Equipment reliability is one of the primary goals of most manufacturers. Unfortunately, it isn’t a goal that can be realized overnight or all at once. It is instead, an arduous process of engineering, implementation and evaluation which yields incremental success. At Nissan North America’s Smyrna Tennessee plant, increasing production demands have elevated the pursuit of world-class reliability to the top of the list and precision lubrication is one of the foundational elements of this ongoing initiative.
In order to meet production goals, machines have to run and when machines fail they’re not running, so the most cost effective solution is to become proactive. Rather than just focusing on failure prediction and efficient repairs, the Smyrna plant has focused on identifying and eliminating the root causes of machine failure. The three predominate causes of machine failure in lubricated equipment are particle contamination in the oil, moisture contamination and using the wrong oil or one that has degraded beyond the point of usefulness.
Precision lubrication is really all about ensuring that the right oil is in the machine, it is suitably free of contaminants and that it is in acceptable condition. The first step in this process was to ensure the proper lubricants were specified for each machine and each machine actually contained the specified lubricant. The second step was to define acceptable limits for particle and moisture contamination. The third step was to identify and implement contamination control measures such as installing high performance filtration systems and designing a world-class lubricant storage and handling process. The final step in this process was to measure the effectiveness of these actions using high quality oil analysis. With an onsite laboratory and dedicated technicians, the plant is able to quickly identify and address any contamination issue or lubricant abnormality.
For years there has been extensive study into the relationship between lubrication and equipment reliability. According to Professor Earnest Rabinowicz of MIT, approximately 50% of lost equipment usefulness is due to mechanical wear and another 20% is due to corrosive wear. The predominant root cause for both corrosive and mechanical wear is lubricant contamination. A joint study by the STLE and the NRCC showed that as much as 82% of mechanical wear is predominately caused by particle contamination of the lubricant.
Prior to implementing the new program, the oil in many critical hydraulic systems was contaminated with different lubricants and heavily contaminated with particles. Typical particle counts were averaging 24/20/13. That means that for particles larger than 3 microns, there were commonly between 80,000 and 160,000 particles in every mL of oil. To achieve the desired reliability from the systems, target cleanliness levels were set at 17/15/12, which is only 640 to 1,300 particles per mL. The systems were drained, cleaned by hand and refilled with new oil. To meet these new targets, 20 gpm kidney loop filtration systems with 3 micron filtration were installed on each system and reservoirs were modified with high efficiency desiccant breathers. The anticipated improvement in oil cleanliness levels was expected to yield a reduction in breakdown frequency and downtime of approximately 75%.
Filtration and reservoir improvements are not the only strategies for contamination control. The storage, handling and application methods for new lubricants also play a critical role. Previously, lubricant were delivered in bulk to 500 gallon totes, transferred with mobile tanks and applied directly to the reservoirs with no filtration or testing. Existing tanks were either scrapped or retrofitted with new pumps and filters, high quality desiccant breathers and dedicated to specific products. To prevent cross-contamination of lubricants, a new lubricant identification system was developed and labels were applied to all storage tanks, application points and transfer equipment. For quality assurance, new oil deliveries are now tested before use to ensure that they are suitably clean, free of moisture and otherwise on spec.
Lubrication PMs were evaluated and, when necessary, redesigned to identify all important procedures for inspections, lubricant application and oil sampling. With a high level of documentation and good accounting methods in place, the new program can be executed with efficiency and measured to ensure compliance.
Even a well designed program can fail without execution, and effective execution often requires expertise. Before implementing the new measures, a training and certification program was established to make sure all of the technicians performing lubrication PM’s were not only sufficiently competent to perform the new tasks, but also that they fully understood the associated benefits. A well educated workforce is an essential component of a precision lubrication program. Though not required, most of the Nissan employees involved in the training voluntarily chose to sit for the ICML MLT level I certification exam and all passed.
The last major step in the plan was to establish a lubrication task force team to identify problems with implementation, formulate solutions and identify further opportunities to advance the program. The team now meets each month to discuss issues, identify successes and failures and keep the program on the right track.
As of April, 2012, the major aspects of the program were completed and benefits were apparent almost from the beginning. Within days of implementing the new contamination control measures, particle contamination was reduced by an average of 90% meeting or exceeding the targets of 17/15/12. By October, enough reliability data had been collected to effectively analyze the results and the improvements were remarkable. After only five months of improved lubrication, breakdown frequency had been reduced by 53% and downtime fell by 54%. It should be noted that the types of failures being eliminated are typically developed over long periods, so the reliability gains experienced in the first five months can be expected to increase in the months and years to come.
The results of this program have certainly been remarkable. The reductions in breakdown frequency and downtime have been dramatic but this is just the first phase of the plan. This study focused only on major systems in the stamping plant and future plans include establishing precision lubrication for the entire plant. The following list outlines some of the major goals for the larger improvement plan:
- All lubrication and conveyor technicians to complete 20 hours of lubrication training by year’s end
- Develop an in-house lubrication refresher course to maintain knowledge for certified technicians
- Process and procedures in place for all lubrication activities plant wide
- Optimize lubrication PM’s plant wide
- Create oil leak remediation team
- Reduce oil leaks by 25% year over year
- Reduce lubrication related equipment failures by 50% with use of Kidney Loop systems and best practice lubrication
- Deploy all best practice activities plant wide
Precision lubrication is only one component of a world-class maintenance and reliability program but it is a big one. With the most common failure modes being directly related to lubrication issues, it stands to reason that no successful program can ignore this issue. With education, planning and perseverance, any program can experience dramatic gains in reliability and most importantly, profitability.