Join us for an educational webinar with guest Tim Dunton from Reliability Solutions. Tim has over 30 years of experience in reliability training and consulting. He will cover the 5 Steps to Maintaining a Successful Lubrication Program.
- Understanding of the important selection criteria for Lubricants
- Understanding the cleanliness standards required by modern equipment
- Understanding the fundamentals of controlling contamination, including handling and storage, sources of contamination, and their prevention.
- Understanding of the correct application of lubricants, including Relubrication frequencies and Quantities
- Digital Lubrication Management
This webinar provides an excellent opportunity for anyone interested in keeping their machinery running efficiently and reliably over time. Don’t miss out on this invaluable insight from a leading industry expert – join us for this must-attend webinar!
Proper lubrication is essential for keeping industrial machinery running smoothly and efficiently. However, creating a successful lubrication program is not just about applying lubricants regularly. It requires a well-planned and executed strategy that takes into account factors such as operating conditions, lubricant selection, contamination control, and application methods. In this webinar, we discuss the 5 essential steps for maintaining a successful lubrication program. Following these steps can help you increase equipment reliability, reduce downtime, and extend the life of your machinery. Whether you are a seasoned maintenance professional or just starting, these steps will provide you with a solid foundation to optimize your lubrication program.
The Role of Lubrication
Before we dive into the 5 steps, it’s important to understand the role of lubricants in extending bearing life. When the lubricant is applied, it creates a thin film between the bearing surfaces, preventing metal-to-metal contact. The thickness of this film is crucial because if it is too thin, the bearing is at risk of premature failure. This failure occurs when microscopic peaks on the surface of the bearing come into contact and cold weld together, creating stress concentrators that lead to fatigue cracks. Therefore, it’s essential to maintain a thick oil film to prevent this from happening. However, certain maintenance practices such as poor alignment and balancing can squash the oil film and shorten the bearing’s lifespan. By following precision maintenance techniques and ensuring the correct lubrication practices, you can significantly extend the life of your machinery.
5 Steps to Maintaining a Successful Lubrication Program
1. Selection of Lubricants
Choosing the right lubricant for a bearing is crucial for its performance and longevity. Viscosity is the most important property to consider when selecting a lubricant because it determines the thickness of the film that will protect the bearing. However, the viscosity of a lubricant decreases as temperature increases. This means that selecting the right viscosity based on the expected operating temperature, rotating speed, and load is critical. Viscosity index improvers can help flatten the curve of the viscosity index and maintain the viscosity within the optimal range. Manufacturers usually provide viscosity information about liquid lubricants, but it may not be available for grease. There are a few different ways to select the right viscosity, which are based on the DN number (bore size multiplied by RPM). Alternatively, the ISO system uses kinematic viscosities, which are measured in centistokes.
Viscosity can be a tricky thing to manage. While increasing viscosity can help create a thicker oil film, it can also increase fluid friction within the barrier, which is the biggest source of friction in rolling element bearings. This can lead to increased temperature in the lubricant, creating more friction and heat without actually solving any problems. So, it’s important to be careful when adjusting viscosity and to make sure that it is specified properly.
Viscosity is by far the most important factor to consider when selecting a lubricant. While there are other properties and additives that can be helpful, they won’t make much difference if the viscosity isn’t right. So, if you want to ensure that your bearings are working smoothly and efficiently, make sure to pay attention to the viscosity of your lubricant.
When it comes to lubricants, it’s important for them to have good oxidation resistance. This means that they won’t break down easily when exposed to high temperatures, which can cause the oil to darken and its viscosity to change. Even worse, harmful deposits like varnishes and gums can form, which can cause problems in hydraulic systems with tight clearances.
The reason why temperature is so important is due to a basic law of chemistry stating that for every 10 degrees Celsius increase in temperature, chemical reactions double in rate. This means that if the temperature of the lubricant goes up, its life span is cut in half. So if you’re running a bearing at a temperature much higher than it was designed for, you’re essentially shortening its lifespan. Therefore, it’s crucial to select a lubricant with good oxidation resistance to ensure your equipment runs smoothly and efficiently for as long as possible.
Water is a major contaminant that can cause serious damage to bearings and compromise the fluid film’s ability to support loads. Even at low concentrations of just 200 parts per million, water can reduce the bearing’s lifespan by 50%. To put this in perspective, one part per million is equivalent to one drop in 14 gallons of liquid. Therefore, any moisture present in lubricants can be harmful. To prevent water from becoming an emulsion, we often use additives such as emulsifiers to keep it separate, similar to how Rain-x keeps water off your windshield.
