Marginal Bearings

PTFE (Polytetrafluoroethylene) and POM (Polyoxymethylene) are just two of the polymers used in the production of marginal bearings. POM is an engineering thermoplastic used in precision parts that require high stiffness, low friction and excellent dimensional stability. Hermann Staudinger, a German chemist who received the 1953 Nobel Prize in Chemistry, first studied the polymerization and structure of POM in the 1920s to research the theory of giant molecules. Due to initial problems with thermal stability it was not commercialized.

PTFE is a fluorocarbon solid, as it is a high molecular weight compound consisting wholly of carbon and fluorine. Neither water and water-containing substances nor oil and oil-containing substances are wet by PTFE, as fluorocarbons demonstrate mitigated London dispersion forces due to the high electronegativity of fluorine. PTFE is used as a non-stick coating for pans and other cookware. It is very non-reactive, partly because of the strength of carbon–fluorine bonds, and so it is often used in containers and pipework for reactive and corrosive chemicals. Where used as a lubricant in marginal bearings, PTFE reduces friction, wear and energy consumption of machinery.

Marginal bearings are used for applications involving intermittent operation or boundary lubrication. In the automotive industry they may be used for suspension joints, kingpin assemblies and stub axles of tucks, automobile driving joint hinges, steering and other linkages, articulation joints, rear chassis hinges and fairleader rollers. In the machine tool building industry as spindles in drill, grinding, and milling machines, ram guide plates in multiram presses. Marginal bearings may also be used in agricultural equipment such as gearbox, clutch, bale trips and wheel caster swivels for bale accumulators, front axle pivot bearings, steering idler box bearings and kingpin bearings for harvesters. They are especially well-suited for applications where lubricant can not be supplied continuously or repeatedly.