Regular Inspection of Critical Lubrication Parameters

Drew Troyer
Tags: onsite oil analysis, oil analysis

Mechanics and/or operators regularly inspect machines. In most cases, the equipment is looked over every day, every shift in some instances. What a wonderful opportunity to verify that proper machinery lubrication is in order. However, except for the obvious steps like checking the level indicator, it is rare to find the lubrication system on the inspection list. Many variables can be quickly and easily monitored with a small time commitment. These inspection items can be revealing, and will serve as the foundation of a precision lubrication management program.

“Routine inspection of the machine’s lubrication system is among the easiest and most productive ways to avoid equipment failure, and should play a pivotal role in the pursuit of precision lubrication.”

I have found that keeping lubrication inspection routes simple produces the best results. This is especially true even if routes are completed by staff members who possess only a basic knowledge of machinery lubrication. In fact, I like to design lubrication inspection routes comprised almost entirely of questions that the inspector can answer “yes” or “no,” or “OK” or “not OK.” This keeps the process fast and simple. If the answer is not yes or no, it should be a simple metric that requires no interpretation (for example, flow meter reading, pressure gauge reading, etc.). After all, the primary purpose for performing routine inspections is to uncover possible problems that require further investigation before reliability is impaired.

Every plant, and for that matter every machine, will require a slightly different inspection routine and frequency. I have outlined six items to consider when setting up an inspection program.

  1. Frequency - Not all machines in the plant are created equal. Some are highly critical and should be inspected on a regular basis, in some cases every shift or every day. Others require only weekly, biweekly or monthly inspection. Because the lubrication inspection process is simple, err on the conservative side and inspect the machines frequently. The program can always be adjusted later. Consider the machine’s propensity to fail, its impact on production and the cost, time and difficulty of restoring it upon failure when deciding upon your inspection frequency. Too often, the sump volume is the primary determining factor. Sump volume is an easy way to group machines, but the cost of the lubricant is usually the least of your concerns. Use a more thoughtful approach.
  2. Observed Parameters - For many machines, the number of observable parameters can reach into the hundreds, even thousands in some cases. Obviously some priorities must be established. Select inspection parameters based upon their relative importance. How will an aberration affect the machine’s performance? How frequently do detectable problems occur with a given inspection? For a detailed discussion about various inspection parameters, refer to Noria’s publication “The Lubrication Field Test and Inspection Guide.”
  3. Training - Those performing the inspections must have some understanding about machinery lubrication, contamination control, etc. They don’t need to be experts in the area if they have experts to turn to, but they do need a basic understanding. They also require task-based training on performing the inspection. For example, they must know that the desiccant is deemed failed when it turns from blue to pink. Modern machinery lubrication practices will be new to many of the people performing the inspections. Don’t hold the team accountable unless they have been properly qualified to do the job.
  4. Collection Mechanism - The trusty index card will work for performing inspections, but this requires the individual to remember the inspection criteria or refer to an inspection list, and make notes about his observations. A clipboard with a predefined set of questions (that can be answered yes or no) for each machine is a definite improvement on the index card method. Be sure to leave a space for comments. Both the index card and clipboard approach require manual entry of the data once it is collected. A more modern approach is to set up the inspection in an industrial-quality personal digital assistant (PDA). For each machine, the inspector can answer yes or no, and as required, write short comments. These comments, too, could be selected from a drop-down menu to minimize inconsistency. The data can then be uploaded to a host computer for storage. This speeds the process, assures that the data will be captured and reduces transposition errors.
  5. Information Management - Be sure to track inspection findings carefully. Software is the best way to do this, and I have found it is best to keep inspection data where other machine condition information is kept to facilitate diagnostics and failure root cause analysis. Tracking the data also helps identify frequently recurring problems, or lubrication “bad actors.” It also helps optimize inspection frequency. It may be necessary to assign a number to the nominal (yes or no) data collected to conform to the requirements of the software used. Usually, zero and one can be used. Some questions will be answered yes if things are OK, others will be answered no if things are OK. I like to consistently assign zero to the OK condition to simplify graphical trending. A scale of one to three or one to five could also be used. It really doesn’t matter as long as it is simple and consistent.
  6. Next Steps - It seems that anytime a problem is encountered with any part of the lubrication system, an oil change is immediately scheduled, assuming this will solve the problem. This is lazy lubrication maintenance - try to drop this habit. Indeed, in certain cases the oil must be changed as a part of a complete and cohesive corrective action. In many cases, however, an oil change is not required. Investigate the problem, identify its root cause and implement a thoughtful corrective action that addresses the problems and eliminates any unnecessary steps.

Figure 1 is a list of recommended inspection items. Not all of the items listed will be appropriate for all plants, and some additional items might need to be added to meet special needs. Also, some of the items listed are not routine, such as the evaluation of used filters and failed parts, so the work will need to be appropriately divided among operators, lubricant technicians, condition-monitoring technicians and plant engineering.

Click here to see Figure 1

Ineffective lubrication remains one of the leading causes for machinery failure, and in most cases, it is the leading cause by a large margin. Routine inspection of the machine’s lubrication system is among the easiest and most productive ways to avoid equipment failure, and should play a pivotal role in the pursuit of precision lubrication. A bonus of this program is that the operators and mechanics who perform the routine inspections will have a new awareness of the importance of effective lubrication. And the quality with which lubrication is applied is bound to improve across the board.

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