When it comes to additives in lubricants, they can be helpful, but if the viscosity isn’t correct, they won’t make much of a difference. Some additives protect machine surfaces from corrosion or extreme pressure, while others improve the performance of the oil or protect the lubricant itself from deteriorating rapidly due to oxygen. However, some additives can actually cause failures, like phosphorus additives that don’t work well with yellow metals. In general, the most important thing is to get the viscosity right. If you take care of the viscosity, everything else will fall into place.
2. Cleanliness Standards
To improve the performance of your lubrication program, it is important to measure the cleanliness of your oil. The ISO cleanliness system is used to measure the number of particles of a particular size in your lubricant. The sequence of three numbers represents the code number that determines the number of particles per milliliter of the sample. Also, the sequence of three numbers represents particles that are four, six, and 14 microns in size. Another important note, the ISO code numbers double the contamination as you go up one ISO code.
So, it is essential to set targets for different types of machines to improve oil cleanliness. The cleanliness code is higher for paper machines and turbines than for servos, proportional valves, and hydraulic systems. However, for bearings in oil pumps and auxiliary equipment, the cleanliness code should be lower than for paper machines. You should aim to achieve these numbers over time to enhance your lubrication program. Using the raw numbers of particles per liter of sample can help communicate with non-specialists in your facility and help them understand the importance of oil cleanliness.
3. Contamination Control
Filtration Alone is Not Enough
To clean oil and meet ISO standards, it’s not enough to use filters. It’s important to prevent contaminants from getting into the system in the first place and to remove any existing contaminants. Unfortunately, even new oil is rarely clean and the quality standards are weak. The infrastructure that supplies lubricants was built almost a century ago and wasn’t designed to deliver clean oil. Modern machines are much less tolerant of contamination than older ones, and even small particles can cause problems. A patch test can reveal the particles in oil, and the samples from totes, road tankers, and barrels are usually dirty. Barrels are the worst way to buy oil because they often sit in yards for months collecting rain and crud. Drum liners can help with cleanliness. Overall, it’s important to be aware of the sources of contamination and take steps to prevent and remove it.
At the end of the day, we have two options to address the issue at hand. One option is to demand that our lubricant suppliers improve their infrastructure, but this would ultimately result in increased costs for us. The other option is to take matters into our own hands through a process called inbound filtration, where we filter new oil before storing it in our containers. While this allows us to manage and control the cleanliness of the oil, it’s important to note that we shouldn’t assume that the new oil we receive is clean. There are many devices on the market that can help you clean your oil, and a filter cart is a great investment. Using a filter cart is like having a dialysis machine for your oil – you can recycle it and pull it through a filter to watch as your lubricants become cleaner and more efficient.
Get a Particle Counter
If you’re trying to improve your lubrication program, get a particle counter. This device can measure the cleanliness of your oil, allowing you to track your progress as you work to improve it. Sure, you could send off oil samples to a lab, but that can take days for results to come back. With a particle counter, you can instantly know when your oil is dirty and needs filtering. Some filter carts even come with a built-in particle counter, which is definitely worth the extra cost.
Identify Contamination Sources
To keep your lubricants clean, it’s important to understand where contamination can come from. One source is the machine itself, which can have built-in contamination from the manufacturing process or external contamination from the environment. Here are some examples:
- In one case, a capital spare was not properly preserved and a corroded shaft caused built-in contamination.
- In another extreme example, an iron ore processing facility had a very dirty environment with iron ore dust everywhere. Hydraulic hoses were left open, and the facility had a mean time between failure of only 35 seconds. The hydraulic systems kept malfunctioning, and the cleanliness standards were horrible. All of this contamination was externally introduced.
To keep your lubricants clean, it’s important to be aware of potential sources of contamination and take steps to prevent it from happening.
Don’t Overlook Sources of Water Contamination
Water is a major contaminant in machines, particularly rolling element bearings. Even a small amount of water, more than a couple of hundred parts per million, can reduce the bearing’s lifespan by 50%. But where does this water come from? It can come from heat exchanges or condensation, which is especially problematic in humid environments like the Southeast.
However, a facility with a dry desert-like environment thought they could get away with using a simple spin-on filter instead of a desiccant water-absorbing breather on their gearboxes. They don’t have humidity or a lot of rain, but they overlooked the fact that they have to spray water to minimize dust. This resulted in water draining into the gearbox, leading to premature failure. Even in dry environments, water can find its way in! It’s important to take steps to prevent water from entering a machine to ensure its longevity and proper functioning.
Handle Solid Contaminants (Even Ones You Can’t See)
Solid contaminants in lubrication systems can be extremely damaging to bearings. Even the tiniest particles can cause stress concentration, leading to fatigue cracks and premature failure. So, it’s not just the visible chunks of contaminants that are harmful, but also the fines – particles that are too small to see with the naked eye.
