Page 74 - An Introduction To Predictive Maintenance

64 An Introduction to Predictive Maintenance

an in-house program, this approach can work; however, this is often not the case.
Turnover and inconsistent results are too often the norm for contract predictive main-
tenance programs. There are good, well-qualified vendors, but there are also many
contract predictive maintenance vendors who are totally unqualified to provide even
minimum levels of performance.

Lube Oil Analysis. The ratio is reversed for lubricating oils analysis. Sixty-eight
percent of these programs are staffed with contractors, and only 15.1 percent use only
in-plant personnel. An additional 17 percent of these programs use a combination of
personnel. This statistic is a little surprising both in the number of users and approach
taken.

Until recently, lube oil analysis was limited to manual laboratory techniques that
would normally preclude the use of in-house staff. As a result, most of the analysis
required for this type of program was contracted to a material-testing laboratory. With
this type of arrangement, we would have expected the survey to show a higher ratio
of in-plant personnel involved in the program. Typically, in-house personnel are
responsible for regular collections of lubricating oil samples, which are then sent to
outside laboratories for analysis. This assumption is supported by the labor distribu-
tion of the tribology programs included in this survey. The mix includes 36 percent
in-house and 56 percent outside services. One would assume from these statistics that
in-house personnel acquire samples and rely on the outside laboratories for wear
particle, ferrographic, or spectrographic analyses.

In the purely technical sense, lubricating oils analysis is not a predictive maintenance
tool. Rather, it is a positive means of selecting and using lubricants in various plant
applications. This technique evaluates the condition of the lubricants, not the condi-
tion of a machine or mechanical system. Although the sample may indicate that a
defect or problem exists in a mechanical system, it does little to isolate the root-cause
of the problem. One could conclude from the survey results that too many plants are
using lubricating oils analysis incorrectly.

Thermography. Thermography programs are almost equally divided between in-
house and contract programs. In-house personnel staff 45.9 percent, outside contrac-
tors provide 42.5 percent, and a combination of personnel account for 11.6 percent.
The higher-than-expected reliance on outside contractors may be caused by the high
initial investment cost of state-of-the-art infrared scanning systems. A typical full-
color system will cost about $60,000 and may be prohibitive in smaller plants.

Derived Benefits
Our survey attempted to quantify the benefits that have been derived from predictive
maintenance programs. Almost 91 percent (90.9%) of participants reported measur-
able savings as a result of their predictive maintenance program. On average, reduc-
tions in maintenance costs and downtime have recovered 113 percent of the total cost
invested in these programs. Based on these statistics, the typical program will gene-
rate a net improvement of 13 percent. When compared to the average maintenance