Benefits of synthetic lubricants in industrial applications

Abstract

AbstractSynthetic lubricants were originally developed and used for applications where petroleum products were inadequate (e.g., at extremely high and low temperatures, under extreme wear conditions) or where special characteristics, such as long life, improved equipment efficiency, or non‐flammability, were needed. However, the use of synthetic lubricants is not restricted to special applications, but is also useful when they can provide cost efficiency in areas such as machine reliability, oil life, energy consumption, biodegradability, and safety. Among many successful applications, typical cases where synthetic fluids have clear advantages over conventional lubricants include: high‐temperature lubricants for plastic calenders (significant lengthening of oil‐change intervals, fewer machine shutdowns): worm gear drives under severe service conditions (increase in efficiency, lower operating temperatures); air compressors (elimination of combustible petroleum residues); hydraulic fluid in fire‐resistant applications (mining equipment, pressure casting machines, steam turbine control systems); and high‐speed greased bearings (reduced friction losses).The benefits of synthetic lubricant base stocks are derived not only from their basic molecular structures but also from the absence of harmful molecular species often unavoidably present in conventional mineral oils in small, but significant, concentrations. There are very many compounds in crude oil, and while many, or most, of the harmful ones are removed or upgraded by refining, depending on the methods used, a significant number will inevitably remain in lubricating oil stocks, whether solvent‐ or hydrotreated. Thus, conventional oils comprise a wide variety of molecular species, many of which are not well characterised. In contrast, synthetic products normally are produced by chemical reactions of very pure, small molecules in which pressure, tempesutuse, und the ratio of reactants cun he curefully controlled. Frequently, the synthesis o j the reaction up to the desised end product includes severul steps, each of which necessitutes a pusifcution of the intermediute psoducts. It is this resulting ji‐eedom jhom undesisuhle compounds that gives synthetic lubricants their distinctiiie characteristics. It also contrihutes to their higher cost, compased to mineral oils, the oiserall cost of u synthetic product being the sum of the costs of the raw materials und the costs of the individual reuction steps.It is estimuted thut approximutely 80% of the worldwide synthetic luhsicants market is repsesented by three generic groups: polyulphaolejins (∼45%), organic esteia (∼25%), and polyglycols (∼10%). Of the remaining synthetic luhricunts, phosphate esters and polyhirtenes make up probably the largest sules volumes, with about S% each in total. This paper. provides an overview of the types, characteristics, uses, und udwrztages of synthetic lubricants, based on these major technology categories.