In hydraulic systems, transmissions, gearboxes, differentials and other lubricated systems, the analysis of oil samples should be done on a routine basis.
Why Implement An Oil Analysis Program?
High levels of aluminum can indicate a potential pump or converter failure. Transmission slippage is often indicated by high levels of copper, while high chromium levels can reveal scored hydraulic cylinder rods or gear and bearing wear.
The cleanliness of hydraulic oil systems is extremely important because of the very close tolerances that exist in the pumps, control valves and between the pistons and hydraulic cylinder walls. In fact, 75% of hydraulic system failures are caused by contamination through dust, dirt and condensation moisture. Therefore, oil analysis should be performed on a regular basis to monitor contamination levels.
Oil analysis can also be used effectively to determine the proper oil drain and filter change intervals in all types of lubricated systems.
To properly interpret the analysis results, the laboratory should be advised as to the viscosity and type of oil, the hours of service, and the make and model of the component or system from which the sample was taken. This information should be printed on a card usually provided in the oil sample carton.
Oil samples should be taken on a regularly scheduled basis and should only be taken after the lubricating system or component has been operated long enough to reach operating temperature. This will ensure that the oil has been thoroughly circulated and will result in an oil sample that is truly representative of the oil in the system. The oil sample should always be taken at the same point in the system, such as from a valve mounted on an oil return line before the oil passes through the filter.
IS OIL ANALYSIS PROACTIVE OR PREDICTIVE?
Industrial oil analysis is both a proactive and a predictive. The operational life of most industrial machinery is directly related to the contamination and chemistry of the lubricants. Water and dust are two common contaminants that drastically increase wear rates and shorten machine life. Degraded oil, wrong oil, and inadequate lubrication are also significant contributors to early failures.
By monitoring, reporting, and recommending the correction of contamination problems, oil analysis is possibly the most valuable proactive condition monitoring technology available for improving plant reliability.
In addition to being proactive oil analysis can effectively forecast the impending catastrophic failure of mechanical and electrical systems through which the oil flows. In the same way as a doctor analyzes blood to discern internal problems of the human body, maintenance professionals can use wear debris analysis (WDA) to discern impending problems in equipment. These four categories represent the bulk of the abnormal wear for industrial machines: abrasive wear, adhesive wear, fatigue wear, and corrosive wear.
Abrasive wear particles are normally indicative of excess dirt or other hard particles in the oil that are cutting away at the load bearing surfaces.
Adhesive wear particles reveal problems with lubricant starvation as a result of either low viscosity, high load, high temperature, slow speed, or inadequate lubricant delivery.
Fatigue wear particles are often associated with mechanical problems such as improper assembly, improper fit, misalignment, imbalance, or other condition.
Corrosive wear particles are the result of corrosive fluids such as water or process materials contacting metal surfaces.
WHAT ARE THE BENEFITS?
Most people quickly understand the value of oil analysis and most industrial plants are doing some amount of oil analysis. However only a few plants are experiencing the measurable benefits of extended machine life and predicted failure through their oil analysis program.
A medium size paper mill typically spends $300,000 per year on lubricants. With this much money on the line, some will offer "free" oil analysis from the lubricant supplier. I have talked to dozens who use free oil analysis, and none could tell me about case histories, few knew of any cost savings, and most just felt like they had the requirement to do oil analysis covered.
General Motors Linden Truck and Bus Plant found out the hard way that this does not work. Eddie Bohn and Frank D'Arcio, reported that two years earlier, GM Linden was relying on their "free" oil analysis when a critical gearbox failed costing them 27 valuable hours of production down-time. Supplier provided oil analysis had just been done giving a clean bill of health to the offending gearbox. Unfortunately the "free" oil analysis did not include tests for particle counting or wear debris analysis so it missed the impending failure.
Off-site lab oil analysis completely capable of finding root causes and predicting wear related failures so long as good samples are collected and correct testing is done.
Many plants send out ten to twenty samples a month and consider they have an acceptable oil analysis program. Once again, this is a false sense of security. There is no way that an industrial plant maintenance department can adequately monitor the condition of lubricated machinery with so few samples.
Whether your plant is a paper mill, automobile assembly plant, chemical plant, steel mill, food processing plant, or a power plant, you will find plenty of need for oil analysis. Each of these diverse plants require hundreds of oil-lubricated machines including gearboxes, pumps, motors, engines, hydraulics, processing machines, rolls, fans, turbines, and compressors. In general you will find a need to analyze 100 to 200 samples per month at most industrial plants. For an integrated steel mill or large mining operation it will take 1000 or more samples per month to do the same.