In fact, experiments on helicopter gearboxes by MacPherson showed that it’s the fines that are really destroying machines and bearings. So, it’s crucial to understand that just because you can’t see any visible contaminants in an oil sample, it doesn’t mean the oil is clean.
When it comes to filtration, it’s not just about the micron rating of the filter, but also its efficiency or beta ratio, which determines how much of the particles will be removed. So, a fine filter with a low beta ratio won’t necessarily clean the oil effectively. To keep lubrication systems clean and functioning properly, it’s important to adjust filtration and cleanliness strategies accordingly, taking into account the harmful effects of both visible and invisible contaminants.
4. Applying Lubricants
Once we have clean oil, the next step is to apply lubricants, particularly greases, to the machine. However, many people struggle with the right amount and frequency of lubrication. The fluid we put in the machine is the biggest source of friction, which produces heat. Although our instinct is to add more grease to a hot bearing to cool it down, it is actually the wrong thing to do. Over-lubrication is a common issue that leads to more bearing destruction than under-lubrication.
The Right Lubrication Quantity
The initial quantity of lubricant needed for a bearing is typically 20-30% of the bearing cavity, not the entire housing. For slow-speed applications with low friction, a full pack may be necessary to keep contaminants out. To calculate the initial quantity of lubricant, use the formula 0.1 times the width of the bearing in inches times the OD of the bearing in inches, or 0.005 times the width of the bearing in millimeters times the OD of the bearing in millimeters for grams. For example, if you have a bearing with a six-inch OD and one inch in width, the initial relubrication quantity should be 0.6 ounces. To manage the lubrication quantity, grease guns are calibrated, and you can use a postal scale to experiment and find out how many strokes equal an ounce.
The Right Lubrication Frequency
Figuring out how much lubricant to apply is easy if you know the size of the bearing. But determining how frequently to lubricate it is a different story. Fortunately, SKF has provided a chart that can help us with that. Let’s take the example of a 4-inch ball bearing running at 1800 RPM. According to the chart, we should relubricate it about every 7,000 to 8,000 hours, or roughly once a year. For this particular bearing, we would need 6/10 of an ounce of lubricant for each relubrication.
It’s worth noting that these are base numbers, and different types of bearings may require more frequent lubrication. For example, cylindrical roller bearings may need to be lubricated almost twice as often, while spherical roller bearings may need lubrication every 800 hours due to their design. The shape of the bearing affects how the lubricant is distributed, with some bearings being able to eject excess lubricant more easily than others.
5. Digital Lubrication Management
Imagine you have an electric motor on a belt drive with two different types of bearings: a ball bearing and a spherical roller bearing. The outboard ball bearing needs to be greased once a year, while the inboard spherical roller bearing needs to be greased once a month.
The question is, does your lubrication program have the necessary granularity to account for these different lubrication frequencies? If not, over-lubrication can lead to bearing failure.
Lubrication used to be an undervalued profession, but it is important to recognize that lubrication technicians hold the key to keeping equipment running smoothly. Managing all of the different lubrication needs of each machine can be complex, but digital lubrication management systems can help keep track of each custom lube point.
So, let’s not underestimate the importance of lubrication technicians and giving them the support they need to do their job effectively in the modern facility with hundreds of lube points each with several data points to track, including relubrication quantity, relubrication frequency, contaminants to watch for, different sampling points, and more.
Digital lubrication management software is crucial for efficient and effective maintenance practices. With traditional paper-based systems, it can be difficult to keep track of all the different lubrication points and their corresponding frequencies, leading to errors and missed lubrication events. However, with lubrication management software, maintenance teams can easily monitor and manage their lubrication programs, ensuring that each point receives the right amount of lubrication at the right time. The software can also provide valuable data and insights, such as equipment health trends and usage patterns, which can inform decisions on maintenance and replacement schedules. Ultimately, digital lubrication management software helps to reduce equipment downtime, extend the lifespan of machinery, and save costs by preventing unnecessary maintenance and repairs.
Take Steps to Optimize Your Lubrication Program
In conclusion, maintaining a successful lubrication program requires attention to several critical factors. The selection of the right lubricant with the appropriate viscosity, oxidation resistance, and additive content is crucial for optimal bearing performance and longevity. Additionally, keeping the lubricant clean and controlling contamination are essential steps to ensure that the equipment runs smoothly and efficiently. Measuring the cleanliness of the oil, setting targets for different types of machines, and preventing contaminants from entering the system can help achieve this goal. By following these steps, companies can minimize equipment downtime, reduce repair costs, and increase productivity and profitability.