Maintenance is frequently regarded as a necessary evil and tends to be delayed or cancelled to meet production demands. Taking equipment out of service to make repairs or improve functionality can be a tough sell, especially if the only maintenance activity is lubrication. As industry has evolved, so have the practices and philosophies for how and when to perform maintenance and lubrication. More options and tools are now available to guide the actions of personnel for nearly all lubrication tasks. However, to truly understand how this evolution has changed the landscape, you must know where maintenance began and where it is today.
Maintenance Philosophies
Most people are familiar with the term “reactive maintenance.” This approach involves repairing machines only after a breakdown or failure. Too often, reactive philosophies are adopted by organizations that are short on manpower or stuck in the “that’s how we’ve always done it” mentality. This leads to overblown maintenance budgets, poor operational performance and a staff that is constantly firefighting. As someone who worked in a reactive mode for years, I can attest to the stress it puts on your team. For instance, it was difficult to know when you were going home each day, if at all. Even on weekends or holidays, there was always the risk of being called into work. This maintenance philosophy is not sustainable and has largely been relegated to non-critical or small pieces of equipment.
In an effort to move away from the reactive state and in cases where safety is paramount, planned or scheduled maintenance was implemented. Known as preventive maintenance, this approach entails having a set period or interval when maintenance is scheduled and then performed. The airline industry provides a good example of this philosophy. Running an airplane engine until failure is not an option because of the safety ramifications. Therefore, maintenance is scheduled based on the number of hours or flights. The same practice was adopted in industry. This included closely following original equipment manufacturer (OEM) recommendations or intervals to prevent a failure. You probably use a similar method with your vehicle’s maintenance. By introducing a scheduling component to your maintenance activities, you can add some direction and continuity to a daily process. Although preventive maintenance can help reduce the chaos of failures, it can still result in high maintenance costs when good parts are replaced.
More recently, new tools and accessories have become available to aid in equipment monitoring and catching potential issues earlier. This monitoring of failure symptoms and faults is known as predictive maintenance. The most common forms of this approach include using vibration analysis, ultrasound, thermography, oil analysis and a host of other technologies to provide an early warning of an impending problem. Predictive maintenance works well for machines that run continuously and often results in a reduction of unplanned downtime. However, it usually comes with considerable upfront costs, not just for the necessary tools but also in training the individuals who are expected to capture the pertinent data. Diligence is required to ensure data is collected from the same place and in the same manner each time. Inconsistent practices will skew the data and make it much more difficult to take appropriate action.
Rather than fixing machines, proactive maintenance eliminates what causes them to fail. It can be used to extend equipment life, as opposed to simply improving the process for repairs or identifying when a machine is going to fail. Proactive maintenance focuses on the root causes of failure and addresses them before they lead to an eventual problem. Much of proactive maintenance occurs before a machine is ever turned on, including alignment and balancing. Without a proactive mindset, equipment failures will continue to plague most maintenance departments. Analyzing what went wrong and taking steps to prevent it from happening again are the hallmarks of being proactive.
4 Oil Analysis Strategies
Oil analysis falls into the realm of condition monitoring but can be used in various ways to determine what is happening inside a mechanical system. It also can be divided into four different strategies:
- Reactive — An oil or grease sample is taken only after a potential problem is identified via a sensory inspection.
- Preventive — Routine samples are extracted, but the results are not analyzed.
- Predictive — Good samples are obtained and analyzed, with action taken on results from the lab.
- Proactive — New lubricants are sampled prior to service. Samples are taken from the right place, in the right way, using the right tests and with the right interpretation strategy.
Lubrication Activities
In a lubrication program, there are tasks for applying lubricants, analyzing their state and eventually disposing of them once they reach the end of their useful lives. Beyond these front-line tasks are management activities to ensure work is completed properly. Perhaps the simplest lubrication task involves the use of a grease gun. However, these devices have been improved in recent years and now incorporate advanced technology. Before utilizing a grease gun, be sure to consider the task in relation to the different maintenance philosophies discussed previously.
Reactive Greasing
You’ve likely heard the phrase, “the squeaky wheel gets the grease.” When performing lubrication in a reactive state, you wait until an issue is experienced before adding grease to a bearing or machine. But greasing in response to a noise or elevated head is very reactive. By the time these symptoms arise, damage has already occurred.
Preventive Greasing
Greasing a machine according to a calendar date or number of operating hours is pervasive in the industry, but adding grease based on time may lead to overgreasing or undergreasing the machine. Although it can help prevent some failures, a lot of manpower will be used to maintain the preventive maintenance (PM) program.
Predictive Greasing
Predictive tools for greasing have gained popularity in recent years due to their ability to identify precise intervals and grease volumes to add. Ultrasound is frequently employed to listen to a bearing and detect if and how much grease is needed. This type of greasing requires an educated staff and the necessary tools, but it can greatly reduce, if not eliminate, the likelihood of overgreasing a machine. Grease sampling and analysis are also becoming more widely used to determine the health of the grease and the machine as well as the optimum relubrication frequency.
Proactive Greasing
By balancing all the best practices, you can be more proactive with your greasing. This begins with selecting the right grease for the application. For critical applications, it may also include sampling the grease prior to use to verify its cleanliness. Also, perform the appropriate bearing calculations to confirm the correct grease volume and to guide your future activities.
This same methodology applies to oil applications. While you may rely on the rotating motion of a machine to apply oil to various internal components, you control many other factors that can provide an indication of success. The workload will vary greatly depending on the mindset of the individual or organization.
| 43% | of lubrication professionals say their plant uses a proactive maintenance strategy, based on a recent poll at MachineryLubrication.com |
Reactive Oiling
Oil is often manually applied from a top-up container or aerosol can based on an abnormal inspection result, such as a sight glass showing a low oil level or a chain that appears dry. Action must be taken immediately in these cases to ensure no lasting damage occurs. With splash-lubricated machines, an oil level that is too low can have catastrophic effects. This also would apply to changing the oil only after it has long exceeded its service life.
Preventive Oiling
Changing your oil based on a time period or operational interval is common for most non-critical or small-volume machines, but it can lead to replacing oil that is still good or going far too long between oil changes. This can be wasteful both in terms of manpower and lubricant.
Predictive Oiling
Using oil analysis to identify the proper oil change interval is the best approach for large oil volumes and critical machines. When an oil sample is tested, you can distinguish many of its characteristics and determine whether it should remain in service and how much more life it may have. This greatly improves your decision-making ability and can minimize the impact of a lubricant failure by planning for a shutdown or switching to an auxiliary machine.
Proactive Oiling
To be proactive when oiling a machine, you must eliminate the root causes of failure. This is accomplished by ensuring the proper oil is applied and that it is clean and defect-free. Your storage and handling practices should be examined and improved to make certain that lubricants are as clean as possible when they reach the machine. This includes filtering the oil prior to service and using transfer containers that can be hermetically sealed. These practices will reduce the number of failures experienced at your plant.
Don’t Overlook Inspections
Inspections are often overlooked as the foundation of a world-class lubrication program. Personnel who walk by machines every day are the greatest source of information to drive your program forward. While I’ve outlined various ways to use the results of inspections to make better lubrication decisions, greater emphasis must be placed on the inspections themselves. Just having a checklist or making simple rounds is not enough. Dig deeper into what you notice about the machine, sight glass or breather. This will be an extremely valuable activity that will bear fruit in all aspects of maintenance, regardless of the philosophy employed.
This article was originally published in the December 2018 issue of Machinery Lubrication.
