Steel Mill Lubrication:
Boosting the Grease Performance For Longer Bearing Service Life Hocine Faci Philip Booker Martin Maass Marcus Totten Abstract
Calcium Sulfonate Grease has been in use in the steel mill industry for more than 15 years. Its success in these applications is mainly due to a set of performances associated with the thickening material itself, which provides a decent carrying capacity and wear protection, good water resistance, corrosion resistance and thermal stability. Experience has demonstrated however that this technology as currently offered, does not meet the totality of the end users expectations, namely on load carrying capacity, thermal stability and mobility, crucial properties for long service life of the bearings. The objective of this project was to build on the existing technology of Calcium Sulfonate greases, a more robust product that would boost the load carrying capacity / antiwar properties to higher levels, while keeping the current corrosion inhibition, water resistance, thermal stability, and grease mobility at least at the current level of performance, if not better. An extensive benchmarking program that involved over 9 different commercially available products has been conducted in the laboratory testing phase where more simulative tests have been performed. This work has led to the development of a product that has met all the specification requirements. The load carrying capacity has been improved as well as the wear protection, the water resistance (under both the sprayoff and washout test conditions), and mechanical stability in the presence of various still mill process waters. Since undergoing trial in a steel mill caster section, this product has shown great mobility, outstanding
Castrol Industrial
thermo-oxidation stability, excellent mechanical stability, excellent grease coverage of the bearing, and more importantly all these benefits were achieved with lower grease consumption. The service life of the bearing was extended from 3 to 4 years, and could be extended further. The detailed work will be compiled in this paper.
Introduction
Prior to the introduction of continuous casting in the 1940/1950s, steel was poured in individual molds to form ingots. Since then, the steel manufacturing has improved drastically. Continuous casting became the process of choice in steel, aluminium and copper industry. Within the steelmaking process, the steel is cooled to form a semi-finished product in the continuous caster area. In a typical installation, molten steel is tapped from ladles on the ladle turret and fills a mold before entering a continuous caster. The mold is cooled externally and an outer skin is formed around the liquid metal core; this will remain liquid until near the end of the casting process (known as the metallurgical length). The caster consists of rollers that are in contact with the cast steel, and these are generally cooled internally with process water. Bearings are installed to allow the rollers to rotate, and these are also water cooled in most casters. The steel is spray cooled at a determined rate, to maintain the metallurgical length. Bearings and rollers are also water cooled in the runout table directly after the caster; at this stage, the cast steel can still be in the region of 800°C. If the internal water cooling system or pipe work fails,
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