Kinetics study of cold rolling lubricant degradation through advanced instrumental techniques

Research was focused on understanding the degradation kinetics of cold rolling oil used in the rolling mill at Tata Steel. Aged rolling oil leads to various surface defects. Ageing phenomenon is influenced through thermo-mechanical behaviour, oxidation, hydrolysis and presence of iron fines. Ageing of cold rolling oil in presence of iron fines was systematically performed at various temperature followed by thermo-mechanical wear tests. With variation in intensity of ageing, change in physico-chemical parameters and fatty acid distribution (FAD) within triglycerides could be observed. The impact of the controlled ageing on performance parameters like lubrication, evaporation kinetics and oxidative stability were also studied. Thermo-oxidative ageing depletes antioxidant concentration within the rolling oil resulting in rapid oxidation of unsaturated fats. This leads to rapid build-up of high molecular weight ingredients resulting in formation of fatty acid soaps or scum. The resultant scum negatively impacts the boundary lubrication and evaporation kinetics of rolling oil.