Avoid Costly Lubricant Related Machine Failures With Routine Oil Analysis

By: Michael Barrett

Insufficient lubrication is one problem that can lead to premature failure. Proper lubrication is defined as the proper amount of the proper lubricant at the proper place. If oil levels are low, or the lubricant delivery system is inadequate, a proper oil film cannot be maintained at the friction surface. This results in metal to metal contact and accelerated wear. Sufficient lubrication can only be achieved when oil levels are correct, and the appropriate lube is in place and functioning properly.

Another problem that can sometimes lead to lubricant related machine failures is lubricant degradation. Nature takes its toll on all of us, and lubricants are no exception. Oxidation breaks down the base oil of a lubricant, additives are depleted, and physical properties change over time. This process is accelerated by high temperatures, heavy loading, and contamination. When a lubricant reaches the end of its useful life, it is no longer capable of protecting equipment components. Steps must be taken to ensure a healthy lubricant is in use at all times.

A third problem that can lead to premature failure is contamination. Contaminated lubricants account for nearly half of all lubricant related failures. Lubricants can become contaminated with either solid or liquid contaminants. Solid contaminants can act as abrasives causing severe damage to components. Oil will hold contaminants in suspension as it flows through the machine. The contaminants are carried away from the friction surface to settle out in the reservoir or be filtered out. Solids can also clog filters and orifices restricting oil flow and resulting in lubricant starvation. Filters need to be checked and maintained on a scheduled routine basis.

Fluid contaminants such as water will alter the load handling ability of oil, and act as a catalyst for lubricant degradation. Many fluids also cause internal corrosion and rust. The proper oil additives will enhance the rust and oxidation inhibiting properties of the oil. When the oil starts to show a high level of degradation, it is time to change the oil removing all the contaminants from the system. The scheduled oil analysis tests will assess the oil condition and degradation. Proper filtration must be maintained, and sources of potential contamination should be identified and controlled to ensure the cleanest lubricant possible.

Lubricant related failures may also include incorrect lubricant selection. When selecting a lubricant for a given application, both equipment specifications and operating parameters should be taken into account. A higher oil viscosity will be required for equipment running at a higher load. There are many types of oil to choose from. Most importantly, the proper grade (viscosity) lubricant must be chosen.

Oil absorbs the heat generated by the friction surface. The oil carries the heat away to the reservoir where it can disperse, cooling before circulating through the equipment again. Oil can be passed through a cooler to disperse the heat more rapidly. The viscosity will determine the amount of heat the oil is meant to withstand. Low viscosity subjected to higher heat temperatures will cause the oil to break down prematurely. Testing the viscosity will assist in confirming that the proper oil is being used for the application at hand.

Secondly the lubricant should have the proper additive package. Lubricating oils are composed of 70% to 95% base oil and the balance is additives. Engine oil has the most additives due to the engines high running temperatures and rough environments. The second highest amount of additives is in gear oil, AW hydraulic oil, and transmission fluid. The least amount of additives is found in turbine oil. Additives enhance rust and oxidation inhibiting properties in turbine oil creating a longer lasting, more durable product. Some oils use alkaline additives to neutralize acid as it is formed.

Other considerations in selecting a lubricant include demulsibility properties and extreme temperature characteristics. Running a base line oil analysis test before the oil is used, confirms the cleanliness of the new oil. This gives a point of comparison for future oil testing as the oil breaks down with age and use. This can be an important part of an efficient Predictive Maintenance Program.

Lubricant related failures are sometimes caused by the use of grease when oil is required. The lubricant functions to reduce friction and wear by physically separating opposing friction surfaces with an oil film. This also reduces the amount of energy needed to complete the task.

Once the proper lube is selected, procedures should be put in place to ensure the selected lubricant is applied at the proper intervals. Always monitor the oil with scheduled oil analysis testing to spot lubricant problems before they turn into costly machine failures.