Plate-out efficiency related to oil-in-water emulsions supply conditions on cold rolling strip

Abstract

Oil-in-water emulsions are generally used in tandem cold rolling mills as lubricants, as they provide good lubricity and cooling performance. Lubricants are supplied by either a recirculation system or a direct application system. The dynamic concentration and the plate-out are known as the two main lubrication mechanisms, respectively, used in the two conventional lubrication applications. But it is difficult to realize direct control of the lubrication characteristics only using the dynamic concentration mechanism while the plate-out mechanism makes it possible. Therefore, this article is concerned with an experimental study of the efficiency of plate-out oil film formation, focusing on emulsion spraying conditions. Emulsion supply conditions are also examined in the plate-out test, which enables extremely rapid evaluation in a time equivalent to that in actual high-speed cold rolling. An air atomizing nozzle, which supplies a mixture of emulsion and air, was more efficient for plate-out oil film formation than the conventional flat nozzle, which only supplies emulsion. Air atomizing expands the space of the emulsion droplet and may prevent outflow of the plate-out oil film. The results of this research suggest that it is important to consider emulsion supply conditions as well as emulsion make-up conditions.

Boundary lubrication of stainless steel and CoCrMo alloy based on phosphorous and boron compounds in oil-in-water emulsion

“…6 and 9, it can be seen that the COF is more dependent on the emulsion, and especially on the additives. A common model for emulsion lubrication is the plate-out theory [10]. When an oil droplet is exposed to a metal surface, the layer formed by the polar orientation of the emulsifier molecule induces droplets to adsorb onto the metal surface.…”

“…Frequently-used emulsifiers in lubrication technology are nonionic surfactants [9]. Researchers have conventionally attributed emulsion effectiveness to the idea that droplets 'plate out' onto exposed metal surfaces [10].…”

Wear particles formation in cold rolling

“…The plate-out theory is based on the idea that a film of essentially pure oil is formed driven by the preferential wetting of the metal surfaces by the oil phase [55,59]. Plate-out theory proposes that oil droplets are trapped on the roll or on the strip because of their polar affinity towards the two metallic bodies, as schematically represented in Figure 2.5a.…”

“…Dynamic concentration theory is based on the idea that once the oil droplets of the emulsion are trapped in the roll bite, the concentration of oil increases while excluding the water from the roll bite [59]. This theory is based on pressure buildup in the roll bite and higher viscosity of the oil.…”

Boundary lubrication of stainless steel and CoCrMo in aqueous systems

“…The 'plate out' process is schematically drawn in Fig. 2.2 [51][52][53]. In stage a), the oil droplets suspend in water, then in stage b) the oil droplets adsorb onto the metal surface.…”