ABSTRACT
Machines have many moving parts that rub against each other during operation. These moving parts are subjected to dynamic forces, and due to friction between the parts, energy is dissipated as heat. Machine designers and manufacturers take care to ensure that these frictional forces are minimized, so that energy is not unnecessarily dissipated. Surfaces that rub or mate against each other are heat treated so that the surface is hard and wear resistant, and a layer of lubricant is applied to reduce friction and dissipate whatever frictional heat is generated. This aspect of the machine is considered in its condition monitoring. No matter how wear resistant the surfaces are, with time, particles from the surface of the mating machine members will be dislodged by a wear phenomenon and will be deposited in the lubricating oil. The concentration of such wear particles, their size, shape, and composition provide clues to the maintenance engineer regarding the health of the machine. Further, due to the deposition of wear particles in the lubricant (which may be oil or grease), the physical and chemical properties of the lubricant change. Thus, by measuring these properties of the lubricating oil, an indication of the machine’s health can be obtained. This chapter presents an overview of the mechanisms of wear and the analysis of wear particles and lubricating oil.
