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In celebration of its 15th anniversary, Machinery Lubrication magazine presents 15 of the best lubrication tips that have been offered through the years. From the very first issue in May 2001 through the March-April 2016 issue, the following advice should be just as helpful for achieving lubrication excellence as when it was first provided.
For certain machines, deviations in lubricant quality can lead to disastrous consequences. This punctuates the need to confirm the quality of new lubricant deliveries, especially when the need for reliability is particularly important. Likewise, a quality-minded lubricant supplier will appreciate receiving feedback, both good and bad, from users who run such tests.
Another important benefit for testing new lubricants is to establish a baseline for routine used-lubricant analysis. Even when new lubricants are well within acceptable quality limits, there may be considerable variations in physical and chemical properties (batch to batch). For instance, viscosity can vary plus or minus 10 percent from the ISO viscosity grade (VG) midpoint and still be “in grade.” Cautionary limits are sometimes set at plus or minus 5 percent from new lubricant viscosity. Hence, the specific new lubricant viscosity must be known.
By taking an active role in testing new lubricants and giving constructive feedback to your supplier, incremental improvements in lubricant quality are bound to result. Lubrication excellence is a collaborative process. Lubricant quality is a measurable property. If it’s important, measure it.
Overgreasing can have many of the same negative side effects as undergreasing, plus the added cost of high lubricant consumption. Greasing can be thought of as a purging or filtering of contaminants from the bearing, but you should not exceed a calculated amount of grease when performing greasing activities.
The calculated quantity of grease for a bearing is based on its geometry and dimensions, which provide the ideal amount for relubrication. The misconception is to apply more grease than needed to purge out contaminants. The right approach is to apply a fraction of the calculated quantity at a shorter time interval. This helps eliminate overgreasing at a given interval but still supplies the benefit of purging contaminants out of the bearing, just like automatic grease systems.
One of the most common ways to overgrease is to use an automatic grease system without proper calibration, maintenance and interval calculations. The premise and benefits of automatic grease systems are to provide a small amount of grease very often to promote a more continuous grease application. In order for this to work and be beneficial, the technician must know how much grease to add at the right time and calibrate the automatic grease system accordingly. If it is not calibrated correctly, it is likely that too much grease will be supplied too often, which can result in a bearing failure and high grease-consumption costs.
You don’t have to remove what you don’t allow in. Indeed, it’s hard to question the logic of controlling water ingression. But because moisture is everywhere, achieving bone-dry through exclusion alone may not be practical or even necessary. Lubricating oils have different degrees of hygroscopicity (water-loving tendencies), making the control of all dissolved water an almost futile exercise. However, for many applications, it’s the free and emulsified water that is the most destructive and, hence, the central target for control.
Exclusion relates to the process of preventing (excluding) the ingress of water from environmental, machine and process sources. Common points of water ingression include:
The top-line priority is to squelch ingression points through tight and well-managed ingression control. Deferring maintenance of worn seals, defective breathers and coolant leaks creates more expensive maintenance events in the future, including the possible cost of premature oil changes, flushing, oil dehydration and replacement of water-damaged parts. Monitoring and promptly closing off ingression sites are by far the wiser use of maintenance resources.
There are many factors that influence the decision of when to change oil. And in many cases, the oil may never need to be changed. With increasing pressure to drive down operating costs in order to boost operating profits, there is a real need to define an optimum approach.
In the past, many organizations have exclusively used interval-based oil change criteria. The interval was based on an assortment of considerations, such as the calendar, operating hours (meter), fuel consumed, miles/kilometers driven or production/work performed. In many cases, an approaching outage and shutdown have a driving influence on the decision, coming from the desire to avoid unscheduled downtime later or the need to change lubricants “on the run.” In addition, new equipment still under warranty may have OEM-specified lube change-out intervals, which can make the matter far less subjective (and optimized).
The condition-based oil change strategy is indeed important in reducing oil consumption and associated costs. However, there are many situations with certain machines when maintenance and reliability are not “optimized” when the strategy is applied. In order to perform a condition-based oil change, there is added cost to monitoring the conditions, namely oil analysis. There may also be added risk from running the oil too close to its end of life, which could lead to such challenges as the following:
Regardless, for most companies and machinery applications, the benefits of the condition-based oil change far outweigh the risk and cost.
