New formulations of sunflower based bio-lubricants with high oleic acid content – VOSOLUB project

VOSOLUB project is a demonstration project supported by Executive Agency for Small and Mediumsized Enterprises (EASME) that aims at testing under real operating conditions new formulations of sunflower-based biolubricants with high oleic acid content. These biolubricant formulations (including hydraulic fluids, greases, and neat oil metal-working fluids) will be tested in three European demonstrating sites. Their technical performance will be evaluated and compared to corresponding mineral lubricants ones. In order to cover the demand for the sunflower base oil, a European SMEs network will be established to ensure the supply of the base at a competitive market price. Results presented concerns the base oil quality confirmed to be in accordance with the specification required, in particular on Free Fatty acid content, Phosphorus content, rancimat induction time and oleic acid content (ITERG). The oil characteristics specific for lubricant application analyzed by BfB Oil Research under normalized methods, match with lubricant specifications requirement such as viscosity, cold & hot properties, surface properties, anti-oxidant properties and thermal stability, anti-wear and EP properties, anti-corrosion properties Performance of the new biolubricant have been assessed by formulators and TEKNIKER First results on the use of new lubricant on real condition for rail Grease (produced by RS CLARE and tested with Sheffield Supertram), Hydraulic oil (produced by BRUGAROLAS) and cutting oil (produced by MOTUL TECH and tested with innovative machining, turning) are described.


Introduction
In the lubricant sector, like in other sectors, there is a growing need to provide more eco-friendly products such as biolubricants.The VOSOLUB project is a demonstration project that aims at testing under real operating conditions new formulations of sunflower-based biolubricants with high oleic acid content.These biolubricant formulations (including hydraulic fluids, greases, and neat oil metal-working fluids) will be tested in three field tests in real conditions of use.Their technical performance and environmental impacts will be evaluated and compared to corresponding mineral lubricants ones.In order to cover the demand for the sunflower base oil, a European SMEs network will be established to ensure the supply of the base at a competitive market price.
The formulations that will be evaluated have been previously developed in the framework of the FP6 IBIOLAB project using base oils derived from a mild refining process for raw materials developed by the project partner ITERG and from new varieties of vegetable oils with higher oxidative stability.The new process coupled with the use of new varieties of vegetable oil enabled to decrease the overall cost and to increase the technical performance of the bio-lubricants.The developed formulations were very promising some of which could be eco-labelled.
This paper presents analytical results on based oil in relation with lubricant specifications requirement and performance tests results on the three targeted application.

Very high oleic sunflower oil (VHOSO) production and Lubricant formulation
Harvest of sunflower seeds have been done by ARTERRIS, Agricola cooperative from the south of France in late September 2012.Harvest has been done in good condition, impurity level and yields were normal.25 T of seeds with 87% of oleic acid minimum content have been identified and traceability has been controlled until delivery to crushed plant.
Crushing has been carried out in middle of October 2012 by MEDIACO located in SETE south of France.Crushing has been done in classical conditions and quality of crude oil was in compliance with classical requirements.15T of crude oil have been produced and sent to PROVENCE HUILES (Vitrolles France) for refining in November 2012.
Refining of crude oil has been done under conditions predefined for a "soft refining".This kind of refining is different from a classical refining (for food application) in which operational conditions are adapted for lubricant application and allow (i) to save energy (due to lowest temperature during deodorization); (ii) to minimize production of by product (deodistillate); and (iii) to minimize loss of natural antioxidant (tocopherol) which have interest for lubricant application.
Process conditions for soft refining used by Provence Huiles were classical neutralization, bleaching 90/100 • C during 30 mn, deodorisation at160 • C during 2 h following by nitrogen inerting before packaging in drums.
Due to industrial constraints (continuous process 24 h/24 h), it was not possible to refine crude oil dedicated to lubrication application in one batch.So 15 tons of "VOSOLUB crude oil" have been injected in on refining run.In order to be sure that the oleic acid content was superior to 87%, monitoring of oleic content have been done during the process for assessment.VHOSO had followed continuously classical neutralised used for sunflower oil.When oil getting out of the neutralizer had 87% of oleic acid content, neutralized oil have been stored in a special tank for feeding the bleacher.The same process has been used for feeding the deodorizer.This procedure that can be reproduced in the future to provide higher quantity of VHOSO allows to guarantee a content of oleic acid superior to 87% that has been confirmed by analytical control on soft refining oil.

