Oil analysis has long been used as a tool for preventing failures. The idea is simple: test oil samples from machinery and interpret the results to detect possible failures. The reality is that even experienced maintenance staff can have difficulty interpreting test results and this has discouraged many companies from pursuing the benefits oil analysis has to offer.

Intelligent software makes failure detection routine and helps users move toward a condition-based strategy where much more significant savings can be realized. The ability to easily assess machine condition and detect failures allows the user to confidently extend oil drains and component life, thereby permanently reducing maintenance costs.

McCoy/Cove, a large gold and silver mine operated by Echo Bay Minerals in Nevada, purchased oil analysis software from Dingo Maintenance Systems in St. Louis, MO. The mine was due to close in 5 years but justified the software purchase due to an estimated short payback period. Oil analysis testing services were maintained with their current lab, which also offered software. Their main criteria in selecting Dingo software were;

1. 1. Timeliness - sample results are now available at the mine site for interpretation at 2:30 p.m. the day after the sample is shipped. The software dials the lab and retrieves results automatically on a user-defined schedule. This precipitated a 7-day operation agreement with, their lab, which now allows mine personnel access to updated oil analysis data every day. Problem investigation and corrective action occur 12 - 24 hours earlier and the weekend backlog has been eliminated.
   
2. Accuracy - results are retrieved electronically so keystroke errors are reduced. All alerts are separated into an "exceptions" list with a built-in audit trail so there is no chance of an alert being missed. Comments can be added to exceptions so personnel know what is planned or what has been done.
   
3. Information sharing - the software operates on Windows® 3.X and 95/NT platforms and can be networked, allowing data to be accessed by key personnel all over the mine. A critical issue in the success of this approach is user-friendliness. Menu design mirrors the sampling cycle and all data is linked to equipment numbers. Menus can be customized and security controlled so users see only the functions they need to use. The PM Technicians now make spot decisions on the shop floor about oil and filter changes using on-screen, graphical equipment trends that include notes about previous maintenance activities.
   
4. Lab independence - changes in oil supply, analysis services and lab ownership now have reduced effect on the site, as software, employee skill base and complete equipment test history are all retained.

Since installing the software, Echo Bay has managed a steady increase in engine oil drain periods. Of their major mining equipment, 40% have been extended from 250 to 375 hours and 50% have been extended from 250 to 500 hours. Transmission, differential and hydraulic oils are now changed based on condition rather than a fixed hourly schedule.

Charlie Westover, the driving force behind these changes, documented a reduction in annual oil consumption during '97 of 14% (30,000 gallons) compared with '96. This represents savings of $32,000 on lubricant alone even though extended oil drains were phased in during the first half of '97, were only fully operational for the last half and premium lubricants were used for the program. Adding the effects of reduced oil change labor and disposal costs would significantly increase the savings figure.

When oil drains are extended, there is an inherent difficulty in interpreting the test results. Wear particles have more time to accumulate so the levels increase beyond those found at the end of a normal drain period. How can you then determine if results are normal or if corrective action is required? In the example graph above, the vertical comment line represents a bearing replacement and oil change. The concentration of iron (FE) and iron wear rate (FEWR) are quite high at that point. The next sample shows reduced values for both. Over the following samples the iron concentration rises, perhaps indicating another bearing change or oil change is required. However, over the same period the wear rate remains relatively constant, indicating a normal wear situation - no action required. Extended drains will result in increased levels of wear metals, which can be misleading. Dingo software calculates wear rate (rate of change) data automatically, allowing quick determination of normal situations.

The bottom-line? Oil analysis data can be overwhelming but appropriate software significantly reduces the time needed to deal with the data, freeing maintenance personnel to focus on reducing overall costs.

Information supplied by Charlie Westover of Echo Bay Minerals and Andrew Ling of Dingo Maintenance Systems, St. Louis, MO; toll-free 1-888-346-4630; web: http://www.dingos.com

(Note:  This is a pre-editorial version of an article submitted for publication in Maintenance Technology Magazine, April 1998 issue)