Corrosion costs companies billions of dollars each year. Much of this loss is due to the corrosion of iron and steel. When exposed to moisture and oxygen, iron and steel will react, forming an oxide. This oxide does not firmly adhere to the surface of the metal and will flake off, causing pitting. Extensive pitting eventually results in weakness and disintegration of the metal, leading to failure.
The best way to stop rust and corrosion is not to allow the metal to come in contact with water, oxygen or acid. In essence, this is exactly what rust and corrosion inhibitors do. These additives are typically compounds that have a high polar attraction toward metal surfaces. They chemically bond to the metal surface, forming a protective film over the underlying metal. This film acts as a barrier that does not physically allow the metal to come in contact with anything that could promote corrosion. Some popular compounds being used are amine succinates and alkaline earth sulfanates.
If rust formation cannot be prevented, the rust particles can flake off and contribute to abrasive wear. The iron oxide is much harder than the steel surfaces it comes in contact with, so massive amounts of three-body abrasion occur.
Rust and corrosion are detrimental to your reliability program. Remember to always fight it at its root causes. Eliminate the root causes of a failure and you will reduce the likelihood of that failure’s occurrence.
Knowing when a piece of equipment is going to fail (predictive maintenance) is much more difficult than making it last long (proactive maintenance). Even more complex is root cause analysis (RCA), which is performed post-mortem, like an autopsy. Still, reliability professionals are increasingly stressing the importance of performing RCAs following all failures of critical machinery. As odd as it sounds, it is more productive to study failures than successes. After all, an apparent success may actually be a failure in disguise, more like a problem waiting to happen. Studying failures teaches insightful lessons in developing predictive and proactive maintenance strategy.
Root cause failure analysis is a process of working backward through a sequence of events or steps that led to functional failure of the machine. This process is often referred to as “asking the repetitive why” or “the five whys.” The first “why” is intended to reveal the obvious and more immediate cause, sometimes referred to as the direct cause. This is the suspect that first, and most often, bears the blame. However, by continuing the series of questions, one can often expose hidden causes that include contributing causes (partners in crime) and intermediate causal agents. With a little luck, your interrogation will lead you to the root cause. Keep in mind there may be multiple root causes.
Interpreting an oil analysis report can be overwhelming to the untrained eye. Oil analysis isn’t cheap, and neither is the equipment on which it reveals information. Every year, industrial plants pay millions of dollars for commercial laboratories to perform analysis on used and new oil samples. Unfortunately, a majority of the plant personnel who receive these lab reports do not understand the basics of how to interpret them.
Typically, an oil analysis report comes with a written summary section that attempts to put the results and recommendations in layman’s terms. However, since the laboratory has never seen the machine or know its full history, these recommended actions are mostly generic and not precisely tailored to your individual circumstances. Therefore, it is the responsibility of the plant personnel who receive the lab report to take the proper action based on all known facts about the machine, the environment and recent lubrication tasks performed.
Changing a filter too late puts the oil and machine in jeopardy. Changing a filter too soon wastes valuable resources. It has been reported that in many cases, the cost of a common oil change can exceed 10 times the apparent cost of the oil and associated labor to change the oil. This multiplier may hold equally true for the cost of a filter change. In addition to the cost of the filter, there are additional costs for labor, inventory, scheduling, used filter disposal, waste oil disposal and oil top-off costs (you always lose a little oil when you change filters).
There are many available technologies to help improve the timing of a filter change. These include pressure-rise profile monitoring, Delta-P indicators, bypass indicators, online particle counting and time-out alerts. Multiple methods used together may be the wise choice in certain cases. Nonetheless, changing filters on condition should be the primary objective in the quest for filter economy.
We all know that filters are consumable machine components. They have two primary jobs to do: remove particles at the same rate that they arrive into the oil and protect sensitive machine components from contaminant invasion. Conventional wisdom tells us to focus on the value proposition presented by better filtration, not on the cost of filtration. However, the astute maintenance professional may choose to have his cake and eat it too.