Cutting fluids performance tests -turning tests
on a real CNC machine (Fig. 1) Tests have been performed in a CNC CMZ lathe TL 15 M 8 (5000 rpm, 14 kW) using a conventional flooding system that impulses the cutting fluid at a conventional pressure with a volume of 40 l/min.Two cutting fluids have been analyzed, the reference mineral (SUPRACO 4018) and the new developed VHOSO based fluid (FIEC 13024).Both cutting oils have been used in pure conditions without emulsifying and have been projected to the cutting zone with and angle of 20 degrees through the conventional piping system.
The material used to perform the machining tests was: Alloy steel AISI4340 (DIN 40NiCrMo7) (quenching and tempering to 31HRc) bars of diameter 110 mm and length 260 mm supplied by IMS group.Concerning the cutting tools, CNMG 120408 LP UE6110 inserts from Mitsubishi with a CVD coated Grade for steel have been used.
The cutting conditions have been selected taking into account mainly some extreme conditions in this interval in order to look for a significant wear during a machining operation of about 20 min and a moderate consumption of machining material.Workpiece surface quality.Roughness (Ra) obtained by portable perfilometer Mitutoyo SJ-201 every 1 or 2 cuts.

Ball-on disc abrasion tests (rotational motion)
"Ball on disc" tests have been made to study the basic tribological properties of the reference mineral fluid (BESLUX HIDRO HV-46) and new developed bio hydraulic Fluid (BESLUX HIDRO ECO-46) under rotational movement.A standard Falex multispecimen tribometer has been used for that purpose.In this test a ceramic ball rotates against a fixed steel disc.The friction coefficient and wear are recorded during the test.By means of this test, the capacity of the test to avoid the abrasion can be evaluated.

FZG Scuffing test (DIN 51354-1/2)
The load capacity of the developed hydraulic fluid has been analyzed with the FZG equipment (see Fig. 2a) according to the DIN 51354-1/2.In this test special gear wheels (Fig. 2b) are run in the lubricant under test, at a constant speed for a fixed time, in a dip lubrication system.Loading of the gear teeth is raised in stages.After load stage 4 the pinion gear teeth flanks are inspected for damage and any changes in tooth appearance are noted.

Grease application performance tests-wheel/rail simulation tests
The simulation wheel/rail tests have been performed in the Twin disc tribometer, using the Twin disc configuration" see Figure 3.It is a test configuration widely used by different research groups in this field, because it is possible to simulate in a simple way the wheel/rail contact.The test consists basically on two small wheels or discs in contact that rotates independently at a fixed angular speed with the defined contact pressure.The test samples have been cut directly from the real wheel and rail.
The testing conditions have been set up, according to the train manufacturer supplied data, trying to simulate the real working conditions.The tests have been performed into two steps, during the first 8 h the testing samples (Wheel and rail) have been submitted to a pressure of 1.3 GPa.After evaluation of the wear occurred during the first step, the same wheel and rail samples have been submitted to a second test of 8 h increasing the pressure to 1.8 GPa and maintaining the rest of testing parameters.

Base oil quality
The oil characteristics specific for lubricant application have been analyzed by Bfb (http://www.iespm.com/bfblab/bfblab/index.html)under normalized methods.As illustrated  by Table 1, Results match with lubricant specifications requirement such as viscosity, cold & hot properties, surface properties, anti-oxidant properties and thermal stability, anti-wear and EP properties, and anti-corrosion properties.

