Despite years of concerted efforts by industry experts and suppliers, some dangerous lubrication myths continue to swirl around many maintenance operations. Motion Industries lubrication specialist Chris Kniestedt takes a down-and-dirty approach to debunk six of them.
Myth 1: All lubricating oils are the same.
From hydraulic fluids to gear lubricants to motor oils, each lubricant, be it synthetic or mineral-based, is uniquely formulated for its application with a specific viscosity; additive package; physical, chemical, and performance properties; and regulatory requirements. Various products may or may not be compatible with each other (see Myth 6).
Myth 2: If a little is good, more is better.
Take grease, for example. Over-greased bearings are a major cause of equipment failure. Blown seals and overheating are just two negative results of using too much grease. A general rule of thumb for normal- or high-speed machinery is that it’s better to err on the side of caution and to always check the OEM’s recommendations.
Overfilling gearboxes will also lead to problems, including failed shaft seals or increased operating temperatures. A gearbox that has too much oil will have to work harder to move through the lubricant, subsequently generating more heat or churning the oil into foam.
Myth 3: Blue, red, or black grease is better than white or clear grease.
Color is not a key factor in selecting grease for an application. There’s no standard for doing so. Instead, pay attention to base-oil viscosity (based on speed, load, and expected operating temperature), thickener type to mitigate incompatibility issues and consistency, and/or how well a product will pump at operating temperatures.
Myth 4: Tacky and stringy greases and oils offer better protection than non-tacky products.
It’s important to understand that lubricants are only 10- to 20-microns thick at the point of contact. Moreover, film thickness is a function of base-oil viscosity at operating temperature and speed (to a lesser degree, load). Thus, always use caution when applying tacky lubricants or greases with higher percentages of thickener at high operating speeds.
Myth 5: Food Grade (NSF H-1) products are never as good as Non-Food Grade (NSF H-2) products.
Advances in base-oil technology and additive chemistry have made Food Grade H1 products stronger than ever, particularly with synthetics. There are many applications where a correct, strong Food Grade H1 product will work as well as a non-Food Grade H2 mineral-oil-based equivalent.
Myth 6: All products are compatible.
Consider greases. In addition to their base oils and additive packages, greases are formulated with various thickeners (lithium, lithium complex, aluminum complex, calcium, polyurea, bentone, and silica gel), which aren’t necessarily compatible with each other. Always exercise caution when changing greases. Laboratory compatibility testing will clear up any doubts. If incompatibility exists between old and new products, purge bearings before changing to the new one. Oils aren’t always compatible either, especially with the new generation of synthetics. Finally, mixing Food Grade H1 lubricants with Non-Food Grade H2 will create contamination issues, which will cause you to lose H1 designation. MT
Chris Kniestedt is lubrication specialist for the San Francisco Division of Birmingham, AL-based Motion Industries. For more information visit www.motionindustries.com.