A proactive approach to machine maintenance is one of the most effective machine maintenance strategies, which is why lubrication strategies are essential to keeping plants up and running. This is Part 1 in a series on the types of lubrication failure modes, and the proactive methods of preventing them.
By Terry Harris, CMRP, Reliable Process Solutions on behalf of UE Systems.
Just because a machine is running like it should today, doesn’t mean it will in the future. Taking care to properly service and maintain these tools, even when they seem to be performing fine, can extend their lifespan by 3 to 8 times, making proactive strategies an integral part of plant performance.
The key to preventing failures is knowing how they occur in the first place. By being able to identify failure modes, maintenance professionals can develop Reliability Centered Maintenance plans aimed at addressing the issues that can arise with selected components.
Why equipment fails
It is important to note that lubricants do not automatically fail – they do so because of practices within the plant that strain them. So by being able to identify failure modes, and where and how they occur, RCM professionals can develop strategies that are aimed at predicting, preventing and eliminating them entirely.
Types of lubricant failure modes
There are five major areas where lubricant failure modes can occur:
1) Temperature failure modes
2) Moisture failure modes
3) Foreign materials/particles
4) Viscosity failures
By understanding the ways in which each of these areas can create lubrication failures, professionals can better enact RCM plans.
Temperature failure modes
One of the biggest contributions to temperature failures can come from overloading. If a plant is constantly looking to expand operations, this could be putting too much strain on its machines. Other failures can come from simply using the oil or grease improperly. Putting too much grease or overfilling lube levels can create temperature failure modes, while using high viscosity lubrication or the wrong viscosity in a certain area can as well. Limited air movement due to location can also produce failures.
Temperature factors play an important role as well, both inside and outside the machine. If the cooling levels are not right, be them inadequate, or nonexistent, lubrication runs a strong likelihood of failing. These are internal factors, but also thermal conditions in the plant can contribute to these failures as well. Sunlight and ambient atmosphere, such as excess heat generated within the plant, can also contribute to plant failure.
There are other reasons for temperature failure modes as well, but at the end of the day the right RCM process needs to address the factors that directly affect the well being of lubrication. A lubricant has a lifespan of roughly 30 years, when kept at a temperature of 70 degrees Fahrenheit. For every 20 degree rise, this time is cut in half, meaning that higher temperatures result in faster oxidation, which ultimately contributes to component wear. If a lubrication is operating in 170 degree conditions, it needs to be replaced just more than once every year.
There are a number of actions one can take to prevent this kind of wear. By reducing temperature with coolant and changing it more often, failure modes become less common. Also, by getting a better understanding of viscosity and the role it plays in specific applications, there is a higher likelihood that failure modes can be prevented. Finally, consider synthetics as they can better withstand temperature failures.
Moisture failure modes
Another area that can create lubricant failure modes is moisture. These issues can arise from different levels of moisture entering the lubricant, be it through conditions like humidity and rain, along with instances of human error such as improper seals and wash down practices. Leaks, improper lube and lube equipment storage methods, and a lack of ventilation can all contribute to moisture failure modes.
When moisture gets into a lubricant, it can have devastating effects on its lifespan. Just 1 percent moisture in oil can reduce component life by up 50 percent, with similar results for other lubricants. For instance, if a professional can reduce the amount of moisture in a lubricant from 100 parts per million to 2 parts per million, it can extend the life span of the equipment by a factor of 10. This is a ratio that continues as the parts per million increases.
Additives also play a crucial role in extending the lifespan of lubricants as they can control oxidation, which, as stated before, can limit corrosion. However, as additives will deplete over time, and with them, so too do lubricant life spans, especially in combination with higher moisture levels. There are numerous kinds of additives that could be in a lubricating oil including, antifoam, dispersants, extreme pressure agents, detergents, anti-wear agents, rust inhibitors, oxidation inhibitors and corrosion inhibitors.
The key is being able to maintain strong additive levels. This means reducing moisture levels in new oil, while eliminating moisture in stored oils, equipment and from the wash down. Also, make sure to monitor moisture levels and replace lube when necessary, while also taking preventive measures, as well. For instance, using desiccant breathers on critical equipment and devices with dry air to remove particles can help cut down on destructive moisture.
These are only two of the areas in which lubrication failure modes can occur. Stay tuned for Part 2 on proper lubrication maintenance and failure mode prevention.
For more information on ultrasound technology and to access valuable resources, including a sound library, presentations, and articles, visit UE Systems’ website at www.uesystems.eu.
Roy Horstink, CMRP, Managing Director UE Systems Europe