Improve Your Lubrication PdM
Ken Bannister | May 27, 2019
Use pilot programs to eliminate wasteful reactive practices from your lubrication program.
Machines and mechanisms almost always fail in a predictable manner. Ensuring machine and mechanical-component reliability is a matter of understanding how failure occurs in the machine’s operating environment. Once understood, developing a proactive strategy will make it possible to predict and prevent system/component failure based on current conditions, not design (new) conditions.
For more than 50 years, predictive maintenance has been a legitimate condition-based maintenance approach. It is arguably based on the original 1939 Schewhart PDCA (Plan, Do, Check, Act) cycle, later revised and popularized by W. Edwards Deming in the 1950s and again in the 1980s. The cycle process follows four simple steps:
Plan: Understand how a system/component displays telltale signs of deterioration and failure. Then determine a suitable predictive technology/method to detect and measure that asset’s current condition.
Do: Set up and use the predictive technology/method on a regular basis.
Check: Analyze/trend the measured results against the new-condition state and previous results to establish a trend and determine whether a change in state, or potential failure, is occurring,
Act: Determine if and when a repair/restore intervention is required to return the asset to its original design state, and perform all necessary repairs prior to any breakdown or significant loss of service.
When implementing a predictive-maintenance (PdM) program, there are four basic rules to achieving continued program success:
• Follow the PDCA cycle.
• Don’t skimp on training. Personnel are often poorly trained in the collection and interpretation of data. This, in turn, can lead to poor decision-making and mistrust of PdM technologies.
• Strive for accuracy and consistency in data collection. Always take the sample data from the same test point(s) under the same operating conditions and ensure sampling is scheduled in a timely and consistent manner to develop accurate trends.
• When an imminent failure is successfully predicted, act immediately to minimize downtime and loss of service.
The theory behind successful PdM is inherently simple: Take sample data from a single or series of collection points in an engineered consistent manner, trend the results, and take immediate remedial action once pre-set control limits are breached.
As with all management-program launches, using an engineered incremental ramp-up approach to implementation will better guarantee success due to the more finite degree of program manageability. The following three steps depict a typical PdM change journey moving from a reactive environment. Note that Steps 1 and 2 are interchangeable and often determined in conjunction with one another:
1. Choose a suitable pilot. The first step in manageability requires the selection of a suitable pilot to commence the PdM program. A typical pilot can include:
• all equipment located within a designated floor, room, physical area
• a type or group of similar equipment (pumps, compressors)
• designated manufacturing line
• designated equipment piece.
Pilot assets are mainly chosen as a result of localized high-failure rate requiring immediate attention, but can be chosen because they have a reliable work history archive, are convenient, allow easy access, or are easily adaptable to the chosen PdM method or tool to be used.
2. Choose a suitable PdM method or tool. The choice of suitable methods or tools will often be determined by immediate need, budget, or legacy. When making a choice, document the reasoning behind it and the
expectations it should fulfill. There are several PdM tools available to the lubrication technician. Here are pros and cons of the most popular choices:
• Fault-code analysis (FCA) is the simplest and least expensive PdM tool. FCA is a methodology for identifying equipment failure or faults by setting up a coding system tracked on the completed work order. The process is greatly facilitated by setting up a computerized maintenance management software (CMMS) or enterprise asset management (EAM) system to record and report on the failure codes. This will allow you to easily identify repeat or cyclical failure incidents.
The FCA method is also excellent for checking the effectiveness of the preventive-maintenance approach. If the task does not include preventive action for the failure type, then it must be revised. If the task is set up to prevent the failure, then the task schedule must be revised to prevent failure before it occurs. This method is inexpensive to introduce and very effective, but relies heavily on the discipline to code all failures and proactively pull reports on a regular basis.
• Wear-particle analysis (WPA), or oil analysis, examines the condition of the lubricant(s) used in moving equipment. Oil is sampled on a regular basis and sent to an approved laboratory to perform tests for additive depletion and wear-particle inclusions.
In turn, the laboratory delivers a diagnostic report on the sample, complete with recommendations. Likened to a medical blood test, sampling and testing a machine’s oil will indicate when to change the oil, based on its condition and whether undesirable wear metals or other indicating elements are present. By understanding the working conditions, laboratory technicians can accurately diagnose any impending machine problems.
Inexpensive to administer, the sample quality relies heavily on acquiring the sample in an engineered, consistent manner on a regular basis. This program is easily set up within the PM work-order system. Working with the laboratory to set up sampling techniques and hardware requirements will significantly reduce the risk of collecting poor samples. Here are some basic tenets:
• Sample when machine is running under load.
• Sample upstream of filters and downstream of lubricated bearings.
• Before taking actual samples, use the 10X flush rule, i.e., flush a volume that is 10 times larger than what you’ll collect before taking the sample volume.
• Always pre-flush sampling equipment (pump and hose).
• Only use virgin clean sample bottles.
• Always sample at the same spot, using the same procedure and equipment.
• Forward sample and completed sample details to lab within 24 hr.
• Infrared thermography (I/R), another important PdM tool, has advanced significantly and now offers sophisticated diagnostic capability in handheld units at a fraction of the cost of earlier generation systems. I/R cameras are able to depict potential problems in image form by displaying object temperatures in various colors, which, based on appropriate training, can lead to quick interpretation and problem diagnosis. I/R can quickly determine whether a bearing is receiving too much or too little lubricant or indicate reservoir-fluid levels where no level indicators are in use. I/R is also used by laboratories in a FTIR (Fourier Transform Infrared) spectroscopy test to determine the lubricant contamination and additive.
In all of the PdM methods and tools described here, the recurring theme is discipline and consistency. This must be factored in when choosing and purchasing a PdM tool by acquiring assistance in set up, operation, and training for the tool’s use.
3. Act on your findings. A true travesty occurs when all efforts and resources invested to accurately predict an impending failure are wasted because no up-front commitment had been made in the planning and scheduling process to combat the failure and its associated, accelerated downtime costs. When an impending failure is evident, create a work order to perform a planned repair as soon as possible, linking the PdM work order as the requestor. This will result in a report that depicts the success of the PdM program. To ensure the work order is generated, issued, and followed up on, develop a standard operating procedure that clearly directs the maintenance department to take action on it.
Once the pilot is deemed successful, the program can be rolled out into other areas using the same PdM method or tool. Then, if needed, the next PdM tool or method can then be piloted in the same manner.
Remember, though, that tools solve problems when implemented and used correctly.
Going from reactive to proactive is a big change but, with a little common sense and knowledge, it’s not impossible. EP
Contributing editor Ken Bannister is co-author, with Heinz Bloch, of the book Practical Lubrication for Industrial Facilities, 3rd Edition (The Fairmont Press, Lilburn, GA). As managing partner and principal consultant for Engtech Industries Inc., Innerkip, Ontario, he specializes in the implementation of lubrication-effectiveness reviews to ISO 55001 standards, asset-management systems, and training. Contact: firstname.lastname@example.org or 519-469-9173.