Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/825468
is important to take caution when the reac- tion has the potential to result in chemical corrosion of more reactive metals. Physics and Chemistry The physical molecular interactions of asperities at the actual contact pressure points are the main concern when unlubri- cated or poorly lubricated machine surfaces come into sliding contact. At this molecular scale of the machine surfaces, boundary conditions are subject to numerous princi- ples of physics and chemistry. The role of oxidation, corrosion, chemisorption and other chemical reactions at the machine surfaces must be carefully balanced when additive compounds are selected for film strength protection. These friction and wear-control additive films on the metal surfaces reduce the shear strength at the contact points. The low-shear-strength films are sacrificial during physical interactions and protect the surface from the effects of adhesive, abra- sive and fatigue wear. These submicron films have a gradation of liquid to solid proper- ties as they get closer to the metal surface. While the base oil is preferred to protect the machine surfaces with hydrodynamic and elastohydrodynamic lubrication, boundary conditions will exist. Therefore, to protect against boundary conditions, a properly formulated lubricant with friction and wear-control additives should be used to provide a film strength that is proportional to the exhibiting mechanical interactions within reasonable limitations. References Fitch, E.C. (1992). "Proactive Mainte- nance for Mechanical Systems." Fitch, J.C., Scott, R., & Leugner, L. (2012). "The Practical Handbook of Machinery Lubrication - Fourth Edition." Fein, R.S. (1991). "Lubrication Engi- neering." Journal of the Society of Tribologists and Lubrication Engineers. Fein, R.S. (1997). "Boundary Lubrication Relations." Tribology Data Handbook. Rabinowicz, E. (2014). "Friction." Access Science. Mortier, R.M., Fox, M.F., & Orszulik, S.T. (2010). "Chemistry and Technology of Lubricants - 3rd Edition." Rigney, D.A. (1980). "Fundamentals of Friction and Wear of Materials." ASM Mate- rials Science Seminar. About the Author Bennett Fitch is a senior technical consultant with Noria Corporation. He is a mechanical engineer who holds a Machine Lubricant Analyst (MLA) Level III certification and a Machine Lubrication Technician (MLT) Level II certifi - cation through the International Council for Machinery Lubrication (ICML). Contact Bennett at bfitch@noria.com. ML