Particles and moisture enter lubricants from a variety of sources and entry points. Many of these contaminants arrive in stages through the chain of custody as lubricants are handled and transported from the blend plant to the ultimate point of use. For small machines, a surprisingly large amount of contamination is introduced at the last stage, between intermediate storage (e.g., drum or tote) and the machine. This is where the sealable and reusable (S&R) container plays a vital role in controlling contaminant ingression during routine oil changes and top-ups (the introduction of makeup oil).
Oil cans with narrow openings are hard to clean. Conversely, wide-mouth S&R containers offer welcomed convenience when it comes to routine cleaning typically done in a parts cleaning station or industrial washing machine. Most importantly, they present little opportunity for invasion of contamination and, hence, there is less need for such periodic cleaning.
Unlike teapot-type oil cans, S&R containers are also tightly sealed to control air exchange and contaminant ingression. The air vent, nozzle and other openings are all snug tight when not in use. You don’t have to filter or clean what doesn’t become dirty.
Yes, air does need to enter during oil dispensing, but S&R containers restrict the exchange of ambient air when not in use. Traditional oil cans, on the other hand, act more like dirt magnets by constantly collecting dust on the oil-wet internal surfaces.
Lubrication requires constant attention. Vigilance is perhaps a better word. It’s easy to forget the things we are not motivated to do, yet rarely do we forget those activities we are passionate about and desire to do. We are all driven by animal instincts to seek out the things that we enjoy or give us a gratifying reward.
Because it’s hard to find happiness in performing most routine maintenance tasks, it’s not uncommon for many of them to become periodically forgotten or perpetually postponed. Much of this is actually “conscious forgetfulness,” similar to procrastinating. Why does this happen? It is most likely due to a lack of rigor, which is due to a lack of structure, measurement and incentive.
Delinquent PMs can become habit-forming, leading to even more delinquency and a general cavalier attitude among maintenance workers toward punctuality and work quality. This “mañana mentality” or constant procrastination can lead to a destructive downward spiral. Common symptoms relating to lubrication include:
Periodically forgetting to perform “the rights of lubrication” is equivalent to periodically accepting preventable failures. We can and should do better.
Although most everyone knows about lubricant starvation in principle and realizes the common sense of adequate lubricant supply, it is frequently ignored because many typical forms are largely hidden from view. For instance, who notices the quasi-dry friction that accelerates wear each time you start an automobile engine? This is a form of lubricant starvation. It’s not a sudden-death failure, but it is a precipitous wear event nonetheless. Each time controllable wear goes uncontrolled, an opportunity is lost to prolong service life and increase reliability.
Machines don’t just need some lubricant or any lubricant. Rather, they need a sustained and adequate supply of the right lubricant. Adequate doesn’t just mean dampness or the nearby presence of lubricant. What’s defined as adequate varies somewhat from machine to machine but is critical nonetheless. High-speed equipment running at full hydrodynamic film has the greatest lubricant appetite and is also the most punished when starved. Machines running at low speeds and loads are more forgiving when lube supply is restricted. Even these machines can fail suddenly when severe starvation occurs.
Lubricant starvation is an almost silent destroyer. While there are telltale signs, they generally aren’t recognized or understood. Of course, there are varying degrees of starvation. Complete starvation is sudden and blatant. However, more moderate partial starvation is what tends to go unnoticed until failure. Then, other suspect causes (the bearing, lubricant, operator, etc.) may be falsely blamed.
Stickers or lube identification tags have been employed for years to guarantee the right lubricant is put in the right place. However, few organizations utilize lube tags to their full potential, while some fail to use them at all. These simple devices not only can help ensure the proper lube is being used, but if managed correctly, they can also improve machine reliability.
A good tagging system is frequently overlooked as a key part of a world-class lubrication program. There are many solutions on the market for color-coding devices that are commonly used in a lubrication program. Some of these include top-up containers, filter carts, grease guns, totes, pumps and other similar products. Although color-coding is a great practice, simply using a color for a single lubricant is often ineffective. With most facilities having more than 10 different lubricants, it can become difficult to distinguish between subtle differences in color, and more clarification is needed.
