condition. Furthermore, grease pipe work did not need to be replaced. Grease within the bearing housings also remained mobile, significantly reducing maintenance time after the cooling water failure.
Pictures of a used bearing running in normal conditions, and one subjected to extreme heat, are shown below (Pictures 3, 4). Discolouration of the brass cage can clearly be seen on the heated bearing, but all roller elements remained free to rotate and clearances were measured and found to be within tolerances defined by the end user.
No scoring marks could be seen on the bearing elements, and the grease did not form hard deposits.
Even when considering a 25% life extension, when bearings cost in excess of €500 each the saving in spare parts alone is significant, but the end user is confident that bearing life can be extended even further. This will be confirmed after the next 12 month maintenance period.
No staining or corrosion was visible in any of the bearings inspected during the maintenance period, indicating that the grease performs extremely well in being able to resist corrosion from the process water.
Final conclusion
Key parameters selected to prove the capabilities of the product were high temperature performance, load carrying capability, performance in wet environments and extended component life.
Taking the performance of greases with a similar technology platform, an initial specification was shaped to benchmark a new development product, targeting high load performance, water resistance, corrosion prevention and mechanical stability (also in the presence of process water).
A continuous caster was selected for a field trial. This application is well known to be a critical area requiring high performance in lubrication to avoid costly breakdowns and increased maintenance.
After the 12 month trial period using Molub Alloy 6080, the performance was evaluated with the end user and the following benefits were observed:
• Grease consumption reduced by 47.62% compared to the previous product
• Grease still appears to have the same consistency as the new product
• No signs of corrosion or surface staining Picture 3 Bearing subjected to heat. • Bearing tolerances remained within specification
• Bearing life extended from three to four years, most likely longer
In addition to the points listed above, the grease did not block pipe work when subjected to extreme heat, giving the added advantage of minimising associated maintenance work.
Acknowledgements
The authors would like to thank Luis Blazquez, Soman Dhar and the customer for the valued contribution to the product field testing.
References 1. C. White, Lubrication, Vol. 77, Nr 1, 1991 2. NLGI Lubricating Grease Guide, Second Edition, 1989 3. A.E. Cichelli, Evaluation of Greases For Steel Mill Service, NLGI Spokesman, August 1973
4. A.E. Cichelli, Grease Lubrication in Steel Mills with Emphasis on Roll Neck Bearings, NLGI Spokesman, April 1980
5. J. Schlobohm Sr., H. Faci, B. Cisler, Steel Mill Greases: Evaluation and Analysis, presented at the 71st NLGI annual meeting, Dana Point, CA, 2004
Picture 4 Standard bearing. Bearing Life:
A selection of bearings were inspected jointly with the end user, and the remainder were inspected by the end user’s maintenance team. All bearings were found to be within a specified tolerance and deemed suitable for further use. Historically, bearings have been replaced every three years as a preventive measure to avoid unplanned downtime. Bearings reaching three year life were also found to be suitable for further use, minimizing bearing replacement costs across the whole of the caster installation. It is fully expected that these three year old bearings will not require replacing during the next 12 monthly maintenance period.
6. Gareth Fish, William C. Ward, Calcium Sulfonate Answers to Water Issues, presented at the ELGI 25th Annual Meeting, Amsterdam, April 20-23, 2013
7. David Autier and al. Calcium Sulfonate Greases. A solution to Water Resistance, presented at the ELGI 25th Annual Meeting, Amsterdam, April 20-23, 2013
8. Johan Leckner, Water + Grease: Fatal Attraction, presented at the ELGI 25th Annual Meeting, Amsterdam, April 22-23, 2013
9. Hocine Faci, John Haspert, Effect of Water on Grease Performance and Lubrication for life in sealed bearings, presented at the NLGI 80th Annual Meeting, Tucson, AZ, June 15-18, 2013
LINK
www.castrol.com
LUBE MAGAZINE NO.123 OCTOBER 2014
11
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65
