Optimization of rolling mill oils evaluation using FT-IR spectroscopy

Abstract

During the cold reduction of steel sheet in a rolling mill, rolling oils are used for lubrication to provide the desired steel surface. Rolling oil formulations consist largely of mineral oils, glycerides and/or synthetic esters, fatty acids, emulsifiers and additives. These oils are generally used as 2-5% emulsions and will be subjected to high temperature and pressure during use. This results in chemical changes within the oil that can affect steel surface cleanliness after annealing. It is advantageous to have rolling oils that are stable but easily removed during annealing and leaving a minimal amount of residues. Thus in the field of rolling mill technology the surface quality of rolled product and stability of rolling oils are critical in the selection of lubricants. Additionally, production cost and environmental impact are also critical in the selection of lubricants. In this study, the performance of vegetable-based rolling oils was investigated by recording the FTIR spectra of the oils using Horizontal Attenuated Total Reflectance, an internal reflection accessory, before and after systematic heat treatment. Evidence was found that the vegetable-based oils degraded on heating and the spectroscopic analysis indicated that this was due to rearrangement of unsaturated components from a cis to a trans configuration.