Mihic, Stefan, et al.
(författare)
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The use of computational fluid dynamics in the analysis of fluid flow and thermal aspects in grinding
- 2017
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture. - : SAGE Publications. - 0954-4054 .- 2041-2975. ; 231:12, s. 2103-2111
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Tidskriftsartikel (refereegranskat)abstract
- A numerical model based on computational fluid dynamics is developed to analyze fluid flow and thermal aspects in grinding. The model uses multiphase fluid flow with heat transfer based on the volume-of-fluid method, convection, conduction in solids and a multiple reference frame model of the porous grinding zone. Fluid velocity vectors, useful flow rate, grinding temperatures and energy partition are predicted using the model. In lieu of direct measurements of these quantities, the verification relies on the indirect assessment of surface integrity. The simulation results provide adequate agreement with the measured residual stress, depth of heat-affected zone and full width at half maximum profile with respect to the grinding temperatures.
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| 7. |
- Pusavec, Franci, et al.
(författare)
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Cooling capability of liquid nitrogen and carbon dioxide in cryogenic milling
- 2019
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Ingår i: CIRP Annals - Manufacturing Technology. - : Elsevier BV. - 1726-0604 .- 0007-8506. ; 68:1, s. 73-76
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses an investigation into the capability of liquid nitrogen (LN 2 ) and liquid carbon dioxide (LCO 2 ) as a coolant in machining. A comparative analysis of the heat-transfer rate was made utilizing cooling of a controlled heat source with an integrated temperature sensor. The analysis was coupled with experimental in-process temperature measurements in cryogenic milling of titanium alloy Ti-6Al-4V (ß). The results indicate that cooling capability differs between these two cryogenic media, in both the observed cooling rate as well as in the achieved steady-state temperature.
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| 8. |
- Pusavec, Franci, et al.
(författare)
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Cryogenic machining and cooling capabilities when applying liquefied nitrogen to the machining zone
- 2016
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Ingår i: 19th International Symposium on Advances in Abrasive Technology, ISAAT 2016; Stockholm; Sweden. ; , s. 257-263
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Konferensbidrag (refereegranskat)abstract
- This paper presents the influence of nitrogen fluid phase on surface heat transfer coefficient in cryogenic machining. A novel optical nitrogen phase sensor is presented for characterizing the cryogenic fluid phase. Surface heat transfer coefficient was established experimentally, with the support of a new heat transfer model for cryogenic machining. Finite element models are developed with experimental data for Inconel 718, simulating the process behavior with varying nitrogen phases. Desired fluid phase at the delivery is found to be the key for achieving truly sustainable cryogenic machining.
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| 9. |
- Pusavec, Franci, et al.
(författare)
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Residual Stresses, Plastic Work, and Microhardness in Cryogenic Machining of Inconel 718
- 2011
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Ingår i: 4th International Swedish Production Symposium. - Lund : Swedish Production Academy. ; , s. 283-288
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Konferensbidrag (refereegranskat)abstract
- In machining of superalloys, a major quality performance characteristic refers to the integrity of the machined surface. In this consideration, the paper deals with a comparative evaluation of surface integrity in dry, minimum quantity lubrication (MQL), and cryogenic turning of Inconel 718. The comparison is concerned with residual stresses, plastic work, and microhardness developed under these different cooling lubrication conditions. The residual stresses generated on the workpiece surface were more tensile in the tangential (hoop) direction than in the axial direction. On the other hand, larger compressive stresses beneath the surface were observed in the axial direction. We have clearly observed that cryogenic machining resulted in higher compressive residual stresses when compared with dry or MQL machining. In addition, cryogenic machining yielded a thicker compressive zone of material beneath the machined surface. The correlation between residual stresses and plastic work suggested that the effects of mechanical loads, in comparison with thermal effects, were minor. It was further shown that the highest machined surface hardness was related to cryogenic cooling lubrication. In contrast to the microhardness variation, no drastic change in microstructure was observed. Moreover, no significant correlation between thermally induced phase transformation in a machined surface layer and microhardness was established.
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| 10. |
- Pusavec, Franci, et al.
(författare)
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Tribology of solid-lubricated liquid carbon dioxide assisted machining
- 2020
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Ingår i: CIRP Annals - Manufacturing Technology. - : Elsevier BV. - 1726-0604 .- 0007-8506. ; 69:1, s. 69-72
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Tidskriftsartikel (refereegranskat)abstract
- An investigation is made into the lubrication capabilities of solid-lubricated liquid carbon dioxide (LCO2) in comparison to flood lubrication, straight LCO2 and oil-lubricated LCO2 (MQL). The coefficient of friction is determined via tribological experiments, similar to machining, using an open tribometer which features an uncoated carbide insert sliding against a workpiece. Tribological experiments reveal superior performance of solid-lubricated LCO2. The milling experiments as well indicate that solid-lubricated LCO2 significantly reduces wear. The machined-surface topography is examined using high-magnification SEM, which shows no presence of adhered solid particles on the workpiece surface, providing a completely dry machining process.
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