Industrial machinery literally runs on oil, and the successful outcome of manufacturing depends on that oil being maintained properly. Plants that turn a blind eye to oil maintenance do so at great risk. Oil that becomes wet, acidic, or abrasive will turn on its host (machine) and become a liability.
Oil maintenance programs, when in place at all, have historically depended on a time-based change program (often at an annual shutdown). While this is better than nothing, roughly 70% of the oils subjected to a time-based change are removed from service unnecessarily! The time-based change also does not guarantee that oils that are well beyond the end of their useful lives are removed before they damage the machine.
Industrial oils run "cold" compared to other (such as automotive-use) oils, and they tend to accumulate moisture. The moisture comes from humidity in the air, or in some cases, it's directly introduced to the oil from coolants and related systems. Moisture affects the lubricity of the oil, decreasing its effectiveness. Moisture in the oil can cause a variety of problems, such as poorly running hydraulic rams, machine sizing, and chatter.
Another negative effect of moisture in oil is acidity. Oil, by its molecular nature, cannot become an acid. But there is always a little moisture present in oils operating at relatively cool temperatures, and that moisture can turn acidic. Acids in a machine's oil sump will corrosively attack internal parts not only the metallic parts, but the seals as well. Corroded valves become ineffective. Many headaches in a machine's operation can be directly attributed to oil condition. Though oils do not respond to the pH test, there is a neutralization test called Total Acid Number (TAN) that can easily spot oil that is becoming problematic.
Industrial oil becomes abrasive from wear metals, abrasive dirt, and particle contamination. The most serious result of abrasive oil is the detrimental effect it has on seals. Machine seals are lubricated by the system's oil, and they will last a long time if the oils are maintained effectively. If they are not maintained properly, the seals will degrade and cause leakage. Leaking machines require pans under them, which need to be vacuumed regularly, and the waste oils pose a disposal problem. Fresh oil is purchased needlessly, running up maintenance costs. Machines that leak oil also run the risk of being run low on oil and having improper oils used as replacement. All these expensive problems can be eliminated by keeping machine oils in serviceable condition.
What About Filtering Oil?
Many industrial operations hire filtration companies to filter insolubles and abrasive contaminants from their oil. Some plants operate their own filtration equipment. Filtering oil that's currently in use is a good idea, and it helps companies avoid needlessly purchasing virgin oil products, but it has limits. Oil that is filtered too many times can contain damaged additives. If the additives are damaged, the oil can't function effectively: the oil loses lubricity and becomes oxidized. There is a point at which the additives either need to be restored or the oil needs to be replaced, and oil analysis is useful in determining this point. It can also help to rate the effectiveness of a company's filtration program.
Not all wear metals and abrasive contaminants can be filtered out of the oil; they tend to accumulate and eventually reach levels that leave the oil unserviceable. A test known as the ISO Cleanliness Code (also called a "Particle Count") can be used to rate the cleanliness of an oil sample. This test also shows the effectiveness of the machine's in-line oil filtration.
We rarely see a mechanical failure developing in an industrial machine. They tend to be over-engineered , and when maintained properly and lubricated with serviceable oil, they tend to operate trouble-free for decades. When a mechanical problem does develop, however, oil analysis may be the only reliable way to detect it. When a machine you depend on for your daily output fails, it costs far more than the cost of repairs a company can lose millions in down time and lost production. When you think of it, the $20 to $30 cost of a routine oil analysis for your machines may be the least expensive insurance you can buy to keep your machines mechanically healthy, well lubricated, and functioning trouble-free.