Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/490438
18 | March - April 2015 | www.machinerylubrication.com Lost revenue due to equipment downtime is often a direct result of some type of contamination, whether from dirt, water, an incorrect lubricant or a combination of these. Oil analysis testing can identify these contaminants, but unless you are aware of the issues that can arise from them, it can be difficult to take the appropriate actions. This article will review the most common contamination types, the oil analysis tests most likely to indicate them, normal test results when these contaminants are present, and recommended actions for correcting each problem. Abrasives Abrasives are the top problem-inducing contaminants because they tend to cause the most damage. They are more likely to be hard contaminants and be in sizes that are well within your clear- ance ranges. The most prevalent forms of abrasives are dust or dirt and product or process contamination. If there is a process that includes any level of particulate, it is possible for this particulate to get into the lubricating system and cause damage no matter how soft the particle is. Degradation from abrasive contamination comes primarily in the form of equipment wear, but another less widespread lubricant degradation problem can also occur. Abrasive wear or cutting wear is usually found in systems with a sliding motion load somewhere in the unit. Commonly with thrust bearings or other softer metal bearings, the abrasive can wedge into the soft metal and gouge the harder steel surface. This is not to say that you can't have copper- alloy cutting wear. The metal produced depends on the contact surfaces in the path of the abrasive contamination and the hard- ness of the contaminant. Systems with rolling actions such as rolling-element bearings, gear teeth, etc., are more likely to have pitting from abrasive contamination. As particulates roll through the load zone, the extreme pressure exerted on the contact point between the races and the rolling elements can pit the surfaces, forming cracks and initiating fatigue wear and spalling. While lubricant degradation usually comes from another source, you may see some lost lubricant life from abrasive contamination. When a unit is wearing, the metal released by the abrasives can become a catalyst, and these particles increase the available surface area on which lubricants can form degradation byproducts. Identifying abrasive contamination and wear is generally done through metals testing. If oil analysis is performed, what you typically By A Aron Bl Ack, Pol Aris l ABorATories OIL ANALYSIS 3 Common Contaminants and the oil Analysis Tests that Can Detect them Abrasives Cutting wear Fatigue/pitting