Cutting fluids performance test results -turning tests
The results concerning tool flank wear and workpiece roughness are illustrated in Figure 4; the tests have been performed under two different conditions with a the depth of cut of 0.3 mm (on the left) and depth cut of 0.5 mm (on the right).At least two repetitions have been performed with each oil, the reference cutting oil SUPRACO 4018 and the new developed oil FIEC 13024.In Figure 4, the approximate medium values in both cases are showed.
Figure 5 collects the pictures of an example of flank wear after every two cuts with the different inserts tested under both machining tests and with both comparative oils.
From these tests it can be concluded that the Turning tests under 2 different cutting conditions with the two studied cutting oils have offered similar results concerning tool wear, which is the main aspect to take into account regarding the general machining performance.Regarding the workpiece roughness, also similar results have been obtained in the case of depth: 0.3 mm and some small variations in the case of depth: 0.5 mm, where the piece is supporting more aggressive cutting conditions; but this difference could be assumed within the scatter range generally associated with this kind of machining tests.

Ball on disc abrasion tests (rotational motion)
The ball-on disc abrasion tests results are summarized in Figure 6: the graphic on the left presents the friction coefficient of the tested fluids versus time and in the table of the right the average wear of the disc and ball are represented.The aspect of the wear scar obtained with each fluid can be seen in Figure 7.
It can be concluded that under the selected testing conditions the new developed hydraulic fluid BESLUX HIDRO-ECO-46 has better behavior than the reference mineral based hydraulic fluid BESLUX HIDRO-ECO-46.
It can be concluded that the BELSUX HIDRO-ECO 46 oil has reached the maximum load stage defined in DIN ISO 14635-1 without scuffing failure appearance.

Grease performance test results
In Figures 8 and 9 summarized the test results obtained.In Figure 8 it can be seen that the friction coefficient obtained with the VOSOLUB grease is much lower that the COF obtained with the reference mineral grease.It must be underlined that under test 2 conditions (2000 N) the tests has been stopped before finishing, the high presence of pitting has produced great vibrations on the system.
In Figure 9 the wear suffered by the rail and the wheel can be observed.During the first test the wheel and the rail suffer an initial wear mechanism of surface polishing.But when increasing the load, a fatigue phenomena appears, which translates into the pitting and micro-pitting suffered by the samples.The wear track obtained in the wheel when testing with    the reference XP 788 grease is deeper than the wear track obtained with the developed VOSOLUB grease.In both wheels also some micropitting is observed.
Concerning the rail, when testing with the VOSOLUB grease, it suffers some micripitting throughout all the rail.In addition this rail also presents 1 pitting failure.On the other hand, the rail tested with the reference XP788 grease suffers important pitting throughout all the rail.
-The friction coefficient of the new developed VOSOLUB grease is much lower than the friction coefficient obtained with the reference grease.Not great differences have been observed in the friction coefficient in the different testing conditions.-Concerning the wear, the XP788 grease suffers higher wear than the new developed grease in terms of mass loss, and also suffer much more pitting and micropitting.
-It can be concluded that under the selected testing conditions new developed VOSOLUB grease has better behavior than the reference mineral XP788 grease.

Conclusion
Based refining VHOSO oil used for biolubricant formulation match specification required.Results on performance tests done on the three targeted applications comply with requirement expected by the formulators.On this base, "field tests" on real condition have been carried out by formulator to assess technical and marketing aspect of "VOSOLUB biolubricant".On the same time developments to obtain Ecolabel are in progress.First results of "field tests" currently in progress are very encouraging and conditions for a successful market uptake of innovative biolubricant are there.
-MOTUL TECH (France): Biobased products with high and long-term performances and a safe HS profile for cutting oil Application.-BRUGAROLAS (Spain): Biobased hydraulic fluid, potentially ecolabelisated, with high performing properties, ecologically safe in case of incidental release to the environment.-Rs CLARE (UK): Ecologically safe, biodegradable lubricant for a Curve side-of-rail lubricant application that has total loss to the environment, while maintaining existing performance levels.

Table 1 .
Analytical results on main specification requirement on based VHOSO oil.