Lubricant Myths That Can Cost You
Ken Bannister | April 13, 2018
Blindly following these old adages can result in damaged equipment, reduced product quality, and wasted revenue.
The world of lubrication is fraught with adages, myths, and misconceptions eagerly handed down from one unsuspecting generation to another with the best intent. Much of today’s folklore surrounding the use and application of lubricants springs from North America’s early 20th-century agrarian roots. This is not to say that our ancestral farm folk were incorrect in their thinking. Far be it. At that time, lubrication decision making was much simpler, driven by heavy over-designed machinery, built to outlast decades of abuse and limited lubricant choices.
Today’s machinery is much more sophisticated, with finer tolerances, and its lubricants and lubrication regimes are an integral part of any machine’s design that will affect machine deliverables and warranty status if not strictly followed.
Lubrication has always been colored with the incorrect perception that its simplicity and inexpensive nature can be successfully managed with little or no knowledge or training. This is further exacerbated when neglect and/or improper application do not result in any immediate bearing or machine failure. Consequently, a number of mistaken ideas, passed down from the early days of industrial lubrication, persist today.
Anything Will Work
The first myth is that oil is oil, grease is grease, and any will do the job, no matter the application.
Based on the vast array of standard and specialty lubricants available today, a red flag should go up immediately when lubricant choice is arbitrary. Following this edict can accelerate lubricant and component failures for a number of reasons, primarily involving viscosity choice, incorrect additive packages, and cross contamination.
Today’s machinery is often operated in a wide range of environmental temperatures. Colder temperatures require less-viscous lubricants and hotter temperatures require thicker, more-viscous lubricants. Choosing the correct viscosity is essential to ensure the lubricant can provide a suitable protective film (especially in tight-tolerance bearings) that will separate the moving surfaces without creating excessive fluid-friction drag, in all temperature environments. Incorrect viscosity can also severely affect the machine energy profile and its performance.
Combining two different lubricants will inevitably mix the additive packages. This could not only deliver a diluted additive package, but also cause essential additives to drop out of suspension, leaving the bearing at risk.
Not all lubricants are made equal. Many are not chemically compatible and can even catalyze and harden when mixed together, essentially changing state within the bearing cavity at the expense of the bearing and all of its lubricant feed lines.
When in doubt, always solicit the assistance of a reputable lubrication consultant and/or lubricant manufacturer/supplier to facilitate an engineered lubricant-consolidation program that will determine the most suitable lubricant selection for all of your bearings. Choose an oil viscosity and additive package that is designed to work in your ambient conditions to cut down on lubricant degradation and reduce the number of oil changes.
You Can Never Have Enough
Our second misconception is the old adage: “More lube is better.” Many bearings are killed with kindness when automated-delivery systems are incorrectly engineered or by using non-standard grease guns that can deliver substantially different shot sizes due to their internal design. Virtually no two grease guns are alike in their grease displacement; a single shot in one grease gun can amount to five or more shots in a different-style gun. Yet, a PM (preventive maintenance) task may ask for two shots of grease, which results in over-greasing.
Furthermore, a good-hearted maintainer may contribute to the problem by choosing to add an extra shot or two in the mistaken belief that more grease is better. If you witness oceans of grease surrounding or dripping from a bearing, it’s a clear indication that the “more is better” assumption is in play.
Ideally, greased bearing cavities should be filled to less than 50% of their capacity to effectively lubricate the bearing. Filling a bearing cavity completely with grease creates a condition known as fluid friction, or churning, in which the bearing requires considerably more input energy to move the lubricant out of the way so that the bearing can operate as designed. As a result, the internal friction causes the lubricant and the bearing temperature to spike, prematurely and simultaneously reducing the lives of the bearing and lubricant.
Similarly, over-filling an oil reservoir can create a lubricant-churning condition, creating heat and foam that can quickly deplete the anti-foam and anti-oxidant additive and reduce protective ability.
The solution? Ensure all grease guns in the plant deliver the same amount of grease displacement. Work with a lubrication-
delivery-system specialist to engineer your application system approach and interval requirements.
The third consideration on our list is neither myth nor misconception. Cleanliness is, without a doubt, next to godliness.
When it comes to bearing health and lubrication, the old cleanliness adage is a mantra worth following. Bearing surface areas and lubrication systems are not dirt tolerant.
Poor work practices and dirty lubricant-storage/handling equipment and areas are responsible for many premature bearing failures. Develop a cleaning regimen as part of any PM task. Ensure the lubricant reservoirs and lubricant delivery devices are always kept scrupulously clean.
Introduce and sustain a machine-cleanliness program that is designed to quickly identify leaks and moisture invasion and prevent dirt from contaminating the lubricant. When dirt contaminates a lubricant, it forms a thermal blanket that raises the lubricant temperature.
This list depicts the 10 major reasons for lubrication failure. The first nine are directly or indirectly related to the acceleration of lubricant, component, and machine failure:
• lack of lubrication training
• lack of lubrication application engineering
• poor housekeeping, i.e., no order or cleanliness
• use of dirty or contaminated new lubricants
• infrequent oil/filter changes
• cross contamination of existing and incompatible lubricants
• incorrect lubricant (additive package)
• bearings mounted out of square or misaligned during setup.
Underestimating your lubrication approach is gambling with your machinery and operational health. When taking a vintage approach to managing maintenance, understand the context of the “advice” and choose wisely. EP
Contributing editor Ken Bannister is co-author, with Heinz Bloch, of the book Practical Lubrication for Industrial Facilities, 3rd Edition (The Fairmont Press, Lilburn, GA). As managing partner and principal consultant for Engtech Industries Inc., Innerkip, Ontario, he specializes in the implementation of lubrication-effectiveness reviews to ISO 55001 standards, asset-management systems, and training. Contact him at firstname.lastname@example.org, or telephone 519-469-9173.