Some organizations have taken the additional step of utilizing a symbol along with a color to specify a particular lubricant for an application. By adding a second identifier, such as a shape scheme, you can exponentially expand the number of unique color and shape combinations to suit the amount of lubricants in your facility. For example, if you were to only use yellow to identify a particular gear fluid, you are limiting the color yellow to a single application. If you were to use yellow and a shape, such as a square, you can then employ yellow for other applications, provided that you utilize a different shape combination.
Choosing the correct oil sample location can be challenging. When installing a sample port, look for a single spot where you can gather as much useful data about the entire system. This is called the primary sampling location. At this location, the goal is to be able to draw a single sample that acts as a snapshot of the entire system. In most circulating systems, this will be on the main return line before the reservoir. By sampling from this one spot, you can check the wear debris from the rest of the system as well as the particle count to get an idea of the total contaminants in the system.
Although the primary sampling location is a great place to start, it often leaves behind a lot of valuable data. This is why secondary sampling locations should be installed on most systems. The goal of a secondary location is to be able to pinpoint the cause of any fault seen on an oil analysis report. Unlike the primary port, which provides an overall look at the entire machine, secondary ports enable you to focus on individual components inside the system.
Most circulating and hydraulic systems should have both a primary and secondary sampling location to ensure that any identified failure mechanism can be tracked back to the component causing the problem. Not only can a secondary port be used to help determine the source of wear debris or particles, but by installing sampling ports behind filters, you can monitor how well the filter is removing particles. So while the primary port may get the most use, the secondary port is invaluable once a fault has been detected.
In the interest of reducing purchasing costs and streamlining storage and handling, many organizations have substantially slashed the number of lubricant stock keeping units (SKUs) they use. They have also re-engineered the precision of their lubricant specification. There are many real and a couple of somewhat imaginary benefits to these consolidation initiatives. Let’s start with the real benefits.
The imaginary relates to the false reality that limiting lubricant SKUs to the catalog products of a single major brand can optimize the selection and number of lubricants in typical process industry plants and factories. For instance, some chemical plants have reported as many as 80,000 lube points, all requiring periodic relubrication. Many of these same companies have bloated inventories of lubricants from as many as 25 brands of more than 200 unique products. These are the companies that stand to benefit the most from consolidation.
Of course, along with the potential for benefits and savings, there are also many real risks and concerns. Most of these are associated with cutting corners and failing to do proper lubrication engineering. This can be avoided by making technically sound decisions with the support and advice of qualified lubrication advisors. Some lubricant suppliers have these capabilities, but others do not. After all, one or two harsh machine failures from placing the wrong lubricant in a high-value machine can wipe out all the potential savings and benefits that might have otherwise been realized.
What is an effective lubrication procedure? It is a step-by-step guideline that directs the user through a specific lubrication task. Of course, there are many types of tasks, including manual bearing lubrication, gearbox filling, gearbox checking, kidney-loop filtration, sample collection, etc. Each of these tasks will have some degree of uniqueness as well as a lot of overlap with other similar lubrication tasks.
When preparing a lubrication procedure, consider the following:
Strategy — How does the procedure support the broader maintenance strategy?
Purpose — What needs to be accomplished?
Procedure — How is the task accomplished, including the many details that determine safety, efficiency and effectiveness?
While there is no single approach to defining the individual tasks for a procedure, certain specifics must be incorporated to remove ambiguity and assure compliance. At a minimum, the purpose should include the name of the item to be addressed, the objective of the work, the identification of the individual to perform the task, the operational and safety conditions, and the amount of time allocated to the task. The details should identify what is to be done, where it is to be done, who will do the work, tools and materials needed, and special issues surrounding the work (safety, operational, etc.).
In the process of devising and writing procedures, expect to find major similarities between like components grouped by maintenance strategy. A template can be created with a significant amount of generic information or structure to facilitate the process without diluting the results.